1 <!doctype book PUBLIC "-//OASIS//DTD DocBook V3.1//EN" [
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8 <date>January 24th, 2003</date>
9 <title>GTK+ 2.0 Tutorial</title>
12 <firstname>Tony</firstname>
13 <surname>Gale</surname>
16 <firstname>Ian</firstname>
17 <surname>Main</surname>
20 <firstname>& the GTK team</firstname>
24 <para>This is a tutorial on how to use GTK (the GIMP Toolkit) through its C
31 <!-- ***************************************************************** -->
32 <chapter id="ch-TutorialDownload">
33 <title>Tutorial Availability</title>
35 <para>A copy of this tutorial in SGML and HTML is distributed with each
36 source code release of GTK+. For binary distributions, please check with
39 <para>A copy is available online for reference at <ulink
40 url="http://www.gtk.org/documentation.html#Tutorials">http://www.gtk.org/documentation.html#Tutorials</ulink>. You can also find other GTK+ tutorials there.</para>
42 <para>A packaged version of this tutorial is available from
43 <ulink url="ftp://ftp.gtk.org/pub/gtk/tutorial/">
44 ftp://ftp.gtk.org/pub/gtk/tutorial</ulink> which contains the tutorial in
45 various different formats. This package is primary for those people wanting
46 to have the tutorial available for offline reference and for printing. Note
47 that the packaged version may be older than the online version.</para>
51 <!-- ***************************************************************** -->
52 <chapter id="ch-Introduction">
53 <title>Introduction</title>
55 <para>GTK (GIMP Toolkit) is a library for creating graphical user
56 interfaces. It is licensed using the LGPL license, so you can develop
57 open software, free software, or even commercial non-free software
58 using GTK without having to spend anything for licenses or royalties.</para>
60 <para>It's called the GIMP toolkit because it was originally written for
61 developing the GNU Image Manipulation Program (GIMP), but GTK has
62 now been used in a large number of software projects, including the
63 GNU Network Object Model Environment (GNOME) project. GTK is built on
64 top of GDK (GIMP Drawing Kit) which is basically a wrapper around the
65 low-level functions for accessing the underlying windowing functions
66 (Xlib in the case of the X windows system), and gdk-pixbuf, a library for
67 client-side image manipulation.</para>
69 <para>GTK is essentially an object oriented application programmers
70 interface (API). Although written completely in C, it is implemented
71 using the idea of classes and callback functions (pointers to
74 <para>There is also a third component called GLib which contains a few
75 replacements for some standard calls, as well as some additional
76 functions for handling linked lists, etc. The replacement functions
77 are used to increase GTK's portability, as some of the functions
78 implemented here are not available or are nonstandard on other Unixes
79 such as g_strerror(). Some also contain enhancements to the libc
80 versions, such as g_malloc() that has enhanced debugging utilities.</para>
82 <para>In version 2.0, GLib has picked up the type system which forms the
83 foundation for GTK's class hierarchy, the signal system which is used
84 throughout GTK, a thread API which abstracts the different native thread APIs
85 of the various platforms and a facility for loading modules.
88 <para>As the last component, GTK uses the Pango library for internationalized
92 <para>This tutorial describes the C interface to GTK. There are GTK
93 bindings for many other languages including C++, Guile, Perl, Python,
94 TOM, Ada95, Objective C, Free Pascal, Eiffel, Java and C#. If you intend to
95 use another language's bindings to GTK, look at that binding's
96 documentation first. In some cases that documentation may describe
97 some important conventions (which you should know first) and then
98 refer you back to this tutorial. There are also some cross-platform
99 APIs (such as wxWindows and V) which use GTK as one of their target
100 platforms; again, consult their documentation first.</para>
102 <para>If you're developing your GTK application in C++, a few extra notes
103 are in order. There's a C++ binding to GTK called GTK--, which
104 provides a more C++-like interface to GTK; you should probably look
105 into this instead. If you don't like that approach for whatever
106 reason, there are two alternatives for using GTK. First, you can use
107 only the C subset of C++ when interfacing with GTK and then use the C
108 interface as described in this tutorial. Second, you can use GTK and
109 C++ together by declaring all callbacks as static functions in C++
110 classes, and again calling GTK using its C interface. If you choose
111 this last approach, you can include as the callback's data value a
112 pointer to the object to be manipulated (the so-called "this" value).
113 Selecting between these options is simply a matter of preference,
114 since in all three approaches you get C++ and GTK. None of these
115 approaches requires the use of a specialized preprocessor, so no
116 matter what you choose you can use standard C++ with GTK.</para>
118 <para>This tutorial is an attempt to document as much as possible of GTK,
119 but it is by no means complete. This tutorial assumes a good
120 understanding of C, and how to create C programs. It would be a great
121 benefit for the reader to have previous X programming experience, but
122 it shouldn't be necessary. If you are learning GTK as your first
123 widget set, please comment on how you found this tutorial, and what
124 you had trouble with. There are also C++, Objective C, ADA, Guile and
125 other language bindings available, but I don't follow these.</para>
127 <para>This document is a "work in progress". Please look for updates on
128 <ulink url="http://www.gtk.org/">http://www.gtk.org/</ulink>.</para>
130 <para>I would very much like to hear of any problems you have learning GTK
131 from this document, and would appreciate input as to how it may be
132 improved. Please see the section on <link linkend="ch-Contributing">Contributing
133 </link> for further information.</para>
137 <!-- ***************************************************************** -->
138 <chapter id="ch-GettingStarted">
139 <title>Getting Started</title>
141 <para>The first thing to do, of course, is download the GTK source and
142 install it. You can always get the latest version from <ulink
143 url="ftp://ftp.gtk.org/pub/gtk">ftp.gtk.org</ulink>. You can also view
144 other sources of GTK information on
145 <ulink url="http://www.gtk.org/">http://www.gtk.org/</ulink>. GTK
146 uses GNU autoconf for configuration. Once untar'd, type
147 <literal>./configure --help</literal> to see a list of options.</para>
149 <para>The GTK source distribution also contains the complete source to all
150 of the examples used in this tutorial, along with Makefiles to aid
153 <para>To begin our introduction to GTK, we'll start with the simplest
154 program possible. This program will create a 200x200 pixel window and
155 has no way of exiting except to be killed by using the shell.</para>
160 <imagedata fileref="images/base.png" format="png">
165 <programlisting role="C">
166 <!-- example-start base base.c -->
168 #include <gtk/gtk.h>
175 gtk_init (&argc, &argv);
177 window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
178 gtk_widget_show (window);
187 <para>You can compile the above program with gcc using:</para>
188 <para><literallayout>
189 <literal>gcc base.c -o base `pkg-config --cflags --libs gtk+-2.0`</literal>
190 </literallayout></para>
192 <para>The meaning of the unusual compilation options is explained below in
193 <link linkend="sec-Compiling">Compiling Hello World</link>.</para>
195 <para>All programs will of course include <filename>gtk/gtk.h</filename> which
196 declares the variables, functions, structures, etc. that will be used in your GTK
199 <para>The next line:</para>
201 <programlisting role="C">
202 gtk_init (&argc, &argv);
205 <para>calls the function gtk_init(gint *argc, gchar ***argv) which will be called
206 in all GTK applications. This sets up a few things for us such as the default visual
207 and color map and then proceeds to call gdk_init(gint *argc, gchar ***argv).
208 This function initializes the library for use, sets up default signal handlers, and
209 checks the arguments passed to your application on the command line, looking for
210 one of the following:</para>
212 <itemizedlist spacing=Compact>
213 <listitem><simpara> <literal>--gtk-module</literal></simpara>
215 <listitem><simpara> <literal>--g-fatal-warnings</literal></simpara>
217 <listitem><simpara> <literal>--gtk-debug</literal></simpara>
219 <listitem><simpara> <literal>--gtk-no-debug</literal></simpara>
221 <listitem><simpara> <literal>--gdk-debug</literal></simpara>
223 <listitem><simpara> <literal>--gdk-no-debug</literal></simpara>
225 <listitem><simpara> <literal>--display</literal></simpara>
227 <listitem><simpara> <literal>--sync</literal></simpara>
229 <listitem><simpara> <literal>--name</literal></simpara>
231 <listitem><simpara> <literal>--class</literal></simpara>
235 <para>It removes these from the argument list, leaving anything it does not
236 recognize for your application to parse or ignore. This creates a set
237 of standard arguments accepted by all GTK applications.</para>
239 <para>The next two lines of code create and display a window.</para>
241 <programlisting role="C">
242 window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
243 gtk_widget_show (window);
246 <para>The <literal>GTK_WINDOW_TOPLEVEL</literal> argument specifies that we want the
247 window to undergo window manager decoration and placement. Rather than
248 create a window of 0x0 size, a window without children is set to
249 200x200 by default so you can still manipulate it.</para>
251 <para>The gtk_widget_show() function lets GTK know that we are done setting
252 the attributes of this widget, and that it can display it.</para>
254 <para>The last line enters the GTK main processing loop.</para>
256 <programlisting role="C">
260 <para>gtk_main() is another call you will see in every GTK application.
261 When control reaches this point, GTK will sleep waiting for X events
262 (such as button or key presses), timeouts, or file IO notifications to
263 occur. In our simple example, however, events are ignored.</para>
265 <!-- ----------------------------------------------------------------- -->
266 <sect1 id="sec-HelloWorld">
267 <title>Hello World in GTK</title>
269 <para>Now for a program with a widget (a button). It's the classic
270 hello world a la GTK.</para>
275 <imagedata fileref="images/helloworld.png" format="png">
280 <programlisting role="C">
281 <!-- example-start helloworld helloworld.c -->
283 #include <gtk/gtk.h>
285 /* This is a callback function. The data arguments are ignored
286 * in this example. More on callbacks below. */
287 static void hello( GtkWidget *widget,
290 g_print ("Hello World\n");
293 static gboolean delete_event( GtkWidget *widget,
297 /* If you return FALSE in the "delete-event" signal handler,
298 * GTK will emit the "destroy" signal. Returning TRUE means
299 * you don't want the window to be destroyed.
300 * This is useful for popping up 'are you sure you want to quit?'
303 g_print ("delete event occurred\n");
305 /* Change TRUE to FALSE and the main window will be destroyed with
306 * a "delete-event". */
311 /* Another callback */
312 static void destroy( GtkWidget *widget,
321 /* GtkWidget is the storage type for widgets */
325 /* This is called in all GTK applications. Arguments are parsed
326 * from the command line and are returned to the application. */
327 gtk_init (&argc, &argv);
329 /* create a new window */
330 window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
332 /* When the window is given the "delete-event" signal (this is given
333 * by the window manager, usually by the "close" option, or on the
334 * titlebar), we ask it to call the delete_event () function
335 * as defined above. The data passed to the callback
336 * function is NULL and is ignored in the callback function. */
337 g_signal_connect (window, "delete-event",
338 G_CALLBACK (delete_event), NULL);
340 /* Here we connect the "destroy" event to a signal handler.
341 * This event occurs when we call gtk_widget_destroy() on the window,
342 * or if we return FALSE in the "delete-event" callback. */
343 g_signal_connect (window, "destroy",
344 G_CALLBACK (destroy), NULL);
346 /* Sets the border width of the window. */
347 gtk_container_set_border_width (GTK_CONTAINER (window), 10);
349 /* Creates a new button with the label "Hello World". */
350 button = gtk_button_new_with_label ("Hello World");
352 /* When the button receives the "clicked" signal, it will call the
353 * function hello() passing it NULL as its argument. The hello()
354 * function is defined above. */
355 g_signal_connect (button, "clicked",
356 G_CALLBACK (hello), NULL);
358 /* This will cause the window to be destroyed by calling
359 * gtk_widget_destroy(window) when "clicked". Again, the destroy
360 * signal could come from here, or the window manager. */
361 g_signal_connect_swapped (button, "clicked",
362 G_CALLBACK (gtk_widget_destroy),
365 /* This packs the button into the window (a gtk container). */
366 gtk_container_add (GTK_CONTAINER (window), button);
368 /* The final step is to display this newly created widget. */
369 gtk_widget_show (button);
372 gtk_widget_show (window);
374 /* All GTK applications must have a gtk_main(). Control ends here
375 * and waits for an event to occur (like a key press or
386 <!-- ----------------------------------------------------------------- -->
387 <sect1 id="sec-Compiling">
388 <title>Compiling Hello World</title>
390 <para>To compile use:</para>
392 <para><literallayout>
393 <literal>gcc -Wall -g helloworld.c -o helloworld `pkg-config --cflags gtk+-2.0` \</literal>
394 <literal> `pkg-config --libs gtk+-2.0`</literal>
395 </literallayout></para>
397 <para>This uses the program <literal>pkg-config</literal>, which can be obtained from
398 <ulink url="http://www.freedesktop.org">www.freedesktop.org</ulink>. This program
399 reads the <filename>.pc</filename> which comes with GTK to determine what
400 compiler switches are needed to compile programs that use GTK.
401 <literal>pkg-config --cflags gtk+-2.0</literal> will output a list of include
402 directories for the compiler to look in, and
403 <literal>pkg-config --libs gtk+-2.0</literal>
404 will output the list of libraries for the compiler to link with and
405 the directories to find them in. In the above example they could have
406 been combined into a single instance, such as
407 <literal>pkg-config --cflags --libs gtk+-2.0</literal>.</para>
409 <para>Note that the type of single quote used in the compile command above
410 is significant.</para>
412 <para>The libraries that are usually linked in are:</para>
415 <listitem><simpara>The GTK library (<literal>-lgtk</literal>), the widget library,
416 based on top of GDK.</simpara>
419 <listitem><simpara>The GDK library (<literal>-lgdk</literal>), the Xlib wrapper.</simpara>
422 <listitem><simpara>The gdk-pixbuf library (<literal>-lgdk_pixbuf</literal>), the image
423 manipulation library.</simpara>
426 <listitem><simpara>The Pango library (<literal>-lpango</literal>) for internationalized
430 <listitem><simpara>The gobject library (<literal>-lgobject</literal>), containing the
431 type system on which GTK is based.</simpara>
434 <listitem><simpara>The gmodule library (<literal>-lgmodule</literal>), which is used
435 to load run time extensions.</simpara>
438 <listitem><simpara>The GLib library (<literal>-lglib</literal>), containing miscellaneous
439 functions; only g_print() is used in this particular example. GTK is built on top
440 of GLib so you will always require this library. See the section on
441 <link linkend="ch-glib">GLib</link> for details.</simpara>
444 <listitem><simpara>The Xlib library (<literal>-lX11</literal>) which is used by GDK.</simpara>
447 <listitem><simpara>The Xext library (<literal>-lXext</literal>). This contains code
448 for shared memory pixmaps and other X extensions.</simpara>
451 <listitem><simpara>The math library (<literal>-lm</literal>). This is used by GTK
452 for various purposes.</simpara>
458 <!-- ----------------------------------------------------------------- -->
459 <sect1 id="sec-TheoryOfSignalsAndCallbacks">
460 <title>Theory of Signals and Callbacks</title>
463 <para>In version 2.0, the signal system has been moved from GTK to GLib, therefore the
464 functions and types explained in this section have a "g_" prefix rather than a "gtk_"
465 prefix. We won't go into details about the extensions which the GLib 2.0 signal system
466 has relative to the GTK 1.2 signal system.</para>
469 <para>Before we look in detail at <emphasis>helloworld</emphasis>, we'll discuss signals
470 and callbacks. GTK is an event driven toolkit, which means it will
471 sleep in gtk_main() until an event occurs and control is passed to the
472 appropriate function.</para>
474 <para>This passing of control is done using the idea of "signals". (Note
475 that these signals are not the same as the Unix system signals, and
476 are not implemented using them, although the terminology is almost
477 identical.) When an event occurs, such as the press of a mouse button,
478 the appropriate signal will be "emitted" by the widget that was
479 pressed. This is how GTK does most of its useful work. There are
480 signals that all widgets inherit, such as "destroy", and there are
481 signals that are widget specific, such as "toggled" on a toggle
484 <para>To make a button perform an action, we set up a signal handler to
485 catch these signals and call the appropriate function. This is done by
486 using a function such as:</para>
488 <programlisting role="C">
489 gulong g_signal_connect( gpointer *object,
492 gpointer func_data );
495 <para>where the first argument is the widget which will be emitting the
496 signal, and the second the name of the signal you wish to catch. The
497 third is the function you wish to be called when it is caught, and the
498 fourth, the data you wish to have passed to this function.</para>
500 <para>The function specified in the third argument is called a "callback
501 function", and should generally be of the form</para>
503 <programlisting role="C">
504 void callback_func( GtkWidget *widget,
505 ... /* other signal arguments */
506 gpointer callback_data );
509 <para>where the first argument will be a pointer to the widget that emitted
510 the signal, and the last a pointer to the data given as the last
511 argument to the g_signal_connect() function as shown above.</para>
513 <para>Note that the above form for a signal callback function declaration is
514 only a general guide, as some widget specific signals generate
515 different calling parameters.</para>
517 <para>Another call used in the <emphasis>helloworld</emphasis> example, is:</para>
519 <programlisting role="C">
520 gulong g_signal_connect_swapped( gpointer *object,
523 gpointer *callback_data );
526 <para>g_signal_connect_swapped() is the same as g_signal_connect() except
527 that the instance on which the signal is emitted and data will be swapped when
528 calling the handler. So when using this function to connect signals, the callback
529 should be of the form</para>
531 <programlisting role="C">
532 void callback_func( gpointer callback_data,
533 ... /* other signal arguments */
537 <para>where the object is usually a widget. We usually don't setup callbacks
538 for g_signal_connect_swapped() however. They are usually used to call a
539 GTK function that accepts a single widget or object as an argument, when a signal
540 is emitted on some <emphasis>other</emphasis> object. In the
541 <emphasis>helloworld</emphasis> example, we connect to the "clicked" signal
542 on the button, but call gtk_widget_destroy() on the window.</para>
544 <para>If your callbacks need additional data, use g_signal_connect() instead
545 of g_signal_connect_swapped().</para>
549 <!-- ----------------------------------------------------------------- -->
550 <sect1 id="sec-Events">
551 <title>Events</title>
553 <para>In addition to the signal mechanism described above, there is a set
554 of <emphasis>events</emphasis> that reflect the X event mechanism. Callbacks may
555 also be attached to these events. These events are:</para>
557 <itemizedlist spacing=Compact>
558 <listitem><simpara> event</simpara>
560 <listitem><simpara> button_press_event</simpara>
562 <listitem><simpara> button_release_event</simpara>
564 <listitem><simpara> scroll_event</simpara>
566 <listitem><simpara> motion_notify_event</simpara>
568 <listitem><simpara> delete_event</simpara>
570 <listitem><simpara> destroy_event</simpara>
572 <listitem><simpara> expose_event</simpara>
574 <listitem><simpara> key_press_event</simpara>
576 <listitem><simpara> key_release_event</simpara>
578 <listitem><simpara> enter_notify_event</simpara>
580 <listitem><simpara> leave_notify_event</simpara>
582 <listitem><simpara> configure_event</simpara>
584 <listitem><simpara> focus_in_event</simpara>
586 <listitem><simpara> focus_out_event</simpara>
588 <listitem><simpara> map_event</simpara>
590 <listitem><simpara> unmap_event</simpara>
592 <listitem><simpara> property_notify_event</simpara>
594 <listitem><simpara> selection_clear_event</simpara>
596 <listitem><simpara> selection_request_event</simpara>
598 <listitem><simpara> selection_notify_event</simpara>
600 <listitem><simpara> proximity_in_event</simpara>
602 <listitem><simpara> proximity_out_event</simpara>
604 <listitem><simpara> visibility_notify_event</simpara>
606 <listitem><simpara> client_event</simpara>
608 <listitem><simpara> no_expose_event</simpara>
610 <listitem><simpara> window_state_event</simpara>
614 <para>In order to connect a callback function to one of these events you
615 use the function g_signal_connect(), as described above, using one of
616 the above event names as the <literal>name</literal> parameter. The callback
617 function for events has a slightly different form than that for
620 <programlisting role="C">
621 gint callback_func( GtkWidget *widget,
623 gpointer callback_data );
626 <para>GdkEvent is a C <literal>union</literal> structure whose type will depend upon
627 which of the above events has occurred. In order for us to tell which event
628 has been issued each of the possible alternatives has a <literal>type</literal>
629 member that reflects the event being issued. The other components
630 of the event structure will depend upon the type of the
631 event. Possible values for the type are:</para>
633 <programlisting role="C">
653 GDK_SELECTION_REQUEST
664 GDK_VISIBILITY_NOTIFY
671 <para>So, to connect a callback function to one of these events we would use
672 something like:</para>
674 <programlisting role="C">
675 g_signal_connect (button, "button_press_event",
676 G_CALLBACK (button_press_callback), NULL);
679 <para>This assumes that <literal>button</literal> is a Button widget. Now, when the
680 mouse is over the button and a mouse button is pressed, the function
681 button_press_callback() will be called. This function may be declared as:</para>
683 <programlisting role="C">
684 static gboolean button_press_callback( GtkWidget *widget,
685 GdkEventButton *event,
689 <para>Note that we can declare the second argument as type
690 <literal>GdkEventButton</literal> as we know what type of event will occur for this
691 function to be called.</para>
693 <para>The value returned from this function indicates whether the event
694 should be propagated further by the GTK event handling
695 mechanism. Returning TRUE indicates that the event has been handled,
696 and that it should not propagate further. Returning FALSE continues
697 the normal event handling. See the section on
698 <link linkend="ch-AdvancedEventsAndSignals">Advanced Event and Signal Handling</link>
699 for more details on this propagation process.</para>
701 <para>For details on the GdkEvent data types, see the appendix entitled
702 <link linkend="app-GDKEventTypes">GDK Event Types</link>.</para>
704 <para>The GDK selection and drag-and-drop APIs also emit a number of events which
705 are reflected in GTK by the signals. See <link
706 linkend="sec-SignalsOnSourceWidgets">Signals on the source widget</link> and <link
707 linkend="sec-SignalsOnDestWidgets">Signals on the destination widget</link>
708 for details on the signatures of the callback functions for these signals:</para>
710 <itemizedlist spacing=Compact>
711 <listitem><simpara> selection_received</simpara>
713 <listitem><simpara> selection_get</simpara>
715 <listitem><simpara> drag_begin_event</simpara>
717 <listitem><simpara> drag_end_event</simpara>
719 <listitem><simpara> drag_data_delete</simpara>
721 <listitem><simpara> drag_motion</simpara>
723 <listitem><simpara> drag_drop</simpara>
725 <listitem><simpara> drag_data_get</simpara>
727 <listitem><simpara> drag_data_received</simpara>
733 <!-- ----------------------------------------------------------------- -->
734 <sect1 id="sec-SteppingThroughHelloWorld">
735 <title>Stepping Through Hello World</title>
737 <para>Now that we know the theory behind this, let's clarify by walking
738 through the example <emphasis>helloworld</emphasis> program.</para>
740 <para>Here is the callback function that will be called when the button is
741 "clicked". We ignore both the widget and the data in this example, but
742 it is not hard to do things with them. The next example will use the
743 data argument to tell us which button was pressed.</para>
745 <programlisting role="C">
746 static void hello( GtkWidget *widget,
749 g_print ("Hello World\n");
753 <para>The next callback is a bit special. The "delete-event" occurs when the
754 window manager sends this event to the application. We have a choice
755 here as to what to do about these events. We can ignore them, make
756 some sort of response, or simply quit the application.</para>
758 <para>The value you return in this callback lets GTK know what action to
759 take. By returning TRUE, we let it know that we don't want to have
760 the "destroy" signal emitted, keeping our application running. By
761 returning FALSE, we ask that "destroy" be emitted, which in turn will
762 call our "destroy" signal handler.</para>
765 <programlisting role="C">
766 static gboolean delete_event( GtkWidget *widget,
770 g_print ("delete event occurred\n");
776 <para>Here is another callback function which causes the program to quit by
777 calling gtk_main_quit(). This function tells GTK that it is to exit
778 from gtk_main when control is returned to it.</para>
780 <programlisting role="C">
781 static void destroy( GtkWidget *widget,
788 <para>I assume you know about the main() function... yes, as with other
789 applications, all GTK applications will also have one of these.</para>
791 <programlisting role="C">
797 <para>This next part declares pointers to a structure of type
798 GtkWidget. These are used below to create a window and a button.</para>
800 <programlisting role="C">
805 <para>Here is our gtk_init() again. As before, this initializes the toolkit,
806 and parses the arguments found on the command line. Any argument it
807 recognizes from the command line, it removes from the list, and
808 modifies argc and argv to make it look like they never existed,
809 allowing your application to parse the remaining arguments.</para>
811 <programlisting role="C">
812 gtk_init (&argc, &argv);
815 <para>Create a new window. This is fairly straightforward. Memory is
816 allocated for the GtkWidget *window structure so it now points to a
817 valid structure. It sets up a new window, but it is not displayed
818 until we call gtk_widget_show(window) near the end of our program.</para>
820 <programlisting role="C">
821 window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
824 <para>Here are two examples of connecting a signal handler to an object, in
825 this case, the window. Here, the "delete-event" and "destroy" signals
826 are caught. The first is emitted when we use the window manager to
827 kill the window. The second is emitted when we use the gtk_widget_destroy() call
828 passing in the window widget as the object to destroy, or when, in the
829 "delete-event" handler, we return FALSE.
831 The <literal>G_CALLBACK</literal> is a macro
832 that performs type casting and checking for us, as well as aid the readability of
835 <programlisting role="C">
836 g_signal_connect (window, "delete-event",
837 G_CALLBACK (delete_event), NULL);
838 g_signal_connect (window, "destroy",
839 G_CALLBACK (destroy), NULL);
842 <para>This next function is used to set an attribute of a container object.
843 This just sets the window so it has a blank area along the inside of
844 it 10 pixels wide where no widgets will go. There are other similar
845 functions which we will look at in the section on
846 <link linkend="ch-SettingWidgetAttributes">Setting Widget Attributes</link></para>
848 <para>And again, <literal>GTK_CONTAINER</literal> is a macro to perform type casting.</para>
850 <programlisting role="C">
851 gtk_container_set_border_width (GTK_CONTAINER (window), 10);
854 <para>This call creates a new button. It allocates space for a new GtkWidget
855 structure in memory, initializes it, and makes the button pointer
856 point to it. It will have the label "Hello World" on it when
859 <programlisting role="C">
860 button = gtk_button_new_with_label ("Hello World");
863 <para>Here, we take this button, and make it do something useful. We attach
864 a signal handler to it so when it emits the "clicked" signal, our
865 hello() function is called. The data is ignored, so we simply pass in
866 NULL to the hello() callback function. Obviously, the "clicked" signal
867 is emitted when we click the button with our mouse pointer.</para>
869 <programlisting role="C">
870 g_signal_connect (button, "clicked",
871 G_CALLBACK (hello), NULL);
874 <para>We are also going to use this button to exit our program. This will
875 illustrate how the "destroy" signal may come from either the window
876 manager, or our program. When the button is "clicked", same as above,
877 it calls the first hello() callback function, and then this one in the
878 order they are set up. You may have as many callback functions as you
879 need, and all will be executed in the order you connected
880 them. Because the gtk_widget_destroy() function accepts only a
881 GtkWidget *widget as an argument, we use the g_signal_connect_swapped()
882 function here instead of straight g_signal_connect().</para>
884 <programlisting role="C">
885 g_signal_connect_swapped (button, "clicked",
886 G_CALLBACK (gtk_widget_destroy),
890 <para>This is a packing call, which will be explained in depth later on in
891 <link linkend="ch-PackingWidgets">Packing Widgets</link>. But it is
892 fairly easy to understand. It simply tells GTK that the button is to
893 be placed in the window where it will be displayed. Note that a GTK
894 container can only contain one widget. There are other widgets, that
895 are described later, which are designed to layout multiple widgets in
899 <programlisting role="C">
900 gtk_container_add (GTK_CONTAINER (window), button);
903 <para>Now we have everything set up the way we want it to be. With all the
904 signal handlers in place, and the button placed in the window where it
905 should be, we ask GTK to "show" the widgets on the screen. The window
906 widget is shown last so the whole window will pop up at once rather
907 than seeing the window pop up, and then the button form inside of
908 it. Although with such a simple example, you'd never notice.</para>
910 <programlisting role="C">
911 gtk_widget_show (button);
913 gtk_widget_show (window);
916 <para>And of course, we call gtk_main() which waits for events to come from
917 the X server and will call on the widgets to emit signals when these
920 <programlisting role="C">
924 <para>And the final return. Control returns here after gtk_main_quit() is called.</para>
926 <programlisting role="C">
930 <para>Now, when we click the mouse button on a GTK button, the widget emits
931 a "clicked" signal. In order for us to use this information, our
932 program sets up a signal handler to catch that signal, which
933 dispatches the function of our choice. In our example, when the button
934 we created is "clicked", the hello() function is called with a NULL
935 argument, and then the next handler for this signal is called. This
936 calls the gtk_widget_destroy() function, passing it the window widget
937 as its argument, destroying the window widget. This causes the window
938 to emit the "destroy" signal, which is caught, and calls our destroy()
939 callback function, which simply exits GTK.</para>
941 <para>Another course of events is to use the window manager to kill the
942 window, which will cause the "delete-event" to be emitted. This will
943 call our "delete-event" handler. If we return TRUE here, the window
944 will be left as is and nothing will happen. Returning FALSE will cause
945 GTK to emit the "destroy" signal which of course calls the "destroy"
946 callback, exiting GTK.</para>
951 <!-- ***************************************************************** -->
952 <chapter id="ch-MovingOn">
953 <title>Moving On</title>
955 <!-- ----------------------------------------------------------------- -->
956 <sect1 id="sec-DataTypes">
957 <title>Data Types</title>
959 <para>There are a few things you probably noticed in the previous examples
960 that need explaining. The gint, gchar, etc. that you see are typedefs
961 to int and char, respectively, that are part of the GLib system. This
962 is done to get around that nasty dependency on the size of simple data
963 types when doing calculations.</para>
965 <para>A good example is "gint32" which will be typedef'd to a 32 bit integer
966 for any given platform, whether it be the 64 bit alpha, or the 32 bit
967 i386. The typedefs are very straightforward and intuitive. They are
968 all defined in <filename>glib/glib.h</filename> (which gets included from
969 <filename>gtk.h</filename>).</para>
971 <para>You'll also notice GTK's ability to use GtkWidget when the function
972 calls for a GtkObject. GTK is an object oriented design, and a widget
977 <!-- ----------------------------------------------------------------- -->
978 <sect1 id="sec-MoreOnSignalHandlers">
979 <title>More on Signal Handlers</title>
981 <para>Lets take another look at the g_signal_connect() declaration.</para>
983 <programlisting role="C">
984 gulong g_signal_connect( gpointer object,
987 gpointer func_data );
990 <para>Notice the gulong return value? This is a tag that identifies your
991 callback function. As stated above, you may have as many callbacks per
992 signal and per object as you need, and each will be executed in turn,
993 in the order they were attached.</para>
995 <para>This tag allows you to remove this callback from the list by using:</para>
997 <programlisting role="C">
998 void g_signal_handler_disconnect( gpointer object,
1002 <para>So, by passing in the widget you wish to remove the handler from, and
1003 the tag returned by one of the signal_connect functions, you can
1004 disconnect a signal handler.</para>
1006 <para>You can also temporarily disable signal handlers with the
1007 g_signal_handler_block() and g_signal_handler_unblock() family of
1010 <programlisting role="C">
1011 void g_signal_handler_block( gpointer object,
1014 void g_signal_handlers_block_by_func( gpointer object,
1018 void g_signal_handler_unblock( gpointer object,
1021 void g_signal_handlers_unblock_by_func( gpointer object,
1028 <!-- ----------------------------------------------------------------- -->
1029 <sect1 id="sec-AnUpgradedHelloWorld">
1030 <title>An Upgraded Hello World</title>
1032 <para>Let's take a look at a slightly improved <emphasis>helloworld</emphasis> with
1033 better examples of callbacks. This will also introduce us to our next
1034 topic, packing widgets.</para>
1039 <imagedata fileref="images/helloworld2.png" format="png">
1041 </inlinemediaobject>
1044 <programlisting role="C">
1045 <!-- example-start helloworld2 helloworld2.c -->
1047 #include <gtk/gtk.h>
1049 /* Our new improved callback. The data passed to this function
1050 * is printed to stdout. */
1051 static void callback( GtkWidget *widget,
1054 g_print ("Hello again - %s was pressed\n", (gchar *) data);
1057 /* another callback */
1058 static gboolean delete_event( GtkWidget *widget,
1069 /* GtkWidget is the storage type for widgets */
1074 /* This is called in all GTK applications. Arguments are parsed
1075 * from the command line and are returned to the application. */
1076 gtk_init (&argc, &argv);
1078 /* Create a new window */
1079 window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
1081 /* This is a new call, which just sets the title of our
1082 * new window to "Hello Buttons!" */
1083 gtk_window_set_title (GTK_WINDOW (window), "Hello Buttons!");
1085 /* Here we just set a handler for delete_event that immediately
1087 g_signal_connect (window, "delete-event",
1088 G_CALLBACK (delete_event), NULL);
1090 /* Sets the border width of the window. */
1091 gtk_container_set_border_width (GTK_CONTAINER (window), 10);
1093 /* We create a box to pack widgets into. This is described in detail
1094 * in the "packing" section. The box is not really visible, it
1095 * is just used as a tool to arrange widgets. */
1096 box1 = gtk_hbox_new (FALSE, 0);
1098 /* Put the box into the main window. */
1099 gtk_container_add (GTK_CONTAINER (window), box1);
1101 /* Creates a new button with the label "Button 1". */
1102 button = gtk_button_new_with_label ("Button 1");
1104 /* Now when the button is clicked, we call the "callback" function
1105 * with a pointer to "button 1" as its argument */
1106 g_signal_connect (button, "clicked",
1107 G_CALLBACK (callback), (gpointer) "button 1");
1109 /* Instead of gtk_container_add, we pack this button into the invisible
1110 * box, which has been packed into the window. */
1111 gtk_box_pack_start (GTK_BOX(box1), button, TRUE, TRUE, 0);
1113 /* Always remember this step, this tells GTK that our preparation for
1114 * this button is complete, and it can now be displayed. */
1115 gtk_widget_show (button);
1117 /* Do these same steps again to create a second button */
1118 button = gtk_button_new_with_label ("Button 2");
1120 /* Call the same callback function with a different argument,
1121 * passing a pointer to "button 2" instead. */
1122 g_signal_connect (button, "clicked",
1123 G_CALLBACK (callback), (gpointer) "button 2");
1125 gtk_box_pack_start(GTK_BOX (box1), button, TRUE, TRUE, 0);
1127 /* The order in which we show the buttons is not really important, but I
1128 * recommend showing the window last, so it all pops up at once. */
1129 gtk_widget_show (button);
1131 gtk_widget_show (box1);
1133 gtk_widget_show (window);
1135 /* Rest in gtk_main and wait for the fun to begin! */
1140 <!-- example-end -->
1143 <para>Compile this program using the same linking arguments as our first
1144 example. You'll notice this time there is no easy way to exit the
1145 program, you have to use your window manager or command line to kill
1146 it. A good exercise for the reader would be to insert a third "Quit"
1147 button that will exit the program. You may also wish to play with the
1148 options to gtk_box_pack_start() while reading the next section. Try
1149 resizing the window, and observe the behavior.</para>
1154 <!-- ***************************************************************** -->
1155 <chapter id="ch-PackingWidgets">
1156 <title>Packing Widgets</title>
1158 <para>When creating an application, you'll want to put more than one widget
1159 inside a window. Our first <emphasis>helloworld</emphasis> example only used one
1160 widget so we could simply use a gtk_container_add() call to "pack" the
1161 widget into the window. But when you want to put more than one widget
1162 into a window, how do you control where that widget is positioned?
1163 This is where packing comes in.</para>
1165 <!-- ----------------------------------------------------------------- -->
1166 <sect1 id="sec-TheoryOfPackingBoxes">
1167 <title>Theory of Packing Boxes</title>
1169 <para>Most packing is done by creating boxes. These
1170 are invisible widget containers that we can pack our widgets into
1171 which come in two forms, a horizontal box, and a vertical box. When
1172 packing widgets into a horizontal box, the objects are inserted
1173 horizontally from left to right or right to left depending on the call
1174 used. In a vertical box, widgets are packed from top to bottom or vice
1175 versa. You may use any combination of boxes inside or beside other
1176 boxes to create the desired effect.</para>
1178 <para>To create a new horizontal box, we use a call to gtk_hbox_new(), and
1179 for vertical boxes, gtk_vbox_new(). The gtk_box_pack_start() and
1180 gtk_box_pack_end() functions are used to place objects inside of these
1181 containers. The gtk_box_pack_start() function will start at the top
1182 and work its way down in a vbox, and pack left to right in an hbox.
1183 gtk_box_pack_end() will do the opposite, packing from bottom to top in
1184 a vbox, and right to left in an hbox. Using these functions allows us
1185 to right justify or left justify our widgets and may be mixed in any
1186 way to achieve the desired effect. We will use gtk_box_pack_start() in
1187 most of our examples. An object may be another container or a
1188 widget. In fact, many widgets are actually containers themselves,
1189 including the button, but we usually only use a label inside a button.</para>
1191 <para>By using these calls, GTK knows where you want to place your widgets
1192 so it can do automatic resizing and other nifty things. There are also
1193 a number of options as to how your widgets should be packed. As you
1194 can imagine, this method gives us a quite a bit of flexibility when
1195 placing and creating widgets.</para>
1199 <!-- ----------------------------------------------------------------- -->
1200 <sect1 id="sec-DetailsOfBoxes">
1201 <title>Details of Boxes</title>
1203 <para>Because of this flexibility, packing boxes in GTK can be confusing at
1204 first. There are a lot of options, and it's not immediately obvious how
1205 they all fit together. In the end, however, there are basically five
1206 different styles.</para>
1211 <imagedata fileref="images/packbox1.png" format="png">
1213 </inlinemediaobject>
1216 <para>Each line contains one horizontal box (hbox) with several buttons. The
1217 call to gtk_box_pack is shorthand for the call to pack each of the
1218 buttons into the hbox. Each of the buttons is packed into the hbox the
1219 same way (i.e., same arguments to the gtk_box_pack_start() function).</para>
1221 <para>This is the declaration of the gtk_box_pack_start() function.</para>
1223 <programlisting role="C">
1224 void gtk_box_pack_start( GtkBox *box,
1231 <para>The first argument is the box you are packing the object into, the
1232 second is the object. The objects will all be buttons for now, so
1233 we'll be packing buttons into boxes.</para>
1235 <para>The expand argument to gtk_box_pack_start() and gtk_box_pack_end()
1236 controls whether the widgets are laid out in the box to fill in all
1237 the extra space in the box so the box is expanded to fill the area
1238 allotted to it (TRUE); or the box is shrunk to just fit the widgets
1239 (FALSE). Setting expand to FALSE will allow you to do right and left
1240 justification of your widgets. Otherwise, they will all expand to fit
1241 into the box, and the same effect could be achieved by using only one
1242 of gtk_box_pack_start() or gtk_box_pack_end().</para>
1244 <para>The fill argument to the gtk_box_pack functions control whether the
1245 extra space is allocated to the objects themselves (TRUE), or as extra
1246 padding in the box around these objects (FALSE). It only has an effect
1247 if the expand argument is also TRUE.</para>
1249 <para>When creating a new box, the function looks like this:</para>
1251 <programlisting role="C">
1252 GtkWidget *gtk_hbox_new ( gboolean homogeneous,
1256 <para>The homogeneous argument to gtk_hbox_new() (and the same for
1257 gtk_vbox_new()) controls whether each object in the box has the same
1258 size (i.e., the same width in an hbox, or the same height in a
1259 vbox). If it is set, the gtk_box_pack() routines function essentially
1260 as if the <literal>expand</literal> argument was always turned on.</para>
1262 <para>What's the difference between spacing (set when the box is created)
1263 and padding (set when elements are packed)? Spacing is added between
1264 objects, and padding is added on either side of an object. The
1265 following figure should make it clearer:</para>
1270 <imagedata fileref="images/packbox2.png" format="png">
1272 </inlinemediaobject>
1275 <para>Here is the code used to create the above images. I've commented it
1276 fairly heavily so I hope you won't have any problems following
1277 it. Compile it yourself and play with it.</para>
1281 <!-- ----------------------------------------------------------------- -->
1282 <sect1 id="sec-PackingDemonstrationProgram">
1283 <title>Packing Demonstration Program</title>
1285 <programlisting role="C">
1286 /* example-start packbox packbox.c */
1288 #include <stdio.h>
1289 #include <stdlib.h>
1290 #include "gtk/gtk.h"
1292 static gboolean delete_event( GtkWidget *widget,
1300 /* Make a new hbox filled with button-labels. Arguments for the
1301 * variables we're interested are passed in to this function.
1302 * We do not show the box, but do show everything inside. */
1303 static GtkWidget *make_box( gboolean homogeneous,
1313 /* Create a new hbox with the appropriate homogeneous
1314 * and spacing settings */
1315 box = gtk_hbox_new (homogeneous, spacing);
1317 /* Create a series of buttons with the appropriate settings */
1318 button = gtk_button_new_with_label ("gtk_box_pack");
1319 gtk_box_pack_start (GTK_BOX (box), button, expand, fill, padding);
1320 gtk_widget_show (button);
1322 button = gtk_button_new_with_label ("(box,");
1323 gtk_box_pack_start (GTK_BOX (box), button, expand, fill, padding);
1324 gtk_widget_show (button);
1326 button = gtk_button_new_with_label ("button,");
1327 gtk_box_pack_start (GTK_BOX (box), button, expand, fill, padding);
1328 gtk_widget_show (button);
1330 /* Create a button with the label depending on the value of
1333 button = gtk_button_new_with_label ("TRUE,");
1335 button = gtk_button_new_with_label ("FALSE,");
1337 gtk_box_pack_start (GTK_BOX (box), button, expand, fill, padding);
1338 gtk_widget_show (button);
1340 /* This is the same as the button creation for "expand"
1341 * above, but uses the shorthand form. */
1342 button = gtk_button_new_with_label (fill ? "TRUE," : "FALSE,");
1343 gtk_box_pack_start (GTK_BOX (box), button, expand, fill, padding);
1344 gtk_widget_show (button);
1346 sprintf (padstr, "%d);", padding);
1348 button = gtk_button_new_with_label (padstr);
1349 gtk_box_pack_start (GTK_BOX (box), button, expand, fill, padding);
1350 gtk_widget_show (button);
1362 GtkWidget *separator;
1367 /* Our init, don't forget this! :) */
1368 gtk_init (&argc, &argv);
1371 fprintf (stderr, "usage: packbox num, where num is 1, 2, or 3.\n");
1372 /* This just does cleanup in GTK and exits with an exit status of 1. */
1376 which = atoi (argv[1]);
1378 /* Create our window */
1379 window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
1381 /* You should always remember to connect the delete_event signal
1382 * to the main window. This is very important for proper intuitive
1384 g_signal_connect (window, "delete-event",
1385 G_CALLBACK (delete_event), NULL);
1386 gtk_container_set_border_width (GTK_CONTAINER (window), 10);
1388 /* We create a vertical box (vbox) to pack the horizontal boxes into.
1389 * This allows us to stack the horizontal boxes filled with buttons one
1390 * on top of the other in this vbox. */
1391 box1 = gtk_vbox_new (FALSE, 0);
1393 /* which example to show. These correspond to the pictures above. */
1396 /* create a new label. */
1397 label = gtk_label_new ("gtk_hbox_new (FALSE, 0);");
1399 /* Align the label to the left side. We'll discuss this function and
1400 * others in the section on Widget Attributes. */
1401 gtk_misc_set_alignment (GTK_MISC (label), 0, 0);
1403 /* Pack the label into the vertical box (vbox box1). Remember that
1404 * widgets added to a vbox will be packed one on top of the other in
1406 gtk_box_pack_start (GTK_BOX (box1), label, FALSE, FALSE, 0);
1408 /* Show the label */
1409 gtk_widget_show (label);
1411 /* Call our make box function - homogeneous = FALSE, spacing = 0,
1412 * expand = FALSE, fill = FALSE, padding = 0 */
1413 box2 = make_box (FALSE, 0, FALSE, FALSE, 0);
1414 gtk_box_pack_start (GTK_BOX (box1), box2, FALSE, FALSE, 0);
1415 gtk_widget_show (box2);
1417 /* Call our make box function - homogeneous = FALSE, spacing = 0,
1418 * expand = TRUE, fill = FALSE, padding = 0 */
1419 box2 = make_box (FALSE, 0, TRUE, FALSE, 0);
1420 gtk_box_pack_start (GTK_BOX (box1), box2, FALSE, FALSE, 0);
1421 gtk_widget_show (box2);
1423 /* Args are: homogeneous, spacing, expand, fill, padding */
1424 box2 = make_box (FALSE, 0, TRUE, TRUE, 0);
1425 gtk_box_pack_start (GTK_BOX (box1), box2, FALSE, FALSE, 0);
1426 gtk_widget_show (box2);
1428 /* Creates a separator, we'll learn more about these later,
1429 * but they are quite simple. */
1430 separator = gtk_hseparator_new ();
1432 /* Pack the separator into the vbox. Remember each of these
1433 * widgets is being packed into a vbox, so they'll be stacked
1435 gtk_box_pack_start (GTK_BOX (box1), separator, FALSE, TRUE, 5);
1436 gtk_widget_show (separator);
1438 /* Create another new label, and show it. */
1439 label = gtk_label_new ("gtk_hbox_new (TRUE, 0);");
1440 gtk_misc_set_alignment (GTK_MISC (label), 0, 0);
1441 gtk_box_pack_start (GTK_BOX (box1), label, FALSE, FALSE, 0);
1442 gtk_widget_show (label);
1444 /* Args are: homogeneous, spacing, expand, fill, padding */
1445 box2 = make_box (TRUE, 0, TRUE, FALSE, 0);
1446 gtk_box_pack_start (GTK_BOX (box1), box2, FALSE, FALSE, 0);
1447 gtk_widget_show (box2);
1449 /* Args are: homogeneous, spacing, expand, fill, padding */
1450 box2 = make_box (TRUE, 0, TRUE, TRUE, 0);
1451 gtk_box_pack_start (GTK_BOX (box1), box2, FALSE, FALSE, 0);
1452 gtk_widget_show (box2);
1454 /* Another new separator. */
1455 separator = gtk_hseparator_new ();
1456 /* The last 3 arguments to gtk_box_pack_start are:
1457 * expand, fill, padding. */
1458 gtk_box_pack_start (GTK_BOX (box1), separator, FALSE, TRUE, 5);
1459 gtk_widget_show (separator);
1465 /* Create a new label, remember box1 is a vbox as created
1466 * near the beginning of main() */
1467 label = gtk_label_new ("gtk_hbox_new (FALSE, 10);");
1468 gtk_misc_set_alignment (GTK_MISC (label), 0, 0);
1469 gtk_box_pack_start (GTK_BOX (box1), label, FALSE, FALSE, 0);
1470 gtk_widget_show (label);
1472 /* Args are: homogeneous, spacing, expand, fill, padding */
1473 box2 = make_box (FALSE, 10, TRUE, FALSE, 0);
1474 gtk_box_pack_start (GTK_BOX (box1), box2, FALSE, FALSE, 0);
1475 gtk_widget_show (box2);
1477 /* Args are: homogeneous, spacing, expand, fill, padding */
1478 box2 = make_box (FALSE, 10, TRUE, TRUE, 0);
1479 gtk_box_pack_start (GTK_BOX (box1), box2, FALSE, FALSE, 0);
1480 gtk_widget_show (box2);
1482 separator = gtk_hseparator_new ();
1483 /* The last 3 arguments to gtk_box_pack_start are:
1484 * expand, fill, padding. */
1485 gtk_box_pack_start (GTK_BOX (box1), separator, FALSE, TRUE, 5);
1486 gtk_widget_show (separator);
1488 label = gtk_label_new ("gtk_hbox_new (FALSE, 0);");
1489 gtk_misc_set_alignment (GTK_MISC (label), 0, 0);
1490 gtk_box_pack_start (GTK_BOX (box1), label, FALSE, FALSE, 0);
1491 gtk_widget_show (label);
1493 /* Args are: homogeneous, spacing, expand, fill, padding */
1494 box2 = make_box (FALSE, 0, TRUE, FALSE, 10);
1495 gtk_box_pack_start (GTK_BOX (box1), box2, FALSE, FALSE, 0);
1496 gtk_widget_show (box2);
1498 /* Args are: homogeneous, spacing, expand, fill, padding */
1499 box2 = make_box (FALSE, 0, TRUE, TRUE, 10);
1500 gtk_box_pack_start (GTK_BOX (box1), box2, FALSE, FALSE, 0);
1501 gtk_widget_show (box2);
1503 separator = gtk_hseparator_new ();
1504 /* The last 3 arguments to gtk_box_pack_start are: expand, fill, padding. */
1505 gtk_box_pack_start (GTK_BOX (box1), separator, FALSE, TRUE, 5);
1506 gtk_widget_show (separator);
1511 /* This demonstrates the ability to use gtk_box_pack_end() to
1512 * right justify widgets. First, we create a new box as before. */
1513 box2 = make_box (FALSE, 0, FALSE, FALSE, 0);
1515 /* Create the label that will be put at the end. */
1516 label = gtk_label_new ("end");
1517 /* Pack it using gtk_box_pack_end(), so it is put on the right
1518 * side of the hbox created in the make_box() call. */
1519 gtk_box_pack_end (GTK_BOX (box2), label, FALSE, FALSE, 0);
1520 /* Show the label. */
1521 gtk_widget_show (label);
1523 /* Pack box2 into box1 (the vbox remember ? :) */
1524 gtk_box_pack_start (GTK_BOX (box1), box2, FALSE, FALSE, 0);
1525 gtk_widget_show (box2);
1527 /* A separator for the bottom. */
1528 separator = gtk_hseparator_new ();
1529 /* This explicitly sets the separator to 400 pixels wide by 5 pixels
1530 * high. This is so the hbox we created will also be 400 pixels wide,
1531 * and the "end" label will be separated from the other labels in the
1532 * hbox. Otherwise, all the widgets in the hbox would be packed as
1533 * close together as possible. */
1534 gtk_widget_set_size_request (separator, 400, 5);
1535 /* pack the separator into the vbox (box1) created near the start
1537 gtk_box_pack_start (GTK_BOX (box1), separator, FALSE, TRUE, 5);
1538 gtk_widget_show (separator);
1541 /* Create another new hbox.. remember we can use as many as we need! */
1542 quitbox = gtk_hbox_new (FALSE, 0);
1544 /* Our quit button. */
1545 button = gtk_button_new_with_label ("Quit");
1547 /* Setup the signal to terminate the program when the button is clicked */
1548 g_signal_connect_swapped (button, "clicked",
1549 G_CALLBACK (gtk_main_quit),
1551 /* Pack the button into the quitbox.
1552 * The last 3 arguments to gtk_box_pack_start are:
1553 * expand, fill, padding. */
1554 gtk_box_pack_start (GTK_BOX (quitbox), button, TRUE, FALSE, 0);
1555 /* pack the quitbox into the vbox (box1) */
1556 gtk_box_pack_start (GTK_BOX (box1), quitbox, FALSE, FALSE, 0);
1558 /* Pack the vbox (box1) which now contains all our widgets, into the
1560 gtk_container_add (GTK_CONTAINER (window), box1);
1562 /* And show everything left */
1563 gtk_widget_show (button);
1564 gtk_widget_show (quitbox);
1566 gtk_widget_show (box1);
1567 /* Showing the window last so everything pops up at once. */
1568 gtk_widget_show (window);
1570 /* And of course, our main function. */
1573 /* Control returns here when gtk_main_quit() is called, but not when
1574 * exit() is used. */
1578 <!-- example-end -->
1583 <!-- ----------------------------------------------------------------- -->
1584 <sect1 id="sec-PackingUsingTables">
1585 <title>Packing Using Tables</title>
1587 <para>Let's take a look at another way of packing - Tables. These can be
1588 extremely useful in certain situations.</para>
1590 <para>Using tables, we create a grid that we can place widgets in. The
1591 widgets may take up as many spaces as we specify.</para>
1593 <para>The first thing to look at, of course, is the gtk_table_new() function:</para>
1595 <programlisting role="C">
1596 GtkWidget *gtk_table_new( guint rows,
1598 gboolean homogeneous );
1601 <para>The first argument is the number of rows to make in the table, while
1602 the second, obviously, is the number of columns.</para>
1604 <para>The homogeneous argument has to do with how the table's boxes are
1605 sized. If homogeneous is TRUE, the table boxes are resized to the size
1606 of the largest widget in the table. If homogeneous is FALSE, the size
1607 of a table boxes is dictated by the tallest widget in its same row,
1608 and the widest widget in its column.</para>
1610 <para>The rows and columns are laid out from 0 to n, where n was the number
1611 specified in the call to gtk_table_new. So, if you specify rows = 2
1612 and columns = 2, the layout would look something like this:</para>
1614 <programlisting role="C">
1616 0+----------+----------+
1618 1+----------+----------+
1620 2+----------+----------+
1623 <para>Note that the coordinate system starts in the upper left hand corner.
1624 To place a widget into a box, use the following function:</para>
1626 <programlisting role="C">
1627 void gtk_table_attach( GtkTable *table,
1632 guint bottom_attach,
1633 GtkAttachOptions xoptions,
1634 GtkAttachOptions yoptions,
1639 <para>The first argument ("table") is the table you've created and the
1640 second ("child") the widget you wish to place in the table.</para>
1642 <para>The left and right attach arguments specify where to place the widget,
1643 and how many boxes to use. If you want a button in the lower right
1644 table entry of our 2x2 table, and want it to fill that entry <emphasis>only</emphasis>,
1645 left_attach would be = 1, right_attach = 2, top_attach = 1,
1646 bottom_attach = 2.</para>
1648 <para>Now, if you wanted a widget to take up the whole top row of our 2x2
1649 table, you'd use left_attach = 0, right_attach = 2, top_attach = 0,
1650 bottom_attach = 1.</para>
1652 <para>The xoptions and yoptions are used to specify packing options and may
1653 be bitwise OR'ed together to allow multiple options.</para>
1655 <para>These options are:</para>
1659 <term><literal>GTK_FILL</literal></term>
1660 <listitem><para>If the table box is larger than the widget, and
1661 <literal>GTK_FILL</literal> is specified, the widget will expand to use all the room
1667 <term><literal>GTK_SHRINK</literal></term>
1668 <listitem><para>If the table widget was allocated less space
1669 then was requested (usually by the user resizing the window), then the
1670 widgets would normally just be pushed off the bottom of the window and
1671 disappear. If <literal>GTK_SHRINK</literal> is specified, the widgets will shrink
1672 with the table.</para>
1677 <term><literal>GTK_EXPAND</literal></term>
1678 <listitem><para>This will cause the table to expand to use up
1679 any remaining space in the window.</para>
1684 <para>Padding is just like in boxes, creating a clear area around the widget
1685 specified in pixels.</para>
1687 <para>gtk_table_attach() has a <emphasis>lot</emphasis> of options.
1688 So, there's a shortcut:</para>
1690 <programlisting role="C">
1691 void gtk_table_attach_defaults( GtkTable *table,
1696 guint bottom_attach );
1699 <para>The X and Y options default to <literal>GTK_FILL | GTK_EXPAND</literal>,
1700 and X and Y padding are set to 0. The rest of the arguments are identical to the
1701 previous function.</para>
1703 <para>We also have gtk_table_set_row_spacing() and
1704 gtk_table_set_col_spacing(). These places spacing between the rows at
1705 the specified row or column.</para>
1707 <programlisting role="C">
1708 void gtk_table_set_row_spacing( GtkTable *table,
1715 <programlisting role="C">
1716 void gtk_table_set_col_spacing ( GtkTable *table,
1721 <para>Note that for columns, the space goes to the right of the column, and
1722 for rows, the space goes below the row.</para>
1724 <para>You can also set a consistent spacing of all rows and/or columns with:</para>
1726 <programlisting role="C">
1727 void gtk_table_set_row_spacings( GtkTable *table,
1733 <programlisting role="C">
1734 void gtk_table_set_col_spacings( GtkTable *table,
1738 <para>Note that with these calls, the last row and last column do not get
1743 <!-- ----------------------------------------------------------------- -->
1744 <sect1 id="sec-TablePackingExamples">
1745 <title>Table Packing Example</title>
1747 <para>Here we make a window with three buttons in a 2x2 table.
1748 The first two buttons will be placed in the upper row.
1749 A third, quit button, is placed in the lower row, spanning both columns.
1750 Which means it should look something like this:</para>
1755 <imagedata fileref="images/table.png" format="png">
1757 </inlinemediaobject>
1760 <para>Here's the source code:</para>
1762 <programlisting role="C">
1763 <!-- example-start table table.c -->
1765 #include <gtk/gtk.h>
1768 * The data passed to this function is printed to stdout */
1769 static void callback( GtkWidget *widget,
1772 g_print ("Hello again - %s was pressed\n", (char *) data);
1775 /* This callback quits the program */
1776 static gboolean delete_event( GtkWidget *widget,
1791 gtk_init (&argc, &argv);
1793 /* Create a new window */
1794 window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
1796 /* Set the window title */
1797 gtk_window_set_title (GTK_WINDOW (window), "Table");
1799 /* Set a handler for delete_event that immediately
1801 g_signal_connect (window, "delete-event",
1802 G_CALLBACK (delete_event), NULL);
1804 /* Sets the border width of the window. */
1805 gtk_container_set_border_width (GTK_CONTAINER (window), 20);
1807 /* Create a 2x2 table */
1808 table = gtk_table_new (2, 2, TRUE);
1810 /* Put the table in the main window */
1811 gtk_container_add (GTK_CONTAINER (window), table);
1813 /* Create first button */
1814 button = gtk_button_new_with_label ("button 1");
1816 /* When the button is clicked, we call the "callback" function
1817 * with a pointer to "button 1" as its argument */
1818 g_signal_connect (button, "clicked",
1819 G_CALLBACK (callback), (gpointer) "button 1");
1822 /* Insert button 1 into the upper left quadrant of the table */
1823 gtk_table_attach_defaults (GTK_TABLE (table), button, 0, 1, 0, 1);
1825 gtk_widget_show (button);
1827 /* Create second button */
1829 button = gtk_button_new_with_label ("button 2");
1831 /* When the button is clicked, we call the "callback" function
1832 * with a pointer to "button 2" as its argument */
1833 g_signal_connect (button, "clicked",
1834 G_CALLBACK (callback), (gpointer) "button 2");
1835 /* Insert button 2 into the upper right quadrant of the table */
1836 gtk_table_attach_defaults (GTK_TABLE (table), button, 1, 2, 0, 1);
1838 gtk_widget_show (button);
1840 /* Create "Quit" button */
1841 button = gtk_button_new_with_label ("Quit");
1843 /* When the button is clicked, we call the "delete-event" function
1844 * and the program exits */
1845 g_signal_connect (button, "clicked",
1846 G_CALLBACK (delete_event), NULL);
1848 /* Insert the quit button into the both
1849 * lower quadrants of the table */
1850 gtk_table_attach_defaults (GTK_TABLE (table), button, 0, 2, 1, 2);
1852 gtk_widget_show (button);
1854 gtk_widget_show (table);
1855 gtk_widget_show (window);
1861 <!-- example-end -->
1867 <!-- ***************************************************************** -->
1868 <chapter id="ch-WidgetOverview">
1869 <title>Widget Overview</title>
1871 <para>The general steps to creating a widget in GTK are:</para>
1873 <listitem><simpara> gtk_*_new() - one of various functions to create a new widget.
1874 These are all detailed in this section.</simpara>
1877 <listitem><simpara> Connect all signals and events we wish to use to the
1878 appropriate handlers.</simpara>
1881 <listitem><simpara> Set the attributes of the widget.</simpara>
1884 <listitem><simpara> Pack the widget into a container using the appropriate call
1885 such as gtk_container_add() or gtk_box_pack_start().</simpara>
1888 <listitem><simpara> gtk_widget_show() the widget.</simpara>
1892 <para>gtk_widget_show() lets GTK know that we are done setting the
1893 attributes of the widget, and it is ready to be displayed. You may
1894 also use gtk_widget_hide to make it disappear again. The order in
1895 which you show the widgets is not important, but I suggest showing the
1896 window last so the whole window pops up at once rather than seeing the
1897 individual widgets come up on the screen as they're formed. The
1898 children of a widget (a window is a widget too) will not be displayed
1899 until the window itself is shown using the gtk_widget_show() function.</para>
1901 <!-- ----------------------------------------------------------------- -->
1902 <sect1 id="sec-Casting">
1903 <title>Casting</title>
1905 <para>You'll notice as you go on that GTK uses a type casting system. This
1906 is always done using macros that both test the ability to cast the
1907 given item, and perform the cast. Some common ones you will see are:</para>
1909 <programlisting role="C">
1913 G_CALLBACK (function)
1914 GTK_CONTAINER (container)
1919 <para>These are all used to cast arguments in functions. You'll see them in the
1920 examples, and can usually tell when to use them simply by looking at the
1921 function's declaration.</para>
1923 <para>As you can see below in the class hierarchy, all GtkWidgets are
1924 derived from the GObject base class. This means you can use a widget
1925 in any place the function asks for an object. Note that many functions
1926 accept a gpointer so there is no need to cast the type.</para>
1928 <para>For example:</para>
1930 <programlisting role="C">
1931 g_signal_connect( button, "clicked",
1932 G_CALLBACK (callback_function), callback_data);
1935 <para>This casts the button into an object, and provides a cast for the
1936 function pointer to the callback.</para>
1938 <para>Many widgets are also containers. If you look in the class hierarchy
1939 below, you'll notice that many widgets derive from the Container
1940 class. Any one of these widgets may be used with the
1941 <literal>GTK_CONTAINER</literal> macro to pass them to functions that ask for
1944 <para>Unfortunately, these macros are not extensively covered in the
1945 tutorial, but I recommend taking a look through the GTK header
1946 files or the GTK API reference manual. It can be very educational. In fact,
1947 it's not difficult to learn how a widget works just by looking at the
1948 function declarations.</para>
1952 <!-- ----------------------------------------------------------------- -->
1953 <sect1 id="sec-WidgetHierarchy">
1954 <title>Widget Hierarchy</title>
1956 <para>For your reference, here is the class hierarchy tree used to implement
1957 widgets. (Deprecated widgets and auxiliary classes have been omitted.)</para>
1959 <programlisting role="C">
1966 | | | `GtkAccelLabel
1973 | | | | `GtkAspectFrame
1975 | | | | +GtkToggleButton
1976 | | | | | `GtkCheckButton
1977 | | | | | `GtkRadioButton
1978 | | | | `GtkOptionMenu
1980 | | | | +GtkMenuItem
1981 | | | | +GtkCheckMenuItem
1982 | | | | | `GtkRadioMenuItem
1983 | | | | +GtkImageMenuItem
1984 | | | | +GtkSeparatorMenuItem
1985 | | | | `GtkTearoffMenuItem
1988 | | | | | +GtkColorSelectionDialog
1989 | | | | | +GtkFileSelection
1990 | | | | | +GtkFontSelectionDialog
1991 | | | | | +GtkInputDialog
1992 | | | | | `GtkMessageDialog
1996 | | | +GtkScrolledWindow
2000 | | | | +GtkHButtonBox
2001 | | | | `GtkVButtonBox
2003 | | | | +GtkColorSelection
2004 | | | | `GtkFontSelection
2045 | +GtkCellRendererPixbuf
2046 | +GtkCellRendererText
2047 | +GtkCellRendererToggle
2055 <!-- ----------------------------------------------------------------- -->
2056 <sect1 id="sec-WidgetsWithoutWindows">
2057 <title>Widgets Without Windows</title>
2059 <para>The following widgets do not have an associated window. If you want to
2060 capture events, you'll have to use the EventBox. See the section on
2061 the <link linkend="sec-EventBox">EventBox</link> widget.</para>
2063 <programlisting role="C">
2090 <para>We'll further our exploration of GTK by examining each widget in turn,
2091 creating a few simple functions to display them. Another good source
2092 is the <literal>testgtk</literal> program that comes with GTK. It can be found in
2093 <filename>tests/testgtk.c</filename>.</para>
2098 <!-- ***************************************************************** -->
2099 <chapter id="ch-ButtonWidget">
2100 <title>The Button Widget</title>
2102 <!-- ----------------------------------------------------------------- -->
2103 <sect1 id="sec-NormalButtons">
2104 <title>Normal Buttons</title>
2106 <para>We've almost seen all there is to see of the button widget. It's
2107 pretty simple. There is however more than one way to create a button. You can
2108 use the gtk_button_new_with_label() or gtk_button_new_with_mnemonic() to create
2109 a button with a label, use gtk_button_new_from_stock() to create a button
2110 containing the image and text from a stock item or use gtk_button_new() to
2111 create a blank button. It's then up to you to pack a label or pixmap into
2112 this new button. To do this, create a new box, and then pack your objects into
2113 this box using the usual gtk_box_pack_start(), and then use gtk_container_add()
2114 to pack the box into the button.</para>
2116 <para>Here's an example of using gtk_button_new() to create a button with a
2117 image and a label in it. I've broken up the code to create a box from the rest
2118 so you can use it in your programs. There are further examples of using images
2119 later in the tutorial.</para>
2124 <imagedata fileref="images/buttons.png" format="png">
2126 </inlinemediaobject>
2129 <programlisting role="C">
2130 <!-- example-start buttons buttons.c -->
2132 #include <stdlib.h>
2133 #include <gtk/gtk.h>
2135 /* Create a new hbox with an image and a label packed into it
2136 * and return the box. */
2138 static GtkWidget *xpm_label_box( gchar *xpm_filename,
2145 /* Create box for image and label */
2146 box = gtk_hbox_new (FALSE, 0);
2147 gtk_container_set_border_width (GTK_CONTAINER (box), 2);
2149 /* Now on to the image stuff */
2150 image = gtk_image_new_from_file (xpm_filename);
2152 /* Create a label for the button */
2153 label = gtk_label_new (label_text);
2155 /* Pack the image and label into the box */
2156 gtk_box_pack_start (GTK_BOX (box), image, FALSE, FALSE, 3);
2157 gtk_box_pack_start (GTK_BOX (box), label, FALSE, FALSE, 3);
2159 gtk_widget_show (image);
2160 gtk_widget_show (label);
2165 /* Our usual callback function */
2166 static void callback( GtkWidget *widget,
2169 g_print ("Hello again - %s was pressed\n", (char *) data);
2175 /* GtkWidget is the storage type for widgets */
2180 gtk_init (&argc, &argv);
2182 /* Create a new window */
2183 window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
2185 gtk_window_set_title (GTK_WINDOW (window), "Pixmap'd Buttons!");
2187 /* It's a good idea to do this for all windows. */
2188 g_signal_connect (window, "destroy",
2189 G_CALLBACK (gtk_main_quit), NULL);
2191 g_signal_connect (window, "delete-event",
2192 G_CALLBACK (gtk_main_quit), NULL);
2194 /* Sets the border width of the window. */
2195 gtk_container_set_border_width (GTK_CONTAINER (window), 10);
2197 /* Create a new button */
2198 button = gtk_button_new ();
2200 /* Connect the "clicked" signal of the button to our callback */
2201 g_signal_connect (button, "clicked",
2202 G_CALLBACK (callback), (gpointer) "cool button");
2204 /* This calls our box creating function */
2205 box = xpm_label_box ("info.xpm", "cool button");
2207 /* Pack and show all our widgets */
2208 gtk_widget_show (box);
2210 gtk_container_add (GTK_CONTAINER (button), box);
2212 gtk_widget_show (button);
2214 gtk_container_add (GTK_CONTAINER (window), button);
2216 gtk_widget_show (window);
2218 /* Rest in gtk_main and wait for the fun to begin! */
2223 <!-- example-end -->
2226 <para>The xpm_label_box() function could be used to pack images and labels into
2227 any widget that can be a container.</para>
2229 <para>The Button widget has the following signals:</para>
2232 <listitem><simpara><literal>pressed</literal> - emitted when pointer button is pressed within
2233 Button widget</simpara>
2235 <listitem><simpara><literal>released</literal> - emitted when pointer button is released within
2236 Button widget</simpara>
2238 <listitem><simpara><literal>clicked</literal> - emitted when pointer button is pressed and then
2239 released within Button widget</simpara>
2241 <listitem><simpara><literal>enter</literal> - emitted when pointer enters Button widget</simpara>
2243 <listitem><simpara><literal>leave</literal> - emitted when pointer leaves Button widget</simpara>
2249 <!-- ----------------------------------------------------------------- -->
2250 <sect1 id="sec-ToggleButtons">
2251 <title>Toggle Buttons</title>
2253 <para>Toggle buttons are derived from normal buttons and are very similar,
2254 except they will always be in one of two states, alternated by a
2255 click. They may be depressed, and when you click again, they will pop
2256 back up. Click again, and they will pop back down.</para>
2258 <para>Toggle buttons are the basis for check buttons and radio buttons, as
2259 such, many of the calls used for toggle buttons are inherited by radio
2260 and check buttons. I will point these out when we come to them.</para>
2262 <para>Creating a new toggle button:</para>
2264 <programlisting role="C">
2265 GtkWidget *gtk_toggle_button_new( void );
2267 GtkWidget *gtk_toggle_button_new_with_label( const gchar *label );
2269 GtkWidget *gtk_toggle_button_new_with_mnemonic( const gchar *label );
2272 <para>As you can imagine, these work identically to the normal button widget
2273 calls. The first creates a blank toggle button, and the last two, a
2274 button with a label widget already packed into it. The _mnemonic() variant
2275 additionally parses the label for '_'-prefixed mnemonic characters.</para>
2277 <para>To retrieve the state of the toggle widget, including radio and check
2278 buttons, we use a construct as shown in our example below. This tests
2279 the state of the toggle button, by accessing the <literal>active</literal> field of the
2280 toggle widget's structure, after first using the
2281 <literal>GTK_TOGGLE_BUTTON</literal> macro to cast the widget pointer into a toggle
2282 widget pointer. The signal of interest to us emitted by toggle
2283 buttons (the toggle button, check button, and radio button widgets) is
2284 the "toggled" signal. To check the state of these buttons, set up a
2285 signal handler to catch the toggled signal, and access the structure
2286 to determine its state. The callback will look something like:</para>
2288 <programlisting role="C">
2289 void toggle_button_callback (GtkWidget *widget, gpointer data)
2291 if (gtk_toggle_button_get_active (GTK_TOGGLE_BUTTON (widget)))
2293 /* If control reaches here, the toggle button is down */
2297 /* If control reaches here, the toggle button is up */
2302 <para>To force the state of a toggle button, and its children, the radio and
2303 check buttons, use this function:</para>
2305 <programlisting role="C">
2306 void gtk_toggle_button_set_active( GtkToggleButton *toggle_button,
2307 gboolean is_active );
2310 <para>The above call can be used to set the state of the toggle button, and
2311 its children the radio and check buttons. Passing in your created
2312 button as the first argument, and a TRUE or FALSE for the second state
2313 argument to specify whether it should be down (depressed) or up
2314 (released). Default is up, or FALSE.</para>
2316 <para>Note that when you use the gtk_toggle_button_set_active() function, and
2317 the state is actually changed, it causes the "clicked" and "toggled"
2318 signals to be emitted from the button.</para>
2320 <programlisting role="C">
2321 gboolean gtk_toggle_button_get_active (GtkToggleButton *toggle_button);
2324 <para>This returns the current state of the toggle button as a boolean
2325 TRUE/FALSE value.</para>
2329 <!-- ----------------------------------------------------------------- -->
2330 <sect1 id="sec-CheckButtons">
2331 <title>Check Buttons</title>
2333 <para>Check buttons inherit many properties and functions from the the
2334 toggle buttons above, but look a little different. Rather than being
2335 buttons with text inside them, they are small squares with the text to
2336 the right of them. These are often used for toggling options on and
2337 off in applications.</para>
2339 <para>The creation functions are similar to those of the normal button.</para>
2341 <programlisting role="C">
2342 GtkWidget *gtk_check_button_new( void );
2344 GtkWidget *gtk_check_button_new_with_label ( const gchar *label );
2346 GtkWidget *gtk_check_button_new_with_mnemonic ( const gchar *label );
2349 <para>The gtk_check_button_new_with_label() function creates a check button
2350 with a label beside it.</para>
2352 <para>Checking the state of the check button is identical to that of the
2353 toggle button.</para>
2357 <!-- ----------------------------------------------------------------- -->
2358 <sect1 id="sec-RadioButtons">
2359 <title>Radio Buttons</title>
2361 <para>Radio buttons are similar to check buttons except they are grouped so
2362 that only one may be selected/depressed at a time. This is good for
2363 places in your application where you need to select from a short list
2366 <para>Creating a new radio button is done with one of these calls:</para>
2368 <programlisting role="C">
2369 GtkWidget *gtk_radio_button_new( GSList *group );
2371 GtkWidget *gtk_radio_button_new_from_widget( GtkRadioButton *group );
2373 GtkWidget *gtk_radio_button_new_with_label( GSList *group,
2374 const gchar *label );
2376 GtkWidget* gtk_radio_button_new_with_label_from_widget( GtkRadioButton *group,
2377 const gchar *label );
2379 GtkWidget *gtk_radio_button_new_with_mnemonic( GSList *group,
2380 const gchar *label );
2382 GtkWidget *gtk_radio_button_new_with_mnemonic_from_widget( GtkRadioButton *group,
2383 const gchar *label );
2387 <para>You'll notice the extra argument to these calls. They require a group
2388 to perform their duty properly. The first call to gtk_radio_button_new() or
2389 gtk_radio_button_new_with_label() should pass NULL as the first argument.
2390 Then create a group using:</para>
2392 <programlisting role="C">
2393 GSList *gtk_radio_button_get_group( GtkRadioButton *radio_button );
2396 <para>The important thing to remember is that gtk_radio_button_get_group() must be
2397 called for each new button added to the group, with the previous button passed
2398 in as an argument. The result is then passed into the next call to
2399 gtk_radio_button_new() or gtk_radio_button_new_with_label(). This allows a
2400 chain of buttons to be established. The example below should make this clear.</para>
2402 <para>You can shorten this slightly by using the following syntax, which
2403 removes the need for a variable to hold the list of buttons:</para>
2405 <programlisting role="C">
2406 button2 = gtk_radio_button_new_with_label(
2407 gtk_radio_button_get_group (GTK_RADIO_BUTTON (button1)),
2412 The _from_widget() variants of the creation functions allow you to shorten this
2413 further, by omitting the gtk_radio_button_get_group() call. This form is used
2414 in the example to create the third button:
2417 <programlisting role="C">
2418 button2 = gtk_radio_button_new_with_label_from_widget(
2419 GTK_RADIO_BUTTON (button1),
2423 <para>It is also a good idea to explicitly set which button should be the
2424 default depressed button with:</para>
2426 <programlisting role="C">
2427 void gtk_toggle_button_set_active( GtkToggleButton *toggle_button,
2431 <para>This is described in the section on toggle buttons, and works in
2432 exactly the same way. Once the radio buttons are grouped together,
2433 only one of the group may be active at a time. If the user clicks on
2434 one radio button, and then on another, the first radio button will
2435 first emit a "toggled" signal (to report becoming inactive), and then
2436 the second will emit its "toggled" signal (to report becoming active).</para>
2438 <para>The following example creates a radio button group with three buttons.</para>
2443 <imagedata fileref="images/radiobuttons.png" format="png">
2445 </inlinemediaobject>
2448 <programlisting role="C">
2449 <!-- example-start radiobuttons radiobuttons.c -->
2451 #include <glib.h>
2452 #include <gtk/gtk.h>
2454 static gboolean close_application( GtkWidget *widget,
2465 GtkWidget *window = NULL;
2469 GtkWidget *separator;
2472 gtk_init (&argc, &argv);
2474 window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
2476 g_signal_connect (window, "delete-event",
2477 G_CALLBACK (close_application),
2480 gtk_window_set_title (GTK_WINDOW (window), "radio buttons");
2481 gtk_container_set_border_width (GTK_CONTAINER (window), 0);
2483 box1 = gtk_vbox_new (FALSE, 0);
2484 gtk_container_add (GTK_CONTAINER (window), box1);
2485 gtk_widget_show (box1);
2487 box2 = gtk_vbox_new (FALSE, 10);
2488 gtk_container_set_border_width (GTK_CONTAINER (box2), 10);
2489 gtk_box_pack_start (GTK_BOX (box1), box2, TRUE, TRUE, 0);
2490 gtk_widget_show (box2);
2492 button = gtk_radio_button_new_with_label (NULL, "button1");
2493 gtk_box_pack_start (GTK_BOX (box2), button, TRUE, TRUE, 0);
2494 gtk_widget_show (button);
2496 group = gtk_radio_button_get_group (GTK_RADIO_BUTTON (button));
2497 button = gtk_radio_button_new_with_label (group, "button2");
2498 gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (button), TRUE);
2499 gtk_box_pack_start (GTK_BOX (box2), button, TRUE, TRUE, 0);
2500 gtk_widget_show (button);
2502 button = gtk_radio_button_new_with_label_from_widget (GTK_RADIO_BUTTON (button),
2504 gtk_box_pack_start (GTK_BOX (box2), button, TRUE, TRUE, 0);
2505 gtk_widget_show (button);
2507 separator = gtk_hseparator_new ();
2508 gtk_box_pack_start (GTK_BOX (box1), separator, FALSE, TRUE, 0);
2509 gtk_widget_show (separator);
2511 box2 = gtk_vbox_new (FALSE, 10);
2512 gtk_container_set_border_width (GTK_CONTAINER (box2), 10);
2513 gtk_box_pack_start (GTK_BOX (box1), box2, FALSE, TRUE, 0);
2514 gtk_widget_show (box2);
2516 button = gtk_button_new_with_label ("close");
2517 g_signal_connect_swapped (button, "clicked",
2518 G_CALLBACK (close_application),
2520 gtk_box_pack_start (GTK_BOX (box2), button, TRUE, TRUE, 0);
2521 gtk_widget_set_can_default (button, TRUE);
2522 gtk_widget_grab_default (button);
2523 gtk_widget_show (button);
2524 gtk_widget_show (window);
2530 <!-- example-end -->
2536 <!-- ***************************************************************** -->
2537 <chapter id="ch-Adjustments">
2538 <title>Adjustments</title>
2540 <para>GTK has various widgets that can be visually adjusted by the user
2541 using the mouse or the keyboard, such as the range widgets, described
2542 in the <link linkend="ch-RangeWidgets">Range Widgets</link>
2543 section. There are also a few widgets that display some adjustable
2544 portion of a larger area of data, such as the text widget and the
2545 viewport widget.</para>
2547 <para>Obviously, an application needs to be able to react to changes the
2548 user makes in range widgets. One way to do this would be to have each
2549 widget emit its own type of signal when its adjustment changes, and
2550 either pass the new value to the signal handler, or require it to look
2551 inside the widget's data structure in order to ascertain the value.
2552 But you may also want to connect the adjustments of several widgets
2553 together, so that adjusting one adjusts the others. The most obvious
2554 example of this is connecting a scrollbar to a panning viewport or a
2555 scrolling text area. If each widget has its own way of setting or
2556 getting the adjustment value, then the programmer may have to write
2557 their own signal handlers to translate between the output of one
2558 widget's signal and the "input" of another's adjustment setting
2561 <para>GTK solves this problem using the Adjustment object, which is not a
2562 widget but a way for widgets to store and pass adjustment information
2563 in an abstract and flexible form. The most obvious use of Adjustment
2564 is to store the configuration parameters and values of range widgets,
2565 such as scrollbars and scale controls. However, since Adjustments are
2566 derived from Object, they have some special powers beyond those of
2567 normal data structures. Most importantly, they can emit signals, just
2568 like widgets, and these signals can be used not only to allow your
2569 program to react to user input on adjustable widgets, but also to
2570 propagate adjustment values transparently between adjustable widgets.</para>
2572 <para>You will see how adjustments fit in when you see the other widgets
2573 that incorporate them:
2574 <link linkend="sec-ProgressBars">Progress Bars</link>,
2575 <link linkend="sec-Viewports">Viewports</link>,
2576 <link linkend="sec-ScrolledWindows">Scrolled Windows</link>, and others.</para>
2578 <!-- ----------------------------------------------------------------- -->
2579 <sect1 id="sec-CreatingAnAdjustment">
2580 <title>Creating an Adjustment</title>
2582 <para>Many of the widgets which use adjustment objects do so automatically,
2583 but some cases will be shown in later examples where you may need to
2584 create one yourself. You create an adjustment using:</para>
2586 <programlisting role="C">
2587 GtkAdjustment *gtk_adjustment_new( gdouble value,
2590 gdouble step_increment,
2591 gdouble page_increment,
2592 gdouble page_size );
2595 <para>The <literal>value</literal> argument is the initial value you want to give to the
2596 adjustment, usually corresponding to the topmost or leftmost position
2597 of an adjustable widget. The <literal>lower</literal> argument specifies the lowest
2598 value which the adjustment can hold. The <literal>step_increment</literal> argument
2599 specifies the "smaller" of the two increments by which the user can
2600 change the value, while the <literal>page_increment</literal> is the "larger" one.
2601 The <literal>page_size</literal> argument usually corresponds somehow to the visible
2602 area of a panning widget. The <literal>upper</literal> argument is used to represent
2603 the bottom most or right most coordinate in a panning widget's
2604 child. Therefore it is <emphasis>not</emphasis> always the largest number that
2605 <literal>value</literal> can take, since the <literal>page_size</literal> of such widgets is
2606 usually non-zero.</para>
2610 <!-- ----------------------------------------------------------------- -->
2611 <sect1 id="sec-UsingAdjustments">
2612 <title>Using Adjustments the Easy Way</title>
2614 <para>The adjustable widgets can be roughly divided into those which use and
2615 require specific units for these values and those which treat them as
2616 arbitrary numbers. The group which treats the values as arbitrary
2617 numbers includes the range widgets (scrollbars and scales, the
2618 progress bar widget, and the spin button widget). These widgets are
2619 all the widgets which are typically "adjusted" directly by the user
2620 with the mouse or keyboard. They will treat the <literal>lower</literal> and
2621 <literal>upper</literal> values of an adjustment as a range within which the user
2622 can manipulate the adjustment's <literal>value</literal>. By default, they will only
2623 modify the <literal>value</literal> of an adjustment.</para>
2625 <para>The other group includes the text widget, the viewport widget, the
2626 compound list widget, and the scrolled window widget. All of these
2627 widgets use pixel values for their adjustments. These are also all
2628 widgets which are typically "adjusted" indirectly using scrollbars.
2629 While all widgets which use adjustments can either create their own
2630 adjustments or use ones you supply, you'll generally want to let this
2631 particular category of widgets create its own adjustments. Usually,
2632 they will eventually override all the values except the <literal>value</literal>
2633 itself in whatever adjustments you give them, but the results are, in
2634 general, undefined (meaning, you'll have to read the source code to
2635 find out, and it may be different from widget to widget).</para>
2637 <para>Now, you're probably thinking, since text widgets and viewports insist
2638 on setting everything except the <literal>value</literal> of their adjustments,
2639 while scrollbars will <emphasis>only</emphasis> touch the adjustment's
2640 <literal>value</literal>, if you <emphasis>share</emphasis> an adjustment
2641 object between a scrollbar and a text widget, manipulating the scrollbar will
2642 automagically adjust the viewport widget? Of course it will! Just like this:</para>
2644 <programlisting role="C">
2645 /* creates its own adjustments */
2646 viewport = gtk_viewport_new (NULL, NULL);
2647 /* uses the newly-created adjustment for the scrollbar as well */
2648 vscrollbar = gtk_vscrollbar_new (gtk_viewport_get_vadjustment (viewport));
2653 <!-- ----------------------------------------------------------------- -->
2654 <sect1 id="sec-AdjustmentInternals">
2655 <title>Adjustment Internals</title>
2657 <para>Ok, you say, that's nice, but what if I want to create my own handlers
2658 to respond when the user adjusts a range widget or a spin button, and
2659 how do I get at the value of the adjustment in these handlers? To
2660 answer these questions and more, let's start by taking a look at
2661 <literal>struct _GtkAdjustment</literal> itself:</para>
2663 <programlisting role="C">
2664 struct _GtkAdjustment
2666 GtkObject parent_instance;
2671 gdouble step_increment;
2672 gdouble page_increment;
2677 <para>If you don't like to poke directly at struct internals like a
2678 <emphasis>real</emphasis> C programmer, you can use the following accessor to
2679 inspect the <literal>value</literal> of an adjustment:</para>
2681 <programlisting role="C">
2682 gdouble gtk_adjustment_get_value( GtkAdjustment *adjustment);
2685 <para>Since, when you set the <literal>value</literal> of an Adjustment, you generally
2686 want the change to be reflected by every widget that uses this
2687 adjustment, GTK provides this convenience function to do this:</para>
2689 <programlisting role="C">
2690 void gtk_adjustment_set_value( GtkAdjustment *adjustment,
2694 <para>As mentioned earlier, Adjustment is a subclass of Object just
2695 like all the various widgets, and thus it is able to emit signals.
2696 This is, of course, why updates happen automagically when you share an
2697 adjustment object between a scrollbar and another adjustable widget;
2698 all adjustable widgets connect signal handlers to their adjustment's
2699 <literal>value_changed</literal> signal, as can your program. Here's the definition
2700 of this signal in <literal>struct _GtkAdjustmentClass</literal>:</para>
2702 <programlisting role="C">
2703 void (* value_changed) (GtkAdjustment *adjustment);
2706 <para>The various widgets that use the Adjustment object will emit this
2707 signal on an adjustment whenever they change its value. This happens
2708 both when user input causes the slider to move on a range widget, as
2709 well as when the program explicitly changes the value with
2710 gtk_adjustment_set_value(). So, for example, if you have a scale
2711 widget, and you want to change the rotation of a picture whenever its
2712 value changes, you would create a callback like this:</para>
2714 <programlisting role="C">
2715 void cb_rotate_picture (GtkAdjustment *adj, GtkWidget *picture)
2717 set_picture_rotation (picture, gtk_adjustment_get_value (adj));
2721 <para>and connect it to the scale widget's adjustment like this:</para>
2723 <programlisting role="C">
2724 g_signal_connect (adj, "value_changed",
2725 G_CALLBACK (cb_rotate_picture), picture);
2728 <para>What about when a widget reconfigures the <literal>upper</literal> or <literal>lower</literal>
2729 fields of its adjustment, such as when a user adds more text to a text
2730 widget? In this case, it emits the <literal>changed</literal> signal, which looks
2733 <programlisting role="C">
2734 void (* changed) (GtkAdjustment *adjustment);
2737 <para>Range widgets typically connect a handler to this signal, which
2738 changes their appearance to reflect the change - for example, the size
2739 of the slider in a scrollbar will grow or shrink in inverse proportion
2740 to the difference between the <literal>lower</literal> and <literal>upper</literal> values of its
2743 <para>You probably won't ever need to attach a handler to this signal,
2744 unless you're writing a new type of range widget. However, if you
2745 change any of the values in a Adjustment directly, you should emit
2746 this signal on it to reconfigure whatever widgets are using it, like
2749 <programlisting role="C">
2750 g_signal_emit_by_name (adjustment, "changed");
2753 <para>Now go forth and adjust!</para>
2758 <!-- ***************************************************************** -->
2759 <chapter id="ch-RangeWidgets">
2760 <title>Range Widgets</title>
2762 <para>The category of range widgets includes the ubiquitous scrollbar widget
2763 and the less common scale widget. Though these two types of widgets
2764 are generally used for different purposes, they are quite similar in
2765 function and implementation. All range widgets share a set of common
2766 graphic elements, each of which has its own X window and receives
2767 events. They all contain a "trough" and a "slider" (what is sometimes
2768 called a "thumbwheel" in other GUI environments). Dragging the slider
2769 with the pointer moves it back and forth within the trough, while
2770 clicking in the trough advances the slider towards the location of the
2771 click, either completely, or by a designated amount, depending on
2772 which mouse button is used.</para>
2774 <para>As mentioned in <link linkend="ch-Adjustments">Adjustments</link> above,
2775 all range widgets are associated with an adjustment object, from which
2776 they calculate the length of the slider and its position within the
2777 trough. When the user manipulates the slider, the range widget will
2778 change the value of the adjustment.</para>
2780 <!-- ----------------------------------------------------------------- -->
2781 <sect1 id="sec-ScrollbarWidgets">
2782 <title>Scrollbar Widgets</title>
2784 <para>These are your standard, run-of-the-mill scrollbars. These should be
2785 used only for scrolling some other widget, such as a list, a text box,
2786 or a viewport (and it's generally easier to use the scrolled window
2787 widget in most cases). For other purposes, you should use scale
2788 widgets, as they are friendlier and more featureful.</para>
2790 <para>There are separate types for horizontal and vertical scrollbars.
2791 There really isn't much to say about these. You create them with the
2792 following functions:</para>
2794 <programlisting role="C">
2795 GtkWidget *gtk_hscrollbar_new( GtkAdjustment *adjustment );
2797 GtkWidget *gtk_vscrollbar_new( GtkAdjustment *adjustment );
2800 <para>and that's about it (if you don't believe me, look in the header
2801 files!). The <literal>adjustment</literal> argument can either be a pointer to an
2802 existing Adjustment, or NULL, in which case one will be created for
2803 you. Specifying NULL might actually be useful in this case, if you
2804 wish to pass the newly-created adjustment to the constructor function
2805 of some other widget which will configure it for you, such as a text
2810 <!-- ----------------------------------------------------------------- -->
2811 <sect1 id="sec-ScaleWidgets">
2812 <title>Scale Widgets</title>
2814 <para>Scale widgets are used to allow the user to visually select and
2815 manipulate a value within a specific range. You might want to use a
2816 scale widget, for example, to adjust the magnification level on a
2817 zoomed preview of a picture, or to control the brightness of a color,
2818 or to specify the number of minutes of inactivity before a screensaver
2819 takes over the screen.</para>
2821 <!-- ----------------------------------------------------------------- -->
2823 <title>Creating a Scale Widget</title>
2825 <para>As with scrollbars, there are separate widget types for horizontal and
2826 vertical scale widgets. (Most programmers seem to favour horizontal
2827 scale widgets.) Since they work essentially the same way, there's no
2828 need to treat them separately here. The following functions create vertical and
2829 horizontal scale widgets, respectively:</para>
2831 <programlisting role="C">
2832 GtkWidget *gtk_vscale_new( GtkAdjustment *adjustment );
2834 GtkWidget *gtk_vscale_new_with_range( gdouble min,
2838 GtkWidget *gtk_hscale_new( GtkAdjustment *adjustment );
2840 GtkWidget *gtk_hscale_new_with_range( gdouble min,
2845 <para>The <literal>adjustment</literal> argument can either be an adjustment which has
2846 already been created with gtk_adjustment_new(), or NULL, in
2847 which case, an anonymous Adjustment is created with all of its
2848 values set to <literal>0.0</literal> (which isn't very useful in this case).
2849 In order to avoid confusing yourself, you probably want to create your
2850 adjustment with a <literal>page_size</literal> of <literal>0.0</literal> so
2851 that its <literal>upper</literal> value actually corresponds to the highest
2852 value the user can select. The _new_with_range()�variants take care of creating
2853 a suitable adjustment. (If you're <emphasis>already</emphasis> thoroughly
2854 confused, read the section on <link linkend="ch-Adjustments">Adjustments</link>
2855 again for an explanation of what exactly adjustments do and how to create and
2856 manipulate them.)</para>
2860 <!-- ----------------------------------------------------------------- -->
2862 <title>Functions and Signals (well, functions, at least)</title>
2864 <para>Scale widgets can display their current value as a number beside the
2865 trough. The default behaviour is to show the value, but you can change
2866 this with this function:</para>
2868 <programlisting role="C">
2869 void gtk_scale_set_draw_value( GtkScale *scale,
2870 gboolean draw_value );
2873 <para>As you might have guessed, <literal>draw_value</literal> is either <literal>TRUE</literal> or
2874 <literal>FALSE</literal>, with predictable consequences for either one.</para>
2876 <para>The value displayed by a scale widget is rounded to one decimal point
2877 by default, as is the <literal>value</literal> field in its Adjustment. You can
2878 change this with:</para>
2880 <programlisting role="C">
2881 void gtk_scale_set_digits( GtkScale *scale,
2885 <para>where <literal>digits</literal> is the number of decimal places you want. You can
2886 set <literal>digits</literal> to anything you like, but no more than 13 decimal
2887 places will actually be drawn on screen.</para>
2889 <para>Finally, the value can be drawn in different positions
2890 relative to the trough:</para>
2892 <programlisting role="C">
2893 void gtk_scale_set_value_pos( GtkScale *scale,
2894 GtkPositionType pos );
2897 <para>The argument <literal>pos</literal> is of type <literal>GtkPositionType</literal>,
2898 which can take one of the following values:</para>
2900 <programlisting role="C">
2907 <para>If you position the value on the "side" of the trough (e.g., on the
2908 top or bottom of a horizontal scale widget), then it will follow the
2909 slider up and down the trough.</para>
2911 <para>All the preceding functions are defined in
2912 <literal><gtk/gtkscale.h></literal>. The header files for all GTK widgets
2913 are automatically included when you include
2914 <literal><gtk/gtk.h></literal>. But you should look over the header files
2915 of all widgets that interest you, in order to learn more about their functions
2916 and features.</para>
2921 <!-- ----------------------------------------------------------------- -->
2922 <sect1 id="sec-CommonRangeFunctions">
2923 <title>Common Range Functions</title>
2925 <para>The Range widget class is fairly complicated internally, but, like
2926 all the "base class" widgets, most of its complexity is only
2927 interesting if you want to hack on it. Also, almost all of the
2928 functions and signals it defines are only really used in writing
2929 derived widgets. There are, however, a few useful functions that are
2930 defined in <literal><gtk/gtkrange.h></literal> and will work on all range
2933 <!-- ----------------------------------------------------------------- -->
2935 <title>Setting the Update Policy</title>
2937 <para>The "update policy" of a range widget defines at what points during
2938 user interaction it will change the <literal>value</literal> field of its
2939 Adjustment and emit the "value_changed" signal on this
2940 Adjustment. The update policies, defined in
2941 <literal><gtk/gtkenums.h></literal> as type <literal>enum GtkUpdateType</literal>,
2946 <term><literal>GTK_UPDATE_CONTINUOUS</literal></term>
2947 <listitem><para>This is the default. The
2948 "value_changed" signal is emitted continuously, i.e., whenever the
2949 slider is moved by even the tiniest amount.</para>
2953 <term><literal>GTK_UPDATE_DISCONTINUOUS</literal></term>
2954 <listitem><para>The "value_changed" signal is
2955 only emitted once the slider has stopped moving and the user has
2956 released the mouse button.</para>
2960 <term><literal>GTK_UPDATE_DELAYED</literal></term>
2961 <listitem><para>The "value_changed" signal is emitted
2962 when the user releases the mouse button, or if the slider stops moving
2963 for a short period of time.</para>
2968 <para>The update policy of a range widget can be set by casting it using the
2969 <literal>GTK_RANGE(widget)</literal> macro and passing it to this function:</para>
2971 <programlisting role="C">
2972 void gtk_range_set_update_policy( GtkRange *range,
2973 GtkUpdateType policy);
2978 <!-- ----------------------------------------------------------------- -->
2980 <title>Getting and Setting Adjustments</title>
2982 <para>Getting and setting the adjustment for a range widget "on the fly" is
2983 done, predictably, with:</para>
2985 <programlisting role="C">
2986 GtkAdjustment* gtk_range_get_adjustment( GtkRange *range );
2988 void gtk_range_set_adjustment( GtkRange *range,
2989 GtkAdjustment *adjustment );
2992 <para><literal>gtk_range_get_adjustment()</literal> returns a pointer to the adjustment to
2993 which <literal>range</literal> is connected.</para>
2995 <para><literal>gtk_range_set_adjustment()</literal> does absolutely nothing if you pass it
2996 the adjustment that <literal>range</literal> is already using, regardless of whether
2997 you changed any of its fields or not. If you pass it a new
2998 Adjustment, it will unreference the old one if it exists (possibly
2999 destroying it), connect the appropriate signals to the new one, and
3000 call the private function <literal>gtk_range_adjustment_changed()</literal>, which
3001 will (or at least, is supposed to...) recalculate the size and/or
3002 position of the slider and redraw if necessary. As mentioned in the
3003 section on adjustments, if you wish to reuse the same Adjustment,
3004 when you modify its values directly, you should emit the "changed"
3005 signal on it, like this:</para>
3007 <programlisting role="C">
3008 g_signal_emit_by_name (adjustment, "changed");
3014 <!-- ----------------------------------------------------------------- -->
3015 <sect1 id="sec-KeyAndMouseBindings">
3016 <title>Key and Mouse bindings</title>
3018 <para>All of the GTK range widgets react to mouse clicks in more or less
3019 the same way. Clicking button-1 in the trough will cause its
3020 adjustment's <literal>page_increment</literal> to be added or subtracted from its
3021 <literal>value</literal>, and the slider to be moved accordingly. Clicking mouse
3022 button-2 in the trough will jump the slider to the point at which the
3023 button was clicked. Clicking button-3 in the trough of a range or any button on
3024 a scrollbar's arrows will cause its adjustment's value to change by
3025 <literal>step_increment</literal> at a time.</para>
3027 <para>Scrollbars are not focusable, thus have no key bindings. The key bindings
3028 for the other range widgets (which are, of course, only active when the widget
3029 has focus) are do <emphasis>not</emphasis> differentiate between horizontal and
3030 vertical range widgets.</para>
3032 <para>All range widgets can be operated with the left, right, up and down arrow
3033 keys, as well as with the <literal>Page Up</literal> and <literal>Page Down</literal>
3034 keys. The arrows move the slider up and down by <literal>step_increment</literal>, while
3035 <literal>Page Up</literal> and <literal>Page Down</literal> move it by
3036 <literal>page_increment</literal>.</para>
3038 <para>The user can also move the slider all the way to one end or the other
3039 of the trough using the keyboard. This is done with the <literal>Home</literal>
3040 and <literal>End</literal> keys.</para>
3044 <!-- ----------------------------------------------------------------- -->
3045 <sect1 id="sec-RangeWidgetsExample">
3046 <title>Example</title>
3048 <para>This example is a somewhat modified version of the "range controls"
3049 test from <filename>testgtk.c</filename>. It basically puts up a window with three
3050 range widgets all connected to the same adjustment, and a couple of
3051 controls for adjusting some of the parameters mentioned above and in
3052 the section on adjustments, so you can see how they affect the way
3053 these widgets work for the user.</para>
3058 <imagedata fileref="images/rangewidgets.png" format="png">
3060 </inlinemediaobject>
3063 <programlisting role="C">
3064 <!-- example-start rangewidgets rangewidgets.c -->
3066 #include <gtk/gtk.h>
3068 GtkWidget *hscale, *vscale;
3070 static void cb_pos_menu_select( GtkWidget *item,
3071 GtkPositionType pos )
3073 /* Set the value position on both scale widgets */
3074 gtk_scale_set_value_pos (GTK_SCALE (hscale), pos);
3075 gtk_scale_set_value_pos (GTK_SCALE (vscale), pos);
3078 static void cb_update_menu_select( GtkWidget *item,
3079 GtkUpdateType policy )
3081 /* Set the update policy for both scale widgets */
3082 gtk_range_set_update_policy (GTK_RANGE (hscale), policy);
3083 gtk_range_set_update_policy (GTK_RANGE (vscale), policy);
3086 static void cb_digits_scale( GtkAdjustment *adj )
3088 /* Set the number of decimal places to which adj->value is rounded */
3089 gtk_scale_set_digits (GTK_SCALE (hscale), (gint) adj->value);
3090 gtk_scale_set_digits (GTK_SCALE (vscale), (gint) adj->value);
3093 static void cb_page_size( GtkAdjustment *get,
3094 GtkAdjustment *set )
3096 /* Set the page size and page increment size of the sample
3097 * adjustment to the value specified by the "Page Size" scale */
3098 set->page_size = get->value;
3099 set->page_increment = get->value;
3101 /* This sets the adjustment and makes it emit the "changed" signal to
3102 reconfigure all the widgets that are attached to this signal. */
3103 gtk_adjustment_set_value (set, CLAMP (set->value,
3105 (set->upper - set->page_size)));
3106 g_signal_emit_by_name(set, "changed");
3109 static void cb_draw_value( GtkToggleButton *button )
3111 /* Turn the value display on the scale widgets off or on depending
3112 * on the state of the checkbutton */
3113 gtk_scale_set_draw_value (GTK_SCALE (hscale), button->active);
3114 gtk_scale_set_draw_value (GTK_SCALE (vscale), button->active);
3117 /* Convenience functions */
3119 static GtkWidget *make_menu_item ( gchar *name,
3125 item = gtk_menu_item_new_with_label (name);
3126 g_signal_connect (item, "activate",
3127 callback, (gpointer) data);
3128 gtk_widget_show (item);
3133 static void scale_set_default_values( GtkScale *scale )
3135 gtk_range_set_update_policy (GTK_RANGE (scale),
3136 GTK_UPDATE_CONTINUOUS);
3137 gtk_scale_set_digits (scale, 1);
3138 gtk_scale_set_value_pos (scale, GTK_POS_TOP);
3139 gtk_scale_set_draw_value (scale, TRUE);
3142 /* makes the sample window */
3144 static void create_range_controls( void )
3147 GtkWidget *box1, *box2, *box3;
3149 GtkWidget *scrollbar;
3150 GtkWidget *separator;
3151 GtkWidget *opt, *menu, *item;
3154 GtkAdjustment *adj1, *adj2;
3156 /* Standard window-creating stuff */
3157 window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
3158 g_signal_connect (window, "destroy",
3159 G_CALLBACK (gtk_main_quit),
3161 gtk_window_set_title (GTK_WINDOW (window), "range controls");
3163 box1 = gtk_vbox_new (FALSE, 0);
3164 gtk_container_add (GTK_CONTAINER (window), box1);
3165 gtk_widget_show (box1);
3167 box2 = gtk_hbox_new (FALSE, 10);
3168 gtk_container_set_border_width (GTK_CONTAINER (box2), 10);
3169 gtk_box_pack_start (GTK_BOX (box1), box2, TRUE, TRUE, 0);
3170 gtk_widget_show (box2);
3172 /* value, lower, upper, step_increment, page_increment, page_size */
3173 /* Note that the page_size value only makes a difference for
3174 * scrollbar widgets, and the highest value you'll get is actually
3175 * (upper - page_size). */
3176 adj1 = gtk_adjustment_new (0.0, 0.0, 101.0, 0.1, 1.0, 1.0);
3178 vscale = gtk_vscale_new (GTK_ADJUSTMENT (adj1));
3179 scale_set_default_values (GTK_SCALE (vscale));
3180 gtk_box_pack_start (GTK_BOX (box2), vscale, TRUE, TRUE, 0);
3181 gtk_widget_show (vscale);
3183 box3 = gtk_vbox_new (FALSE, 10);
3184 gtk_box_pack_start (GTK_BOX (box2), box3, TRUE, TRUE, 0);
3185 gtk_widget_show (box3);
3187 /* Reuse the same adjustment */
3188 hscale = gtk_hscale_new (GTK_ADJUSTMENT (adj1));
3189 gtk_widget_set_size_request (GTK_WIDGET (hscale), 200, -1);
3190 scale_set_default_values (GTK_SCALE (hscale));
3191 gtk_box_pack_start (GTK_BOX (box3), hscale, TRUE, TRUE, 0);
3192 gtk_widget_show (hscale);
3194 /* Reuse the same adjustment again */
3195 scrollbar = gtk_hscrollbar_new (GTK_ADJUSTMENT (adj1));
3196 /* Notice how this causes the scales to always be updated
3197 * continuously when the scrollbar is moved */
3198 gtk_range_set_update_policy (GTK_RANGE (scrollbar),
3199 GTK_UPDATE_CONTINUOUS);
3200 gtk_box_pack_start (GTK_BOX (box3), scrollbar, TRUE, TRUE, 0);
3201 gtk_widget_show (scrollbar);
3203 box2 = gtk_hbox_new (FALSE, 10);
3204 gtk_container_set_border_width (GTK_CONTAINER (box2), 10);
3205 gtk_box_pack_start (GTK_BOX (box1), box2, TRUE, TRUE, 0);
3206 gtk_widget_show (box2);
3208 /* A checkbutton to control whether the value is displayed or not */
3209 button = gtk_check_button_new_with_label("Display value on scale widgets");
3210 gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (button), TRUE);
3211 g_signal_connect (button, "toggled",
3212 G_CALLBACK (cb_draw_value), NULL);
3213 gtk_box_pack_start (GTK_BOX (box2), button, TRUE, TRUE, 0);
3214 gtk_widget_show (button);
3216 box2 = gtk_hbox_new (FALSE, 10);
3217 gtk_container_set_border_width (GTK_CONTAINER (box2), 10);
3219 /* An option menu to change the position of the value */
3220 label = gtk_label_new ("Scale Value Position:");
3221 gtk_box_pack_start (GTK_BOX (box2), label, FALSE, FALSE, 0);
3222 gtk_widget_show (label);
3224 opt = gtk_option_menu_new ();
3225 menu = gtk_menu_new ();
3227 item = make_menu_item ("Top",
3228 G_CALLBACK (cb_pos_menu_select),
3229 GINT_TO_POINTER (GTK_POS_TOP));
3230 gtk_menu_shell_append (GTK_MENU_SHELL (menu), item);
3232 item = make_menu_item ("Bottom", G_CALLBACK (cb_pos_menu_select),
3233 GINT_TO_POINTER (GTK_POS_BOTTOM));
3234 gtk_menu_shell_append (GTK_MENU_SHELL (menu), item);
3236 item = make_menu_item ("Left", G_CALLBACK (cb_pos_menu_select),
3237 GINT_TO_POINTER (GTK_POS_LEFT));
3238 gtk_menu_shell_append (GTK_MENU_SHELL (menu), item);
3240 item = make_menu_item ("Right", G_CALLBACK (cb_pos_menu_select),
3241 GINT_TO_POINTER (GTK_POS_RIGHT));
3242 gtk_menu_shell_append (GTK_MENU_SHELL (menu), item);
3244 gtk_option_menu_set_menu (GTK_OPTION_MENU (opt), menu);
3245 gtk_box_pack_start (GTK_BOX (box2), opt, TRUE, TRUE, 0);
3246 gtk_widget_show (opt);
3248 gtk_box_pack_start (GTK_BOX (box1), box2, TRUE, TRUE, 0);
3249 gtk_widget_show (box2);
3251 box2 = gtk_hbox_new (FALSE, 10);
3252 gtk_container_set_border_width (GTK_CONTAINER (box2), 10);
3254 /* Yet another option menu, this time for the update policy of the
3256 label = gtk_label_new ("Scale Update Policy:");
3257 gtk_box_pack_start (GTK_BOX (box2), label, FALSE, FALSE, 0);
3258 gtk_widget_show (label);
3260 opt = gtk_option_menu_new ();
3261 menu = gtk_menu_new ();
3263 item = make_menu_item ("Continuous",
3264 G_CALLBACK (cb_update_menu_select),
3265 GINT_TO_POINTER (GTK_UPDATE_CONTINUOUS));
3266 gtk_menu_shell_append (GTK_MENU_SHELL (menu), item);
3268 item = make_menu_item ("Discontinuous",
3269 G_CALLBACK (cb_update_menu_select),
3270 GINT_TO_POINTER (GTK_UPDATE_DISCONTINUOUS));
3271 gtk_menu_shell_append (GTK_MENU_SHELL (menu), item);
3273 item = make_menu_item ("Delayed",
3274 G_CALLBACK (cb_update_menu_select),
3275 GINT_TO_POINTER (GTK_UPDATE_DELAYED));
3276 gtk_menu_shell_append (GTK_MENU_SHELL (menu), item);
3278 gtk_option_menu_set_menu (GTK_OPTION_MENU (opt), menu);
3279 gtk_box_pack_start (GTK_BOX (box2), opt, TRUE, TRUE, 0);
3280 gtk_widget_show (opt);
3282 gtk_box_pack_start (GTK_BOX (box1), box2, TRUE, TRUE, 0);
3283 gtk_widget_show (box2);
3285 box2 = gtk_hbox_new (FALSE, 10);
3286 gtk_container_set_border_width (GTK_CONTAINER (box2), 10);
3288 /* An HScale widget for adjusting the number of digits on the
3290 label = gtk_label_new ("Scale Digits:");
3291 gtk_box_pack_start (GTK_BOX (box2), label, FALSE, FALSE, 0);
3292 gtk_widget_show (label);
3294 adj2 = gtk_adjustment_new (1.0, 0.0, 5.0, 1.0, 1.0, 0.0);
3295 g_signal_connect (adj2, "value_changed",
3296 G_CALLBACK (cb_digits_scale), NULL);
3297 scale = gtk_hscale_new (GTK_ADJUSTMENT (adj2));
3298 gtk_scale_set_digits (GTK_SCALE (scale), 0);
3299 gtk_box_pack_start (GTK_BOX (box2), scale, TRUE, TRUE, 0);
3300 gtk_widget_show (scale);
3302 gtk_box_pack_start (GTK_BOX (box1), box2, TRUE, TRUE, 0);
3303 gtk_widget_show (box2);
3305 box2 = gtk_hbox_new (FALSE, 10);
3306 gtk_container_set_border_width (GTK_CONTAINER (box2), 10);
3308 /* And, one last HScale widget for adjusting the page size of the
3310 label = gtk_label_new ("Scrollbar Page Size:");
3311 gtk_box_pack_start (GTK_BOX (box2), label, FALSE, FALSE, 0);
3312 gtk_widget_show (label);
3314 adj2 = gtk_adjustment_new (1.0, 1.0, 101.0, 1.0, 1.0, 0.0);
3315 g_signal_connect (adj2, "value_changed",
3316 G_CALLBACK (cb_page_size), (gpointer) adj1);
3317 scale = gtk_hscale_new (GTK_ADJUSTMENT (adj2));
3318 gtk_scale_set_digits (GTK_SCALE (scale), 0);
3319 gtk_box_pack_start (GTK_BOX (box2), scale, TRUE, TRUE, 0);
3320 gtk_widget_show (scale);
3322 gtk_box_pack_start (GTK_BOX (box1), box2, TRUE, TRUE, 0);
3323 gtk_widget_show (box2);
3325 separator = gtk_hseparator_new ();
3326 gtk_box_pack_start (GTK_BOX (box1), separator, FALSE, TRUE, 0);
3327 gtk_widget_show (separator);
3329 box2 = gtk_vbox_new (FALSE, 10);
3330 gtk_container_set_border_width (GTK_CONTAINER (box2), 10);
3331 gtk_box_pack_start (GTK_BOX (box1), box2, FALSE, TRUE, 0);
3332 gtk_widget_show (box2);
3334 button = gtk_button_new_with_label ("Quit");
3335 g_signal_connect_swapped (button, "clicked",
3336 G_CALLBACK (gtk_main_quit),
3338 gtk_box_pack_start (GTK_BOX (box2), button, TRUE, TRUE, 0);
3339 gtk_widget_set_can_default (button, TRUE);
3340 gtk_widget_grab_default (button);
3341 gtk_widget_show (button);
3343 gtk_widget_show (window);
3349 gtk_init (&argc, &argv);
3351 create_range_controls ();
3358 <!-- example-end -->
3361 <para>You will notice that the program does not call g_signal_connect()
3362 for the "delete-event", but only for the "destroy" signal. This will
3363 still perform the desired function, because an unhandled
3364 "delete-event" will result in a "destroy" signal being given to the
3370 <!-- ***************************************************************** -->
3371 <chapter id="ch-MiscWidgets">
3372 <title>Miscellaneous Widgets</title>
3374 <!-- ----------------------------------------------------------------- -->
3375 <sect1 id="sec-Labels">
3376 <title>Labels</title>
3378 <para>Labels are used a lot in GTK, and are relatively simple. Labels emit
3379 no signals as they do not have an associated X window. If you need to
3380 catch signals, or do clipping, place it inside a <link linkend="sec-EventBox">
3381 EventBox</link> widget or a Button widget.</para>
3383 <para>To create a new label, use:</para>
3385 <programlisting role="C">
3386 GtkWidget *gtk_label_new( const char *str );
3388 GtkWidget *gtk_label_new_with_mnemonic( const char *str );
3391 <para>The sole argument is the string you wish the label to display.</para>
3393 <para>To change the label's text after creation, use the function:</para>
3395 <programlisting role="C">
3396 void gtk_label_set_text( GtkLabel *label,
3400 <para>The first argument is the label you created previously (cast
3401 using the <literal>GTK_LABEL()</literal> macro), and the second is the new string.</para>
3403 <para>The space needed for the new string will be automatically adjusted if
3404 needed. You can produce multi-line labels by putting line breaks in
3405 the label string.</para>
3407 <para>To retrieve the current string, use:</para>
3409 <programlisting role="C">
3410 const gchar* gtk_label_get_text( GtkLabel *label );
3413 <para>Do not free the returned string, as it is used internally by GTK.</para>
3415 <para>The label text can be justified using:</para>
3417 <programlisting role="C">
3418 void gtk_label_set_justify( GtkLabel *label,
3419 GtkJustification jtype );
3422 <para>Values for <literal>jtype</literal> are:</para>
3423 <programlisting role="C">
3426 GTK_JUSTIFY_CENTER (the default)
3430 <para>The label widget is also capable of line wrapping the text
3431 automatically. This can be activated using:</para>
3433 <programlisting role="C">
3434 void gtk_label_set_line_wrap (GtkLabel *label,
3438 <para>The <literal>wrap</literal> argument takes a TRUE or FALSE value.</para>
3440 <para>If you want your label underlined, then you can set a pattern on the
3443 <programlisting role="C">
3444 void gtk_label_set_pattern (GtkLabel *label,
3445 const gchar *pattern);
3448 <para>The pattern argument indicates how the underlining should look. It
3449 consists of a string of underscore and space characters. An underscore
3450 indicates that the corresponding character in the label should be
3451 underlined. For example, the string <literal>"__ __"</literal> would underline the
3452 first two characters and eight and ninth characters.</para>
3454 <note><para>If you simply want to have an underlined accelerator ("mnemonic")
3455 in your label, you should use gtk_label_new_with_mnemonic() or
3456 gtk_label_set_text_with_mnemonic(), not gtk_label_set_pattern().</para>
3459 <para>Below is a short example to illustrate these functions. This example
3460 makes use of the Frame widget to better demonstrate the label
3461 styles. You can ignore this for now as the <link linkend="sec-Frames">Frame</link>
3462 widget is explained later on.</para>
3464 <para>In GTK+ 2.0, label texts can contain markup for font and other text attribute
3465 changes, and labels may be selectable (for copy-and-paste). These advanced features
3466 won't be explained here.</para>
3471 <imagedata fileref="images/label.png" format="png">
3473 </inlinemediaobject>
3476 <programlisting role="C">
3477 <!-- example-start label label.c -->
3479 #include <gtk/gtk.h>
3484 static GtkWidget *window = NULL;
3490 /* Initialise GTK */
3491 gtk_init (&argc, &argv);
3493 window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
3494 g_signal_connect (window, "destroy",
3495 G_CALLBACK (gtk_main_quit),
3498 gtk_window_set_title (GTK_WINDOW (window), "Label");
3499 vbox = gtk_vbox_new (FALSE, 5);
3500 hbox = gtk_hbox_new (FALSE, 5);
3501 gtk_container_add (GTK_CONTAINER (window), hbox);
3502 gtk_box_pack_start (GTK_BOX (hbox), vbox, FALSE, FALSE, 0);
3503 gtk_container_set_border_width (GTK_CONTAINER (window), 5);
3505 frame = gtk_frame_new ("Normal Label");
3506 label = gtk_label_new ("This is a Normal label");
3507 gtk_container_add (GTK_CONTAINER (frame), label);
3508 gtk_box_pack_start (GTK_BOX (vbox), frame, FALSE, FALSE, 0);
3510 frame = gtk_frame_new ("Multi-line Label");
3511 label = gtk_label_new ("This is a Multi-line label.\nSecond line\n" \
3513 gtk_container_add (GTK_CONTAINER (frame), label);
3514 gtk_box_pack_start (GTK_BOX (vbox), frame, FALSE, FALSE, 0);
3516 frame = gtk_frame_new ("Left Justified Label");
3517 label = gtk_label_new ("This is a Left-Justified\n" \
3518 "Multi-line label.\nThird line");
3519 gtk_label_set_justify (GTK_LABEL (label), GTK_JUSTIFY_LEFT);
3520 gtk_container_add (GTK_CONTAINER (frame), label);
3521 gtk_box_pack_start (GTK_BOX (vbox), frame, FALSE, FALSE, 0);
3523 frame = gtk_frame_new ("Right Justified Label");
3524 label = gtk_label_new ("This is a Right-Justified\nMulti-line label.\n" \
3525 "Fourth line, (j/k)");
3526 gtk_label_set_justify (GTK_LABEL (label), GTK_JUSTIFY_RIGHT);
3527 gtk_container_add (GTK_CONTAINER (frame), label);
3528 gtk_box_pack_start (GTK_BOX (vbox), frame, FALSE, FALSE, 0);
3530 vbox = gtk_vbox_new (FALSE, 5);
3531 gtk_box_pack_start (GTK_BOX (hbox), vbox, FALSE, FALSE, 0);
3532 frame = gtk_frame_new ("Line wrapped label");
3533 label = gtk_label_new ("This is an example of a line-wrapped label. It " \
3534 "should not be taking up the entire " /* big space to test spacing */\
3535 "width allocated to it, but automatically " \
3536 "wraps the words to fit. " \
3537 "The time has come, for all good men, to come to " \
3538 "the aid of their party. " \
3539 "The sixth sheik's six sheep's sick.\n" \
3540 " It supports multiple paragraphs correctly, " \
3541 "and correctly adds "\
3542 "many extra spaces. ");
3543 gtk_label_set_line_wrap (GTK_LABEL (label), TRUE);
3544 gtk_container_add (GTK_CONTAINER (frame), label);
3545 gtk_box_pack_start (GTK_BOX (vbox), frame, FALSE, FALSE, 0);
3547 frame = gtk_frame_new ("Filled, wrapped label");
3548 label = gtk_label_new ("This is an example of a line-wrapped, filled label. " \
3549 "It should be taking "\
3550 "up the entire width allocated to it. " \
3551 "Here is a sentence to prove "\
3552 "my point. Here is another sentence. "\
3553 "Here comes the sun, do de do de do.\n"\
3554 " This is a new paragraph.\n"\
3555 " This is another newer, longer, better " \
3556 "paragraph. It is coming to an end, "\
3558 gtk_label_set_justify (GTK_LABEL (label), GTK_JUSTIFY_FILL);
3559 gtk_label_set_line_wrap (GTK_LABEL (label), TRUE);
3560 gtk_container_add (GTK_CONTAINER (frame), label);
3561 gtk_box_pack_start (GTK_BOX (vbox), frame, FALSE, FALSE, 0);
3563 frame = gtk_frame_new ("Underlined label");
3564 label = gtk_label_new ("This label is underlined!\n"
3565 "This one is underlined in quite a funky fashion");
3566 gtk_label_set_justify (GTK_LABEL (label), GTK_JUSTIFY_LEFT);
3567 gtk_label_set_pattern (GTK_LABEL (label),
3568 "_________________________ _ _________ _ ______ __ _______ ___");
3569 gtk_container_add (GTK_CONTAINER (frame), label);
3570 gtk_box_pack_start (GTK_BOX (vbox), frame, FALSE, FALSE, 0);
3572 gtk_widget_show_all (window);
3578 <!-- example-end -->
3583 <!-- ----------------------------------------------------------------- -->
3584 <sect1 id="sec-Arrows">
3585 <title>Arrows</title>
3587 <para>The Arrow widget draws an arrowhead, facing in a number of possible
3588 directions and having a number of possible styles. It can be very
3589 useful when placed on a button in many applications. Like the Label
3590 widget, it emits no signals.</para>
3592 <para>There are only two functions for manipulating an Arrow widget:</para>
3594 <programlisting role="C">
3595 GtkWidget *gtk_arrow_new( GtkArrowType arrow_type,
3596 GtkShadowType shadow_type );
3598 void gtk_arrow_set( GtkArrow *arrow,
3599 GtkArrowType arrow_type,
3600 GtkShadowType shadow_type );
3603 <para>The first creates a new arrow widget with the indicated type and
3604 appearance. The second allows these values to be altered
3605 retrospectively. The <literal>arrow_type</literal> argument may take one of the
3606 following values:</para>
3608 <programlisting role="C">
3615 <para>These values obviously indicate the direction in which the arrow will
3616 point. The <literal>shadow_type</literal> argument may take one of these values:</para>
3618 <programlisting role="C">
3620 GTK_SHADOW_OUT (the default)
3621 GTK_SHADOW_ETCHED_IN
3622 GTK_SHADOW_ETCHED_OUT
3625 <para>Here's a brief example to illustrate their use.</para>
3630 <imagedata fileref="images/arrow.png" format="png">
3632 </inlinemediaobject>
3635 <programlisting role="C">
3636 <!-- example-start arrow arrow.c -->
3638 #include <gtk/gtk.h>
3640 /* Create an Arrow widget with the specified parameters
3641 * and pack it into a button */
3642 static GtkWidget *create_arrow_button( GtkArrowType arrow_type,
3643 GtkShadowType shadow_type )
3648 button = gtk_button_new ();
3649 arrow = gtk_arrow_new (arrow_type, shadow_type);
3651 gtk_container_add (GTK_CONTAINER (button), arrow);
3653 gtk_widget_show (button);
3654 gtk_widget_show (arrow);
3662 /* GtkWidget is the storage type for widgets */
3667 /* Initialize the toolkit */
3668 gtk_init (&argc, &argv);
3670 /* Create a new window */
3671 window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
3673 gtk_window_set_title (GTK_WINDOW (window), "Arrow Buttons");
3675 /* It's a good idea to do this for all windows. */
3676 g_signal_connect (window, "destroy",
3677 G_CALLBACK (gtk_main_quit), NULL);
3679 /* Sets the border width of the window. */
3680 gtk_container_set_border_width (GTK_CONTAINER (window), 10);
3682 /* Create a box to hold the arrows/buttons */
3683 box = gtk_hbox_new (FALSE, 0);
3684 gtk_container_set_border_width (GTK_CONTAINER (box), 2);
3685 gtk_container_add (GTK_CONTAINER (window), box);
3687 /* Pack and show all our widgets */
3688 gtk_widget_show (box);
3690 button = create_arrow_button (GTK_ARROW_UP, GTK_SHADOW_IN);
3691 gtk_box_pack_start (GTK_BOX (box), button, FALSE, FALSE, 3);
3693 button = create_arrow_button (GTK_ARROW_DOWN, GTK_SHADOW_OUT);
3694 gtk_box_pack_start (GTK_BOX (box), button, FALSE, FALSE, 3);
3696 button = create_arrow_button (GTK_ARROW_LEFT, GTK_SHADOW_ETCHED_IN);
3697 gtk_box_pack_start (GTK_BOX (box), button, FALSE, FALSE, 3);
3699 button = create_arrow_button (GTK_ARROW_RIGHT, GTK_SHADOW_ETCHED_OUT);
3700 gtk_box_pack_start (GTK_BOX (box), button, FALSE, FALSE, 3);
3702 gtk_widget_show (window);
3704 /* Rest in gtk_main and wait for the fun to begin! */
3709 <!-- example-end -->
3714 <!-- ----------------------------------------------------------------- -->
3715 <sect1 id="sec-TheTooltipsObject">
3716 <title>The Tooltips Object</title>
3718 <para>These are the little text strings that pop up when you leave your
3719 pointer over a button or other widget for a few seconds. They are easy
3720 to use, so I will just explain them without giving an example. If you
3721 want to see some code, take a look at the <filename>testgtk.c</filename> program
3722 distributed with GTK.</para>
3724 <para>Widgets that do not receive events (widgets that do not have their
3725 own window) will not work with tooltips.</para>
3727 <para>The first call you will use creates a new tooltip. You only need to do
3728 this once for a set of tooltips as the <literal>GtkTooltips</literal> object this
3729 function returns can be used to create multiple tooltips.</para>
3731 <programlisting role="C">
3732 GtkTooltips *gtk_tooltips_new( void );
3735 <para>Once you have created a new tooltip, and the widget you wish to use it
3736 on, simply use this call to set it:</para>
3738 <programlisting role="C">
3739 void gtk_tooltips_set_tip( GtkTooltips *tooltips,
3741 const gchar *tip_text,
3742 const gchar *tip_private );
3745 <para>The first argument is the tooltip you've already created, followed by
3746 the widget you wish to have this tooltip pop up for, and the text you
3747 wish it to say. The last argument is a text string that can be used as
3748 an identifier when using GtkTipsQuery to implement context sensitive
3749 help. For now, you can set it to NULL.</para>
3751 <!-- TODO: sort out what how to do the context sensitive help -->
3753 <para>Here's a short example:</para>
3755 <programlisting role="C">
3756 GtkTooltips *tooltips;
3761 tooltips = gtk_tooltips_new ();
3762 button = gtk_button_new_with_label ("button 1");
3766 gtk_tooltips_set_tip (tooltips, button, "This is button 1", NULL);
3769 <para>There are other calls that can be used with tooltips. I will just list
3770 them with a brief description of what they do.</para>
3772 <programlisting role="C">
3773 void gtk_tooltips_enable( GtkTooltips *tooltips );
3776 <para>Enable a disabled set of tooltips.</para>
3778 <programlisting role="C">
3779 void gtk_tooltips_disable( GtkTooltips *tooltips );
3782 <para>Disable an enabled set of tooltips.</para>
3784 <para>And that's all the functions associated with tooltips. More than
3785 you'll ever want to know :-)</para>
3789 <!-- ----------------------------------------------------------------- -->
3790 <sect1 id="sec-ProgressBars">
3791 <title>Progress Bars</title>
3793 <para>Progress bars are used to show the status of an operation. They are
3794 pretty easy to use, as you will see with the code below. But first
3795 lets start out with the calls to create a new progress bar.</para>
3797 <programlisting role="C">
3798 GtkWidget *gtk_progress_bar_new( void );
3801 <para>Now that the progress bar has been created we can use it.</para>
3803 <programlisting role="C">
3804 void gtk_progress_bar_set_fraction ( GtkProgressBar *pbar,
3808 <para>The first argument is the progress bar you wish to operate on, and the
3809 second argument is the amount "completed", meaning the amount the
3810 progress bar has been filled from 0-100%. This is passed to the
3811 function as a real number ranging from 0 to 1.</para>
3813 <para>GTK v1.2 has added new functionality to the progress bar that enables
3814 it to display its value in different ways, and to inform the user of
3815 its current value and its range.</para>
3817 <para>A progress bar may be set to one of a number of orientations using the
3820 <programlisting role="C">
3821 void gtk_progress_bar_set_orientation( GtkProgressBar *pbar,
3822 GtkProgressBarOrientation orientation );
3825 <para>The <literal>orientation</literal> argument may take one of the following
3826 values to indicate the direction in which the progress bar moves:</para>
3828 <programlisting role="C">
3829 GTK_PROGRESS_LEFT_TO_RIGHT
3830 GTK_PROGRESS_RIGHT_TO_LEFT
3831 GTK_PROGRESS_BOTTOM_TO_TOP
3832 GTK_PROGRESS_TOP_TO_BOTTOM
3835 <para>As well as indicating the amount of progress that has occured, the
3836 progress bar may be set to just indicate that there is some activity.
3837 This can be useful in situations where progress cannot be measured against
3838 a value range. The following function indicates that some progress has been
3841 <programlisting role="C">
3842 void gtk_progress_bar_pulse ( GtkProgressBar *progress );
3845 <para>The step size of the activity indicator is set using the following
3848 <programlisting role="C">
3849 void gtk_progress_bar_set_pulse_step( GtkProgressBar *pbar,
3853 <para>When not in activity mode, the progress bar can also display a
3854 configurable text string within its trough, using the following
3857 <programlisting role="C">
3858 void gtk_progress_bar_set_text( GtkProgressBar *progress,
3859 const gchar *text );
3862 <note><para>Note that gtk_progress_set_text() doesn't support the printf()-like formatting
3863 of the GTK+ 1.2 Progressbar.</para></note>
3865 <para>You can turn off the display of the string by calling gtk_progess_bar_set_text()
3866 again with NULL as second argument.</para>
3868 <para>The current text setting of a progressbar can be retrieved with the
3869 following function. Do not free the returned string.</para>
3871 <programlisting role="C">
3872 const gchar *gtk_progress_bar_get_text( GtkProgressBar *pbar );
3875 <para>Progress Bars are usually used with timeouts or other such functions
3876 (see section on <link linkend="ch-Timeouts">Timeouts, I/O and Idle Functions</link>)
3877 to give the illusion of multitasking. All will employ the
3878 gtk_progress_bar_set_fraction() or gtk_progress_bar_pulse() functions in the
3881 <para>Here is an example of the progress bar, updated using timeouts. This
3882 code also shows you how to reset the Progress Bar.</para>
3887 <imagedata fileref="images/progressbar.png" format="png">
3889 </inlinemediaobject>
3892 <programlisting role="C">
3893 <!-- example-start progressbar progressbar.c -->
3895 #include <gtk/gtk.h>
3897 typedef struct _ProgressData {
3901 gboolean activity_mode;
3904 /* Update the value of the progress bar so that we get
3906 static gboolean progress_timeout( gpointer data )
3908 ProgressData *pdata = (ProgressData *)data;
3911 if (pdata->activity_mode)
3912 gtk_progress_bar_pulse (GTK_PROGRESS_BAR (pdata->pbar));
3915 /* Calculate the value of the progress bar using the
3916 * value range set in the adjustment object */
3918 new_val = gtk_progress_bar_get_fraction (GTK_PROGRESS_BAR (pdata->pbar)) + 0.01;
3920 if (new_val > 1.0)
3923 /* Set the new value */
3924 gtk_progress_bar_set_fraction (GTK_PROGRESS_BAR (pdata->pbar), new_val);
3927 /* As this is a timeout function, return TRUE so that it
3928 * continues to get called */
3932 /* Callback that toggles the text display within the progress bar trough */
3933 static void toggle_show_text( GtkWidget *widget,
3934 ProgressData *pdata )
3938 text = gtk_progress_bar_get_text (GTK_PROGRESS_BAR (pdata->pbar));
3939 if (text && *text)
3940 gtk_progress_bar_set_text (GTK_PROGRESS_BAR (pdata->pbar), "");
3942 gtk_progress_bar_set_text (GTK_PROGRESS_BAR (pdata->pbar), "some text");
3945 /* Callback that toggles the activity mode of the progress bar */
3946 static void toggle_activity_mode( GtkWidget *widget,
3947 ProgressData *pdata )
3949 pdata->activity_mode = !pdata->activity_mode;
3950 if (pdata->activity_mode)
3951 gtk_progress_bar_pulse (GTK_PROGRESS_BAR (pdata->pbar));
3953 gtk_progress_bar_set_fraction (GTK_PROGRESS_BAR (pdata->pbar), 0.0);
3957 /* Callback that toggles the orientation of the progress bar */
3958 static void toggle_orientation( GtkWidget *widget,
3959 ProgressData *pdata )
3961 switch (gtk_progress_bar_get_orientation (GTK_PROGRESS_BAR (pdata->pbar))) {
3962 case GTK_PROGRESS_LEFT_TO_RIGHT:
3963 gtk_progress_bar_set_orientation (GTK_PROGRESS_BAR (pdata->pbar),
3964 GTK_PROGRESS_RIGHT_TO_LEFT);
3966 case GTK_PROGRESS_RIGHT_TO_LEFT:
3967 gtk_progress_bar_set_orientation (GTK_PROGRESS_BAR (pdata->pbar),
3968 GTK_PROGRESS_LEFT_TO_RIGHT);
3976 /* Clean up allocated memory and remove the timer */
3977 static void destroy_progress( GtkWidget *widget,
3978 ProgressData *pdata)
3980 g_source_remove (pdata->timer);
3981 pdata->timer = 0;
3982 pdata->window = NULL;
3990 ProgressData *pdata;
3992 GtkWidget *separator;
3998 gtk_init (&argc, &argv);
4000 /* Allocate memory for the data that is passed to the callbacks */
4001 pdata = g_malloc (sizeof (ProgressData));
4003 pdata->window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
4004 gtk_window_set_resizable (GTK_WINDOW (pdata->window), TRUE);
4006 g_signal_connect (pdata->window, "destroy",
4007 G_CALLBACK (destroy_progress),
4009 gtk_window_set_title (GTK_WINDOW (pdata->window), "GtkProgressBar");
4010 gtk_container_set_border_width (GTK_CONTAINER (pdata->window), 0);
4012 vbox = gtk_vbox_new (FALSE, 5);
4013 gtk_container_set_border_width (GTK_CONTAINER (vbox), 10);
4014 gtk_container_add (GTK_CONTAINER (pdata->window), vbox);
4015 gtk_widget_show (vbox);
4017 /* Create a centering alignment object */
4018 align = gtk_alignment_new (0.5, 0.5, 0, 0);
4019 gtk_box_pack_start (GTK_BOX (vbox), align, FALSE, FALSE, 5);
4020 gtk_widget_show (align);
4022 /* Create the GtkProgressBar */
4023 pdata->pbar = gtk_progress_bar_new ();
4024 pdata->activity_mode = FALSE;
4026 gtk_container_add (GTK_CONTAINER (align), pdata->pbar);
4027 gtk_widget_show (pdata->pbar);
4029 /* Add a timer callback to update the value of the progress bar */
4030 pdata->timer = g_timeout_add (100, progress_timeout, pdata);
4032 separator = gtk_hseparator_new ();
4033 gtk_box_pack_start (GTK_BOX (vbox), separator, FALSE, FALSE, 0);
4034 gtk_widget_show (separator);
4036 /* rows, columns, homogeneous */
4037 table = gtk_table_new (2, 3, FALSE);
4038 gtk_box_pack_start (GTK_BOX (vbox), table, FALSE, TRUE, 0);
4039 gtk_widget_show (table);
4041 /* Add a check button to select displaying of the trough text */
4042 check = gtk_check_button_new_with_label ("Show text");
4043 gtk_table_attach (GTK_TABLE (table), check, 0, 1, 0, 1,
4044 GTK_EXPAND | GTK_FILL, GTK_EXPAND | GTK_FILL,
4046 g_signal_connect (check, "clicked",
4047 G_CALLBACK (toggle_show_text),
4049 gtk_widget_show (check);
4051 /* Add a check button to toggle activity mode */
4052 check = gtk_check_button_new_with_label ("Activity mode");
4053 gtk_table_attach (GTK_TABLE (table), check, 0, 1, 1, 2,
4054 GTK_EXPAND | GTK_FILL, GTK_EXPAND | GTK_FILL,
4056 g_signal_connect (check, "clicked",
4057 G_CALLBACK (toggle_activity_mode),
4059 gtk_widget_show (check);
4061 /* Add a check button to toggle orientation */
4062 check = gtk_check_button_new_with_label ("Right to Left");
4063 gtk_table_attach (GTK_TABLE (table), check, 0, 1, 2, 3,
4064 GTK_EXPAND | GTK_FILL, GTK_EXPAND | GTK_FILL,
4066 g_signal_connect (check, "clicked",
4067 G_CALLBACK (toggle_orientation),
4069 gtk_widget_show (check);
4071 /* Add a button to exit the program */
4072 button = gtk_button_new_with_label ("close");
4073 g_signal_connect_swapped (button, "clicked",
4074 G_CALLBACK (gtk_widget_destroy),
4076 gtk_box_pack_start (GTK_BOX (vbox), button, FALSE, FALSE, 0);
4078 /* This makes it so the button is the default. */
4079 gtk_widget_set_can_default (button, TRUE);
4081 /* This grabs this button to be the default button. Simply hitting
4082 * the "Enter" key will cause this button to activate. */
4083 gtk_widget_grab_default (button);
4084 gtk_widget_show (button);
4086 gtk_widget_show (pdata->window);
4092 <!-- example-end -->
4097 <!-- ----------------------------------------------------------------- -->
4098 <sect1 id="sec-Dialogs">
4099 <title>Dialogs</title>
4101 <para>The Dialog widget is very simple, and is actually just a window with a
4102 few things pre-packed into it for you. The structure for a Dialog is:</para>
4104 <programlisting role="C">
4110 GtkWidget *action_area;
4114 <para>So you see, it simply creates a window, and then packs a vbox into the
4115 top, which contains a separator and then an hbox called the
4116 "action_area".</para>
4118 <para>The Dialog widget can be used for pop-up messages to the user, and
4119 other similar tasks. There are two functions to create a new Dialog.</para>
4121 <programlisting role="C">
4122 GtkWidget *gtk_dialog_new( void );
4124 GtkWidget *gtk_dialog_new_with_buttons( const gchar *title,
4126 GtkDialogFlags flags,
4127 const gchar *first_button_text,
4131 <para>The first function will create an empty dialog, and it is now up to you to use
4132 it. You could pack a button in the action_area by doing something like this:</para>
4134 <programlisting role="C">
4136 gtk_box_pack_start (GTK_BOX (GTK_DIALOG (window)->action_area),
4137 button, TRUE, TRUE, 0);
4138 gtk_widget_show (button);
4141 <para>And you could add to the vbox area by packing, for instance, a label
4142 in it, try something like this:</para>
4144 <programlisting role="C">
4145 label = gtk_label_new ("Dialogs are groovy");
4146 gtk_box_pack_start (GTK_BOX (GTK_DIALOG (window)->vbox),
4147 label, TRUE, TRUE, 0);
4148 gtk_widget_show (label);
4151 <para>As an example in using the dialog box, you could put two buttons in
4152 the action_area, a Cancel button and an Ok button, and a label in the
4153 vbox area, asking the user a question or giving an error etc. Then
4154 you could attach a different signal to each of the buttons and perform
4155 the operation the user selects.</para>
4157 <para>If the simple functionality provided by the default vertical and
4158 horizontal boxes in the two areas doesn't give you enough control for
4159 your application, then you can simply pack another layout widget into
4160 the boxes provided. For example, you could pack a table into the
4161 vertical box.</para>
4163 <para>The more complicated _new_with_buttons() variant allows to set one or
4164 more of the following flags.</para>
4168 <term><literal>GTK_DIALOG_MODAL</literal></term>
4169 <listitem><para>make the dialog modal.
4173 <term><literal>GTK_DIALOG_DESTROY_WITH_PARENT</literal></term>
4174 <listitem><para>ensures that the dialog window is destroyed together with the specified
4175 parent.</para></listitem>
4178 <term><literal>GTK_DIALOG_NO_SEPARATOR</literal></term>
4179 <listitem><para>omits the separator between the vbox and the action_area.
4185 <!-- ----------------------------------------------------------------- -->
4186 <sect1 id="sec-Rulers">
4187 <title>Rulers</title>
4189 <para>Ruler widgets are used to indicate the location of the mouse pointer
4190 in a given window. A window can have a vertical ruler spanning across
4191 the height and a horizontal ruler spanning down the width. A small
4192 triangular indicator on the ruler shows the exact location of the
4193 pointer relative to the ruler.</para>
4195 <para>A ruler must first be created. Horizontal and vertical rulers are
4196 created using</para>
4198 <programlisting role="C">
4199 GtkWidget *gtk_hruler_new( void ); /* horizontal ruler */
4201 GtkWidget *gtk_vruler_new( void ); /* vertical ruler */
4204 <para>Once a ruler is created, we can define the unit of measurement. Units
4205 of measure for rulers can be <literal>GTK_PIXELS</literal>, <literal>GTK_INCHES</literal> or
4206 <literal>GTK_CENTIMETERS</literal>. This is set using</para>
4208 <programlisting role="C">
4209 void gtk_ruler_set_metric( GtkRuler *ruler,
4210 GtkMetricType metric );
4213 <para>The default measure is <literal>GTK_PIXELS</literal>.</para>
4215 <programlisting role="C">
4216 gtk_ruler_set_metric( GTK_RULER(ruler), GTK_PIXELS );
4219 <para>Other important characteristics of a ruler are how to mark the units
4220 of scale and where the position indicator is initially placed. These
4221 are set for a ruler using</para>
4223 <programlisting role="C">
4224 void gtk_ruler_set_range( GtkRuler *ruler,
4231 <para>The lower and upper arguments define the extent of the ruler, and
4232 max_size is the largest possible number that will be displayed.
4233 Position defines the initial position of the pointer indicator within
4236 <para>A vertical ruler can span an 800 pixel wide window thus</para>
4238 <programlisting role="C">
4239 gtk_ruler_set_range( GTK_RULER(vruler), 0, 800, 0, 800);
4242 <para>The markings displayed on the ruler will be from 0 to 800, with a
4243 number for every 100 pixels. If instead we wanted the ruler to range
4244 from 7 to 16, we would code</para>
4246 <programlisting role="C">
4247 gtk_ruler_set_range( GTK_RULER(vruler), 7, 16, 0, 20);
4250 <para>The indicator on the ruler is a small triangular mark that indicates
4251 the position of the pointer relative to the ruler. If the ruler is
4252 used to follow the mouse pointer, the motion_notify_event signal
4253 should be connected to the motion_notify_event method of the ruler.
4254 To follow all mouse movements within a window area, we would use</para>
4256 <programlisting role="C">
4257 #define EVENT_METHOD(i, x) GTK_WIDGET_GET_CLASS(i)->x
4259 g_signal_connect_swapped (area, "motion_notify_event",
4260 G_CALLBACK (EVENT_METHOD (ruler, motion_notify_event)),
4264 <para>The following example creates a drawing area with a horizontal ruler
4265 above it and a vertical ruler to the left of it. The size of the
4266 drawing area is 600 pixels wide by 400 pixels high. The horizontal
4267 ruler spans from 7 to 13 with a mark every 100 pixels, while the
4268 vertical ruler spans from 0 to 400 with a mark every 100 pixels.
4269 Placement of the drawing area and the rulers is done using a table.</para>
4274 <imagedata fileref="images/rulers.png" format="png">
4276 </inlinemediaobject>
4279 <programlisting role="C">
4280 <!-- example-start rulers rulers.c -->
4282 #include <gtk/gtk.h>
4284 #define EVENT_METHOD(i, x) GTK_WIDGET_GET_CLASS(i)->x
4289 /* This routine gets control when the close button is clicked */
4290 static gboolean close_application( GtkWidget *widget,
4298 /* The main routine */
4301 GtkWidget *window, *table, *area, *hrule, *vrule;
4303 /* Initialize GTK and create the main window */
4304 gtk_init (&argc, &argv);
4306 window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
4307 g_signal_connect (window, "delete-event",
4308 G_CALLBACK (close_application), NULL);
4309 gtk_container_set_border_width (GTK_CONTAINER (window), 10);
4311 /* Create a table for placing the ruler and the drawing area */
4312 table = gtk_table_new (3, 2, FALSE);
4313 gtk_container_add (GTK_CONTAINER (window), table);
4315 area = gtk_drawing_area_new ();
4316 gtk_widget_set_size_request (GTK_WIDGET (area), XSIZE, YSIZE);
4317 gtk_table_attach (GTK_TABLE (table), area, 1, 2, 1, 2,
4318 GTK_EXPAND|GTK_FILL, GTK_FILL, 0, 0);
4319 gtk_widget_set_events (area, GDK_POINTER_MOTION_MASK |
4320 GDK_POINTER_MOTION_HINT_MASK);
4322 /* The horizontal ruler goes on top. As the mouse moves across the
4323 * drawing area, a motion_notify_event is passed to the
4324 * appropriate event handler for the ruler. */
4325 hrule = gtk_hruler_new ();
4326 gtk_ruler_set_metric (GTK_RULER (hrule), GTK_PIXELS);
4327 gtk_ruler_set_range (GTK_RULER (hrule), 7, 13, 0, 20);
4328 g_signal_connect_swapped (area, "motion_notify_event",
4329 G_CALLBACK (EVENT_METHOD (hrule, motion_notify_event)),
4331 gtk_table_attach (GTK_TABLE (table), hrule, 1, 2, 0, 1,
4332 GTK_EXPAND|GTK_SHRINK|GTK_FILL, GTK_FILL, 0, 0);
4334 /* The vertical ruler goes on the left. As the mouse moves across
4335 * the drawing area, a motion_notify_event is passed to the
4336 * appropriate event handler for the ruler. */
4337 vrule = gtk_vruler_new ();
4338 gtk_ruler_set_metric (GTK_RULER (vrule), GTK_PIXELS);
4339 gtk_ruler_set_range (GTK_RULER (vrule), 0, YSIZE, 10, YSIZE );
4340 g_signal_connect_swapped (area, "motion_notify_event",
4341 G_CALLBACK (EVENT_METHOD (vrule, motion_notify_event)),
4343 gtk_table_attach (GTK_TABLE (table), vrule, 0, 1, 1, 2,
4344 GTK_FILL, GTK_EXPAND|GTK_SHRINK|GTK_FILL, 0, 0);
4346 /* Now show everything */
4347 gtk_widget_show (area);
4348 gtk_widget_show (hrule);
4349 gtk_widget_show (vrule);
4350 gtk_widget_show (table);
4351 gtk_widget_show (window);
4356 <!-- example-end -->
4361 <!-- ----------------------------------------------------------------- -->
4362 <sect1 id="sec-Statusbars">
4363 <title>Statusbars</title>
4365 <para>Statusbars are simple widgets used to display a text message. They
4366 keep a stack of the messages pushed onto them, so that popping the
4367 current message will re-display the previous text message.</para>
4369 <para>In order to allow different parts of an application to use the same
4370 statusbar to display messages, the statusbar widget issues Context
4371 Identifiers which are used to identify different "users". The message
4372 on top of the stack is the one displayed, no matter what context it is
4373 in. Messages are stacked in last-in-first-out order, not context
4374 identifier order.</para>
4376 <para>A statusbar is created with a call to:</para>
4378 <programlisting role="C">
4379 GtkWidget *gtk_statusbar_new( void );
4382 <para>A new Context Identifier is requested using a call to the following
4383 function with a short textual description of the context:</para>
4385 <programlisting role="C">
4386 guint gtk_statusbar_get_context_id( GtkStatusbar *statusbar,
4387 const gchar *context_description );
4390 <para>There are three functions that can operate on statusbars:</para>
4392 <programlisting role="C">
4393 guint gtk_statusbar_push( GtkStatusbar *statusbar,
4395 const gchar *text );
4397 void gtk_statusbar_pop( GtkStatusbar *statusbar)
4400 void gtk_statusbar_remove( GtkStatusbar *statusbar,
4405 <para>The first, gtk_statusbar_push(), is used to add a new message to the
4406 statusbar. It returns a Message Identifier, which can be passed later
4407 to the function gtk_statusbar_remove to remove the message with the
4408 given Message and Context Identifiers from the statusbar's stack.</para>
4410 <para>The function gtk_statusbar_pop() removes the message highest in the
4411 stack with the given Context Identifier.</para>
4413 <para>In addition to messages, statusbars may also display a resize grip, which
4414 can be dragged with the mouse to resize the toplevel window containing the statusbar,
4415 similar to dragging the window frame. The following functions control the display
4416 of the resize grip.</para>
4418 <programlisting role="C">
4419 void gtk_statusbar_set_has_resize_grip( GtkStatusbar *statusbar,
4422 gboolean gtk_statusbar_get_has_resize_grip( GtkStatusbar *statusbar );
4425 <para>The following example creates a statusbar and two buttons, one for
4426 pushing items onto the statusbar, and one for popping the last item
4432 <imagedata fileref="images/statusbar.png" format="png">
4434 </inlinemediaobject>
4437 <programlisting role="C">
4438 <!-- example-start statusbar statusbar.c -->
4440 #include <stdlib.h>
4441 #include <gtk/gtk.h>
4442 #include <glib.h>
4444 GtkWidget *status_bar;
4446 static void push_item( GtkWidget *widget,
4449 static int count = 1;
4452 buff = g_strdup_printf ("Item %d", count++);
4453 gtk_statusbar_push (GTK_STATUSBAR (status_bar), GPOINTER_TO_INT (data), buff);
4457 static void pop_item( GtkWidget *widget,
4460 gtk_statusbar_pop (GTK_STATUSBAR (status_bar), GPOINTER_TO_INT (data));
4473 gtk_init (&argc, &argv);
4475 /* create a new window */
4476 window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
4477 gtk_widget_set_size_request (GTK_WIDGET (window), 200, 100);
4478 gtk_window_set_title (GTK_WINDOW (window), "GTK Statusbar Example");
4479 g_signal_connect (window, "delete-event",
4480 G_CALLBACK (exit), NULL);
4482 vbox = gtk_vbox_new (FALSE, 1);
4483 gtk_container_add (GTK_CONTAINER (window), vbox);
4484 gtk_widget_show (vbox);
4486 status_bar = gtk_statusbar_new ();
4487 gtk_box_pack_start (GTK_BOX (vbox), status_bar, TRUE, TRUE, 0);
4488 gtk_widget_show (status_bar);
4490 context_id = gtk_statusbar_get_context_id(
4491 GTK_STATUSBAR (status_bar), "Statusbar example");
4493 button = gtk_button_new_with_label ("push item");
4494 g_signal_connect (button, "clicked",
4495 G_CALLBACK (push_item), GINT_TO_POINTER (context_id));
4496 gtk_box_pack_start (GTK_BOX (vbox), button, TRUE, TRUE, 2);
4497 gtk_widget_show (button);
4499 button = gtk_button_new_with_label ("pop last item");
4500 g_signal_connect (button, "clicked",
4501 G_CALLBACK (pop_item), GINT_TO_POINTER (context_id));
4502 gtk_box_pack_start (GTK_BOX (vbox), button, TRUE, TRUE, 2);
4503 gtk_widget_show (button);
4505 /* always display the window as the last step so it all splashes on
4506 * the screen at once. */
4507 gtk_widget_show (window);
4513 <!-- example-end -->
4518 <!-- ----------------------------------------------------------------- -->
4519 <sect1 id="sec-TextEntries">
4520 <title>Text Entries</title>
4522 <para>The Entry widget allows text to be typed and displayed in a single line
4523 text box. The text may be set with function calls that allow new text
4524 to replace, prepend or append the current contents of the Entry widget.</para>
4526 <para>Create a new Entry widget with the following function.</para>
4528 <programlisting role="C">
4529 GtkWidget *gtk_entry_new( void );
4532 <para>The next function alters the text which is currently
4533 within the Entry widget.</para>
4535 <programlisting role="C">
4536 void gtk_entry_set_text( GtkEntry *entry,
4537 const gchar *text );
4540 <para>The function gtk_entry_set_text() sets the contents of the Entry widget,
4541 replacing the current contents. Note that the class Entry implements the Editable
4542 interface (yes, gobject supports Java-like interfaces) which contains some more
4543 functions for manipulating the contents.
4546 <para>The contents of the Entry can be retrieved by using a call to the
4547 following function. This is useful in the callback functions described below.</para>
4549 <programlisting role="C">
4550 const gchar *gtk_entry_get_text( GtkEntry *entry );
4553 <para>The value returned by this function is used internally, and must not
4554 be freed using either free() or g_free().</para>
4556 <para>If we don't want the contents of the Entry to be changed by someone typing
4557 into it, we can change its editable state.</para>
4559 <programlisting role="C">
4560 void gtk_editable_set_editable( GtkEditable *entry,
4561 gboolean editable );
4564 <para>The function above allows us to toggle the editable state of the
4565 Entry widget by passing in a TRUE or FALSE value for the <literal>editable</literal>
4568 <para>If we are using the Entry where we don't want the text entered to be
4569 visible, for example when a password is being entered, we can use the
4570 following function, which also takes a boolean flag.</para>
4572 <programlisting role="C">
4573 void gtk_entry_set_visibility( GtkEntry *entry,
4577 <para>A region of the text may be set as selected by using the following
4578 function. This would most often be used after setting some default
4579 text in an Entry, making it easy for the user to remove it.</para>
4581 <programlisting role="C">
4582 void gtk_editable_select_region( GtkEditable *entry,
4587 <para>If we want to catch when the user has entered text, we can connect to
4588 the <literal>activate</literal> or <literal>changed</literal> signal. Activate is raised when the
4589 user hits the enter key within the Entry widget. Changed is raised
4590 when the text changes at all, e.g., for every character entered or
4593 <para>The following code is an example of using an Entry widget.</para>
4598 <imagedata fileref="images/entry.png" format="png">
4600 </inlinemediaobject>
4603 <programlisting role="C">
4604 <!-- example-start entry entry.c -->
4606 #include <stdio.h>
4607 #include <stdlib.h>
4608 #include <gtk/gtk.h>
4610 static void enter_callback( GtkWidget *widget,
4613 const gchar *entry_text;
4614 entry_text = gtk_entry_get_text (GTK_ENTRY (entry));
4615 printf ("Entry contents: %s\n", entry_text);
4618 static void entry_toggle_editable( GtkWidget *checkbutton,
4621 gtk_editable_set_editable (GTK_EDITABLE (entry),
4622 GTK_TOGGLE_BUTTON (checkbutton)->active);
4625 static void entry_toggle_visibility( GtkWidget *checkbutton,
4628 gtk_entry_set_visibility (GTK_ENTRY (entry),
4629 GTK_TOGGLE_BUTTON (checkbutton)->active);
4637 GtkWidget *vbox, *hbox;
4643 gtk_init (&argc, &argv);
4645 /* create a new window */
4646 window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
4647 gtk_widget_set_size_request (GTK_WIDGET (window), 200, 100);
4648 gtk_window_set_title (GTK_WINDOW (window), "GTK Entry");
4649 g_signal_connect (window, "destroy",
4650 G_CALLBACK (gtk_main_quit), NULL);
4651 g_signal_connect_swapped (window, "delete-event",
4652 G_CALLBACK (gtk_widget_destroy),
4655 vbox = gtk_vbox_new (FALSE, 0);
4656 gtk_container_add (GTK_CONTAINER (window), vbox);
4657 gtk_widget_show (vbox);
4659 entry = gtk_entry_new ();
4660 gtk_entry_set_max_length (GTK_ENTRY (entry), 50);
4661 g_signal_connect (entry, "activate",
4662 G_CALLBACK (enter_callback),
4664 gtk_entry_set_text (GTK_ENTRY (entry), "hello");
4665 tmp_pos = GTK_ENTRY (entry)->text_length;
4666 gtk_editable_insert_text (GTK_EDITABLE (entry), " world", -1, &tmp_pos);
4667 gtk_editable_select_region (GTK_EDITABLE (entry),
4668 0, GTK_ENTRY (entry)->text_length);
4669 gtk_box_pack_start (GTK_BOX (vbox), entry, TRUE, TRUE, 0);
4670 gtk_widget_show (entry);
4672 hbox = gtk_hbox_new (FALSE, 0);
4673 gtk_container_add (GTK_CONTAINER (vbox), hbox);
4674 gtk_widget_show (hbox);
4676 check = gtk_check_button_new_with_label ("Editable");
4677 gtk_box_pack_start (GTK_BOX (hbox), check, TRUE, TRUE, 0);
4678 g_signal_connect (check, "toggled",
4679 G_CALLBACK (entry_toggle_editable), entry);
4680 gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (check), TRUE);
4681 gtk_widget_show (check);
4683 check = gtk_check_button_new_with_label ("Visible");
4684 gtk_box_pack_start (GTK_BOX (hbox), check, TRUE, TRUE, 0);
4685 g_signal_connect (check, "toggled",
4686 G_CALLBACK (entry_toggle_visibility), entry);
4687 gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (check), TRUE);
4688 gtk_widget_show (check);
4690 button = gtk_button_new_from_stock (GTK_STOCK_CLOSE);
4691 g_signal_connect_swapped (button, "clicked",
4692 G_CALLBACK (gtk_widget_destroy),
4694 gtk_box_pack_start (GTK_BOX (vbox), button, TRUE, TRUE, 0);
4695 gtk_widget_set_can_default (button, TRUE);
4696 gtk_widget_grab_default (button);
4697 gtk_widget_show (button);
4699 gtk_widget_show (window);
4705 <!-- example-end -->
4710 <!-- ----------------------------------------------------------------- -->
4711 <sect1 id="sec-SpinButtons">
4712 <title>Spin Buttons</title>
4714 <para>The Spin Button widget is generally used to allow the user to select a
4715 value from a range of numeric values. It consists of a text
4716 entry box with up and down arrow buttons attached to the
4717 side. Selecting one of the buttons causes the value to "spin" up and
4718 down the range of possible values. The entry box may also be edited
4719 directly to enter a specific value.</para>
4721 <para>The Spin Button allows the value to have zero or a number of decimal
4722 places and to be incremented/decremented in configurable steps. The
4723 action of holding down one of the buttons optionally results in an
4724 acceleration of change in the value according to how long it is
4727 <para>The Spin Button uses an <link linkend="ch-Adjustments">Adjustment</link>
4728 object to hold information about the range of values that the spin
4729 button can take. This makes for a powerful Spin Button widget.</para>
4731 <para>Recall that an adjustment widget is created with the following
4732 function, which illustrates the information that it holds:</para>
4734 <programlisting role="C">
4735 GtkAdjustment *gtk_adjustment_new( gdouble value,
4738 gdouble step_increment,
4739 gdouble page_increment,
4740 gdouble page_size );
4743 <para>These attributes of an Adjustment are used by the Spin Button in the
4744 following way:</para>
4747 <listitem><simpara> <literal>value</literal>: initial value for the Spin Button</simpara>
4749 <listitem><simpara> <literal>lower</literal>: lower range value</simpara>
4751 <listitem><simpara> <literal>upper</literal>: upper range value</simpara>
4753 <listitem><simpara> <literal>step_increment</literal>: value to increment/decrement when pressing
4754 mouse button 1 on a button</simpara>
4756 <listitem><simpara> <literal>page_increment</literal>: value to increment/decrement when pressing
4757 mouse button 2 on a button</simpara>
4759 <listitem><simpara> <literal>page_size</literal>: unused</simpara>
4763 <para>Additionally, mouse button 3 can be used to jump directly to the
4764 <literal>upper</literal> or <literal>lower</literal> values when used to select one of the
4765 buttons. Lets look at how to create a Spin Button:</para>
4767 <programlisting role="C">
4768 GtkWidget *gtk_spin_button_new( GtkAdjustment *adjustment,
4773 <para>The <literal>climb_rate</literal> argument take a value between 0.0 and 1.0 and
4774 indicates the amount of acceleration that the Spin Button has. The
4775 <literal>digits</literal> argument specifies the number of decimal places to which
4776 the value will be displayed.</para>
4778 <para>A Spin Button can be reconfigured after creation using the following
4781 <programlisting role="C">
4782 void gtk_spin_button_configure( GtkSpinButton *spin_button,
4783 GtkAdjustment *adjustment,
4788 <para>The <literal>spin_button</literal> argument specifies the Spin Button widget that is
4789 to be reconfigured. The other arguments are as specified above.</para>
4791 <para>The adjustment can be set and retrieved independantly using the
4792 following two functions:</para>
4794 <programlisting role="C">
4795 void gtk_spin_button_set_adjustment( GtkSpinButton *spin_button,
4796 GtkAdjustment *adjustment );
4798 GtkAdjustment *gtk_spin_button_get_adjustment( GtkSpinButton *spin_button );
4801 <para>The number of decimal places can also be altered using:</para>
4803 <programlisting role="C">
4804 void gtk_spin_button_set_digits( GtkSpinButton *spin_button,
4808 <para>The value that a Spin Button is currently displaying can be changed
4809 using the following function:</para>
4811 <programlisting role="C">
4812 void gtk_spin_button_set_value( GtkSpinButton *spin_button,
4816 <para>The current value of a Spin Button can be retrieved as either a
4817 floating point or integer value with the following functions:</para>
4819 <programlisting role="C">
4820 gdouble gtk_spin_button_get_value ( GtkSpinButton *spin_button );
4822 gint gtk_spin_button_get_value_as_int( GtkSpinButton *spin_button );
4825 <para>If you want to alter the value of a Spin Button relative to its current
4826 value, then the following function can be used:</para>
4828 <programlisting role="C">
4829 void gtk_spin_button_spin( GtkSpinButton *spin_button,
4830 GtkSpinType direction,
4831 gdouble increment );
4834 <para>The <literal>direction</literal> parameter can take one of the following values:</para>
4836 <programlisting role="C">
4837 GTK_SPIN_STEP_FORWARD
4838 GTK_SPIN_STEP_BACKWARD
4839 GTK_SPIN_PAGE_FORWARD
4840 GTK_SPIN_PAGE_BACKWARD
4843 GTK_SPIN_USER_DEFINED
4846 <para>This function packs in quite a bit of functionality, which I will
4847 attempt to clearly explain. Many of these settings use values from the
4848 Adjustment object that is associated with a Spin Button.</para>
4850 <para><literal>GTK_SPIN_STEP_FORWARD</literal> and <literal>GTK_SPIN_STEP_BACKWARD</literal> change the
4851 value of the Spin Button by the amount specified by <literal>increment</literal>,
4852 unless <literal>increment</literal> is equal to 0, in which case the value is
4853 changed by the value of <literal>step_increment</literal> in theAdjustment.</para>
4855 <para><literal>GTK_SPIN_PAGE_FORWARD</literal> and <literal>GTK_SPIN_PAGE_BACKWARD</literal> simply
4856 alter the value of the Spin Button by <literal>increment</literal>.</para>
4858 <para><literal>GTK_SPIN_HOME</literal> sets the value of the Spin Button to the bottom of
4859 the Adjustments range.</para>
4861 <para><literal>GTK_SPIN_END</literal> sets the value of the Spin Button to the top of the
4862 Adjustments range.</para>
4864 <para><literal>GTK_SPIN_USER_DEFINED</literal> simply alters the value of the Spin Button
4865 by the specified amount.</para>
4867 <para>We move away from functions for setting and retreving the range attributes
4868 of the Spin Button now, and move onto functions that affect the
4869 appearance and behaviour of the Spin Button widget itself.</para>
4871 <para>The first of these functions is used to constrain the text box of the
4872 Spin Button such that it may only contain a numeric value. This
4873 prevents a user from typing anything other than numeric values into
4874 the text box of a Spin Button:</para>
4876 <programlisting role="C">
4877 void gtk_spin_button_set_numeric( GtkSpinButton *spin_button,
4881 <para>You can set whether a Spin Button will wrap around between the upper
4882 and lower range values with the following function:</para>
4884 <programlisting role="C">
4885 void gtk_spin_button_set_wrap( GtkSpinButton *spin_button,
4889 <para>You can set a Spin Button to round the value to the nearest
4890 <literal>step_increment</literal>, which is set within the Adjustment object used
4891 with the Spin Button. This is accomplished with the following
4894 <programlisting role="C">
4895 void gtk_spin_button_set_snap_to_ticks( GtkSpinButton *spin_button,
4896 gboolean snap_to_ticks );
4899 <para>The update policy of a Spin Button can be changed with the following
4902 <programlisting role="C">
4903 void gtk_spin_button_set_update_policy( GtkSpinButton *spin_button,
4904 GtkSpinButtonUpdatePolicy policy );
4907 <para>The possible values of <literal>policy</literal> are either <literal>GTK_UPDATE_ALWAYS</literal> or
4908 <literal>GTK_UPDATE_IF_VALID</literal>.</para>
4910 <para>These policies affect the behavior of a Spin Button when parsing
4911 inserted text and syncing its value with the values of the
4914 <para>In the case of <literal>GTK_UPDATE_IF_VALID</literal> the Spin Button value only
4915 gets changed if the text input is a numeric value that is within the
4916 range specified by the Adjustment. Otherwise the text is reset to the
4917 current value.</para>
4919 <para>In case of <literal>GTK_UPDATE_ALWAYS</literal> we ignore errors while converting
4920 text into a numeric value.</para>
4922 <para>Finally, you can explicitly request that a Spin Button update itself:</para>
4924 <programlisting role="C">
4925 void gtk_spin_button_update( GtkSpinButton *spin_button );
4928 <para>It's example time again.</para>
4933 <imagedata fileref="images/spinbutton.png" format="png">
4935 </inlinemediaobject>
4938 <programlisting role="C">
4939 <!-- example-start spinbutton spinbutton.c -->
4941 #include <stdio.h>
4942 #include <gtk/gtk.h>
4944 static GtkWidget *spinner1;
4946 static void toggle_snap( GtkWidget *widget,
4947 GtkSpinButton *spin )
4949 gtk_spin_button_set_snap_to_ticks (spin, GTK_TOGGLE_BUTTON (widget)->active);
4952 static void toggle_numeric( GtkWidget *widget,
4953 GtkSpinButton *spin )
4955 gtk_spin_button_set_numeric (spin, GTK_TOGGLE_BUTTON (widget)->active);
4958 static void change_digits( GtkWidget *widget,
4959 GtkSpinButton *spin )
4961 gtk_spin_button_set_digits (GTK_SPIN_BUTTON (spinner1),
4962 gtk_spin_button_get_value_as_int (spin));
4965 static void get_value( GtkWidget *widget,
4970 GtkSpinButton *spin;
4972 spin = GTK_SPIN_BUTTON (spinner1);
4973 label = GTK_LABEL (g_object_get_data (G_OBJECT (widget), "user_data"));
4974 if (GPOINTER_TO_INT (data) == 1)
4975 buf = g_strdup_printf ("%d", gtk_spin_button_get_value_as_int (spin));
4977 buf = g_strdup_printf ("%0.*f", spin->digits,
4978 gtk_spin_button_get_value (spin));
4979 gtk_label_set_text (label, buf);
4990 GtkWidget *main_vbox;
4993 GtkWidget *spinner2;
4997 GtkWidget *val_label;
5000 /* Initialise GTK */
5001 gtk_init (&argc, &argv);
5003 window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
5005 g_signal_connect (window, "destroy",
5006 G_CALLBACK (gtk_main_quit),
5009 gtk_window_set_title (GTK_WINDOW (window), "Spin Button");
5011 main_vbox = gtk_vbox_new (FALSE, 5);
5012 gtk_container_set_border_width (GTK_CONTAINER (main_vbox), 10);
5013 gtk_container_add (GTK_CONTAINER (window), main_vbox);
5015 frame = gtk_frame_new ("Not accelerated");
5016 gtk_box_pack_start (GTK_BOX (main_vbox), frame, TRUE, TRUE, 0);
5018 vbox = gtk_vbox_new (FALSE, 0);
5019 gtk_container_set_border_width (GTK_CONTAINER (vbox), 5);
5020 gtk_container_add (GTK_CONTAINER (frame), vbox);
5022 /* Day, month, year spinners */
5024 hbox = gtk_hbox_new (FALSE, 0);
5025 gtk_box_pack_start (GTK_BOX (vbox), hbox, TRUE, TRUE, 5);
5027 vbox2 = gtk_vbox_new (FALSE, 0);
5028 gtk_box_pack_start (GTK_BOX (hbox), vbox2, TRUE, TRUE, 5);
5030 label = gtk_label_new ("Day :");
5031 gtk_misc_set_alignment (GTK_MISC (label), 0, 0.5);
5032 gtk_box_pack_start (GTK_BOX (vbox2), label, FALSE, TRUE, 0);
5034 adj = gtk_adjustment_new (1.0, 1.0, 31.0, 1.0, 5.0, 0.0);
5035 spinner = gtk_spin_button_new (adj, 0, 0);
5036 gtk_spin_button_set_wrap (GTK_SPIN_BUTTON (spinner), TRUE);
5037 gtk_box_pack_start (GTK_BOX (vbox2), spinner, FALSE, TRUE, 0);
5039 vbox2 = gtk_vbox_new (FALSE, 0);
5040 gtk_box_pack_start (GTK_BOX (hbox), vbox2, TRUE, TRUE, 5);
5042 label = gtk_label_new ("Month :");
5043 gtk_misc_set_alignment (GTK_MISC (label), 0, 0.5);
5044 gtk_box_pack_start (GTK_BOX (vbox2), label, FALSE, TRUE, 0);
5046 adj = gtk_adjustment_new (1.0, 1.0, 12.0, 1.0, 5.0, 0.0);
5047 spinner = gtk_spin_button_new (adj, 0, 0);
5048 gtk_spin_button_set_wrap (GTK_SPIN_BUTTON (spinner), TRUE);
5049 gtk_box_pack_start (GTK_BOX (vbox2), spinner, FALSE, TRUE, 0);
5051 vbox2 = gtk_vbox_new (FALSE, 0);
5052 gtk_box_pack_start (GTK_BOX (hbox), vbox2, TRUE, TRUE, 5);
5054 label = gtk_label_new ("Year :");
5055 gtk_misc_set_alignment (GTK_MISC (label), 0, 0.5);
5056 gtk_box_pack_start (GTK_BOX (vbox2), label, FALSE, TRUE, 0);
5058 adj = gtk_adjustment_new (1998.0, 0.0, 2100.0, 1.0, 100.0, 0.0);
5059 spinner = gtk_spin_button_new (adj, 0, 0);
5060 gtk_spin_button_set_wrap (GTK_SPIN_BUTTON (spinner), FALSE);
5061 gtk_widget_set_size_request (spinner, 55, -1);
5062 gtk_box_pack_start (GTK_BOX (vbox2), spinner, FALSE, TRUE, 0);
5064 frame = gtk_frame_new ("Accelerated");
5065 gtk_box_pack_start (GTK_BOX (main_vbox), frame, TRUE, TRUE, 0);
5067 vbox = gtk_vbox_new (FALSE, 0);
5068 gtk_container_set_border_width (GTK_CONTAINER (vbox), 5);
5069 gtk_container_add (GTK_CONTAINER (frame), vbox);
5071 hbox = gtk_hbox_new (FALSE, 0);
5072 gtk_box_pack_start (GTK_BOX (vbox), hbox, FALSE, TRUE, 5);
5074 vbox2 = gtk_vbox_new (FALSE, 0);
5075 gtk_box_pack_start (GTK_BOX (hbox), vbox2, TRUE, TRUE, 5);
5077 label = gtk_label_new ("Value :");
5078 gtk_misc_set_alignment (GTK_MISC (label), 0, 0.5);
5079 gtk_box_pack_start (GTK_BOX (vbox2), label, FALSE, TRUE, 0);
5081 adj = gtk_adjustment_new (0.0, -10000.0, 10000.0, 0.5, 100.0, 0.0);
5082 spinner1 = gtk_spin_button_new (adj, 1.0, 2);
5083 gtk_spin_button_set_wrap (GTK_SPIN_BUTTON (spinner1), TRUE);
5084 gtk_widget_set_size_request (spinner1, 100, -1);
5085 gtk_box_pack_start (GTK_BOX (vbox2), spinner1, FALSE, TRUE, 0);
5087 vbox2 = gtk_vbox_new (FALSE, 0);
5088 gtk_box_pack_start (GTK_BOX (hbox), vbox2, TRUE, TRUE, 5);
5090 label = gtk_label_new ("Digits :");
5091 gtk_misc_set_alignment (GTK_MISC (label), 0, 0.5);
5092 gtk_box_pack_start (GTK_BOX (vbox2), label, FALSE, TRUE, 0);
5094 adj = gtk_adjustment_new (2, 1, 5, 1, 1, 0);
5095 spinner2 = gtk_spin_button_new (adj, 0.0, 0);
5096 gtk_spin_button_set_wrap (GTK_SPIN_BUTTON (spinner2), TRUE);
5097 g_signal_connect (adj, "value_changed",
5098 G_CALLBACK (change_digits),
5100 gtk_box_pack_start (GTK_BOX (vbox2), spinner2, FALSE, TRUE, 0);
5102 hbox = gtk_hbox_new (FALSE, 0);
5103 gtk_box_pack_start (GTK_BOX (vbox), hbox, FALSE, TRUE, 5);
5105 button = gtk_check_button_new_with_label ("Snap to 0.5-ticks");
5106 g_signal_connect (button, "clicked",
5107 G_CALLBACK (toggle_snap),
5109 gtk_box_pack_start (GTK_BOX (vbox), button, TRUE, TRUE, 0);
5110 gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (button), TRUE);
5112 button = gtk_check_button_new_with_label ("Numeric only input mode");
5113 g_signal_connect (button, "clicked",
5114 G_CALLBACK (toggle_numeric),
5116 gtk_box_pack_start (GTK_BOX (vbox), button, TRUE, TRUE, 0);
5117 gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (button), TRUE);
5119 val_label = gtk_label_new ("");
5121 hbox = gtk_hbox_new (FALSE, 0);
5122 gtk_box_pack_start (GTK_BOX (vbox), hbox, FALSE, TRUE, 5);
5123 button = gtk_button_new_with_label ("Value as Int");
5124 g_object_set_data (G_OBJECT (button), "user_data", val_label);
5125 g_signal_connect (button, "clicked",
5126 G_CALLBACK (get_value),
5127 GINT_TO_POINTER (1));
5128 gtk_box_pack_start (GTK_BOX (hbox), button, TRUE, TRUE, 5);
5130 button = gtk_button_new_with_label ("Value as Float");
5131 g_object_set_data (G_OBJECT (button), "user_data", val_label);
5132 g_signal_connect (button, "clicked",
5133 G_CALLBACK (get_value),
5134 GINT_TO_POINTER (2));
5135 gtk_box_pack_start (GTK_BOX (hbox), button, TRUE, TRUE, 5);
5137 gtk_box_pack_start (GTK_BOX (vbox), val_label, TRUE, TRUE, 0);
5138 gtk_label_set_text (GTK_LABEL (val_label), "0");
5140 hbox = gtk_hbox_new (FALSE, 0);
5141 gtk_box_pack_start (GTK_BOX (main_vbox), hbox, FALSE, TRUE, 0);
5143 button = gtk_button_new_with_label ("Close");
5144 g_signal_connect_swapped (button, "clicked",
5145 G_CALLBACK (gtk_widget_destroy),
5147 gtk_box_pack_start (GTK_BOX (hbox), button, TRUE, TRUE, 5);
5149 gtk_widget_show_all (window);
5151 /* Enter the event loop */
5157 <!-- example-end -->
5162 <!-- ----------------------------------------------------------------- -->
5163 <sect1 id="sec-ComboBox">
5164 <title>Combo Box</title>
5166 <para>The combo box is another fairly simple widget that is really just a
5167 collection of other widgets. From the user's point of view, the widget
5168 consists of a text entry box and a pull down menu from which the user
5169 can select one of a set of predefined entries. Alternatively, the user
5170 can type a different option directly into the text box.</para>
5172 <para>The following extract from the structure that defines a Combo Box
5173 identifies several of the components:</para>
5175 <programlisting role="C">
5186 <para>As you can see, the Combo Box has two principal parts that you really
5187 care about: an entry and a list.</para>
5189 <para>First off, to create a combo box, use:</para>
5191 <programlisting role="C">
5192 GtkWidget *gtk_combo_new( void );
5195 <para>Now, if you want to set the string in the entry section of the combo
5196 box, this is done by manipulating the <literal>entry</literal> widget directly:</para>
5198 <programlisting role="C">
5199 gtk_entry_set_text (GTK_ENTRY (GTK_COMBO (combo)->entry), "My String.");
5202 <para>To set the values in the popdown list, one uses the function:</para>
5204 <programlisting role="C">
5205 void gtk_combo_set_popdown_strings( GtkCombo *combo,
5209 <para>Before you can do this, you have to assemble a GList of the strings
5210 that you want. GList is a linked list implementation that is part of
5211 <link linkend="ch-GLib">GLib</link>, a library supporting GTK. For the
5212 moment, the quick and dirty explanation is that you need to set up a
5213 GList pointer, set it equal to NULL, then append strings to it with</para>
5215 <programlisting role="C">
5216 GList *g_list_append( GList *glist,
5220 <para>It is important that you set the initial GList pointer to NULL. The
5221 value returned from the g_list_append() function must be used as the new
5222 pointer to the GList.</para>
5224 <para>Here's a typical code segment for creating a set of options:</para>
5226 <programlisting role="C">
5227 GList *glist = NULL;
5229 glist = g_list_append (glist, "String 1");
5230 glist = g_list_append (glist, "String 2");
5231 glist = g_list_append (glist, "String 3");
5232 glist = g_list_append (glist, "String 4");
5234 gtk_combo_set_popdown_strings (GTK_COMBO (combo), glist);
5236 /* can free glist now, combo takes a copy */
5239 <para>The combo widget makes a copy of the strings passed to it in the glist
5240 structure. As a result, you need to make sure you free the memory used
5241 by the list if that is appropriate for your application.</para>
5243 <para>At this point you have a working combo box that has been set up.
5244 There are a few aspects of its behavior that you can change. These
5245 are accomplished with the functions: </para>
5247 <programlisting role="C">
5248 void gtk_combo_set_use_arrows( GtkCombo *combo,
5251 void gtk_combo_set_use_arrows_always( GtkCombo *combo,
5254 void gtk_combo_set_case_sensitive( GtkCombo *combo,
5258 <para>gtk_combo_set_use_arrows() lets the user change the value in the
5259 entry using the up/down arrow keys. This doesn't bring up the list, but
5260 rather replaces the current text in the entry with the next list entry
5261 (up or down, as your key choice indicates). It does this by searching
5262 in the list for the item corresponding to the current value in the
5263 entry and selecting the previous/next item accordingly. Usually in an
5264 entry the arrow keys are used to change focus (you can do that anyway
5265 using TAB). Note that when the current item is the last of the list
5266 and you press arrow-down it changes the focus (the same applies with
5267 the first item and arrow-up).</para>
5269 <para>If the current value in the entry is not in the list, then the
5270 function of gtk_combo_set_use_arrows() is disabled.</para>
5272 <para>gtk_combo_set_use_arrows_always() similarly allows the use the
5273 the up/down arrow keys to cycle through the choices in the dropdown
5274 list, except that it wraps around the values in the list, completely
5275 disabling the use of the up and down arrow keys for changing focus.</para>
5277 <para>gtk_combo_set_case_sensitive() toggles whether or not GTK
5278 searches for entries in a case sensitive manner. This is used when the
5279 Combo widget is asked to find a value from the list using the current
5280 entry in the text box. This completion can be performed in either a
5281 case sensitive or insensitive manner, depending upon the use of this
5282 function. The Combo widget can also simply complete the current entry
5283 if the user presses the key combination MOD-1 and "Tab". MOD-1 is
5284 often mapped to the "Alt" key, by the <literal>xmodmap</literal> utility. Note,
5285 however that some window managers also use this key combination, which
5286 will override its use within GTK.</para>
5288 <para>Now that we have a combo box, tailored to look and act how we want it,
5289 all that remains is being able to get data from the combo box. This is
5290 relatively straightforward. The majority of the time, all you are
5291 going to care about getting data from is the entry. The entry is
5292 accessed simply by <literal>GTK_ENTRY (GTK_COMBO (combo)->entry)</literal>. The
5293 two principal things that you are going to want to do with it are
5294 connect to the activate signal, which indicates that the user has
5295 pressed the Return or Enter key, and read the text. The first is
5296 accomplished using something like:</para>
5298 <programlisting role="C">
5299 g_signal_connect (GTK_COMBO (combo)->entry, "activate",
5300 G_CALLBACK (my_callback_function), my_data);
5303 <para>Getting the text at any arbitrary time is accomplished by simply using
5304 the entry function:</para>
5306 <programlisting role="C">
5307 gchar *gtk_entry_get_text( GtkEntry *entry );
5310 <para>Such as:</para>
5312 <programlisting role="C">
5315 string = gtk_entry_get_text (GTK_ENTRY (GTK_COMBO (combo)->entry));
5318 <para>That's about all there is to it. There is a function</para>
5320 <programlisting role="C">
5321 void gtk_combo_disable_activate( GtkCombo *combo );
5324 <para>that will disable the activate signal on the entry widget in the combo
5325 box. Personally, I can't think of why you'd want to use it, but it
5328 <!-- There is also a function to set the string on a particular item, void
5329 gtk_combo_set_item_string(GtkCombo *combo, GtkItem *item, const gchar
5330 *item_value), but this requires that you have a pointer to the
5331 appropriate Item. Frankly, I have no idea how to do that.
5336 <!-- ----------------------------------------------------------------- -->
5337 <sect1 id="sec-Calendar">
5338 <title>Calendar</title>
5340 <para>The Calendar widget is an effective way to display and retrieve
5341 monthly date related information. It is a very simple widget to create
5342 and work with.</para>
5344 <para>Creating a GtkCalendar widget is a simple as: </para>
5346 <programlisting role="C">
5347 GtkWidget *gtk_calendar_new( void );
5350 <para>There might be times where you need to change a lot of information
5351 within this widget and the following functions allow you to make
5352 multiple change to a Calendar widget without the user seeing multiple
5353 on-screen updates.</para>
5355 <programlisting role="C">
5356 void gtk_calendar_freeze( GtkCalendar *Calendar );
5358 void gtk_calendar_thaw( GtkCalendar *Calendar );
5361 <para>They work just like the freeze/thaw functions of every other
5364 <para>The Calendar widget has a few options that allow you to change the way
5365 the widget both looks and operates by using the function</para>
5367 <programlisting role="C">
5368 void gtk_calendar_set_display_options( GtkCalendar *calendar,
5369 GtkCalendarDisplayOptions flags );
5372 <para>The <literal>flags</literal> argument can be formed by combining either of the
5373 following five options using the logical bitwise OR (|) operation:</para>
5377 <term><literal>GTK_CALENDAR_SHOW_HEADING</literal></term>
5378 <listitem><para>this option specifies that the month and year should be shown
5379 when drawing the calendar.</para>
5383 <term><literal>GTK_CALENDAR_SHOW_DAY_NAMES</literal></term>
5384 <listitem><para>this option specifies that the three letter descriptions should
5385 be displayed for each day (eg Mon,Tue, etc.).</para>
5389 <term><literal>GTK_CALENDAR_NO_MONTH_CHANGE</literal></term>
5390 <listitem><para>this option states that the user
5391 should not and can not change the currently displayed month. This can
5392 be good if you only need to display a particular month such as if you
5393 are displaying 12 calendar widgets for every month in a particular
5398 <term><literal>GTK_CALENDAR_SHOW_WEEK_NUMBERS</literal></term>
5399 <listitem><para>this option specifies that the
5400 number for each week should be displayed down the left side of the
5401 calendar. (eg. Jan 1 = Week 1,Dec 31 = Week 52).</para>
5406 <para>The following functions are used to set the the currently displayed
5409 <programlisting role="C">
5410 gint gtk_calendar_select_month( GtkCalendar *calendar,
5414 void gtk_calendar_select_day( GtkCalendar *calendar,
5418 <para>The return value from <literal>gtk_calendar_select_month()</literal> is a boolean
5419 value indicating whether the selection was successful.</para>
5421 <para>With <literal>gtk_calendar_select_day()</literal> the specified day number is
5422 selected within the current month, if that is possible. A
5423 <literal>day</literal> value of 0 will deselect any current selection.</para>
5425 <para>In addition to having a day selected, any number of days in the month
5426 may be "marked". A marked day is highlighted within the calendar
5427 display. The following functions are provided to manipulate marked
5430 <programlisting role="C">
5431 gint gtk_calendar_mark_day( GtkCalendar *calendar,
5434 gint gtk_calendar_unmark_day( GtkCalendar *calendar,
5437 void gtk_calendar_clear_marks( GtkCalendar *calendar);
5440 <para>The currently marked days are stored within an array within the
5441 GtkCalendar structure. This array is 31 elements long so to test
5442 whether a particular day is currently marked, you need to access the
5443 corresponding element of the array (don't forget in C that array
5444 elements are numbered 0 to n-1). For example:</para>
5446 <programlisting role="C">
5447 GtkCalendar *calendar;
5448 calendar = gtk_calendar_new ();
5452 /* Is day 7 marked? */
5453 if (calendar->marked_date[7-1])
5457 <para>Note that marks are persistent across month and year changes.</para>
5459 <para>The final Calendar widget function is used to retrieve the currently
5460 selected date, month and/or year.</para>
5462 <programlisting role="C">
5463 void gtk_calendar_get_date( GtkCalendar *calendar,
5469 <para>This function requires you to pass the addresses of <literal>guint</literal>
5470 variables, into which the result will be placed. Passing <literal>NULL</literal> as
5471 a value will result in the corresponding value not being returned.</para>
5473 <para>The Calendar widget can generate a number of signals indicating date
5474 selection and change. The names of these signals are self explanatory,
5478 <listitem><simpara> <literal>month_changed</literal></simpara>
5480 <listitem><simpara> <literal>day_selected</literal></simpara>
5482 <listitem><simpara> <literal>day_selected_double_click</literal></simpara>
5484 <listitem><simpara> <literal>prev_month</literal></simpara>
5486 <listitem><simpara> <literal>next_month</literal></simpara>
5488 <listitem><simpara> <literal>prev_year</literal></simpara>
5490 <listitem><simpara> <literal>next_year</literal></simpara>
5494 <para>That just leaves us with the need to put all of this together into
5495 example code.</para>
5500 <imagedata fileref="images/calendar.png" format="png">
5502 </inlinemediaobject>
5505 <programlisting role="C">
5506 <!-- example-start calendar calendar.c -->
5508 * Copyright (C) 1998 Cesar Miquel, Shawn T. Amundson, Mattias Gr�nlund
5509 * Copyright (C) 2000 Tony Gale
5511 * This program is free software; you can redistribute it and/or modify
5512 * it under the terms of the GNU General Public License as published by
5513 * the Free Software Foundation; either version 2 of the License, or
5514 * (at your option) any later version.
5516 * This program is distributed in the hope that it will be useful,
5517 * but WITHOUT ANY WARRANTY; without even the implied warranty of
5518 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
5519 * GNU General Public License for more details.
5521 * You should have received a copy of the GNU General Public License
5522 * along with this program; if not, write to the Free Software
5523 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
5526 #include <stdio.h>
5527 #include <string.h>
5528 #include <gtk/gtk.h>
5531 #define DEF_PAD_SMALL 5
5533 #define TM_YEAR_BASE 1900
5535 typedef struct _CalendarData {
5536 GtkWidget *flag_checkboxes[5];
5537 gboolean settings[5];
5538 GtkWidget *font_dialog;
5540 GtkWidget *prev2_sig;
5541 GtkWidget *prev_sig;
5542 GtkWidget *last_sig;
5547 calendar_show_header,
5549 calendar_month_change,
5551 calendar_monday_first
5558 static void calendar_date_to_string( CalendarData *data,
5563 guint year, month, day;
5565 gtk_calendar_get_date (GTK_CALENDAR (data->window),
5566 &year, &month, &day);
5567 g_date_set_dmy (&date, day, month + 1, year);
5568 g_date_strftime (buffer, buff_len - 1, "%x", &date);
5572 static void calendar_set_signal_strings( char *sig_str,
5573 CalendarData *data )
5575 const gchar *prev_sig;
5577 prev_sig = gtk_label_get_text (GTK_LABEL (data->prev_sig));
5578 gtk_label_set_text (GTK_LABEL (data->prev2_sig), prev_sig);
5580 prev_sig = gtk_label_get_text (GTK_LABEL (data->last_sig));
5581 gtk_label_set_text (GTK_LABEL (data->prev_sig), prev_sig);
5582 gtk_label_set_text (GTK_LABEL (data->last_sig), sig_str);
5585 static void calendar_month_changed( GtkWidget *widget,
5586 CalendarData *data )
5588 char buffer[256] = "month_changed: ";
5590 calendar_date_to_string (data, buffer + 15, 256 - 15);
5591 calendar_set_signal_strings (buffer, data);
5594 static void calendar_day_selected( GtkWidget *widget,
5595 CalendarData *data )
5597 char buffer[256] = "day_selected: ";
5599 calendar_date_to_string (data, buffer + 14, 256 - 14);
5600 calendar_set_signal_strings (buffer, data);
5603 static void calendar_day_selected_double_click ( GtkWidget *widget,
5604 CalendarData *data )
5606 char buffer[256] = "day_selected_double_click: ";
5609 calendar_date_to_string (data, buffer + 27, 256 - 27);
5610 calendar_set_signal_strings (buffer, data);
5612 gtk_calendar_get_date (GTK_CALENDAR (data->window),
5613 NULL, NULL, &day);
5615 if (GTK_CALENDAR (data->window)->marked_date[day-1] == 0) {
5616 gtk_calendar_mark_day (GTK_CALENDAR (data->window), day);
5618 gtk_calendar_unmark_day (GTK_CALENDAR (data->window), day);
5622 static void calendar_prev_month( GtkWidget *widget,
5623 CalendarData *data )
5625 char buffer[256] = "prev_month: ";
5627 calendar_date_to_string (data, buffer + 12, 256 - 12);
5628 calendar_set_signal_strings (buffer, data);
5631 static void calendar_next_month( GtkWidget *widget,
5632 CalendarData *data )
5634 char buffer[256] = "next_month: ";
5636 calendar_date_to_string (data, buffer + 12, 256 - 12);
5637 calendar_set_signal_strings (buffer, data);
5640 static void calendar_prev_year( GtkWidget *widget,
5641 CalendarData *data )
5643 char buffer[256] = "prev_year: ";
5645 calendar_date_to_string (data, buffer + 11, 256 - 11);
5646 calendar_set_signal_strings (buffer, data);
5649 static void calendar_next_year( GtkWidget *widget,
5650 CalendarData *data )
5652 char buffer[256] = "next_year: ";
5654 calendar_date_to_string (data, buffer + 11, 256 - 11);
5655 calendar_set_signal_strings (buffer, data);
5659 static void calendar_set_flags( CalendarData *calendar )
5663 for (i = 0;i < 5; i++)
5664 if (calendar->settings[i])
5666 options = options + (1 << i);
5668 if (calendar->window)
5669 gtk_calendar_set_display_options (GTK_CALENDAR (calendar->window), options);
5672 static void calendar_toggle_flag( GtkWidget *toggle,
5673 CalendarData *calendar)
5678 for (i = 0; i < 5; i++)
5679 if (calendar->flag_checkboxes[i] == toggle)
5682 calendar->settings[j] = !calendar->settings[j];
5683 calendar_set_flags (calendar);
5687 static void calendar_font_selection_ok( GtkWidget *button,
5688 CalendarData *calendar )
5693 if (calendar->window)
5695 font_name = gtk_font_selection_dialog_get_font_name (GTK_FONT_SELECTION_DIALOG (calendar->font_dialog));
5698 style = gtk_rc_style_new ();
5699 pango_font_description_free (style->font_desc);
5700 style->font_desc = pango_font_description_from_string (font_name);
5701 gtk_widget_modify_style (calendar->window, style);
5706 gtk_widget_destroy (calendar->font_dialog);
5709 static void calendar_select_font( GtkWidget *button,
5710 CalendarData *calendar )
5714 if (!calendar->font_dialog) {
5715 window = gtk_font_selection_dialog_new ("Font Selection Dialog");
5716 g_return_if_fail (GTK_IS_FONT_SELECTION_DIALOG (window));
5717 calendar->font_dialog = window;
5719 gtk_window_set_position (GTK_WINDOW (window), GTK_WIN_POS_MOUSE);
5721 g_signal_connect (window, "destroy",
5722 G_CALLBACK (gtk_widget_destroyed),
5723 &calendar->font_dialog);
5725 g_signal_connect (GTK_FONT_SELECTION_DIALOG (window)->ok_button,
5726 "clicked", G_CALLBACK (calendar_font_selection_ok),
5728 g_signal_connect_swapped (GTK_FONT_SELECTION_DIALOG (window)->cancel_button,
5729 "clicked", G_CALLBACK (gtk_widget_destroy),
5730 calendar->font_dialog);
5732 window = calendar->font_dialog;
5733 if (!gtk_widget_get_visible (window))
5734 gtk_widget_show (window);
5736 gtk_widget_destroy (window);
5740 static void create_calendar( void )
5743 GtkWidget *vbox, *vbox2, *vbox3;
5746 GtkWidget *calendar;
5750 GtkWidget *separator;
5753 static CalendarData calendar_data;
5761 { "Show Day Names" },
5762 { "No Month Change" },
5763 { "Show Week Numbers" },
5764 { "Week Start Monday" }
5768 calendar_data.window = NULL;
5769 calendar_data.font_dialog = NULL;
5771 for (i = 0; i < 5; i++) {
5772 calendar_data.settings[i] = 0;
5775 window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
5776 gtk_window_set_title (GTK_WINDOW (window), "GtkCalendar Example");
5777 gtk_container_set_border_width (GTK_CONTAINER (window), 5);
5778 g_signal_connect (window, "destroy",
5779 G_CALLBACK (gtk_main_quit),
5781 g_signal_connect (window, "delete-event",
5782 G_CALLBACK (gtk_false),
5784 gtk_window_set_resizable (GTK_WINDOW (window), FALSE);
5786 vbox = gtk_vbox_new (FALSE, DEF_PAD);
5787 gtk_container_add (GTK_CONTAINER (window), vbox);
5790 * The top part of the window, Calendar, flags and fontsel.
5793 hbox = gtk_hbox_new (FALSE, DEF_PAD);
5794 gtk_box_pack_start (GTK_BOX (vbox), hbox, TRUE, TRUE, DEF_PAD);
5795 hbbox = gtk_hbutton_box_new ();
5796 gtk_box_pack_start (GTK_BOX (hbox), hbbox, FALSE, FALSE, DEF_PAD);
5797 gtk_button_box_set_layout (GTK_BUTTON_BOX (hbbox), GTK_BUTTONBOX_SPREAD);
5798 gtk_box_set_spacing (GTK_BOX (hbbox), 5);
5800 /* Calendar widget */
5801 frame = gtk_frame_new ("Calendar");
5802 gtk_box_pack_start(GTK_BOX (hbbox), frame, FALSE, TRUE, DEF_PAD);
5803 calendar=gtk_calendar_new ();
5804 calendar_data.window = calendar;
5805 calendar_set_flags (&calendar_data);
5806 gtk_calendar_mark_day (GTK_CALENDAR (calendar), 19);
5807 gtk_container_add (GTK_CONTAINER (frame), calendar);
5808 g_signal_connect (calendar, "month_changed",
5809 G_CALLBACK (calendar_month_changed),
5810 &calendar_data);
5811 g_signal_connect (calendar, "day_selected",
5812 G_CALLBACK (calendar_day_selected),
5813 &calendar_data);
5814 g_signal_connect (calendar, "day_selected_double_click",
5815 G_CALLBACK (calendar_day_selected_double_click),
5816 &calendar_data);
5817 g_signal_connect (calendar, "prev_month",
5818 G_CALLBACK (calendar_prev_month),
5819 &calendar_data);
5820 g_signal_connect (calendar, "next_month",
5821 G_CALLBACK (calendar_next_month),
5822 &calendar_data);
5823 g_signal_connect (calendar, "prev_year",
5824 G_CALLBACK (calendar_prev_year),
5825 &calendar_data);
5826 g_signal_connect (calendar, "next_year",
5827 G_CALLBACK (calendar_next_year),
5828 &calendar_data);
5831 separator = gtk_vseparator_new ();
5832 gtk_box_pack_start (GTK_BOX (hbox), separator, FALSE, TRUE, 0);
5834 vbox2 = gtk_vbox_new (FALSE, DEF_PAD);
5835 gtk_box_pack_start (GTK_BOX (hbox), vbox2, FALSE, FALSE, DEF_PAD);
5837 /* Build the Right frame with the flags in */
5839 frame = gtk_frame_new ("Flags");
5840 gtk_box_pack_start (GTK_BOX (vbox2), frame, TRUE, TRUE, DEF_PAD);
5841 vbox3 = gtk_vbox_new (TRUE, DEF_PAD_SMALL);
5842 gtk_container_add (GTK_CONTAINER (frame), vbox3);
5844 for (i = 0; i < 5; i++)
5846 toggle = gtk_check_button_new_with_label (flags[i].label);
5847 g_signal_connect (toggle,
5849 G_CALLBACK (calendar_toggle_flag),
5850 &calendar_data);
5851 gtk_box_pack_start (GTK_BOX (vbox3), toggle, TRUE, TRUE, 0);
5852 calendar_data.flag_checkboxes[i] = toggle;
5854 /* Build the right font-button */
5855 button = gtk_button_new_with_label ("Font...");
5856 g_signal_connect (button,
5858 G_CALLBACK (calendar_select_font),
5859 &calendar_data);
5860 gtk_box_pack_start (GTK_BOX (vbox2), button, FALSE, FALSE, 0);
5863 * Build the Signal-event part.
5866 frame = gtk_frame_new ("Signal events");
5867 gtk_box_pack_start (GTK_BOX (vbox), frame, TRUE, TRUE, DEF_PAD);
5869 vbox2 = gtk_vbox_new (TRUE, DEF_PAD_SMALL);
5870 gtk_container_add (GTK_CONTAINER (frame), vbox2);
5872 hbox = gtk_hbox_new (FALSE, 3);
5873 gtk_box_pack_start (GTK_BOX (vbox2), hbox, FALSE, TRUE, 0);
5874 label = gtk_label_new ("Signal:");
5875 gtk_box_pack_start (GTK_BOX (hbox), label, FALSE, TRUE, 0);
5876 calendar_data.last_sig = gtk_label_new ("");
5877 gtk_box_pack_start (GTK_BOX (hbox), calendar_data.last_sig, FALSE, TRUE, 0);
5879 hbox = gtk_hbox_new (FALSE, 3);
5880 gtk_box_pack_start (GTK_BOX (vbox2), hbox, FALSE, TRUE, 0);
5881 label = gtk_label_new ("Previous signal:");
5882 gtk_box_pack_start (GTK_BOX (hbox), label, FALSE, TRUE, 0);
5883 calendar_data.prev_sig = gtk_label_new ("");
5884 gtk_box_pack_start (GTK_BOX (hbox), calendar_data.prev_sig, FALSE, TRUE, 0);
5886 hbox = gtk_hbox_new (FALSE, 3);
5887 gtk_box_pack_start (GTK_BOX (vbox2), hbox, FALSE, TRUE, 0);
5888 label = gtk_label_new ("Second previous signal:");
5889 gtk_box_pack_start (GTK_BOX (hbox), label, FALSE, TRUE, 0);
5890 calendar_data.prev2_sig = gtk_label_new ("");
5891 gtk_box_pack_start (GTK_BOX (hbox), calendar_data.prev2_sig, FALSE, TRUE, 0);
5893 bbox = gtk_hbutton_box_new ();
5894 gtk_box_pack_start (GTK_BOX (vbox), bbox, FALSE, FALSE, 0);
5895 gtk_button_box_set_layout (GTK_BUTTON_BOX (bbox), GTK_BUTTONBOX_END);
5897 button = gtk_button_new_with_label ("Close");
5898 g_signal_connect (button, "clicked",
5899 G_CALLBACK (gtk_main_quit),
5901 gtk_container_add (GTK_CONTAINER (bbox), button);
5902 gtk_widget_set_can_default (button, TRUE);
5903 gtk_widget_grab_default (button);
5905 gtk_widget_show_all (window);
5912 gtk_init (&argc, &argv);
5920 <!-- example-end -->
5925 <!-- ----------------------------------------------------------------- -->
5926 <sect1 id="sec-ColorSelection">
5927 <title>Color Selection</title>
5929 <para>The color selection widget is, not surprisingly, a widget for
5930 interactive selection of colors. This composite widget lets the user
5931 select a color by manipulating RGB (Red, Green, Blue) and HSV (Hue,
5932 Saturation, Value) triples. This is done either by adjusting single
5933 values with sliders or entries, or by picking the desired color from a
5934 hue-saturation wheel/value bar. Optionally, the opacity of the color
5935 can also be set.</para>
5937 <para>The color selection widget currently emits only one signal,
5938 "color_changed", which is emitted whenever the current color in the
5939 widget changes, either when the user changes it or if it's set
5940 explicitly through gtk_color_selection_set_color().</para>
5942 <para>Lets have a look at what the color selection widget has to offer
5943 us. The widget comes in two flavours: GtkColorSelection and
5944 GtkColorSelectionDialog.</para>
5946 <programlisting role="C">
5947 GtkWidget *gtk_color_selection_new( void );
5950 <para>You'll probably not be using this constructor directly. It creates an
5951 orphan ColorSelection widget which you'll have to parent
5952 yourself. The ColorSelection widget inherits from the VBox
5955 <programlisting role="C">
5956 GtkWidget *gtk_color_selection_dialog_new( const gchar *title );
5959 <para>This is the most common color selection constructor. It creates a
5960 ColorSelectionDialog. It consists of a Frame containing a
5961 ColorSelection widget, an HSeparator and an HBox with three buttons,
5962 "Ok", "Cancel" and "Help". You can reach these buttons by accessing
5963 the "ok_button", "cancel_button" and "help_button" widgets in the
5964 ColorSelectionDialog structure,
5965 (i.e., <literal>GTK_COLOR_SELECTION_DIALOG (colorseldialog)->ok_button</literal>)).</para>
5967 <programlisting role="C">
5968 void gtk_color_selection_set_has_opacity_control( GtkColorSelection *colorsel,
5969 gboolean has_opacity );
5972 <para>The color selection widget supports adjusting the opacity of a color
5973 (also known as the alpha channel). This is disabled by
5974 default. Calling this function with has_opacity set to TRUE enables
5975 opacity. Likewise, has_opacity set to FALSE will disable opacity.</para>
5977 <programlisting role="C">
5978 void gtk_color_selection_set_current_color( GtkColorSelection *colorsel,
5981 void gtk_color_selection_set_current_alpha( GtkColorSelection *colorsel,
5985 <para>You can set the current color explicitly by calling
5986 gtk_color_selection_set_current_color() with a pointer to a GdkColor.
5987 Setting the opacity (alpha channel) is done with
5988 gtk_color_selection_set_current_alpha(). The alpha value should be between
5989 0 (fully transparent) and 65535 (fully opaque).
5992 <programlisting role="C">
5993 void gtk_color_selection_get_current_color( GtkColorSelection *colorsel,
5996 void gtk_color_selection_get_current_alpha( GtkColorSelection *colorsel,
6000 <para>When you need to query the current color, typically when you've
6001 received a "color_changed" signal, you use these functions.</para>
6003 <para><!-- Need to do a whole section on DnD - TRG
6005 -------------</para>
6007 <para>The color sample areas (right under the hue-saturation wheel) supports
6008 drag and drop. The type of drag and drop is "application/x-color". The
6009 message data consists of an array of 4 (or 5 if opacity is enabled)
6010 gdouble values, where the value at position 0 is 0.0 (opacity on) or
6011 1.0 (opacity off) followed by the red, green and blue values at
6012 positions 1,2 and 3 respectively. If opacity is enabled, the opacity
6013 is passed in the value at position 4.
6016 <para>Here's a simple example demonstrating the use of the
6017 ColorSelectionDialog. The program displays a window containing a
6018 drawing area. Clicking on it opens a color selection dialog, and
6019 changing the color in the color selection dialog changes the
6020 background color.</para>
6025 <imagedata fileref="images/colorsel.png" format="png">
6027 </inlinemediaobject>
6030 <programlisting role="C">
6031 <!-- example-start colorsel colorsel.c -->
6033 #include <glib.h>
6034 #include <gdk/gdk.h>
6035 #include <gtk/gtk.h>
6037 GtkWidget *colorseldlg = NULL;
6038 GtkWidget *drawingarea = NULL;
6041 /* Color changed handler */
6043 static void color_changed_cb( GtkWidget *widget,
6044 GtkColorSelection *colorsel )
6048 gtk_color_selection_get_current_color (colorsel, &ncolor);
6049 gtk_widget_modify_bg (drawingarea, GTK_STATE_NORMAL, &ncolor);
6052 /* Drawingarea event handler */
6054 static gboolean area_event( GtkWidget *widget,
6056 gpointer client_data )
6058 gint handled = FALSE;
6060 GtkColorSelection *colorsel;
6062 /* Check if we've received a button pressed event */
6064 if (event->type == GDK_BUTTON_PRESS)
6068 /* Create color selection dialog */
6069 if (colorseldlg == NULL)
6070 colorseldlg = gtk_color_selection_dialog_new ("Select background color");
6072 /* Get the ColorSelection widget */
6073 colorsel = GTK_COLOR_SELECTION (GTK_COLOR_SELECTION_DIALOG (colorseldlg)->colorsel);
6075 gtk_color_selection_set_previous_color (colorsel, &color);
6076 gtk_color_selection_set_current_color (colorsel, &color);
6077 gtk_color_selection_set_has_palette (colorsel, TRUE);
6079 /* Connect to the "color_changed" signal, set the client-data
6080 * to the colorsel widget */
6081 g_signal_connect (colorsel, "color_changed",
6082 G_CALLBACK (color_changed_cb), (gpointer) colorsel);
6084 /* Show the dialog */
6085 response = gtk_dialog_run (GTK_DIALOG (colorseldlg));
6087 if (response == GTK_RESPONSE_OK)
6088 gtk_color_selection_get_current_color (colorsel, &color);
6090 gtk_widget_modify_bg (drawingarea, GTK_STATE_NORMAL, &color);
6092 gtk_widget_hide (colorseldlg);
6098 /* Close down and exit handler */
6100 static gboolean destroy_window( GtkWidget *widget,
6102 gpointer client_data )
6110 gint main( gint argc,
6115 /* Initialize the toolkit, remove gtk-related commandline stuff */
6117 gtk_init (&argc, &argv);
6119 /* Create toplevel window, set title and policies */
6121 window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
6122 gtk_window_set_title (GTK_WINDOW (window), "Color selection test");
6123 gtk_window_set_resizable ((GTK_WINDOW (window), TRUE);
6125 /* Attach to the "delete" and "destroy" events so we can exit */
6127 g_signal_connect (window, "delete-event",
6128 G_CALLBACK (destroy_window), (gpointer) window);
6130 /* Create drawingarea, set size and catch button events */
6132 drawingarea = gtk_drawing_area_new ();
6137 gtk_widget_modify_bg (drawingarea, GTK_STATE_NORMAL, &color);
6139 gtk_widget_set_size_request (GTK_WIDGET (drawingarea), 200, 200);
6141 gtk_widget_set_events (drawingarea, GDK_BUTTON_PRESS_MASK);
6143 g_signal_connect (GTK_OBJECT (drawingarea), "event",
6144 G_CALLBACK (area_event), (gpointer) drawingarea);
6146 /* Add drawingarea to window, then show them both */
6148 gtk_container_add (GTK_CONTAINER (window), drawingarea);
6150 gtk_widget_show (drawingarea);
6151 gtk_widget_show (window);
6153 /* Enter the gtk main loop (this never returns) */
6157 /* Satisfy grumpy compilers */
6161 <!-- example-end -->
6166 <!-- ----------------------------------------------------------------- -->
6167 <sect1 id="sec-FileSelections">
6168 <title>File Selections</title>
6170 <para>The file selection widget is a quick and simple way to display a File
6171 dialog box. It comes complete with Ok, Cancel, and Help buttons, a
6172 great way to cut down on programming time.</para>
6174 <para>To create a new file selection box use:</para>
6176 <programlisting role="C">
6177 GtkWidget *gtk_file_selection_new( const gchar *title );
6180 <para>To set the filename, for example to bring up a specific directory, or
6181 give a default filename, use this function:</para>
6183 <programlisting role="C">
6184 void gtk_file_selection_set_filename( GtkFileSelection *filesel,
6185 const gchar *filename );
6188 <para>To grab the text that the user has entered or clicked on, use this
6191 <programlisting role="C">
6192 gchar *gtk_file_selection_get_filename( GtkFileSelection *filesel );
6195 <para>There are also pointers to the widgets contained within the file
6196 selection widget. These are:</para>
6198 <programlisting role="C">
6209 <para>Most likely you will want to use the ok_button, cancel_button, and
6210 help_button pointers in signaling their use.</para>
6212 <para>Included here is an example stolen from <filename>testgtk.c</filename>,
6213 modified to run on its own. As you will see, there is nothing much to creating a file
6214 selection widget. While in this example the Help button appears on the
6215 screen, it does nothing as there is not a signal attached to it.</para>
6220 <imagedata fileref="images/filesel.png" format="png">
6222 </inlinemediaobject>
6225 <programlisting role="C">
6226 <!-- example-start filesel filesel.c -->
6228 #include <gtk/gtk.h>
6230 /* Get the selected filename and print it to the console */
6231 static void file_ok_sel( GtkWidget *w,
6232 GtkFileSelection *fs )
6234 g_print ("%s\n", gtk_file_selection_get_filename (GTK_FILE_SELECTION (fs)));
6242 gtk_init (&argc, &argv);
6244 /* Create a new file selection widget */
6245 filew = gtk_file_selection_new ("File selection");
6247 g_signal_connect (filew, "destroy",
6248 G_CALLBACK (gtk_main_quit), NULL);
6249 /* Connect the ok_button to file_ok_sel function */
6250 g_signal_connect (GTK_FILE_SELECTION (filew)->ok_button,
6251 "clicked", G_CALLBACK (file_ok_sel), (gpointer) filew);
6253 /* Connect the cancel_button to destroy the widget */
6254 g_signal_connect_swapped (GTK_FILE_SELECTION (filew)->cancel_button,
6255 "clicked", G_CALLBACK (gtk_widget_destroy),
6258 /* Lets set the filename, as if this were a save dialog, and we are giving
6259 a default filename */
6260 gtk_file_selection_set_filename (GTK_FILE_SELECTION(filew),
6263 gtk_widget_show (filew);
6267 <!-- example-end -->
6273 <!-- ***************************************************************** -->
6274 <chapter id="ch-ContainerWidgets">
6275 <title>Container Widgets</title>
6277 <!-- ----------------------------------------------------------------- -->
6278 <sect1 id="sec-EventBox">
6279 <title>The EventBox</title>
6281 <para>Some GTK widgets don't have associated X windows, so they just draw on
6282 their parents. Because of this, they cannot receive events and if they
6283 are incorrectly sized, they don't clip so you can get messy
6284 overwriting, etc. If you require more from these widgets, the EventBox
6287 <para>At first glance, the EventBox widget might appear to be totally
6288 useless. It draws nothing on the screen and responds to no
6289 events. However, it does serve a function - it provides an X window
6290 for its child widget. This is important as many GTK widgets do not
6291 have an associated X window. Not having an X window saves memory and
6292 improves performance, but also has some drawbacks. A widget without an
6293 X window cannot receive events, and does not perform any clipping on
6294 its contents. Although the name <emphasis>EventBox</emphasis> emphasizes the
6295 event-handling function, the widget can also be used for clipping.
6296 (and more, see the example below).</para>
6298 <para>To create a new EventBox widget, use:</para>
6300 <programlisting role="C">
6301 GtkWidget *gtk_event_box_new( void );
6304 <para>A child widget can then be added to this EventBox:</para>
6306 <programlisting role="C">
6307 gtk_container_add (GTK_CONTAINER (event_box), child_widget);
6310 <para>The following example demonstrates both uses of an EventBox - a label
6311 is created that is clipped to a small box, and set up so that a
6312 mouse-click on the label causes the program to exit. Resizing the
6313 window reveals varying amounts of the label.</para>
6318 <imagedata fileref="images/eventbox.png" format="png">
6320 </inlinemediaobject>
6323 <programlisting role="C">
6324 <!-- example-start eventbox eventbox.c -->
6326 #include <stdlib.h>
6327 #include <gtk/gtk.h>
6333 GtkWidget *event_box;
6336 gtk_init (&argc, &argv);
6338 window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
6340 gtk_window_set_title (GTK_WINDOW (window), "Event Box");
6342 g_signal_connect (window, "destroy",
6343 G_CALLBACK (exit), NULL);
6345 gtk_container_set_border_width (GTK_CONTAINER (window), 10);
6347 /* Create an EventBox and add it to our toplevel window */
6349 event_box = gtk_event_box_new ();
6350 gtk_container_add (GTK_CONTAINER (window), event_box);
6351 gtk_widget_show (event_box);
6353 /* Create a long label */
6355 label = gtk_label_new ("Click here to quit, quit, quit, quit, quit");
6356 gtk_container_add (GTK_CONTAINER (event_box), label);
6357 gtk_widget_show (label);
6359 /* Clip it short. */
6360 gtk_widget_set_size_request (label, 110, 20);
6362 /* And bind an action to it */
6363 gtk_widget_set_events (event_box, GDK_BUTTON_PRESS_MASK);
6364 g_signal_connect (event_box, "button_press_event",
6365 G_CALLBACK (exit), NULL);
6367 /* Yet one more thing you need an X window for ... */
6369 gtk_widget_realize (event_box);
6370 gdk_window_set_cursor (event_box->window, gdk_cursor_new (GDK_HAND1));
6372 gtk_widget_show (window);
6378 <!-- example-end -->
6383 <!-- ----------------------------------------------------------------- -->
6384 <sect1 id="sec-TheAlignmentWidget">
6385 <title>The Alignment widget</title>
6387 <para>The alignment widget allows you to place a widget within its window at
6388 a position and size relative to the size of the Alignment widget
6389 itself. For example, it can be very useful for centering a widget
6390 within the window.</para>
6392 <para>There are only two functions associated with the Alignment widget:</para>
6394 <programlisting role="C">
6395 GtkWidget* gtk_alignment_new( gfloat xalign,
6400 void gtk_alignment_set( GtkAlignment *alignment,
6407 <para>The first function creates a new Alignment widget with the specified
6408 parameters. The second function allows the alignment parameters of an
6409 exisiting Alignment widget to be altered.</para>
6411 <para>All four alignment parameters are floating point numbers which can
6412 range from 0.0 to 1.0. The <literal>xalign</literal> and <literal>yalign</literal> arguments
6413 affect the position of the widget placed within the Alignment
6414 widget. The <literal>xscale</literal> and <literal>yscale</literal> arguments affect the amount of
6415 space allocated to the widget.</para>
6417 <para>A child widget can be added to this Alignment widget using:</para>
6419 <programlisting role="C">
6420 gtk_container_add (GTK_CONTAINER (alignment), child_widget);
6423 <para>For an example of using an Alignment widget, refer to the example for
6424 the <link linkend="sec-ProgressBars">Progress Bar</link> widget.</para>
6428 <!-- ----------------------------------------------------------------- -->
6429 <sect1 id="sec-FixedContainer">
6430 <title>Fixed Container</title>
6432 <para>The Fixed container allows you to place widgets at a fixed position
6433 within it's window, relative to it's upper left hand corner. The
6434 position of the widgets can be changed dynamically.</para>
6436 <para>There are only a few functions associated with the fixed widget:</para>
6438 <programlisting role="C">
6439 GtkWidget* gtk_fixed_new( void );
6441 void gtk_fixed_put( GtkFixed *fixed,
6446 void gtk_fixed_move( GtkFixed *fixed,
6452 <para>The function gtk_fixed_new() allows you to create a new Fixed
6455 <para>gtk_fixed_put() places <literal>widget</literal> in the container <literal>fixed</literal> at
6456 the position specified by <literal>x</literal> and <literal>y</literal>.</para>
6458 <para>gtk_fixed_move() allows the specified widget to be moved to a new
6461 <programlisting role="C">
6462 void gtk_widget_set_has_window( GtkWidget *widget,
6463 gboolean has_window );
6465 gboolean gtk_widget_get_has_window( GtkWidget *widget );
6468 <para>Normally, Fixed widgets don't have their own X window. Since this is
6469 different from the behaviour of Fixed widgets in earlier releases of GTK,
6470 the function gtk_widget_set_has_window() allows the creation of Fixed widgets
6471 <emphasis>with</emphasis> their own window. It has to be called before
6472 realizing the widget.</para>
6474 <para>The following example illustrates how to use the Fixed Container.</para>
6479 <imagedata fileref="images/fixed.png" format="png">
6481 </inlinemediaobject>
6484 <programlisting role="C">
6485 <!-- example-start fixed fixed.c -->
6487 #include <gtk/gtk.h>
6489 /* I'm going to be lazy and use some global variables to
6490 * store the position of the widget within the fixed
6495 /* This callback function moves the button to a new position
6496 * in the Fixed container. */
6497 static void move_button( GtkWidget *widget,
6502 gtk_fixed_move (GTK_FIXED (fixed), widget, x, y);
6508 /* GtkWidget is the storage type for widgets */
6514 /* Initialise GTK */
6515 gtk_init (&argc, &argv);
6517 /* Create a new window */
6518 window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
6519 gtk_window_set_title (GTK_WINDOW (window), "Fixed Container");
6521 /* Here we connect the "destroy" event to a signal handler */
6522 g_signal_connect (window, "destroy",
6523 G_CALLBACK (gtk_main_quit), NULL);
6525 /* Sets the border width of the window. */
6526 gtk_container_set_border_width (GTK_CONTAINER (window), 10);
6528 /* Create a Fixed Container */
6529 fixed = gtk_fixed_new ();
6530 gtk_container_add (GTK_CONTAINER (window), fixed);
6531 gtk_widget_show (fixed);
6533 for (i = 1 ; i <= 3 ; i++) {
6534 /* Creates a new button with the label "Press me" */
6535 button = gtk_button_new_with_label ("Press me");
6537 /* When the button receives the "clicked" signal, it will call the
6538 * function move_button() passing it the Fixed Container as its
6540 g_signal_connect (button, "clicked",
6541 G_CALLBACK (move_button), (gpointer) fixed);
6543 /* This packs the button into the fixed containers window. */
6544 gtk_fixed_put (GTK_FIXED (fixed), button, i*50, i*50);
6546 /* The final step is to display this newly created widget. */
6547 gtk_widget_show (button);
6550 /* Display the window */
6551 gtk_widget_show (window);
6553 /* Enter the event loop */
6558 <!-- example-end -->
6563 <!-- ----------------------------------------------------------------- -->
6564 <sect1 id="sec-LayoutContainer">
6565 <title>Layout Container</title>
6567 <para>The Layout container is similar to the Fixed container except that it
6568 implements an infinite (where infinity is less than 2^32) scrolling
6569 area. The X window system has a limitation where windows can be at
6570 most 32767 pixels wide or tall. The Layout container gets around this
6571 limitation by doing some exotic stuff using window and bit gravities,
6572 so that you can have smooth scrolling even when you have many child
6573 widgets in your scrolling area.</para>
6575 <para>A Layout container is created using:</para>
6577 <programlisting role="C">
6578 GtkWidget *gtk_layout_new( GtkAdjustment *hadjustment,
6579 GtkAdjustment *vadjustment );
6582 <para>As you can see, you can optionally specify the Adjustment objects that
6583 the Layout widget will use for its scrolling.</para>
6585 <para>You can add and move widgets in the Layout container using the
6586 following two functions:</para>
6588 <programlisting role="C">
6589 void gtk_layout_put( GtkLayout *layout,
6594 void gtk_layout_move( GtkLayout *layout,
6600 <para>The size of the Layout container can be set using the next function:</para>
6602 <programlisting role="C">
6603 void gtk_layout_set_size( GtkLayout *layout,
6608 <para>The final four functions for use with Layout widgets are for
6609 manipulating the horizontal and vertical adjustment widgets:</para>
6611 <programlisting role="C">
6612 GtkAdjustment* gtk_layout_get_hadjustment( GtkLayout *layout );
6614 GtkAdjustment* gtk_layout_get_vadjustment( GtkLayout *layout );
6616 void gtk_layout_set_hadjustment( GtkLayout *layout,
6617 GtkAdjustment *adjustment );
6619 void gtk_layout_set_vadjustment( GtkLayout *layout,
6620 GtkAdjustment *adjustment);
6625 <!-- ----------------------------------------------------------------- -->
6626 <sect1 id="sec-Frames">
6627 <title>Frames</title>
6629 <para>Frames can be used to enclose one or a group of widgets with a box
6630 which can optionally be labelled. The position of the label and the
6631 style of the box can be altered to suit.</para>
6633 <para>A Frame can be created with the following function:</para>
6635 <programlisting role="C">
6636 GtkWidget *gtk_frame_new( const gchar *label );
6639 <para>The label is by default placed in the upper left hand corner of the
6640 frame. A value of NULL for the <literal>label</literal> argument will result in no
6641 label being displayed. The text of the label can be changed using the
6642 next function.</para>
6644 <programlisting role="C">
6645 void gtk_frame_set_label( GtkFrame *frame,
6646 const gchar *label );
6649 <para>The position of the label can be changed using this function:</para>
6651 <programlisting role="C">
6652 void gtk_frame_set_label_align( GtkFrame *frame,
6657 <para><literal>xalign</literal> and <literal>yalign</literal> take values between 0.0 and 1.0. <literal>xalign</literal>
6658 indicates the position of the label along the top horizontal of the
6659 frame. <literal>yalign</literal> is not currently used. The default value of xalign
6660 is 0.0 which places the label at the left hand end of the frame.</para>
6662 <para>The next function alters the style of the box that is used to outline
6665 <programlisting role="C">
6666 void gtk_frame_set_shadow_type( GtkFrame *frame,
6667 GtkShadowType type);
6670 <para>The <literal>type</literal> argument can take one of the following values:</para>
6671 <programlisting role="C">
6675 GTK_SHADOW_ETCHED_IN (the default)
6676 GTK_SHADOW_ETCHED_OUT
6679 <para>The following code example illustrates the use of the Frame widget.</para>
6684 <imagedata fileref="images/frame.png" format="png">
6686 </inlinemediaobject>
6689 <programlisting role="C">
6690 <!-- example-start frame frame.c -->
6692 #include <gtk/gtk.h>
6697 /* GtkWidget is the storage type for widgets */
6701 /* Initialise GTK */
6702 gtk_init (&argc, &argv);
6704 /* Create a new window */
6705 window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
6706 gtk_window_set_title (GTK_WINDOW (window), "Frame Example");
6708 /* Here we connect the "destroy" event to a signal handler */
6709 g_signal_connect (window, "destroy",
6710 G_CALLBACK (gtk_main_quit), NULL);
6712 gtk_widget_set_size_request (window, 300, 300);
6713 /* Sets the border width of the window. */
6714 gtk_container_set_border_width (GTK_CONTAINER (window), 10);
6716 /* Create a Frame */
6717 frame = gtk_frame_new (NULL);
6718 gtk_container_add (GTK_CONTAINER (window), frame);
6720 /* Set the frame's label */
6721 gtk_frame_set_label (GTK_FRAME (frame), "GTK Frame Widget");
6723 /* Align the label at the right of the frame */
6724 gtk_frame_set_label_align (GTK_FRAME (frame), 1.0, 0.0);
6726 /* Set the style of the frame */
6727 gtk_frame_set_shadow_type (GTK_FRAME (frame), GTK_SHADOW_ETCHED_OUT);
6729 gtk_widget_show (frame);
6731 /* Display the window */
6732 gtk_widget_show (window);
6734 /* Enter the event loop */
6739 <!-- example-end -->
6743 <!-- ----------------------------------------------------------------- -->
6744 <sect1 id="sec-AspectFrames">
6745 <title>Aspect Frames</title>
6747 <para>The aspect frame widget is like a frame widget, except that it also
6748 enforces the aspect ratio (that is, the ratio of the width to the
6749 height) of the child widget to have a certain value, adding extra
6750 space if necessary. This is useful, for instance, if you want to
6751 preview a larger image. The size of the preview should vary when the
6752 user resizes the window, but the aspect ratio needs to always match
6753 the original image.</para>
6755 <para>To create a new aspect frame use:</para>
6757 <programlisting role="C">
6758 GtkWidget *gtk_aspect_frame_new( const gchar *label,
6762 gboolean obey_child);
6765 <para><literal>xalign</literal> and <literal>yalign</literal> specify alignment as with Alignment
6766 widgets. If <literal>obey_child</literal> is TRUE, the aspect ratio of a child
6767 widget will match the aspect ratio of the ideal size it requests.
6768 Otherwise, it is given by <literal>ratio</literal>.</para>
6770 <para>To change the options of an existing aspect frame, you can use:</para>
6772 <programlisting role="C">
6773 void gtk_aspect_frame_set( GtkAspectFrame *aspect_frame,
6777 gboolean obey_child);
6780 <para>As an example, the following program uses an AspectFrame to present a
6781 drawing area whose aspect ratio will always be 2:1, no matter how the
6782 user resizes the top-level window.</para>
6787 <imagedata fileref="images/aspectframe.png" format="png">
6789 </inlinemediaobject>
6792 <programlisting role="C">
6793 <!-- example-start aspectframe aspectframe.c -->
6795 #include <gtk/gtk.h>
6801 GtkWidget *aspect_frame;
6802 GtkWidget *drawing_area;
6803 gtk_init (&argc, &argv);
6805 window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
6806 gtk_window_set_title (GTK_WINDOW (window), "Aspect Frame");
6807 g_signal_connect (window, "destroy",
6808 G_CALLBACK (gtk_main_quit), NULL);
6809 gtk_container_set_border_width (GTK_CONTAINER (window), 10);
6811 /* Create an aspect_frame and add it to our toplevel window */
6813 aspect_frame = gtk_aspect_frame_new ("2x1", /* label */
6816 2, /* xsize/ysize = 2 */
6817 FALSE /* ignore child's aspect */);
6819 gtk_container_add (GTK_CONTAINER (window), aspect_frame);
6820 gtk_widget_show (aspect_frame);
6822 /* Now add a child widget to the aspect frame */
6824 drawing_area = gtk_drawing_area_new ();
6826 /* Ask for a 200x200 window, but the AspectFrame will give us a 200x100
6827 * window since we are forcing a 2x1 aspect ratio */
6828 gtk_widget_set_size_request (drawing_area, 200, 200);
6829 gtk_container_add (GTK_CONTAINER (aspect_frame), drawing_area);
6830 gtk_widget_show (drawing_area);
6832 gtk_widget_show (window);
6836 <!-- example-end -->
6841 <!-- ----------------------------------------------------------------- -->
6842 <sect1 id="sec-PanedWindowWidgets">
6843 <title>Paned Window Widgets</title>
6845 <para>The paned window widgets are useful when you want to divide an area
6846 into two parts, with the relative size of the two parts controlled by
6847 the user. A groove is drawn between the two portions with a handle
6848 that the user can drag to change the ratio. The division can either be
6849 horizontal (HPaned) or vertical (VPaned).</para>
6851 <para>To create a new paned window, call one of:</para>
6853 <programlisting role="C">
6854 GtkWidget *gtk_hpaned_new (void);
6856 GtkWidget *gtk_vpaned_new (void);
6859 <para>After creating the paned window widget, you need to add child widgets
6860 to its two halves. To do this, use the functions:</para>
6862 <programlisting role="C">
6863 void gtk_paned_add1 (GtkPaned *paned, GtkWidget *child);
6865 void gtk_paned_add2 (GtkPaned *paned, GtkWidget *child);
6868 <para><literal>gtk_paned_add1()</literal> adds the child widget to the left or top half of
6869 the paned window. <literal>gtk_paned_add2()</literal> adds the child widget to the
6870 right or bottom half of the paned window.</para>
6872 <para>As an example, we will create part of the user interface of an
6873 imaginary email program. A window is divided into two portions
6874 vertically, with the top portion being a list of email messages and
6875 the bottom portion the text of the email message. Most of the program
6876 is pretty straightforward. A couple of points to note: text can't be
6877 added to a Text widget until it is realized. This could be done by
6878 calling gtk_widget_realize(), but as a demonstration of an
6879 alternate technique, we connect a handler to the "realize" signal to
6880 add the text. Also, we need to add the <literal>GTK_SHRINK</literal> option to some
6881 of the items in the table containing the text window and its
6882 scrollbars, so that when the bottom portion is made smaller, the
6883 correct portions shrink instead of being pushed off the bottom of the
6889 <imagedata fileref="images/paned.png" format="png">
6891 </inlinemediaobject>
6894 <programlisting role="C">
6895 <!-- example-start paned paned.c -->
6897 #include <stdio.h>
6898 #include <gtk/gtk.h>
6900 /* Create the list of "messages" */
6901 static GtkWidget *create_list( void )
6904 GtkWidget *scrolled_window;
6905 GtkWidget *tree_view;
6906 GtkListStore *model;
6908 GtkCellRenderer *cell;
6909 GtkTreeViewColumn *column;
6913 /* Create a new scrolled window, with scrollbars only if needed */
6914 scrolled_window = gtk_scrolled_window_new (NULL, NULL);
6915 gtk_scrolled_window_set_policy (GTK_SCROLLED_WINDOW (scrolled_window),
6916 GTK_POLICY_AUTOMATIC,
6917 GTK_POLICY_AUTOMATIC);
6919 model = gtk_list_store_new (1, G_TYPE_STRING);
6920 tree_view = gtk_tree_view_new ();
6921 gtk_container_add (GTK_CONTAINER (scrolled_window), tree_view);
6922 gtk_tree_view_set_model (GTK_TREE_VIEW (tree_view), GTK_TREE_MODEL (model));
6923 gtk_widget_show (tree_view);
6925 /* Add some messages to the window */
6926 for (i = 0; i < 10; i++) {
6927 gchar *msg = g_strdup_printf ("Message #%d", i);
6928 gtk_list_store_append (GTK_LIST_STORE (model), &iter);
6929 gtk_list_store_set (GTK_LIST_STORE (model),
6936 cell = gtk_cell_renderer_text_new ();
6938 column = gtk_tree_view_column_new_with_attributes ("Messages",
6943 gtk_tree_view_append_column (GTK_TREE_VIEW (tree_view),
6944 GTK_TREE_VIEW_COLUMN (column));
6946 return scrolled_window;
6949 /* Add some text to our text widget - this is a callback that is invoked
6950 when our window is realized. We could also force our window to be
6951 realized with gtk_widget_realize, but it would have to be part of
6952 a hierarchy first */
6954 static void insert_text( GtkTextBuffer *buffer )
6958 gtk_text_buffer_get_iter_at_offset (buffer, &iter, 0);
6960 gtk_text_buffer_insert (buffer, &iter,
6961 "From: pathfinder@nasa.gov\n"
6962 "To: mom@nasa.gov\n"
6963 "Subject: Made it!\n"
6965 "We just got in this morning. The weather has been\n"
6966 "great - clear but cold, and there are lots of fun sights.\n"
6967 "Sojourner says hi. See you soon.\n"
6971 /* Create a scrolled text area that displays a "message" */
6972 static GtkWidget *create_text( void )
6974 GtkWidget *scrolled_window;
6976 GtkTextBuffer *buffer;
6978 view = gtk_text_view_new ();
6979 buffer = gtk_text_view_get_buffer (GTK_TEXT_VIEW (view));
6981 scrolled_window = gtk_scrolled_window_new (NULL, NULL);
6982 gtk_scrolled_window_set_policy (GTK_SCROLLED_WINDOW (scrolled_window),
6983 GTK_POLICY_AUTOMATIC,
6984 GTK_POLICY_AUTOMATIC);
6986 gtk_container_add (GTK_CONTAINER (scrolled_window), view);
6987 insert_text (buffer);
6989 gtk_widget_show_all (scrolled_window);
6991 return scrolled_window;
7002 gtk_init (&argc, &argv);
7004 window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
7005 gtk_window_set_title (GTK_WINDOW (window), "Paned Windows");
7006 g_signal_connect (window, "destroy",
7007 G_CALLBACK (gtk_main_quit), NULL);
7008 gtk_container_set_border_width (GTK_CONTAINER (window), 10);
7009 gtk_widget_set_size_request (GTK_WIDGET (window), 450, 400);
7011 /* create a vpaned widget and add it to our toplevel window */
7013 vpaned = gtk_vpaned_new ();
7014 gtk_container_add (GTK_CONTAINER (window), vpaned);
7015 gtk_widget_show (vpaned);
7017 /* Now create the contents of the two halves of the window */
7019 list = create_list ();
7020 gtk_paned_add1 (GTK_PANED (vpaned), list);
7021 gtk_widget_show (list);
7023 text = create_text ();
7024 gtk_paned_add2 (GTK_PANED (vpaned), text);
7025 gtk_widget_show (text);
7026 gtk_widget_show (window);
7032 <!-- example-end -->
7037 <!-- ----------------------------------------------------------------- -->
7038 <sect1 id="sec-Viewports">
7039 <title>Viewports</title>
7041 <para>It is unlikely that you will ever need to use the Viewport widget
7042 directly. You are much more likely to use the
7043 <link linkend="sec-ScrolledWindows">Scrolled Window</link> widget which
7044 itself uses the Viewport.</para>
7046 <para>A viewport widget allows you to place a larger widget within it such
7047 that you can view a part of it at a time. It uses
7048 <link linkend="ch-Adjustments">Adjustments</link> to define the area that
7049 is currently in view.</para>
7051 <para>A Viewport is created with the function</para>
7053 <programlisting role="C">
7054 GtkWidget *gtk_viewport_new( GtkAdjustment *hadjustment,
7055 GtkAdjustment *vadjustment );
7058 <para>As you can see you can specify the horizontal and vertical Adjustments
7059 that the widget is to use when you create the widget. It will create
7060 its own if you pass NULL as the value of the arguments.</para>
7062 <para>You can get and set the adjustments after the widget has been created
7063 using the following four functions:</para>
7065 <programlisting role="C">
7066 GtkAdjustment *gtk_viewport_get_hadjustment( GtkViewport *viewport );
7068 GtkAdjustment *gtk_viewport_get_vadjustment( GtkViewport *viewport );
7070 void gtk_viewport_set_hadjustment( GtkViewport *viewport,
7071 GtkAdjustment *adjustment );
7073 void gtk_viewport_set_vadjustment( GtkViewport *viewport,
7074 GtkAdjustment *adjustment );
7077 <para>The only other viewport function is used to alter its appearance:</para>
7079 <programlisting role="C">
7080 void gtk_viewport_set_shadow_type( GtkViewport *viewport,
7081 GtkShadowType type );
7084 <para>Possible values for the <literal>type</literal> parameter are:</para>
7085 <programlisting role="C">
7089 GTK_SHADOW_ETCHED_IN,
7090 GTK_SHADOW_ETCHED_OUT
7095 <!-- ----------------------------------------------------------------- -->
7096 <sect1 id="sec-ScrolledWindows"
7097 <title>Scrolled Windows</title>
7099 <para>Scrolled windows are used to create a scrollable area with another
7100 widget inside it. You may insert any type of widget into a scrolled
7101 window, and it will be accessible regardless of the size by using the
7104 <para>The following function is used to create a new scrolled window.</para>
7106 <programlisting role="C">
7107 GtkWidget *gtk_scrolled_window_new( GtkAdjustment *hadjustment,
7108 GtkAdjustment *vadjustment );
7111 <para>Where the first argument is the adjustment for the horizontal
7112 direction, and the second, the adjustment for the vertical direction.
7113 These are almost always set to NULL.</para>
7115 <programlisting role="C">
7116 void gtk_scrolled_window_set_policy( GtkScrolledWindow *scrolled_window,
7117 GtkPolicyType hscrollbar_policy,
7118 GtkPolicyType vscrollbar_policy );
7121 <para>This sets the policy to be used with respect to the scrollbars.
7122 The first argument is the scrolled window you wish to change. The second
7123 sets the policy for the horizontal scrollbar, and the third the policy for
7124 the vertical scrollbar.</para>
7126 <para>The policy may be one of <literal>GTK_POLICY_AUTOMATIC</literal> or
7127 <literal>GTK_POLICY_ALWAYS</literal>. <literal>GTK_POLICY_AUTOMATIC</literal> will automatically
7128 decide whether you need scrollbars, whereas <literal>GTK_POLICY_ALWAYS</literal>
7129 will always leave the scrollbars there.</para>
7131 <para>You can then place your object into the scrolled window using the
7132 following function.</para>
7134 <programlisting role="C">
7135 void gtk_scrolled_window_add_with_viewport( GtkScrolledWindow *scrolled_window,
7139 <para>Here is a simple example that packs a table with 100 toggle buttons
7140 into a scrolled window. I've only commented on the parts that may be
7146 <imagedata fileref="images/scrolledwin.png" format="png">
7148 </inlinemediaobject>
7151 <programlisting role="C">
7152 <!-- example-start scrolledwin scrolledwin.c -->
7154 #include <stdio.h>
7155 #include <gtk/gtk.h>
7157 static void destroy( GtkWidget *widget,
7166 static GtkWidget *window;
7167 GtkWidget *scrolled_window;
7173 gtk_init (&argc, &argv);
7175 /* Create a new dialog window for the scrolled window to be
7177 window = gtk_dialog_new ();
7178 g_signal_connect (window, "destroy",
7179 G_CALLBACK (destroy), NULL);
7180 gtk_window_set_title (GTK_WINDOW (window), "GtkScrolledWindow example");
7181 gtk_container_set_border_width (GTK_CONTAINER (window), 0);
7182 gtk_widget_set_size_request (window, 300, 300);
7184 /* create a new scrolled window. */
7185 scrolled_window = gtk_scrolled_window_new (NULL, NULL);
7187 gtk_container_set_border_width (GTK_CONTAINER (scrolled_window), 10);
7189 /* the policy is one of GTK_POLICY AUTOMATIC, or GTK_POLICY_ALWAYS.
7190 * GTK_POLICY_AUTOMATIC will automatically decide whether you need
7191 * scrollbars, whereas GTK_POLICY_ALWAYS will always leave the scrollbars
7192 * there. The first one is the horizontal scrollbar, the second,
7194 gtk_scrolled_window_set_policy (GTK_SCROLLED_WINDOW (scrolled_window),
7195 GTK_POLICY_AUTOMATIC, GTK_POLICY_ALWAYS);
7196 /* The dialog window is created with a vbox packed into it. */
7197 gtk_box_pack_start (GTK_BOX (GTK_DIALOG(window)->vbox), scrolled_window,
7199 gtk_widget_show (scrolled_window);
7201 /* create a table of 10 by 10 squares. */
7202 table = gtk_table_new (10, 10, FALSE);
7204 /* set the spacing to 10 on x and 10 on y */
7205 gtk_table_set_row_spacings (GTK_TABLE (table), 10);
7206 gtk_table_set_col_spacings (GTK_TABLE (table), 10);
7208 /* pack the table into the scrolled window */
7209 gtk_scrolled_window_add_with_viewport (
7210 GTK_SCROLLED_WINDOW (scrolled_window), table);
7211 gtk_widget_show (table);
7213 /* this simply creates a grid of toggle buttons on the table
7214 * to demonstrate the scrolled window. */
7215 for (i = 0; i < 10; i++)
7216 for (j = 0; j < 10; j++) {
7217 sprintf (buffer, "button (%d,%d)\n", i, j);
7218 button = gtk_toggle_button_new_with_label (buffer);
7219 gtk_table_attach_defaults (GTK_TABLE (table), button,
7221 gtk_widget_show (button);
7224 /* Add a "close" button to the bottom of the dialog */
7225 button = gtk_button_new_with_label ("close");
7226 g_signal_connect_swapped (button, "clicked",
7227 G_CALLBACK (gtk_widget_destroy),
7230 /* this makes it so the button is the default. */
7232 gtk_widget_set_can_default (button, TRUE);
7233 gtk_box_pack_start (GTK_BOX (GTK_DIALOG (window)->action_area), button, TRUE, TRUE, 0);
7235 /* This grabs this button to be the default button. Simply hitting
7236 * the "Enter" key will cause this button to activate. */
7237 gtk_widget_grab_default (button);
7238 gtk_widget_show (button);
7240 gtk_widget_show (window);
7246 <!-- example-end -->
7249 <para>Try playing with resizing the window. You'll notice how the scrollbars
7250 react. You may also wish to use the gtk_widget_set_size_request() call to set
7251 the default size of the window or other widgets.</para>
7255 <!-- ----------------------------------------------------------------- -->
7256 <sect1 id="sec-ButtonBoxes">
7257 <title>Button Boxes</title>
7259 <para>Button Boxes are a convenient way to quickly layout a group of
7260 buttons. They come in both horizontal and vertical flavours. You
7261 create a new Button Box with one of the following calls, which create
7262 a horizontal or vertical box, respectively:</para>
7264 <programlisting role="C">
7265 GtkWidget *gtk_hbutton_box_new( void );
7267 GtkWidget *gtk_vbutton_box_new( void );
7270 <para>Buttons are added to a Button Box using the usual function:</para>
7272 <programlisting role="C">
7273 gtk_container_add (GTK_CONTAINER (button_box), child_widget);
7276 <para>Here's an example that illustrates all the different layout settings
7277 for Button Boxes.</para>
7282 <imagedata fileref="images/buttonbox.png" format="png">
7284 </inlinemediaobject>
7287 <programlisting role="C">
7288 <!-- example-start buttonbox buttonbox.c -->
7290 #include <gtk/gtk.h>
7292 /* Create a Button Box with the specified parameters */
7293 static GtkWidget *create_bbox( gint horizontal,
7304 frame = gtk_frame_new (title);
7307 bbox = gtk_hbutton_box_new ();
7309 bbox = gtk_vbutton_box_new ();
7311 gtk_container_set_border_width (GTK_CONTAINER (bbox), 5);
7312 gtk_container_add (GTK_CONTAINER (frame), bbox);
7314 /* Set the appearance of the Button Box */
7315 gtk_button_box_set_layout (GTK_BUTTON_BOX (bbox), layout);
7316 gtk_box_set_spacing (GTK_BOX (bbox), spacing);
7318 button = gtk_button_new_from_stock (GTK_STOCK_OK);
7319 gtk_container_add (GTK_CONTAINER (bbox), button);
7321 button = gtk_button_new_from_stock (GTK_STOCK_CANCEL);
7322 gtk_container_add (GTK_CONTAINER (bbox), button);
7324 button = gtk_button_new_from_stock (GTK_STOCK_HELP);
7325 gtk_container_add (GTK_CONTAINER (bbox), button);
7333 static GtkWidget* window = NULL;
7334 GtkWidget *main_vbox;
7337 GtkWidget *frame_horz;
7338 GtkWidget *frame_vert;
7340 /* Initialize GTK */
7341 gtk_init (&argc, &argv);
7343 window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
7344 gtk_window_set_title (GTK_WINDOW (window), "Button Boxes");
7346 g_signal_connect (window, "destroy",
7347 G_CALLBACK (gtk_main_quit),
7350 gtk_container_set_border_width (GTK_CONTAINER (window), 10);
7352 main_vbox = gtk_vbox_new (FALSE, 0);
7353 gtk_container_add (GTK_CONTAINER (window), main_vbox);
7355 frame_horz = gtk_frame_new ("Horizontal Button Boxes");
7356 gtk_box_pack_start (GTK_BOX (main_vbox), frame_horz, TRUE, TRUE, 10);
7358 vbox = gtk_vbox_new (FALSE, 0);
7359 gtk_container_set_border_width (GTK_CONTAINER (vbox), 10);
7360 gtk_container_add (GTK_CONTAINER (frame_horz), vbox);
7362 gtk_box_pack_start (GTK_BOX (vbox),
7363 create_bbox (TRUE, "Spread (spacing 40)", 40, 85, 20, GTK_BUTTONBOX_SPREAD),
7366 gtk_box_pack_start (GTK_BOX (vbox),
7367 create_bbox (TRUE, "Edge (spacing 30)", 30, 85, 20, GTK_BUTTONBOX_EDGE),
7370 gtk_box_pack_start (GTK_BOX (vbox),
7371 create_bbox (TRUE, "Start (spacing 20)", 20, 85, 20, GTK_BUTTONBOX_START),
7374 gtk_box_pack_start (GTK_BOX (vbox),
7375 create_bbox (TRUE, "End (spacing 10)", 10, 85, 20, GTK_BUTTONBOX_END),
7378 frame_vert = gtk_frame_new ("Vertical Button Boxes");
7379 gtk_box_pack_start (GTK_BOX (main_vbox), frame_vert, TRUE, TRUE, 10);
7381 hbox = gtk_hbox_new (FALSE, 0);
7382 gtk_container_set_border_width (GTK_CONTAINER (hbox), 10);
7383 gtk_container_add (GTK_CONTAINER (frame_vert), hbox);
7385 gtk_box_pack_start (GTK_BOX (hbox),
7386 create_bbox (FALSE, "Spread (spacing 5)", 5, 85, 20, GTK_BUTTONBOX_SPREAD),
7389 gtk_box_pack_start (GTK_BOX (hbox),
7390 create_bbox (FALSE, "Edge (spacing 30)", 30, 85, 20, GTK_BUTTONBOX_EDGE),
7393 gtk_box_pack_start (GTK_BOX (hbox),
7394 create_bbox (FALSE, "Start (spacing 20)", 20, 85, 20, GTK_BUTTONBOX_START),
7397 gtk_box_pack_start (GTK_BOX (hbox),
7398 create_bbox (FALSE, "End (spacing 20)", 20, 85, 20, GTK_BUTTONBOX_END),
7401 gtk_widget_show_all (window);
7403 /* Enter the event loop */
7408 <!-- example-end -->
7413 <!-- ----------------------------------------------------------------- -->
7414 <sect1 id="sec-Toolbar">
7415 <title>Toolbar</title>
7417 <para>Toolbars are usually used to group some number of widgets in order to
7418 simplify customization of their look and layout. Typically a toolbar
7419 consists of buttons with icons, labels and tooltips, but any other
7420 widget can also be put inside a toolbar. Finally, items can be
7421 arranged horizontally or vertically and buttons can be displayed with
7422 icons, labels, or both.</para>
7424 <para>Creating a toolbar is (as one may already suspect) done with the
7425 following function:</para>
7427 <programlisting role="C">
7428 GtkWidget *gtk_toolbar_new( void );
7431 <para>After creating a toolbar one can append, prepend and insert items
7432 (that means simple text strings) or elements (that means any widget
7433 types) into the toolbar. To describe an item we need a label text, a
7434 tooltip text, a private tooltip text, an icon for the button and a
7435 callback function for it. For example, to append or prepend an item
7436 you may use the following functions:</para>
7438 <programlisting role="C">
7439 GtkWidget *gtk_toolbar_append_item( GtkToolbar *toolbar,
7441 const char *tooltip_text,
7442 const char *tooltip_private_text,
7444 GtkSignalFunc callback,
7445 gpointer user_data );
7447 GtkWidget *gtk_toolbar_prepend_item( GtkToolbar *toolbar,
7449 const char *tooltip_text,
7450 const char *tooltip_private_text,
7452 GtkSignalFunc callback,
7453 gpointer user_data );
7456 <para>If you want to use gtk_toolbar_insert_item(), the only additional
7457 parameter which must be specified is the position in which the item
7458 should be inserted, thus:</para>
7460 <programlisting role="C">
7461 GtkWidget *gtk_toolbar_insert_item( GtkToolbar *toolbar,
7463 const char *tooltip_text,
7464 const char *tooltip_private_text,
7466 GtkSignalFunc callback,
7471 <para>To simplify adding spaces between toolbar items, you may use the
7472 following functions:</para>
7474 <programlisting role="C">
7475 void gtk_toolbar_append_space( GtkToolbar *toolbar );
7477 void gtk_toolbar_prepend_space( GtkToolbar *toolbar );
7479 void gtk_toolbar_insert_space( GtkToolbar *toolbar,
7483 <para>If it's required, the orientation of a toolbar and its style can be
7484 changed "on the fly" using the following functions:</para>
7486 <programlisting role="C">
7487 void gtk_toolbar_set_orientation( GtkToolbar *toolbar,
7488 GtkOrientation orientation );
7490 void gtk_toolbar_set_style( GtkToolbar *toolbar,
7491 GtkToolbarStyle style );
7493 void gtk_toolbar_set_tooltips( GtkToolbar *toolbar,
7497 <para>Where <literal>orientation</literal> is one of <literal>GTK_ORIENTATION_HORIZONTAL</literal> or
7498 <literal>GTK_ORIENTATION_VERTICAL</literal>. The <literal>style</literal> is used to set
7499 appearance of the toolbar items by using one of
7500 <literal>GTK_TOOLBAR_ICONS</literal>, <literal>GTK_TOOLBAR_TEXT</literal>, or
7501 <literal>GTK_TOOLBAR_BOTH</literal>.</para>
7503 <para>To show some other things that can be done with a toolbar, let's take
7504 the following program (we'll interrupt the listing with some
7505 additional explanations):</para>
7507 <programlisting role="C">
7508 #include <gtk/gtk.h>
7510 /* This function is connected to the Close button or
7511 * closing the window from the WM */
7512 static gboolean delete_event( GtkWidget *widget,
7521 <para>The above beginning seems for sure familiar to you if it's not your first
7522 GTK program. There is one additional thing though, we include a nice XPM
7523 picture to serve as an icon for all of the buttons.</para>
7525 <programlisting role="C">
7526 GtkWidget* close_button; /* This button will emit signal to close
7528 GtkWidget* tooltips_button; /* to enable/disable tooltips */
7529 GtkWidget* text_button,
7531 * both_button; /* radio buttons for toolbar style */
7532 GtkWidget* entry; /* a text entry to show packing any widget into
7536 <para>In fact not all of the above widgets are needed here, but to make things
7537 clearer I put them all together.</para>
7539 <programlisting role="C">
7540 /* that's easy... when one of the buttons is toggled, we just
7541 * check which one is active and set the style of the toolbar
7543 * ATTENTION: our toolbar is passed as data to callback ! */
7544 static void radio_event( GtkWidget *widget,
7547 if (GTK_TOGGLE_BUTTON (text_button)->active)
7548 gtk_toolbar_set_style (GTK_TOOLBAR (data), GTK_TOOLBAR_TEXT);
7549 else if (GTK_TOGGLE_BUTTON (icon_button)->active)
7550 gtk_toolbar_set_style (GTK_TOOLBAR (data), GTK_TOOLBAR_ICONS);
7551 else if (GTK_TOGGLE_BUTTON (both_button)->active)
7552 gtk_toolbar_set_style (GTK_TOOLBAR (data), GTK_TOOLBAR_BOTH);
7555 /* even easier, just check given toggle button and enable/disable
7557 static void toggle_event( GtkWidget *widget,
7560 gtk_toolbar_set_tooltips (GTK_TOOLBAR (data),
7561 GTK_TOGGLE_BUTTON (widget)->active );
7565 <para>The above are just two callback functions that will be called when
7566 one of the buttons on a toolbar is pressed. You should already be
7567 familiar with things like this if you've already used toggle buttons (and
7568 radio buttons).</para>
7570 <programlisting role="C">
7571 int main (int argc, char *argv[])
7573 /* Here is our main window (a dialog) and a handle for the handlebox */
7575 GtkWidget* handlebox;
7577 /* Ok, we need a toolbar, an icon with a mask (one for all of
7578 the buttons) and an icon widget to put this icon in (but
7579 we'll create a separate widget for each button) */
7580 GtkWidget * toolbar;
7583 /* this is called in all GTK application. */
7584 gtk_init (&argc, &argv);
7586 /* create a new window with a given title, and nice size */
7587 dialog = gtk_dialog_new ();
7588 gtk_window_set_title (GTK_WINDOW (dialog), "GTKToolbar Tutorial");
7589 gtk_widget_set_size_request (GTK_WIDGET (dialog), 600, 300);
7591 /* typically we quit if someone tries to close us */
7592 g_signal_connect (dialog, "delete-event",
7593 G_CALLBACK (delete_event), NULL);
7595 /* we need to realize the window because we use pixmaps for
7596 * items on the toolbar in the context of it */
7597 gtk_widget_realize (dialog);
7599 /* to make it nice we'll put the toolbar into the handle box,
7600 * so that it can be detached from the main window */
7601 handlebox = gtk_handle_box_new ();
7602 gtk_box_pack_start (GTK_BOX (GTK_DIALOG (dialog)->vbox),
7603 handlebox, FALSE, FALSE, 5);
7606 <para>The above should be similar to any other GTK application. Just
7607 initialization of GTK, creating the window, etc. There is only one
7608 thing that probably needs some explanation: a handle box. A handle box
7609 is just another box that can be used to pack widgets in to. The
7610 difference between it and typical boxes is that it can be detached
7611 from a parent window (or, in fact, the handle box remains in the
7612 parent, but it is reduced to a very small rectangle, while all of its
7613 contents are reparented to a new freely floating window). It is
7614 usually nice to have a detachable toolbar, so these two widgets occur
7615 together quite often.</para>
7617 <programlisting role="C">
7618 /* toolbar will be horizontal, with both icons and text, and
7619 * with 5pxl spaces between items and finally,
7620 * we'll also put it into our handlebox */
7621 toolbar = gtk_toolbar_new ();
7622 gtk_toolbar_set_orientation (GTK_TOOLBAR (toolbar), GTK_ORIENTATION_HORIZONTAL);
7623 gtk_toolbar_set_style (GTK_TOOLBAR (toolbar), GTK_TOOLBAR_BOTH);
7624 gtk_container_set_border_width (GTK_CONTAINER (toolbar), 5);
7625 gtk_toolbar_set_space_size (GTK_TOOLBAR (toolbar), 5);
7626 gtk_container_add (GTK_CONTAINER (handlebox), toolbar);
7629 <para>Well, what we do above is just a straightforward initialization of
7630 the toolbar widget.</para>
7632 <programlisting role="C">
7633 /* our first item is <close> button */
7634 iconw = gtk_image_new_from_file ("gtk.xpm"); /* icon widget */
7636 gtk_toolbar_append_item (GTK_TOOLBAR (toolbar), /* our toolbar */
7637 "Close", /* button label */
7638 "Closes this app", /* this button's tooltip */
7639 "Private", /* tooltip private info */
7640 iconw, /* icon widget */
7641 G_CALLBACK (delete_event), /* a signal */
7643 gtk_toolbar_append_space (GTK_TOOLBAR (toolbar)); /* space after item */
7646 <para>In the above code you see the simplest case: adding a button to
7647 toolbar. Just before appending a new item, we have to construct an
7648 image widget to serve as an icon for this item; this step will have
7649 to be repeated for each new item. Just after the item we also add a
7650 space, so the following items will not touch each other. As you see
7651 gtk_toolbar_append_item() returns a pointer to our newly created button
7652 widget, so that we can work with it in the normal way.</para>
7654 <programlisting role="C">
7655 /* now, let's make our radio buttons group... */
7656 iconw = gtk_image_new_from_file ("gtk.xpm");
7657 icon_button = gtk_toolbar_append_element (
7658 GTK_TOOLBAR (toolbar),
7659 GTK_TOOLBAR_CHILD_RADIOBUTTON, /* a type of element */
7660 NULL, /* pointer to widget */
7662 "Only icons in toolbar", /* tooltip */
7663 "Private", /* tooltip private string */
7665 G_CALLBACK (radio_event), /* signal */
7666 toolbar); /* data for signal */
7667 gtk_toolbar_append_space (GTK_TOOLBAR (toolbar));
7670 <para>Here we begin creating a radio buttons group. To do this we use
7671 gtk_toolbar_append_element. In fact, using this function one can also
7672 +add simple items or even spaces (type = <literal>GTK_TOOLBAR_CHILD_SPACE</literal>
7673 or +<literal>GTK_TOOLBAR_CHILD_BUTTON</literal>). In the above case we start
7674 creating a radio group. In creating other radio buttons for this group
7675 a pointer to the previous button in the group is required, so that a
7676 list of buttons can be easily constructed (see the section on <link
7677 linkend="sec-RadioButtons">Radio Buttons</link> earlier in this
7680 <programlisting role="C">
7681 /* following radio buttons refer to previous ones */
7682 iconw = gtk_image_new_from_file ("gtk.xpm");
7684 gtk_toolbar_append_element (GTK_TOOLBAR (toolbar),
7685 GTK_TOOLBAR_CHILD_RADIOBUTTON,
7688 "Only texts in toolbar",
7691 G_CALLBACK (radio_event),
7693 gtk_toolbar_append_space (GTK_TOOLBAR (toolbar));
7695 iconw = gtk_image_new_from_file ("gtk.xpm");
7697 gtk_toolbar_append_element (GTK_TOOLBAR (toolbar),
7698 GTK_TOOLBAR_CHILD_RADIOBUTTON,
7701 "Icons and text in toolbar",
7704 G_CALLBACK (radio_event),
7706 gtk_toolbar_append_space (GTK_TOOLBAR (toolbar));
7707 gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (both_button), TRUE);
7710 <para>In the end we have to set the state of one of the buttons manually
7711 (otherwise they all stay in active state, preventing us from switching
7712 between them).</para>
7714 <programlisting role="C">
7715 /* here we have just a simple toggle button */
7716 iconw = gtk_image_new_from_file ("gtk.xpm");
7718 gtk_toolbar_append_element (GTK_TOOLBAR (toolbar),
7719 GTK_TOOLBAR_CHILD_TOGGLEBUTTON,
7722 "Toolbar with or without tips",
7725 G_CALLBACK (toggle_event),
7727 gtk_toolbar_append_space (GTK_TOOLBAR (toolbar));
7728 gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (tooltips_button), TRUE);
7731 <para>A toggle button can be created in the obvious way (if one knows how to create
7732 radio buttons already).</para>
7734 <programlisting role="C">
7735 /* to pack a widget into toolbar, we only have to
7736 * create it and append it with an appropriate tooltip */
7737 entry = gtk_entry_new ();
7738 gtk_toolbar_append_widget (GTK_TOOLBAR (toolbar),
7740 "This is just an entry",
7743 /* well, it isn't created within the toolbar, so we must still show it */
7744 gtk_widget_show (entry);
7747 <para>As you see, adding any kind of widget to a toolbar is simple. The
7748 one thing you have to remember is that this widget must be shown manually
7749 (contrary to other items which will be shown together with the toolbar).</para>
7751 <programlisting role="C">
7752 /* that's it ! let's show everything. */
7753 gtk_widget_show (toolbar);
7754 gtk_widget_show (handlebox);
7755 gtk_widget_show (dialog);
7757 /* rest in gtk_main and wait for the fun to begin! */
7764 <para>So, here we are at the end of toolbar tutorial. Of course, to appreciate
7765 it in full you need also this nice XPM icon, so here it is:</para>
7767 <programlisting role="C">
7769 static char * gtk_xpm[] = {
7776 "................+...............",
7777 "..............+++++.............",
7778 "............+++++@@++...........",
7779 "..........+++++@@@@@@++.........",
7780 "........++++@@@@@@@@@@++........",
7781 "......++++@@++++++++@@@++.......",
7782 ".....+++@@@+++++++++++@@@++.....",
7783 "...+++@@@@+++@@@@@@++++@@@@+....",
7784 "..+++@@@@+++@@@@@@@@+++@@@@@++..",
7785 ".++@@@@@@+++@@@@@@@@@@@@@@@@@@++",
7786 ".+#+@@@@@@++@@@@+++@@@@@@@@@@@@+",
7787 ".+##++@@@@+++@@@+++++@@@@@@@@$@.",
7788 ".+###++@@@@+++@@@+++@@@@@++$$$@.",
7789 ".+####+++@@@+++++++@@@@@+@$$$$@.",
7790 ".+#####+++@@@@+++@@@@++@$$$$$$+.",
7791 ".+######++++@@@@@@@++@$$$$$$$$+.",
7792 ".+#######+##+@@@@+++$$$$$$@@$$+.",
7793 ".+###+++##+##+@@++@$$$$$$++$$$+.",
7794 ".+###++++##+##+@@$$$$$$$@+@$$@+.",
7795 ".+###++++++#+++@$$@+@$$@++$$$@+.",
7796 ".+####+++++++#++$$@+@$$++$$$$+..",
7797 ".++####++++++#++$$@+@$++@$$$$+..",
7798 ".+#####+++++##++$$++@+++$$$$$+..",
7799 ".++####+++##+#++$$+++++@$$$$$+..",
7800 ".++####+++####++$$++++++@$$$@+..",
7801 ".+#####++#####++$$+++@++++@$@+..",
7802 ".+#####++#####++$$++@$$@+++$@@..",
7803 ".++####++#####++$$++$$$$$+@$@++.",
7804 ".++####++#####++$$++$$$$$$$$+++.",
7805 ".+++####+#####++$$++$$$$$$$@+++.",
7806 "..+++#########+@$$+@$$$$$$+++...",
7807 "...+++########+@$$$$$$$$@+++....",
7808 ".....+++######+@$$$$$$$+++......",
7809 "......+++#####+@$$$$$@++........",
7810 ".......+++####+@$$$$+++.........",
7811 ".........++###+$$$@++...........",
7812 "..........++##+$@+++............",
7813 "...........+++++++..............",
7814 ".............++++..............."};
7819 <!-- ----------------------------------------------------------------- -->
7820 <sect1 id="sec-Notebooks">
7821 <title>Notebooks</title>
7823 <para>The NoteBook Widget is a collection of "pages" that overlap each
7824 other, each page contains different information with only one page
7825 visible at a time. This widget has become more common lately in GUI
7826 programming, and it is a good way to show blocks of similar
7827 information that warrant separation in their display.</para>
7829 <para>The first function call you will need to know, as you can probably
7830 guess by now, is used to create a new notebook widget.</para>
7832 <programlisting role="C">
7833 GtkWidget *gtk_notebook_new( void );
7836 <para>Once the notebook has been created, there are a number of functions
7837 that operate on the notebook widget. Let's look at them individually.</para>
7839 <para>The first one we will look at is how to position the page indicators.
7840 These page indicators or "tabs" as they are referred to, can be
7841 positioned in four ways: top, bottom, left, or right.</para>
7843 <programlisting role="C">
7844 void gtk_notebook_set_tab_pos( GtkNotebook *notebook,
7845 GtkPositionType pos );
7848 <para>GtkPositionType will be one of the following, which are pretty self
7850 <programlisting role="C">
7857 <para><literal>GTK_POS_TOP</literal> is the default.</para>
7859 <para>Next we will look at how to add pages to the notebook. There are three
7860 ways to add pages to the NoteBook. Let's look at the first two
7861 together as they are quite similar.</para>
7863 <programlisting role="C">
7864 void gtk_notebook_append_page( GtkNotebook *notebook,
7866 GtkWidget *tab_label );
7868 void gtk_notebook_prepend_page( GtkNotebook *notebook,
7870 GtkWidget *tab_label );
7873 <para>These functions add pages to the notebook by inserting them from the
7874 back of the notebook (append), or the front of the notebook (prepend).
7875 <literal>child</literal> is the widget that is placed within the notebook page, and
7876 <literal>tab_label</literal> is the label for the page being added. The <literal>child</literal>
7877 widget must be created separately, and is typically a set of options
7878 setup witin one of the other container widgets, such as a table.</para>
7880 <para>The final function for adding a page to the notebook contains all of
7881 the properties of the previous two, but it allows you to specify what
7882 position you want the page to be in the notebook.</para>
7884 <programlisting role="C">
7885 void gtk_notebook_insert_page( GtkNotebook *notebook,
7887 GtkWidget *tab_label,
7891 <para>The parameters are the same as _append_ and _prepend_ except it
7892 contains an extra parameter, <literal>position</literal>. This parameter is used to
7893 specify what place this page will be inserted into the first page
7894 having position zero.</para>
7896 <para>Now that we know how to add a page, lets see how we can remove a page
7897 from the notebook.</para>
7899 <programlisting role="C">
7900 void gtk_notebook_remove_page( GtkNotebook *notebook,
7904 <para>This function takes the page specified by <literal>page_num</literal> and removes it
7905 from the widget pointed to by <literal>notebook</literal>.</para>
7907 <para>To find out what the current page is in a notebook use the function:</para>
7909 <programlisting role="C">
7910 gint gtk_notebook_get_current_page( GtkNotebook *notebook );
7913 <para>These next two functions are simple calls to move the notebook page
7914 forward or backward. Simply provide the respective function call with
7915 the notebook widget you wish to operate on. Note: When the NoteBook is
7916 currently on the last page, and gtk_notebook_next_page() is called, the
7917 notebook will wrap back to the first page. Likewise, if the NoteBook
7918 is on the first page, and gtk_notebook_prev_page() is called, the
7919 notebook will wrap to the last page.</para>
7921 <programlisting role="C">
7922 void gtk_notebook_next_page( GtkNoteBook *notebook );
7924 void gtk_notebook_prev_page( GtkNoteBook *notebook );
7927 <para>This next function sets the "active" page. If you wish the notebook to
7928 be opened to page 5 for example, you would use this function. Without
7929 using this function, the notebook defaults to the first page.</para>
7931 <programlisting role="C">
7932 void gtk_notebook_set_current_page( GtkNotebook *notebook,
7936 <para>The next two functions add or remove the notebook page tabs and the
7937 notebook border respectively.</para>
7939 <programlisting role="C">
7940 void gtk_notebook_set_show_tabs( GtkNotebook *notebook,
7941 gboolean show_tabs );
7943 void gtk_notebook_set_show_border( GtkNotebook *notebook,
7944 gboolean show_border );
7947 <para>The next function is useful when the you have a large number of pages,
7948 and the tabs don't fit on the page. It allows the tabs to be scrolled
7949 through using two arrow buttons.</para>
7951 <programlisting role="C">
7952 void gtk_notebook_set_scrollable( GtkNotebook *notebook,
7953 gboolean scrollable );
7956 <para><literal>show_tabs</literal>, <literal>show_border</literal> and <literal>scrollable</literal> can be either
7957 TRUE or FALSE.</para>
7959 <para>Now let's look at an example, it is expanded from the
7960 <filename>testgtk.c</filename> code
7961 that comes with the GTK distribution. This small program creates a
7962 window with a notebook and six buttons. The notebook contains 11
7963 pages, added in three different ways, appended, inserted, and
7964 prepended. The buttons allow you rotate the tab positions, add/remove
7965 the tabs and border, remove a page, change pages in both a forward and
7966 backward manner, and exit the program.</para>
7971 <imagedata fileref="images/notebook.png" format="png">
7973 </inlinemediaobject>
7976 <programlisting role="C">
7977 <!-- example-start notebook notebook.c -->
7979 #include <stdio.h>
7980 #include <gtk/gtk.h>
7982 /* This function rotates the position of the tabs */
7983 static void rotate_book( GtkButton *button,
7984 GtkNotebook *notebook )
7986 gtk_notebook_set_tab_pos (notebook, (notebook->tab_pos + 1) % 4);
7989 /* Add/Remove the page tabs and the borders */
7990 static void tabsborder_book( GtkButton *button,
7991 GtkNotebook *notebook )
7995 if (notebook->show_tabs == 0)
7997 if (notebook->show_border == 0)
8000 gtk_notebook_set_show_tabs (notebook, tval);
8001 gtk_notebook_set_show_border (notebook, bval);
8004 /* Remove a page from the notebook */
8005 static void remove_book( GtkButton *button,
8006 GtkNotebook *notebook )
8010 page = gtk_notebook_get_current_page (notebook);
8011 gtk_notebook_remove_page (notebook, page);
8012 /* Need to refresh the widget --
8013 This forces the widget to redraw itself. */
8014 gtk_widget_queue_draw (GTK_WIDGET (notebook));
8017 static gboolean delete( GtkWidget *widget,
8031 GtkWidget *notebook;
8034 GtkWidget *checkbutton;
8039 gtk_init (&argc, &argv);
8041 window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
8043 g_signal_connect (window, "delete-event",
8044 G_CALLBACK (delete), NULL);
8046 gtk_container_set_border_width (GTK_CONTAINER (window), 10);
8048 table = gtk_table_new (3, 6, FALSE);
8049 gtk_container_add (GTK_CONTAINER (window), table);
8051 /* Create a new notebook, place the position of the tabs */
8052 notebook = gtk_notebook_new ();
8053 gtk_notebook_set_tab_pos (GTK_NOTEBOOK (notebook), GTK_POS_TOP);
8054 gtk_table_attach_defaults (GTK_TABLE (table), notebook, 0, 6, 0, 1);
8055 gtk_widget_show (notebook);
8057 /* Let's append a bunch of pages to the notebook */
8058 for (i = 0; i < 5; i++) {
8059 sprintf(bufferf, "Append Frame %d", i + 1);
8060 sprintf(bufferl, "Page %d", i + 1);
8062 frame = gtk_frame_new (bufferf);
8063 gtk_container_set_border_width (GTK_CONTAINER (frame), 10);
8064 gtk_widget_set_size_request (frame, 100, 75);
8065 gtk_widget_show (frame);
8067 label = gtk_label_new (bufferf);
8068 gtk_container_add (GTK_CONTAINER (frame), label);
8069 gtk_widget_show (label);
8071 label = gtk_label_new (bufferl);
8072 gtk_notebook_append_page (GTK_NOTEBOOK (notebook), frame, label);
8075 /* Now let's add a page to a specific spot */
8076 checkbutton = gtk_check_button_new_with_label ("Check me please!");
8077 gtk_widget_set_size_request (checkbutton, 100, 75);
8078 gtk_widget_show (checkbutton);
8080 label = gtk_label_new ("Add page");
8081 gtk_notebook_insert_page (GTK_NOTEBOOK (notebook), checkbutton, label, 2);
8083 /* Now finally let's prepend pages to the notebook */
8084 for (i = 0; i < 5; i++) {
8085 sprintf (bufferf, "Prepend Frame %d", i + 1);
8086 sprintf (bufferl, "PPage %d", i + 1);
8088 frame = gtk_frame_new (bufferf);
8089 gtk_container_set_border_width (GTK_CONTAINER (frame), 10);
8090 gtk_widget_set_size_request (frame, 100, 75);
8091 gtk_widget_show (frame);
8093 label = gtk_label_new (bufferf);
8094 gtk_container_add (GTK_CONTAINER (frame), label);
8095 gtk_widget_show (label);
8097 label = gtk_label_new (bufferl);
8098 gtk_notebook_prepend_page (GTK_NOTEBOOK (notebook), frame, label);
8101 /* Set what page to start at (page 4) */
8102 gtk_notebook_set_current_page (GTK_NOTEBOOK (notebook), 3);
8104 /* Create a bunch of buttons */
8105 button = gtk_button_new_with_label ("close");
8106 g_signal_connect_swapped (button, "clicked",
8107 G_CALLBACK (delete), NULL);
8108 gtk_table_attach_defaults (GTK_TABLE (table), button, 0, 1, 1, 2);
8109 gtk_widget_show (button);
8111 button = gtk_button_new_with_label ("next page");
8112 g_signal_connect_swapped (button, "clicked",
8113 G_CALLBACK (gtk_notebook_next_page),
8115 gtk_table_attach_defaults (GTK_TABLE (table), button, 1, 2, 1, 2);
8116 gtk_widget_show (button);
8118 button = gtk_button_new_with_label ("prev page");
8119 g_signal_connect_swapped (button, "clicked",
8120 G_CALLBACK (gtk_notebook_prev_page),
8122 gtk_table_attach_defaults (GTK_TABLE (table), button, 2, 3, 1, 2);
8123 gtk_widget_show (button);
8125 button = gtk_button_new_with_label ("tab position");
8126 g_signal_connect (button, "clicked",
8127 G_CALLBACK (rotate_book),
8129 gtk_table_attach_defaults (GTK_TABLE (table), button, 3, 4, 1, 2);
8130 gtk_widget_show (button);
8132 button = gtk_button_new_with_label ("tabs/border on/off");
8133 g_signal_connect (button, "clicked",
8134 G_CALLBACK (tabsborder_book),
8136 gtk_table_attach_defaults (GTK_TABLE (table), button, 4, 5, 1, 2);
8137 gtk_widget_show (button);
8139 button = gtk_button_new_with_label ("remove page");
8140 g_signal_connect (button, "clicked",
8141 G_CALLBACK (remove_book),
8143 gtk_table_attach_defaults (GTK_TABLE (table), button, 5, 6, 1, 2);
8144 gtk_widget_show (button);
8146 gtk_widget_show (table);
8147 gtk_widget_show (window);
8153 <!-- example-end -->
8156 <para>I hope this helps you on your way with creating notebooks for your
8157 GTK applications.</para>
8162 <!-- ***************************************************************** -->
8163 <chapter id="ch-MenuWidget">
8164 <title>Menu Widget</title>
8166 <para>There are two ways to create menus: there's the easy way, and there's
8167 the hard way. Both have their uses, but you can usually use the
8168 Itemfactory (the easy way). The "hard" way is to create all the menus
8169 using the calls directly. The easy way is to use the gtk_item_factory
8170 calls. This is much simpler, but there are advantages and
8171 disadvantages to each approach.</para>
8173 <para>The Itemfactory is much easier to use, and to add new menus to,
8174 although writing a few wrapper functions to create menus using the
8175 manual method could go a long way towards usability. With the
8176 Itemfactory, it is not possible to add images or the character '/' to
8179 <!-- ----------------------------------------------------------------- -->
8180 <sect1 id="sec-ManualMenuCreation">
8181 <title>Manual Menu Creation</title>
8183 <para>In the true tradition of teaching, we'll show you the hard way
8184 first. <literal>:)</literal></para>
8186 <para>There are three widgets that go into making a menubar and submenus:</para>
8189 <listitem><simpara>a menu item, which is what the user wants to select, e.g.,
8192 <listitem><simpara>a menu, which acts as a container for the menu items, and</simpara>
8194 <listitem><simpara>a menubar, which is a container for each of the individual
8199 <para>This is slightly complicated by the fact that menu item widgets are
8200 used for two different things. They are both the widgets that are
8201 packed into the menu, and the widget that is packed into the menubar,
8202 which, when selected, activates the menu.</para>
8204 <para>Let's look at the functions that are used to create menus and
8205 menubars. This first function is used to create a new menubar.</para>
8207 <programlisting role="C">
8208 GtkWidget *gtk_menu_bar_new( void );
8211 <para>This rather self explanatory function creates a new menubar. You use
8212 gtk_container_add() to pack this into a window, or the box_pack
8213 functions to pack it into a box - the same as buttons.</para>
8215 <programlisting role="C">
8216 GtkWidget *gtk_menu_new( void );
8219 <para>This function returns a pointer to a new menu; it is never actually
8220 shown (with gtk_widget_show()), it is just a container for the menu
8221 items. I hope this will become more clear when you look at the
8222 example below.</para>
8224 <para>The next three calls are used to create menu items that are packed into
8225 the menu (and menubar).</para>
8227 <programlisting role="C">
8228 GtkWidget *gtk_menu_item_new( void );
8230 GtkWidget *gtk_menu_item_new_with_label( const char *label );
8232 GtkWidget *gtk_menu_item_new_with_mnemonic( const char *label );
8235 <para>These calls are used to create the menu items that are to be
8236 displayed. Remember to differentiate between a "menu" as created with
8237 gtk_menu_new() and a "menu item" as created by the gtk_menu_item_new()
8238 functions. The menu item will be an actual button with an associated
8239 action, whereas a menu will be a container holding menu items.</para>
8241 <para>The gtk_menu_item_new_with_label() and gtk_menu_item_new() functions are just as
8242 you'd expect after reading about the buttons. One creates a new menu
8243 item with a label already packed into it, and the other just creates a
8244 blank menu item.</para>
8246 <para>Once you've created a menu item you have to put it into a menu. This
8247 is done using the function gtk_menu_shelll_append. In order to capture when
8248 the item is selected by the user, we need to connect to the
8249 <literal>activate</literal> signal in the usual way. So, if we wanted to create a
8250 standard <literal>File</literal> menu, with the options <literal>Open</literal>, <literal>Save</literal>, and
8251 <literal>Quit</literal>, the code would look something like:</para>
8253 <programlisting role="C">
8254 file_menu = gtk_menu_new (); /* Don't need to show menus */
8256 /* Create the menu items */
8257 open_item = gtk_menu_item_new_with_label ("Open");
8258 save_item = gtk_menu_item_new_with_label ("Save");
8259 quit_item = gtk_menu_item_new_with_label ("Quit");
8261 /* Add them to the menu */
8262 gtk_menu_shell_append (GTK_MENU_SHELL (file_menu), open_item);
8263 gtk_menu_shell_append (GTK_MENU_SHELL (file_menu), save_item);
8264 gtk_menu_shell_append (GTK_MENU_SHELL (file_menu), quit_item);
8266 /* Attach the callback functions to the activate signal */
8267 g_signal_connect_swapped (open_item, "activate",
8268 G_CALLBACK (menuitem_response),
8269 (gpointer) "file.open");
8270 g_signal_connect_swapped (save_item, "activate",
8271 G_CALLBACK (menuitem_response),
8272 (gpointer) "file.save");
8274 /* We can attach the Quit menu item to our exit function */
8275 g_signal_connect_swapped (quit_item, "activate",
8276 G_CALLBACK (destroy),
8277 (gpointer) "file.quit");
8279 /* We do need to show menu items */
8280 gtk_widget_show (open_item);
8281 gtk_widget_show (save_item);
8282 gtk_widget_show (quit_item);
8285 <para>At this point we have our menu. Now we need to create a menubar and a
8286 menu item for the <literal>File</literal> entry, to which we add our menu. The code
8287 looks like this:</para>
8289 <programlisting role="C">
8290 menu_bar = gtk_menu_bar_new ();
8291 gtk_container_add (GTK_CONTAINER (window), menu_bar);
8292 gtk_widget_show (menu_bar);
8294 file_item = gtk_menu_item_new_with_label ("File");
8295 gtk_widget_show (file_item);
8298 <para>Now we need to associate the menu with <literal>file_item</literal>. This is done
8299 with the function</para>
8301 <programlisting role="C">
8302 void gtk_menu_item_set_submenu( GtkMenuItem *menu_item,
8303 GtkWidget *submenu );
8306 <para>So, our example would continue with</para>
8308 <programlisting role="C">
8309 gtk_menu_item_set_submenu (GTK_MENU_ITEM (file_item), file_menu);
8312 <para>All that is left to do is to add the menu to the menubar, which is
8313 accomplished using the function</para>
8315 <programlisting role="C">
8316 void gtk_menu_bar_append( GtkMenuBar *menu_bar,
8317 GtkWidget *menu_item );
8320 <para>which in our case looks like this:</para>
8322 <programlisting role="C">
8323 gtk_menu_bar_append (GTK_MENU_BAR (menu_bar), file_item);
8326 <para>If we wanted the menu right justified on the menubar, such as help
8327 menus often are, we can use the following function (again on
8328 <literal>file_item</literal> in the current example) before attaching it to the
8331 <programlisting role="C">
8332 void gtk_menu_item_right_justify( GtkMenuItem *menu_item );
8335 <para>Here is a summary of the steps needed to create a menu bar with menus
8339 <listitem><simpara> Create a new menu using gtk_menu_new()</simpara>
8342 <listitem><simpara> Use multiple calls to gtk_menu_item_new() for each item you
8343 wish to have on your menu. And use gtk_menu_shell_append() to put each of
8344 these new items on to the menu.</simpara>
8347 <listitem><simpara> Create a menu item using gtk_menu_item_new(). This will be the
8348 root of the menu, the text appearing here will be on the menubar
8352 <listitem><simpara>Use gtk_menu_item_set_submenu() to attach the menu to the root
8353 menu item (the one created in the above step).</simpara>
8356 <listitem><simpara> Create a new menubar using gtk_menu_bar_new. This step only
8357 needs to be done once when creating a series of menus on one menu bar.</simpara>
8360 <listitem><simpara> Use gtk_menu_bar_append() to put the root menu onto the menubar.</simpara>
8364 <para>Creating a popup menu is nearly the same. The difference is that the
8365 menu is not posted "automatically" by a menubar, but explicitly by
8366 calling the function gtk_menu_popup() from a button-press event, for
8367 example. Take these steps:</para>
8370 <listitem><simpara>Create an event handling function. It needs to have the
8372 <programlisting role="C">
8373 static gboolean handler( GtkWidget *widget,
8376 <simpara>and it will use the event to find out where to pop up the menu.</simpara>
8379 <listitem><simpara>In the event handler, if the event is a mouse button press,
8380 treat <literal>event</literal> as a button event (which it is) and use it as
8381 shown in the sample code to pass information to gtk_menu_popup().</simpara>
8384 <listitem><simpara>Bind that event handler to a widget with</simpara>
8385 <programlisting role="C">
8386 g_signal_connect_swapped (widget, "event",
8387 G_CALLBACK (handler),
8390 <simpara>where <literal>widget</literal> is the widget you are binding to,
8391 <literal>handler</literal> is the handling function, and <literal>menu</literal> is a menu
8392 created with gtk_menu_new(). This can be a menu which is also posted
8393 by a menu bar, as shown in the sample code.</simpara>
8399 <!-- ----------------------------------------------------------------- -->
8400 <sect1 id="sec-ManualMenuExample">
8401 <title>Manual Menu Example</title>
8403 <para>That should about do it. Let's take a look at an example to help clarify.</para>
8408 <imagedata fileref="images/menu.png" format="png">
8410 </inlinemediaobject>
8413 <programlisting role="C">
8414 <!-- example-start menu menu.c -->
8416 #include <stdio.h>
8417 #include <gtk/gtk.h>
8419 static gboolean button_press (GtkWidget *, GdkEvent *);
8420 static void menuitem_response (gchar *);
8428 GtkWidget *menu_bar;
8429 GtkWidget *root_menu;
8430 GtkWidget *menu_items;
8436 gtk_init (&argc, &argv);
8438 /* create a new window */
8439 window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
8440 gtk_widget_set_size_request (GTK_WIDGET (window), 200, 100);
8441 gtk_window_set_title (GTK_WINDOW (window), "GTK Menu Test");
8442 g_signal_connect (window, "delete-event",
8443 G_CALLBACK (gtk_main_quit), NULL);
8445 /* Init the menu-widget, and remember -- never
8446 * gtk_show_widget() the menu widget!!
8447 * This is the menu that holds the menu items, the one that
8448 * will pop up when you click on the "Root Menu" in the app */
8449 menu = gtk_menu_new ();
8451 /* Next we make a little loop that makes three menu-entries for "test-menu".
8452 * Notice the call to gtk_menu_shell_append. Here we are adding a list of
8453 * menu items to our menu. Normally, we'd also catch the "clicked"
8454 * signal on each of the menu items and setup a callback for it,
8455 * but it's omitted here to save space. */
8457 for (i = 0; i < 3; i++)
8459 /* Copy the names to the buf. */
8460 sprintf (buf, "Test-undermenu - %d", i);
8462 /* Create a new menu-item with a name... */
8463 menu_items = gtk_menu_item_new_with_label (buf);
8465 /* ...and add it to the menu. */
8466 gtk_menu_shell_append (GTK_MENU_SHELL (menu), menu_items);
8468 /* Do something interesting when the menuitem is selected */
8469 g_signal_connect_swapped (menu_items, "activate",
8470 G_CALLBACK (menuitem_response),
8471 (gpointer) g_strdup (buf));
8473 /* Show the widget */
8474 gtk_widget_show (menu_items);
8477 /* This is the root menu, and will be the label
8478 * displayed on the menu bar. There won't be a signal handler attached,
8479 * as it only pops up the rest of the menu when pressed. */
8480 root_menu = gtk_menu_item_new_with_label ("Root Menu");
8482 gtk_widget_show (root_menu);
8484 /* Now we specify that we want our newly created "menu" to be the menu
8485 * for the "root menu" */
8486 gtk_menu_item_set_submenu (GTK_MENU_ITEM (root_menu), menu);
8488 /* A vbox to put a menu and a button in: */
8489 vbox = gtk_vbox_new (FALSE, 0);
8490 gtk_container_add (GTK_CONTAINER (window), vbox);
8491 gtk_widget_show (vbox);
8493 /* Create a menu-bar to hold the menus and add it to our main window */
8494 menu_bar = gtk_menu_bar_new ();
8495 gtk_box_pack_start (GTK_BOX (vbox), menu_bar, FALSE, FALSE, 2);
8496 gtk_widget_show (menu_bar);
8498 /* Create a button to which to attach menu as a popup */
8499 button = gtk_button_new_with_label ("press me");
8500 g_signal_connect_swapped (button, "event",
8501 G_CALLBACK (button_press),
8503 gtk_box_pack_end (GTK_BOX (vbox), button, TRUE, TRUE, 2);
8504 gtk_widget_show (button);
8506 /* And finally we append the menu-item to the menu-bar -- this is the
8507 * "root" menu-item I have been raving about =) */
8508 gtk_menu_shell_append (GTK_MENU_SHELL (menu_bar), root_menu);
8510 /* always display the window as the last step so it all splashes on
8511 * the screen at once. */
8512 gtk_widget_show (window);
8519 /* Respond to a button-press by posting a menu passed in as widget.
8521 * Note that the "widget" argument is the menu being posted, NOT
8522 * the button that was pressed.
8525 static gboolean button_press( GtkWidget *widget,
8529 if (event->type == GDK_BUTTON_PRESS) {
8530 GdkEventButton *bevent = (GdkEventButton *) event;
8531 gtk_menu_popup (GTK_MENU (widget), NULL, NULL, NULL, NULL,
8532 bevent->button, bevent->time);
8533 /* Tell calling code that we have handled this event; the buck
8538 /* Tell calling code that we have not handled this event; pass it on. */
8543 /* Print a string when a menu item is selected */
8545 static void menuitem_response( gchar *string )
8547 printf ("%s\n", string);
8549 <!-- example-end -->
8552 <para>You may also set a menu item to be insensitive and, using an accelerator
8553 table, bind keys to menu functions.</para>
8557 <!-- ----------------------------------------------------------------- -->
8558 <sect1 id="sec-UsingItemFactory">
8559 <title>Using ItemFactory</title>
8561 <para>Now that we've shown you the hard way, here's how you do it using the
8562 gtk_item_factory calls.</para>
8564 <para>ItemFactory creates a menu out of an array of ItemFactory entries. This
8565 means you can define your menu in its simplest form and then create the
8566 menu/menubar widgets with a minimum of function calls.</para>
8568 <!-- ----------------------------------------------------------------- -->
8569 <sect2 id="sec-ItemFactoryEntries">
8570 <title>ItemFactory entries</title>
8572 <para>At the core of ItemFactory is the ItemFactoryEntry. This structure defines
8573 one menu item, and when an array of these entries is defined a whole
8574 menu is formed. The ItemFactory entry struct definition looks like this:</para>
8576 <programlisting role="C">
8577 struct _GtkItemFactoryEntry
8582 GtkItemFactoryCallback callback;
8583 guint callback_action;
8589 <para>Each field defines part of the menu item.</para>
8591 <para><literal>*path</literal> is a string which defines both the name and the
8592 path of a menu item, for example, "/File/Open" would be the name of a menu
8593 item which would come under the ItemFactory entry with path "/File". Note however
8594 that "/File/Open" would be displayed in the File menu as "Open". Also note
8595 since the forward slashes are used to define the path of the menu,
8596 they cannot be used as part of the name. A letter preceded by an underscore
8597 indicates an accelerator (shortcut) key once the menu is open.</para>
8600 <literal>*accelerator</literal> is a string that indicates a key combination
8601 that can be used as a shortcut to that menu item. The string can be made up
8602 of either a single character, or a combination of modifier keys with a single
8603 character. It is case insensitive.</para>
8606 <para>The available modifier keys are:</para>
8608 <programlisting role="C">
8610 "<CTL>" or "<CTRL>" or "<CONTROL>" - control
8611 "<MOD1>" to "<MOD5>" - modn
8612 "<SHFT>" or "<SHIFT>" - shift
8615 <para>Examples:</para>
8616 <programlisting role="C">
8618 "<SHFT><ALT><CONTROL>X"
8622 <literal>callback</literal> is the function that is called when the menu item
8623 emits the "activate" signal. The form of the callback is described
8624 in the <link linkend="sec-ItemFactoryCallback">Callback Description</link>
8628 The value of <literal>callback_action</literal> is passed to the callback
8629 function. It also affects the function prototype, as shown
8630 in the <link linkend="sec-ItemFactoryCallback">Callback Description</link>
8634 <literal>item_type</literal> is a string that defines what type of widget is
8635 packed into the menu items container. It can be:</para>
8637 <programlisting role="C">
8638 NULL or "" or "<Item>" - create a simple item
8639 "<Title>" - create a title item
8640 "<CheckItem>" - create a check item
8641 "<ToggleItem>" - create a toggle item
8642 "<RadioItem>" - create a (root) radio item
8643 "Path" - create a sister radio item
8644 "<Tearoff>" - create a tearoff
8645 "<Separator>" - create a separator
8646 "<Branch>" - create an item to hold submenus (optional)
8647 "<LastBranch>" - create a right justified branch
8648 "<StockItem>" - create a simple item with a stock image.
8649 see <filename>gtkstock.h</filename> for builtin stock items
8653 <para>Note that <LastBranch> is only useful for one submenu of
8656 <!-- ----------------------------------------------------------------- -->
8657 <sect3 id="sec-ItemFactoryCallback">
8658 <title>Callback Description</title>
8661 The callback for an ItemFactory entry can take two forms. If
8662 <literal>callback_action</literal> is zero, it is of the following
8665 <programlisting role="C">
8666 void callback( void )
8669 <para>otherwise it is of the form:</para>
8671 <programlisting role="C">
8672 void callback( gpointer callback_data,
8673 guint callback_action,
8678 <literal>callback_data</literal> is a pointer to an arbitrary piece of data and
8679 is set during the call to gtk_item_factory_create_items().</para>
8682 <literal>callback_action</literal> is the same value as
8683 <literal>callback_action</literal> in the ItemFactory entry.</para>
8686 <literal>*widget</literal> is a pointer to a menu item widget
8687 (described in <link linkend="sec-ManualMenuCreation">Manual Menu Creation</link>).
8691 <!-- ----------------------------------------------------------------- -->
8692 <sect3 id="sec-ItemFactoryEntryExamples">
8693 <title>ItemFactory entry examples</title>
8695 <para>Creating a simple menu item:</para>
8697 <programlisting role="C">
8698 GtkItemFactoryEntry entry = {"/_File/_Open...", "<CTRL>O", print_hello,
8702 <para>This will define a new simple menu entry "/File/Open" (displayed as "Open"),
8703 under the menu entry "/File". It has the accelerator (shortcut) control+'O'
8704 that when clicked calls the function print_hello(). print_hello() is of
8705 the form <literal>void print_hello(void)</literal> since the callback_action
8706 field is zero. When displayed the 'O' in "Open" will be underlined and if the
8707 menu item is visible on the screen pressing 'O' will activate the item. Note
8708 that "File/_Open" could also have been used as the path instead of
8709 "/_File/_Open".</para>
8711 <para>Creating an entry with a more complex callback:</para>
8713 <programlisting role="C">
8714 GtkItemFactoryEntry entry = {"/_View/Display _FPS", NULL, print_state,
8715 7,"<CheckItem>"};
8718 <para>This defines a new menu item displayed as "Display FPS" which is under
8719 the menu item "View". When clicked the function print_state() will be called.
8720 Since <literal>callback_action</literal> is not zero print_state() is of the
8723 <programlisting role="C">
8724 void print_state( gpointer callback_data,
8725 guint callback_action,
8729 <para>with <literal>callback_action</literal> equal to 7.</para>
8731 <para>Creating a radio button set:</para>
8733 <programlisting role="C">
8734 GtkItemFactoryEntry entry1 = {"/_View/_Low Resolution", NULL, change_resolution,
8735 1, "<RadioButton>"};
8736 GtkItemFactoryEntry entry2 = {"/_View/_High Resolution", NULL, change_resolution,
8737 2, "/View/Low Resolution"};
8740 <para><literal>entry1</literal> defines a lone radio button that when toggled
8741 calls the function change_resolution() with the parameter
8742 <literal>callback_action</literal> equal to 1. change_resolution() is of
8745 <programlisting role="C">
8746 void change_resolution(gpointer callback_data,
8747 guint callback_action,
8751 <para><literal>entry2</literal> defines a radio button that belongs to the
8752 radio group that entry1 belongs to. It calls the same function when toggled
8753 but with the parameter <literal>callback_action</literal> equal to 2. Note that
8754 the item_type of <literal>entry2</literal> is the path of entry1
8755 <emphasis>without</emphasis> the accelerators ('_'). If another radio button was
8756 required in the same group then it would be defined in the same way as
8757 <literal>entry2</literal> was with its <literal>item_type</literal> again
8758 equal to "/View/Low Resolution".</para>
8761 <!-- ----------------------------------------------------------------- -->
8762 <sect3 id="sec-ItemFactoryEntryArrays">
8763 <title>ItemFactoryEntry Arrays</title>
8765 <para>An ItemFactoryEntry on it's own however isn't useful. An array of
8766 entries is what's required to define a menu. Below is an example of how
8767 you'd declare this array.</para>
8769 <programlisting role="C">
8770 static GtkItemFactoryEntry entries[] = {
8771 { "/_File", NULL, NULL, 0, "<Branch>" },
8772 { "/File/tear1", NULL, NULL, 0, "<Tearoff>" },
8773 { "/File/_New", "<CTRL>N", new_file, 1, "<Item>" },
8774 { "/File/_Open...", "<CTRL>O", open_file, 1, "<Item>" },
8775 { "/File/sep1", NULL, NULL, 0, "<Separator>" },
8776 { "/File/_Quit", "<CTRL>Q", quit_program, 0, "<StockItem>", GTK_STOCK_QUIT } };
8781 <!-- ----------------------------------------------------------------- -->
8782 <sect2 id="sec-ItemFactoryCreation">
8783 <title>Creating an ItemFactory</title>
8785 <para>An array of GtkItemFactoryEntry items defines a menu. Once this
8786 array is defined then the item factory can be created. The function that
8787 does this is:</para>
8789 <programlisting role="C">
8790 GtkItemFactory* gtk_item_factory_new( GtkType container_type,
8792 GtkAccelGroup *accel_group );
8795 <para><literal>container_type</literal> can be one of:</para>
8797 <programlisting role="C">
8800 GTK_TYPE_OPTION_MENU
8803 <para><literal>container_type</literal> defines what type of menu
8804 you want, so when you extract it later it is either a menu (for pop-ups
8805 for instance), a menu bar, or an option menu (like a combo box but with
8806 a menu of pull downs).</para>
8808 <para><literal>path</literal> defines the path of the root of the menu.
8809 Basically it is a unique name for the root of the menu, it must be
8810 surrounded by "<>". This is important for the naming of the
8811 accelerators and should be unique. It should be unique both for each
8812 menu and between each program. For example in a program named 'foo', the
8813 main menu should be called "<FooMain>", and a pop-up menu
8814 "<FooImagePopUp>", or similar. What's important is that they're unique.</para>
8816 <para><literal>accel_group</literal> is a pointer to a gtk_accel_group. The
8817 item factory sets up the accelerator table while generating menus. New
8818 accelerator groups are generated by gtk_accel_group_new().</para>
8820 <para>But this is just the first step. To convert the array of GtkItemFactoryEntry
8821 information into widgets the following function is used:</para>
8823 <programlisting role="C">
8824 void gtk_item_factory_create_items( GtkItemFactory *ifactory,
8826 GtkItemFactoryEntry *entries,
8827 gpointer callback_data );
8830 <para><literal>*ifactory</literal> a pointer to the above created item factory.</para>
8831 <para><literal>n_entries</literal> is the number of entries in the
8832 GtkItemFactoryEntry array.</para>
8833 <para><literal>*entries</literal> is a pointer to the GtkItemFactoryEntry array.</para>
8834 <para><literal>callback_data</literal> is what gets passed to all the callback functions
8835 for all the entries with callback_action != 0.</para>
8837 <para>The accelerator group has now been formed, so you'll probably want
8838 to attach it to the window the menu is in:</para>
8840 <programlisting role="C">
8841 void gtk_window_add_accel_group( GtkWindow *window,
8842 GtkAccelGroup *accel_group);
8846 <!-- ----------------------------------------------------------------- -->
8847 <sect2 id="sec-UsingMenuandItems">
8848 <title>Making use of the menu and its menu items</title>
8850 <para>The last thing to do is make use of the menu. The following function
8851 extracts the relevant widgets from the ItemFactory:</para>
8853 <programlisting role="C">
8854 GtkWidget* gtk_item_factory_get_widget( GtkItemFactory *ifactory,
8855 const gchar *path );
8858 <para>For instance if an ItemFactory has two entries "/File" and "/File/New",
8859 using a path of "/File" would retrieve a <emphasis>menu</emphasis> widget from the
8860 ItemFactory. Using a path of "/File/New" would retrieve a
8861 <emphasis>menu item</emphasis> widget. This makes it possible to set the initial state
8862 of menu items. For example to set the default radio
8863 item to the one with the path "/Shape/Oval" then the following code would
8866 <programlisting role="C">
8867 gtk_check_menu_item_set_active(
8868 GTK_CHECK_MENU_ITEM (gtk_item_factory_get_item (item_factory, "/Shape/Oval")),
8872 <para>Finally to retrieve the root of the menu use gtk_item_factory_get_item()
8873 with a path of "<main>" (or whatever path was used in
8874 gtk_item_factory_new()). In the case of the ItemFactory being created with
8875 type GTK_TYPE_MENU_BAR this returns a menu bar widget. With type GTK_TYPE_MENU
8876 a menu widget is returned. With type GTK_TYPE_OPTION_MENU an option menu
8877 widget is returned.</para>
8879 <para><emphasis>Remember</emphasis> for an entry defined with path "/_File"
8880 the path here is actually "/File".</para>
8882 <para>Now you have a menubar or menu which can be manipulated in the same
8884 <link linkend="sec-ManualMenuCreation">Manual Menu Creation</link>
8889 <!-- ----------------------------------------------------------------- -->
8890 <sect1 id="sec-ItemFactoryExample">
8891 <title>Item Factory Example</title>
8893 <para>Here is an example using the GTK item factory.</para>
8895 <programlisting role="C">
8896 <!-- example-start menu itemfactory.c -->
8898 #include <gtk/gtk.h>
8900 /* Obligatory basic callback */
8901 static void print_hello( GtkWidget *w,
8904 g_message ("Hello, World!\n");
8907 /* For the check button */
8908 static void print_toggle( gpointer callback_data,
8909 guint callback_action,
8910 GtkWidget *menu_item )
8912 g_message ("Check button state - %d\n",
8913 GTK_CHECK_MENU_ITEM (menu_item)->active);
8916 /* For the radio buttons */
8917 static void print_selected( gpointer callback_data,
8918 guint callback_action,
8919 GtkWidget *menu_item )
8921 if(GTK_CHECK_MENU_ITEM(menu_item)->active)
8922 g_message ("Radio button %d selected\n", callback_action);
8925 /* Our menu, an array of GtkItemFactoryEntry structures that defines each menu item */
8926 static GtkItemFactoryEntry menu_items[] = {
8927 { "/_File", NULL, NULL, 0, "<Branch>" },
8928 { "/File/_New", "<control>N", print_hello, 0, "<StockItem>", GTK_STOCK_NEW },
8929 { "/File/_Open", "<control>O", print_hello, 0, "<StockItem>", GTK_STOCK_OPEN },
8930 { "/File/_Save", "<control>S", print_hello, 0, "<StockItem>", GTK_STOCK_SAVE },
8931 { "/File/Save _As", NULL, NULL, 0, "<Item>" },
8932 { "/File/sep1", NULL, NULL, 0, "<Separator>" },
8933 { "/File/_Quit", "<CTRL>Q", gtk_main_quit, 0, "<StockItem>", GTK_STOCK_QUIT },
8934 { "/_Options", NULL, NULL, 0, "<Branch>" },
8935 { "/Options/tear", NULL, NULL, 0, "<Tearoff>" },
8936 { "/Options/Check", NULL, print_toggle, 1, "<CheckItem>" },
8937 { "/Options/sep", NULL, NULL, 0, "<Separator>" },
8938 { "/Options/Rad1", NULL, print_selected, 1, "<RadioItem>" },
8939 { "/Options/Rad2", NULL, print_selected, 2, "/Options/Rad1" },
8940 { "/Options/Rad3", NULL, print_selected, 3, "/Options/Rad1" },
8941 { "/_Help", NULL, NULL, 0, "<LastBranch>" },
8942 { "/_Help/About", NULL, NULL, 0, "<Item>" },
8945 static gint nmenu_items = sizeof (menu_items) / sizeof (menu_items[0]);
8947 /* Returns a menubar widget made from the above menu */
8948 static GtkWidget *get_menubar_menu( GtkWidget *window )
8950 GtkItemFactory *item_factory;
8951 GtkAccelGroup *accel_group;
8953 /* Make an accelerator group (shortcut keys) */
8954 accel_group = gtk_accel_group_new ();
8956 /* Make an ItemFactory (that makes a menubar) */
8957 item_factory = gtk_item_factory_new (GTK_TYPE_MENU_BAR, "<main>",
8960 /* This function generates the menu items. Pass the item factory,
8961 the number of items in the array, the array itself, and any
8962 callback data for the the menu items. */
8963 gtk_item_factory_create_items (item_factory, nmenu_items, menu_items, NULL);
8965 /* Attach the new accelerator group to the window. */
8966 gtk_window_add_accel_group (GTK_WINDOW (window), accel_group);
8968 /* Finally, return the actual menu bar created by the item factory. */
8969 return gtk_item_factory_get_widget (item_factory, "<main>");
8972 /* Popup the menu when the popup button is pressed */
8973 static gboolean popup_cb( GtkWidget *widget,
8977 GdkEventButton *bevent = (GdkEventButton *)event;
8979 /* Only take button presses */
8980 if (event->type != GDK_BUTTON_PRESS)
8984 gtk_menu_popup (GTK_MENU(menu), NULL, NULL,
8985 NULL, NULL, bevent->button, bevent->time);
8990 /* Same as with get_menubar_menu() but just return a button with a signal to
8991 call a popup menu */
8992 GtkWidget *get_popup_menu( void )
8994 GtkItemFactory *item_factory;
8995 GtkWidget *button, *menu;
8997 /* Same as before but don't bother with the accelerators */
8998 item_factory = gtk_item_factory_new (GTK_TYPE_MENU, "<main>",
9000 gtk_item_factory_create_items (item_factory, nmenu_items, menu_items, NULL);
9001 menu = gtk_item_factory_get_widget (item_factory, "<main>");
9003 /* Make a button to activate the popup menu */
9004 button = gtk_button_new_with_label ("Popup");
9005 /* Make the menu popup when clicked */
9006 g_signal_connect (button,
9008 G_CALLBACK(popup_cb),
9014 /* Same again but return an option menu */
9015 GtkWidget *get_option_menu( void )
9017 GtkItemFactory *item_factory;
9018 GtkWidget *option_menu;
9020 /* Same again, not bothering with the accelerators */
9021 item_factory = gtk_item_factory_new (GTK_TYPE_OPTION_MENU, "<main>",
9023 gtk_item_factory_create_items (item_factory, nmenu_items, menu_items, NULL);
9024 option_menu = gtk_item_factory_get_widget (item_factory, "<main>");
9029 /* You have to start somewhere */
9034 GtkWidget *main_vbox;
9035 GtkWidget *menubar, *option_menu, *popup_button;
9037 /* Initialize GTK */
9038 gtk_init (&argc, &argv);
9041 window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
9042 g_signal_connect (window, "destroy",
9043 G_CALLBACK (gtk_main_quit),
9045 gtk_window_set_title (GTK_WINDOW(window), "Item Factory");
9046 gtk_widget_set_size_request (GTK_WIDGET(window), 300, 200);
9048 /* Make a vbox to put the three menus in */
9049 main_vbox = gtk_vbox_new (FALSE, 1);
9050 gtk_container_set_border_width (GTK_CONTAINER (main_vbox), 1);
9051 gtk_container_add (GTK_CONTAINER (window), main_vbox);
9053 /* Get the three types of menu */
9054 /* Note: all three menus are separately created, so they are not the
9056 menubar = get_menubar_menu (window);
9057 popup_button = get_popup_menu ();
9058 option_menu = get_option_menu ();
9060 /* Pack it all together */
9061 gtk_box_pack_start (GTK_BOX (main_vbox), menubar, FALSE, TRUE, 0);
9062 gtk_box_pack_end (GTK_BOX (main_vbox), popup_button, FALSE, TRUE, 0);
9063 gtk_box_pack_end (GTK_BOX (main_vbox), option_menu, FALSE, TRUE, 0);
9065 /* Show the widgets */
9066 gtk_widget_show_all (window);
9073 <!-- example-end -->
9079 <!-- ***************************************************************** -->
9080 <chapter id="ch-UndocWidgets">
9081 <title>Undocumented Widgets</title>
9083 <para>These all require authors! :) Please consider contributing to our
9086 <para>If you must use one of these widgets that are undocumented, I strongly
9087 suggest you take a look at their respective header files in the GTK
9088 distribution. GTK's function names are very descriptive. Once you
9089 have an understanding of how things work, it's not difficult to figure
9090 out how to use a widget simply by looking at its function
9091 declarations. This, along with a few examples from others' code, and
9092 it should be no problem.</para>
9094 <para>When you do come to understand all the functions of a new undocumented
9095 widget, please consider writing a tutorial on it so others may benefit
9096 from your time.</para>
9098 <!-- ----------------------------------------------------------------- -->
9099 <sect1 id="sec-AccelLabel">
9100 <title>Accel Label</title>
9106 <!-- ----------------------------------------------------------------- -->
9107 <sect1 id="sec-OptionMenu">
9108 <title>Option Menu</title>
9114 <!-- ----------------------------------------------------------------- -->
9115 <sect1 id="sec-MenuItems">
9116 <title>Menu Items</title>
9120 <sect2 id="sec-CheckMenuItem">
9121 <title>Check Menu Item</title>
9126 <sect2 id="sec-RadioMenuItem">
9127 <title>Radio Menu Item</title>
9132 <sect2 id="sec-SeparatorMenuItem">
9133 <title>Separator Menu Item</title>
9138 <sect2 id="sec-TearoffMenuItem">
9139 <title>Tearoff Menu Item</title>
9145 <!-- ----------------------------------------------------------------- -->
9146 <sect1 id="sec-Curves">
9147 <title>Curves</title>
9153 <!-- ----------------------------------------------------------------- -->
9154 <sect1 id="sec-DrawingArea">
9155 <title>Drawing Area</title>
9161 <!-- ----------------------------------------------------------------- -->
9162 <sect1 id="sec-FontSelectionDialog">
9163 <title>Font Selection Dialog</title>
9169 <!-- ----------------------------------------------------------------- -->
9170 <sect1 id="sec-MessageDialog">
9171 <title>Message Dialog</title>
9177 <!-- ----------------------------------------------------------------- -->
9178 <sect1 id="sec-GammaCurve">
9179 <title>Gamma Curve</title>
9185 <!-- ----------------------------------------------------------------- -->
9186 <sect1 id="sec-Image">
9187 <title>Image</title>
9193 <!-- ----------------------------------------------------------------- -->
9194 <sect1 id="sec-PlugsAndSockets">
9195 <title>Plugs and Sockets</title>
9201 <!-- ----------------------------------------------------------------- -->
9202 <sect1 id="sec-TreeView">
9203 <title>Tree View</title>
9209 <!-- ----------------------------------------------------------------- -->
9210 <sect1 id="sec-TextView">
9211 <title>Text View</title>
9218 <!-- ***************************************************************** -->
9219 <chapter id="ch-SettingWidgetAttributes">
9220 <title>Setting Widget Attributes</title>
9222 <para>This describes the functions used to operate on widgets. These can be
9223 used to set style, padding, size, etc.</para>
9225 <para>(Maybe I should make a whole section on accelerators.)</para>
9227 <programlisting role="C">
9228 void gtk_widget_activate( GtkWidget *widget );
9230 void gtk_widget_set_name( GtkWidget *widget,
9233 gchar *gtk_widget_get_name( GtkWidget *widget );
9235 void gtk_widget_set_sensitive( GtkWidget *widget,
9236 gboolean sensitive );
9238 void gtk_widget_set_style( GtkWidget *widget,
9241 GtkStyle *gtk_widget_get_style( GtkWidget *widget );
9243 GtkStyle *gtk_widget_get_default_style( void );
9245 void gtk_widget_set_size_request( GtkWidget *widget,
9249 void gtk_widget_grab_focus( GtkWidget *widget );
9251 void gtk_widget_show( GtkWidget *widget );
9253 void gtk_widget_hide( GtkWidget *widget );
9258 <!-- ***************************************************************** -->
9259 <chapter id="ch-Timeouts">
9260 <title>Timeouts, IO and Idle Functions</title>
9262 <!-- ----------------------------------------------------------------- -->
9263 <sect1 id="sec-Timeouts">
9264 <title>Timeouts</title>
9266 <para>You may be wondering how you make GTK do useful work when in gtk_main.
9267 Well, you have several options. Using the following function you can
9268 create a timeout function that will be called every "interval"
9269 milliseconds.</para>
9271 <programlisting role="C">
9272 gint g_timeout_add (guint32 interval,
9273 GtkFunction function,
9277 <para>The first argument is the number of milliseconds between calls to your
9278 function. The second argument is the function you wish to have called,
9279 and the third, the data passed to this callback function. The return
9280 value is an integer "tag" which may be used to stop the timeout by
9283 <programlisting role="C">
9284 void g_source_remove (gint tag);
9287 <para>You may also stop the timeout function by returning zero or FALSE from
9288 your callback function. Obviously this means if you want your function
9289 to continue to be called, it should return a non-zero value,
9292 <para>The declaration of your callback should look something like this:</para>
9294 <programlisting role="C">
9295 gint timeout_callback (gpointer data);
9300 <!-- ----------------------------------------------------------------- -->
9301 <sect1 id="sec-MonitoringIO">
9302 <title>Monitoring IO</title>
9304 <para>A nifty feature of GDK (the library that underlies GTK), is the
9305 ability to have it check for data on a file descriptor for you (as
9306 returned by open(2) or socket(2)). This is especially useful for
9307 networking applications. The function:</para>
9309 <programlisting role="C">
9310 gint gdk_input_add( gint source,
9311 GdkInputCondition condition,
9312 GdkInputFunction function,
9316 <para>Where the first argument is the file descriptor you wish to have
9317 watched, and the second specifies what you want GDK to look for. This
9318 may be one of:</para>
9321 <listitem><simpara><literal>GDK_INPUT_READ</literal> - Call your function when there is data
9322 ready for reading on your file descriptor.</simpara>
9325 <listitem><simpara><literal>GDK_INPUT_WRITE</literal> - Call your function when the file
9326 descriptor is ready for writing.</simpara>
9330 <para>As I'm sure you've figured out already, the third argument is the
9331 function you wish to have called when the above conditions are
9332 satisfied, and the fourth is the data to pass to this function.</para>
9334 <para>The return value is a tag that may be used to stop GDK from monitoring
9335 this file descriptor using the following function.</para>
9337 <programlisting role="C">
9338 void gdk_input_remove( gint tag );
9341 <para>The callback function should be declared as:</para>
9343 <programlisting role="C">
9344 void input_callback( gpointer data,
9346 GdkInputCondition condition );
9349 <para>Where <literal>source</literal> and <literal>condition</literal> are as specified above.</para>
9353 <!-- ----------------------------------------------------------------- -->
9354 <sect1 id="sec-IdleFunctions">
9355 <title>Idle Functions</title>
9357 <para><!-- TODO: Need to check on idle priorities - TRG -->
9358 What if you have a function which you want to be called when nothing
9359 else is happening ?</para>
9361 <programlisting role="C">
9362 guint g_idle_add( GSourceFunc function,
9366 <para>This causes GTK to call the specified function whenever nothing else
9367 is happening.</para>
9369 <programlisting role="C">
9370 void g_source_remove( guint tag );
9373 <para>I won't explain the meaning of the arguments as they follow very much
9374 like the ones above. The function pointed to by the first argument to
9375 g_idle_add will be called whenever the opportunity arises. As with
9376 the others, returning FALSE will stop the idle function from being
9382 <!-- ***************************************************************** -->
9383 <chapter id="ch-AdvancedEventsAndSignals">
9384 <title>Advanced Event and Signal Handling</title>
9386 <!-- ----------------------------------------------------------------- -->
9387 <sect1 id="sec-SignalFunctions">
9388 <title>Signal Functions</title>
9390 <!-- ----------------------------------------------------------------- -->
9392 <title>Connecting and Disconnecting Signal Handlers</title>
9394 <programlisting role="C">
9395 gulong g_signal_connect( GObject *object,
9398 gpointer func_data );
9400 gulong g_signal_connect_after( GObject *object,
9403 gpointer func_data );
9405 gulong g_signal_connect_swapped( GObject *object,
9408 GObject *slot_object );
9410 void g_signal_handler_disconnect( GObject *object,
9411 gulong handler_id );
9413 void g_signal_handlers_disconnect_by_func( GObject *object,
9420 <!-- ----------------------------------------------------------------- -->
9422 <title>Blocking and Unblocking Signal Handlers</title>
9424 <programlisting role="C">
9425 void g_signal_handler_block( GObject *object,
9428 void g_signal_handlers_block_by_func( GObject *object,
9432 void g_signal_handler_unblock( GObject *object,
9433 gulong handler_id );
9435 void g_signal_handler_unblock_by_func( GObject *object,
9442 <!-- ----------------------------------------------------------------- -->
9444 <title>Emitting and Stopping Signals</title>
9446 <programlisting role="C">
9447 void g_signal_emit( GObject *object,
9451 void g_signal_emit_by_name( GObject *object,
9455 void g_signal_emitv( const GValue *instance_and_params,
9458 GValue *return_value );
9460 void g_signal_stop_emission( GObject *object,
9464 void g_signal_stop_emission_by_name( GObject *object,
9465 const gchar *detailed_signal );
9471 <!-- ----------------------------------------------------------------- -->
9472 <sect1 id="sec-SignalEmissionAndPropagation">
9473 <title>Signal Emission and Propagation</title>
9475 <para>Signal emission is the process whereby GTK runs all handlers for a
9476 specific object and signal.</para>
9478 <para>First, note that the return value from a signal emission is the return
9479 value of the <emphasis>last</emphasis> handler executed. Since event signals are
9480 all of type <literal>GTK_RUN_LAST</literal>, this will be the default (GTK supplied)
9481 handler, unless you connect with gtk_signal_connect_after().</para>
9483 <para>The way an event (say "button_press_event") is handled, is:</para>
9486 <listitem><simpara>Start with the widget where the event occured.</simpara>
9489 <listitem><simpara>Emit the generic "event" signal. If that signal handler returns
9490 a value of TRUE, stop all processing.</simpara>
9493 <listitem><simpara>Otherwise, emit a specific, "button_press_event" signal. If that
9494 returns TRUE, stop all processing.</simpara>
9497 <listitem><simpara>Otherwise, go to the widget's parent, and repeat the above two
9501 <listitem><simpara>Continue until some signal handler returns TRUE, or until the
9502 top-level widget is reached.</simpara>
9506 <para>Some consequences of the above are:</para>
9509 <listitem><simpara>Your handler's return value will have no effect if there is a
9510 default handler, unless you connect with gtk_signal_connect_after().</simpara>
9513 <listitem><simpara>To prevent the default handler from being run, you need to
9514 connect with gtk_signal_connect() and use
9515 gtk_signal_emit_stop_by_name() - the return value only affects whether
9516 the signal is propagated, not the current emission.</simpara>
9523 <!-- continue GTK+ 2.0 review here -->
9525 <!-- ***************************************************************** -->
9526 <chapter id="ch-ManagingSelections">
9527 <title>Managing Selections</title>
9529 <!-- ----------------------------------------------------------------- -->
9530 <sect1 id="sec-SelectionsOverview">
9531 <title>Overview</title>
9533 <para>One type of interprocess communication supported by X and GTK is
9534 <emphasis>selections</emphasis>. A selection identifies a chunk of data, for
9535 instance, a portion of text, selected by the user in some fashion, for
9536 instance, by dragging with the mouse. Only one application on a
9537 display (the <emphasis>owner</emphasis>) can own a particular selection at one
9538 time, so when a selection is claimed by one application, the previous
9539 owner must indicate to the user that selection has been
9540 relinquished. Other applications can request the contents of a
9541 selection in different forms, called <emphasis>targets</emphasis>. There can be
9542 any number of selections, but most X applications only handle one, the
9543 <emphasis>primary selection</emphasis>.</para>
9545 <para>In most cases, it isn't necessary for a GTK application to deal with
9546 selections itself. The standard widgets, such as the Entry widget,
9547 already have the capability to claim the selection when appropriate
9548 (e.g., when the user drags over text), and to retrieve the contents of
9549 the selection owned by another widget or another application (e.g.,
9550 when the user clicks the second mouse button). However, there may be
9551 cases in which you want to give other widgets the ability to supply
9552 the selection, or you wish to retrieve targets not supported by
9555 <para>A fundamental concept needed to understand selection handling is that
9556 of the <emphasis>atom</emphasis>. An atom is an integer that uniquely identifies a
9557 string (on a certain display). Certain atoms are predefined by the X
9558 server, and in some cases there are constants in <literal>gtk.h</literal>
9559 corresponding to these atoms. For instance the constant
9560 <literal>GDK_PRIMARY_SELECTION</literal> corresponds to the string "PRIMARY".
9561 In other cases, you should use the functions
9562 <literal>gdk_atom_intern()</literal>, to get the atom corresponding to a string,
9563 and <literal>gdk_atom_name()</literal>, to get the name of an atom. Both
9564 selections and targets are identified by atoms.</para>
9567 <!-- ----------------------------------------------------------------- -->
9568 <sect1 id="sec-RetrievingTheSelection">
9569 <title>Retrieving the selection</title>
9571 <para>Retrieving the selection is an asynchronous process. To start the
9572 process, you call:</para>
9574 <programlisting role="C">
9575 gboolean gtk_selection_convert( GtkWidget *widget,
9581 <para>This <emphasis>converts</emphasis> the selection into the form specified by
9582 <literal>target</literal>. If at all possible, the time field should be the time
9583 from the event that triggered the selection. This helps make sure that
9584 events occur in the order that the user requested them. However, if it
9585 is not available (for instance, if the conversion was triggered by a
9586 "clicked" signal), then you can use the constant
9587 <literal>GDK_CURRENT_TIME</literal>.</para>
9589 <para>When the selection owner responds to the request, a
9590 "selection_received" signal is sent to your application. The handler
9591 for this signal receives a pointer to a <literal>GtkSelectionData</literal>
9592 structure, which is defined as:</para>
9594 <programlisting role="C">
9595 struct _GtkSelectionData
9606 <para><literal>selection</literal> and <literal>target</literal> are the values you gave in your
9607 <literal>gtk_selection_convert()</literal> call. <literal>type</literal> is an atom that
9608 identifies the type of data returned by the selection owner. Some
9609 possible values are "STRING", a string of latin-1 characters, "ATOM",
9610 a series of atoms, "INTEGER", an integer, etc. Most targets can only
9611 return one type. <literal>format</literal> gives the length of the units (for
9612 instance characters) in bits. Usually, you don't care about this when
9613 receiving data. <literal>data</literal> is a pointer to the returned data, and
9614 <literal>length</literal> gives the length of the returned data, in bytes. If
9615 <literal>length</literal> is negative, then an error occurred and the selection
9616 could not be retrieved. This might happen if no application owned the
9617 selection, or if you requested a target that the application didn't
9618 support. The buffer is actually guaranteed to be one byte longer than
9619 <literal>length</literal>; the extra byte will always be zero, so it isn't
9620 necessary to make a copy of strings just to nul-terminate them.</para>
9622 <para>In the following example, we retrieve the special target "TARGETS",
9623 which is a list of all targets into which the selection can be
9626 <programlisting role="C">
9627 <!-- example-start selection gettargets.c -->
9629 #include <stdlib.h>
9630 #include <gtk/gtk.h>
9632 static void selection_received( GtkWidget *widget,
9633 GtkSelectionData *selection_data,
9636 /* Signal handler invoked when user clicks on the "Get Targets" button */
9637 static void get_targets( GtkWidget *widget,
9640 static GdkAtom targets_atom = GDK_NONE;
9641 GtkWidget *window = (GtkWidget *)data;
9643 /* Get the atom corresponding to the string "TARGETS" */
9644 if (targets_atom == GDK_NONE)
9645 targets_atom = gdk_atom_intern ("TARGETS", FALSE);
9647 /* And request the "TARGETS" target for the primary selection */
9648 gtk_selection_convert (window, GDK_SELECTION_PRIMARY, targets_atom,
9652 /* Signal handler called when the selections owner returns the data */
9653 static void selection_received( GtkWidget *widget,
9654 GtkSelectionData *selection_data,
9661 /* **** IMPORTANT **** Check to see if retrieval succeeded */
9662 if (selection_data->length < 0)
9664 g_print ("Selection retrieval failed\n");
9667 /* Make sure we got the data in the expected form */
9668 if (selection_data->type != GDK_SELECTION_TYPE_ATOM)
9670 g_print ("Selection \"TARGETS\" was not returned as atoms!\n");
9674 /* Print out the atoms we received */
9675 atoms = (GdkAtom *)selection_data->data;
9678 for (i = 0; i < selection_data->length / sizeof(GdkAtom); i++)
9681 name = gdk_atom_name (atoms[i]);
9683 g_print ("%s\n",name);
9685 g_print ("(bad atom)\n");
9697 gtk_init (&argc, &argv);
9699 /* Create the toplevel window */
9701 window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
9702 gtk_window_set_title (GTK_WINDOW (window), "Event Box");
9703 gtk_container_set_border_width (GTK_CONTAINER (window), 10);
9705 g_signal_connect (window, "destroy",
9706 G_CALLBACK (exit), NULL);
9708 /* Create a button the user can click to get targets */
9710 button = gtk_button_new_with_label ("Get Targets");
9711 gtk_container_add (GTK_CONTAINER (window), button);
9713 g_signal_connect (button, "clicked",
9714 G_CALLBACK (get_targets), (gpointer) window);
9715 g_signal_connect (window, "selection_received",
9716 G_CALLBACK (selection_received), NULL);
9718 gtk_widget_show (button);
9719 gtk_widget_show (window);
9725 <!-- example-end -->
9729 <!-- ----------------------------------------------------------------- -->
9730 <sect1 id="sec-SupplyingTheSelection">
9731 <title>Supplying the selection</title>
9733 <para>Supplying the selection is a bit more complicated. You must register
9734 handlers that will be called when your selection is requested. For
9735 each selection/target pair you will handle, you make a call to:</para>
9737 <programlisting role="C">
9738 void gtk_selection_add_target( GtkWidget *widget,
9744 <para><literal>widget</literal>, <literal>selection</literal>, and <literal>target</literal> identify the requests
9745 this handler will manage. When a request for a selection is received,
9746 the "selection_get" signal will be called. <literal>info</literal> can be used as an
9747 enumerator to identify the specific target within the callback function.</para>
9749 <para>The callback function has the signature:</para>
9751 <programlisting role="C">
9752 void "selection_get"( GtkWidget *widget,
9753 GtkSelectionData *selection_data,
9758 <para>The GtkSelectionData is the same as above, but this time, we're
9759 responsible for filling in the fields <literal>type</literal>, <literal>format</literal>,
9760 <literal>data</literal>, and <literal>length</literal>. (The <literal>format</literal> field is actually
9761 important here - the X server uses it to figure out whether the data
9762 needs to be byte-swapped or not. Usually it will be 8 - <emphasis>i.e.</emphasis> a
9763 character - or 32 - <emphasis>i.e.</emphasis> an integer.) This is done by calling the
9766 <programlisting role="C">
9767 void gtk_selection_data_set( GtkSelectionData *selection_data,
9774 <para>This function takes care of properly making a copy of the data so that
9775 you don't have to worry about keeping it around. (You should not fill
9776 in the fields of the GtkSelectionData structure by hand.)</para>
9778 <para>When prompted by the user, you claim ownership of the selection by
9781 <programlisting role="C">
9782 gboolean gtk_selection_owner_set( GtkWidget *widget,
9787 <para>If another application claims ownership of the selection, you will
9788 receive a "selection_clear_event".</para>
9790 <para>As an example of supplying the selection, the following program adds
9791 selection functionality to a toggle button. When the toggle button is
9792 depressed, the program claims the primary selection. The only target
9793 supported (aside from certain targets like "TARGETS" supplied by GTK
9794 itself), is the "STRING" target. When this target is requested, a
9795 string representation of the time is returned.</para>
9797 <programlisting role="C">
9798 <!-- example-start selection setselection.c -->
9800 #include <stdlib.h>
9801 #include <gtk/gtk.h>
9802 #include <time.h>
9803 #include <string.h>
9805 GtkWidget *selection_button;
9806 GtkWidget *selection_widget;
9808 /* Callback when the user toggles the selection */
9809 static void selection_toggled( GtkWidget *widget,
9810 gint *have_selection )
9812 if (GTK_TOGGLE_BUTTON (widget)->active)
9814 *have_selection = gtk_selection_owner_set (selection_widget,
9815 GDK_SELECTION_PRIMARY,
9817 /* if claiming the selection failed, we return the button to
9819 if (!*have_selection)
9820 gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (widget), FALSE);
9824 if (*have_selection)
9826 /* Before clearing the selection by setting the owner to NULL,
9827 we check if we are the actual owner */
9828 if (gdk_selection_owner_get (GDK_SELECTION_PRIMARY) == widget->window)
9829 gtk_selection_owner_set (NULL, GDK_SELECTION_PRIMARY,
9831 *have_selection = FALSE;
9836 /* Called when another application claims the selection */
9837 static gboolean selection_clear( GtkWidget *widget,
9838 GdkEventSelection *event,
9839 gint *have_selection )
9841 *have_selection = FALSE;
9842 gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (selection_button), FALSE);
9847 /* Supplies the current time as the selection. */
9848 static void selection_handle( GtkWidget *widget,
9849 GtkSelectionData *selection_data,
9855 time_t current_time;
9857 current_time = time (NULL);
9858 timestr = asctime (localtime (&current_time));
9859 /* When we return a single string, it should not be null terminated.
9860 That will be done for us */
9862 gtk_selection_data_set (selection_data, GDK_SELECTION_TYPE_STRING,
9863 8, timestr, strlen (timestr));
9871 static int have_selection = FALSE;
9873 gtk_init (&argc, &argv);
9875 /* Create the toplevel window */
9877 window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
9878 gtk_window_set_title (GTK_WINDOW (window), "Event Box");
9879 gtk_container_set_border_width (GTK_CONTAINER (window), 10);
9881 g_signal_connect (window, "destroy",
9882 G_CALLBACK (exit), NULL);
9884 /* Create a toggle button to act as the selection */
9886 selection_widget = gtk_invisible_new ();
9887 selection_button = gtk_toggle_button_new_with_label ("Claim Selection");
9888 gtk_container_add (GTK_CONTAINER (window), selection_button);
9889 gtk_widget_show (selection_button);
9891 g_signal_connect (selection_button, "toggled",
9892 G_CALLBACK (selection_toggled), (gpointer) &have_selection);
9893 g_signal_connect (selection_widget, "selection_clear_event",
9894 G_CALLBACK (selection_clear), (gpointer) &have_selection);
9896 gtk_selection_add_target (selection_widget,
9897 GDK_SELECTION_PRIMARY,
9898 GDK_SELECTION_TYPE_STRING,
9900 g_signal_connect (selection_widget, "selection_get",
9901 G_CALLBACK (selection_handle), (gpointer) &have_selection);
9903 gtk_widget_show (selection_button);
9904 gtk_widget_show (window);
9910 <!-- example-end -->
9916 <!-- ***************************************************************** -->
9917 <chapter id="ch-DragAngDrop">
9918 <title>Drag-and-drop (DND)</title>
9920 <para>GTK+ has a high level set of functions for doing inter-process
9921 communication via the drag-and-drop system. GTK+ can perform
9922 drag-and-drop on top of the low level Xdnd and Motif drag-and-drop
9925 <!-- ----------------------------------------------------------------- -->
9926 <sect1 id="sec-DragAndDropOverview">
9927 <title>Overview</title>
9929 <para>An application capable of GTK+ drag-and-drop first defines and sets up
9930 the GTK+ widget(s) for drag-and-drop. Each widget can be a source
9931 and/or destination for drag-and-drop. Note that these GTK+ widgets must have
9932 an associated X Window, check using gtk_widget_get_has_window (widget).</para>
9934 <para>Source widgets can send out drag data, thus allowing the user to drag
9935 things off of them, while destination widgets can receive drag data.
9936 Drag-and-drop destinations can limit who they accept drag data from,
9937 e.g. the same application or any application (including itself).</para>
9939 <para>Sending and receiving drop data makes use of GTK+ signals.
9940 Dropping an item to a destination widget requires both a data
9941 request (for the source widget) and data received signal handler (for
9942 the target widget). Additional signal handers can be connected if you
9943 want to know when a drag begins (at the very instant it starts), to
9944 when a drop is made, and when the entire drag-and-drop procedure has
9945 ended (successfully or not).</para>
9947 <para>Your application will need to provide data for source widgets when
9948 requested, that involves having a drag data request signal handler. For
9949 destination widgets they will need a drop data received signal
9952 <para>So a typical drag-and-drop cycle would look as follows:</para>
9954 <listitem><simpara> Drag begins.</simpara>
9956 <listitem><simpara> Drag data request (when a drop occurs).</simpara>
9958 <listitem><simpara> Drop data received (may be on same or different
9959 application).</simpara>
9961 <listitem><simpara> Drag data delete (if the drag was a move).</simpara>
9963 <listitem><simpara> Drag-and-drop procedure done.</simpara>
9967 <para>There are a few minor steps that go in between here and there, but we
9968 will get into detail about that later.</para>
9972 <!-- ----------------------------------------------------------------- -->
9973 <sect1 id="sec-DragAndDropProperties">
9974 <title>Properties</title>
9976 <para>Drag data has the following properties:</para>
9979 <listitem><simpara> Drag action type (ie GDK_ACTION_COPY, GDK_ACTION_MOVE).</simpara>
9982 <listitem><simpara> Client specified arbitrary drag-and-drop type (a name and number pair).</simpara>
9985 <listitem><simpara> Sent and received data format type.</simpara>
9989 <para>Drag actions are quite obvious, they specify if the widget can
9990 drag with the specified action(s), e.g. GDK_ACTION_COPY and/or
9991 GDK_ACTION_MOVE. A GDK_ACTION_COPY would be a typical drag-and-drop
9992 without the source data being deleted while GDK_ACTION_MOVE would be
9993 just like GDK_ACTION_COPY but the source data will be 'suggested' to be
9994 deleted after the received signal handler is called. There are
9995 additional drag actions including GDK_ACTION_LINK which you may want to
9996 look into when you get to more advanced levels of drag-and-drop.</para>
9998 <para>The client specified arbitrary drag-and-drop type is much more
9999 flexible, because your application will be defining and checking for
10000 that specifically. You will need to set up your destination widgets to
10001 receive certain drag-and-drop types by specifying a name and/or number.
10002 It would be more reliable to use a name since another application may
10003 just happen to use the same number for an entirely different
10006 <para>Sent and received data format types (<emphasis>selection
10007 target</emphasis>) come into play only in your request and received
10008 data handler functions. The term <emphasis>selection target</emphasis>
10009 is somewhat misleading. It is a term adapted from GTK+ selection
10010 (cut/copy and paste). What <emphasis>selection target</emphasis>
10011 actually means is the data's format type (i.e. GdkAtom, integer, or
10012 string) that being sent or received. Your request data handler function
10013 needs to specify the type (<emphasis>selection target</emphasis>) of
10014 data that it sends out and your received data handler needs to handle
10015 the type (<emphasis>selection target</emphasis>) of data
10020 <!-- ----------------------------------------------------------------- -->
10021 <sect1 id="sec-DragAndDropFunctions">
10022 <title>Functions</title>
10024 <!-- ----------------------------------------------------------------- -->
10025 <sect2 id="sec-DNDSourceWidgets">
10026 <title>Setting up the source widget</title>
10028 <para>The function <literal>gtk_drag_source_set()</literal> specifies a
10029 set of target types for a drag operation on a widget.</para>
10031 <programlisting role="C">
10032 void gtk_drag_source_set( GtkWidget *widget,
10033 GdkModifierType start_button_mask,
10034 const GtkTargetEntry *targets,
10036 GdkDragAction actions );
10039 <para>The parameters signify the following:</para>
10041 <listitem><simpara><literal>widget</literal> specifies the drag source
10044 <listitem><simpara><literal>start_button_mask</literal> specifies a
10045 bitmask of buttons that can start the drag (e.g. GDK_BUTTON1_MASK)</simpara>
10047 <listitem><simpara><literal>targets</literal> specifies a table of
10048 target data types the drag will support</simpara>
10050 <listitem><simpara><literal>n_targets</literal> specifies the number of
10051 targets above</simpara>
10053 <listitem><simpara><literal>actions</literal> specifies a bitmask of
10054 possible actions for a drag from this window</simpara>
10058 <para>The <literal>targets</literal> parameter is an array of the
10059 following structure:</para>
10061 <programlisting role="C">
10062 struct GtkTargetEntry {
10069 <para>The fields specify a string representing the drag type, optional
10070 flags and application assigned integer identifier.</para>
10072 <para>If a widget is no longer required to act as a source for
10073 drag-and-drop operations, the function
10074 <literal>gtk_drag_source_unset()</literal> can be used to remove a set
10075 of drag-and-drop target types.</para>
10077 <programlisting role="C">
10078 void gtk_drag_source_unset( GtkWidget *widget );
10083 <!-- ----------------------------------------------------------------- -->
10084 <sect2 id="sec-SignalsOnSourceWidgets">
10085 <title>Signals on the source widget:</title>
10087 <para>The source widget is sent the following signals during a
10088 drag-and-drop operation.</para>
10091 <title>Source widget signals</title>
10093 <colspec colname="Name" colwidth="150">
10094 <colspec colname="Prototype">
10097 <entry align="left" valign="middle">drag_begin</entry>
10098 <entry align="left" valign="middle"><literal>void (*drag_begin)(GtkWidget *widget,
10099 GdkDragContext *dc, gpointer data)</literal></entry>
10102 <entry align="left" valign="middle">drag_motion</entry>
10103 <entry align="left" valign="middle"><literal>gboolean (*drag_motion)(GtkWidget *widget,
10104 GdkDragContext *dc, gint x, gint y, guint t, gpointer data)</literal></entry>
10107 <entry align="left" valign="middle">drag_data_get</entry>
10108 <entry align="left" valign="middle"><literal>void (*drag_data_get)(GtkWidget *widget,
10109 GdkDragContext *dc, GtkSelectionData *selection_data, guint info, guint t, gpointer data)</literal></entry>
10112 <entry align="left" valign="middle">drag_data_delete</entry>
10113 <entry align="left" valign="middle"><literal>void (*drag_data_delete)(GtkWidget *widget,
10114 GdkDragContext *dc, gpointer data)</literal></entry>
10117 <entry align="left" valign="middle">drag_drop</entry>
10118 <entry align="left" valign="middle"><literal>gboolean (*drag_drop)(GtkWidget *widget,
10119 GdkDragContext *dc, gint x, gint y, guint t, gpointer data)</literal></entry>
10122 <entry align="left" valign="middle">drag_end</entry>
10123 <entry align="left" valign="middle"><literal>void (*drag_end)(GtkWidget *widget,
10124 GdkDragContext *dc, gpointer data)</literal></entry>
10132 <!-- ----------------------------------------------------------------- -->
10133 <sect2 id="sec-DNDDestWidgets">
10134 <title>Setting up a destination widget:</title>
10136 <para> <literal> gtk_drag_dest_set()</literal> specifies
10137 that this widget can receive drops and specifies what types of drops it
10138 can receive.</para>
10140 <para> <literal> gtk_drag_dest_unset()</literal> specifies
10141 that the widget can no longer receive drops.</para>
10143 <programlisting role="C">
10144 void gtk_drag_dest_set( GtkWidget *widget,
10145 GtkDestDefaults flags,
10146 const GtkTargetEntry *targets,
10148 GdkDragAction actions );
10150 void gtk_drag_dest_unset( GtkWidget *widget );
10155 <!-- ----------------------------------------------------------------- -->
10156 <sect2 id="sec-SignalsOnDestWidgets">
10157 <title>Signals on the destination widget:</title>
10159 <para>The destination widget is sent the following signals during a
10160 drag-and-drop operation.</para>
10163 <title>Destination widget signals</title>
10165 <colspec colname="Name" colwidth="150">
10166 <colspec colname="Prototype">
10169 <entry align="left" valign="middle">drag_data_received</entry>
10170 <entry align="left" valign="middle"><literal>void (*drag_data_received)(GtkWidget *widget,
10171 GdkDragContext *dc, gint x, gint y, GtkSelectionData *selection_data, guint info, guint t,
10172 gpointer data)</literal></entry>
10182 <!-- ***************************************************************** -->
10183 <chapter id="ch-GLib">
10184 <title>GLib</title>
10186 <para>GLib is a lower-level library that provides many useful definitions
10187 and functions available for use when creating GDK and GTK
10188 applications. These include definitions for basic types and their
10189 limits, standard macros, type conversions, byte order, memory
10190 allocation, warnings and assertions, message logging, timers, string
10191 utilities, hook functions, a lexical scanner, dynamic loading of
10192 modules, and automatic string completion. A number of data structures
10193 (and their related operations) are also defined, including memory
10194 chunks, doubly-linked lists, singly-linked lists, hash tables, strings
10195 (which can grow dynamically), string chunks (groups of strings),
10196 arrays (which can grow in size as elements are added), balanced binary
10197 trees, N-ary trees, quarks (a two-way association of a string and a
10198 unique integer identifier), keyed data lists (lists of data elements
10199 accessible by a string or integer id), relations and tuples (tables of
10200 data which can be indexed on any number of fields), and caches.</para>
10202 <para>A summary of some of GLib's capabilities follows; not every function,
10203 data structure, or operation is covered here. For more complete
10204 information about the GLib routines, see the GLib documentation. One
10205 source of GLib documentation is <ulink url="http://www.gtk.org/">http://www.gtk.org/</ulink>.</para>
10207 <para>If you are using a language other than C, you should consult your
10208 language's binding documentation. In some cases your language may
10209 have equivalent functionality built-in, while in other cases it may
10212 <!-- ----------------------------------------------------------------- -->
10213 <sect1 id="sec-Definitions">
10214 <title>Definitions</title>
10216 <para>Definitions for the extremes of many of the standard types are:</para>
10218 <programlisting role="C">
10237 <para>Also, the following typedefs. The ones left unspecified are dynamically set
10238 depending on the architecture. Remember to avoid counting on the size of a
10239 pointer if you want to be portable! E.g., a pointer on an Alpha is 8
10240 bytes, but 4 on Intel 80x86 family CPUs.</para>
10242 <programlisting role="C">
10249 unsigned char guchar;
10250 unsigned short gushort;
10251 unsigned long gulong;
10252 unsigned int guint;
10257 unsigned int gsize;
10261 const void* gconstpointer;
10275 <!-- ----------------------------------------------------------------- -->
10276 <sect1 id="sec-DoublyLinkedLists">
10277 <title>Doubly Linked Lists</title>
10279 <para>The following functions are used to create, manage, and destroy
10280 standard doubly linked lists. Each element in the list contains a
10281 piece of data, together with pointers which link to the previous and
10282 next elements in the list. This enables easy movement in either
10283 direction through the list. The data item is of type "gpointer",
10284 which means the data can be a pointer to your real data or (through
10285 casting) a numeric value (but do not assume that int and gpointer have
10286 the same size!). These routines internally allocate list elements in
10287 blocks, which is more efficient than allocating elements individually.</para>
10289 <para>There is no function to specifically create a list. Instead, simply
10290 create a variable of type GList* and set its value to NULL; NULL is
10291 considered to be the empty list.</para>
10293 <para>To add elements to a list, use the g_list_append(), g_list_prepend(),
10294 g_list_insert(), or g_list_insert_sorted() routines. In all cases
10295 they accept a pointer to the beginning of the list, and return the
10296 (possibly changed) pointer to the beginning of the list. Thus, for
10297 all of the operations that add or remove elements, be sure to save the
10298 returned value!</para>
10300 <programlisting role="C">
10301 GList *g_list_append( GList *list,
10305 <para>This adds a new element (with value <literal>data</literal>) onto the end of the
10308 <programlisting role="C">
10309 GList *g_list_prepend( GList *list,
10313 <para>This adds a new element (with value <literal>data</literal>) to the beginning of the
10316 <programlisting role="C">
10317 GList *g_list_insert( GList *list,
10322 <para>This inserts a new element (with value data) into the list at the
10323 given position. If position is 0, this is just like g_list_prepend();
10324 if position is less than 0, this is just like g_list_append().</para>
10326 <programlisting role="C">
10327 GList *g_list_remove( GList *list,
10331 <para>This removes the element in the list with the value <literal>data</literal>;
10332 if the element isn't there, the list is unchanged.</para>
10334 <programlisting role="C">
10335 void g_list_free( GList *list );
10338 <para>This frees all of the memory used by a GList. If the list elements
10339 refer to dynamically-allocated memory, then they should be freed
10342 <para>There are many other GLib functions that support doubly linked lists;
10343 see the glib documentation for more information. Here are a few of
10344 the more useful functions' signatures:</para>
10346 <programlisting role="C">
10347 GList *g_list_remove_link( GList *list,
10350 GList *g_list_reverse( GList *list );
10352 GList *g_list_nth( GList *list,
10355 GList *g_list_find( GList *list,
10358 GList *g_list_last( GList *list );
10360 GList *g_list_first( GList *list );
10362 gint g_list_length( GList *list );
10364 void g_list_foreach( GList *list,
10366 gpointer user_data );
10371 <!-- ----------------------------------------------------------------- -->
10372 <sect1 id="sec-SinglyLinkedLists">
10373 <title>Singly Linked Lists</title>
10375 <para>Many of the above functions for singly linked lists are identical to the
10376 above. Here is a list of some of their operations:</para>
10378 <programlisting role="C">
10379 GSList *g_slist_append( GSList *list,
10382 GSList *g_slist_prepend( GSList *list,
10385 GSList *g_slist_insert( GSList *list,
10389 GSList *g_slist_remove( GSList *list,
10392 GSList *g_slist_remove_link( GSList *list,
10395 GSList *g_slist_reverse( GSList *list );
10397 GSList *g_slist_nth( GSList *list,
10400 GSList *g_slist_find( GSList *list,
10403 GSList *g_slist_last( GSList *list );
10405 gint g_slist_length( GSList *list );
10407 void g_slist_foreach( GSList *list,
10409 gpointer user_data );
10415 <!-- ----------------------------------------------------------------- -->
10416 <sect1 id="sec-MemoryManagement">
10417 <title>Memory Management</title>
10419 <programlisting role="C">
10420 gpointer g_malloc( gulong size );
10423 <para>This is a replacement for malloc(). You do not need to check the return
10424 value as it is done for you in this function. If the memory allocation
10425 fails for whatever reasons, your applications will be terminated.</para>
10427 <programlisting role="C">
10428 gpointer g_malloc0( gulong size );
10431 <para>Same as above, but zeroes the memory before returning a pointer to it.</para>
10433 <programlisting role="C">
10434 gpointer g_realloc( gpointer mem,
10438 <para>Relocates "size" bytes of memory starting at "mem". Obviously, the
10439 memory should have been previously allocated.</para>
10441 <programlisting role="C">
10442 void g_free( gpointer mem );
10445 <para>Frees memory. Easy one. If <literal>mem</literal> is NULL it simply returns.</para>
10447 <programlisting role="C">
10448 void g_mem_profile( void );
10451 <para>Dumps a profile of used memory, but requires that you add <literal>#define
10452 MEM_PROFILE</literal> to the top of glib/gmem.c and re-make and make install.</para>
10454 <programlisting role="C">
10455 void g_mem_check( gpointer mem );
10458 <para>Checks that a memory location is valid. Requires you add <literal>#define
10459 MEM_CHECK</literal> to the top of gmem.c and re-make and make install.</para>
10463 <!-- ----------------------------------------------------------------- -->
10464 <sect1 id="sec-Timers">
10465 <title>Timers</title>
10467 <para>Timer functions can be used to time operations (e.g., to see how much
10468 time has elapsed). First, you create a new timer with g_timer_new().
10469 You can then use g_timer_start() to start timing an operation,
10470 g_timer_stop() to stop timing an operation, and g_timer_elapsed() to
10471 determine the elapsed time.</para>
10473 <programlisting role="C">
10474 GTimer *g_timer_new( void );
10476 void g_timer_destroy( GTimer *timer );
10478 void g_timer_start( GTimer *timer );
10480 void g_timer_stop( GTimer *timer );
10482 void g_timer_reset( GTimer *timer );
10484 gdouble g_timer_elapsed( GTimer *timer,
10485 gulong *microseconds );
10490 <!-- ----------------------------------------------------------------- -->
10491 <sect1 id="sec-StringHandling">
10492 <title>String Handling</title>
10494 <para>GLib defines a new type called a GString, which is similar to a
10495 standard C string but one that grows automatically. Its string data
10496 is null-terminated. What this gives you is protection from buffer
10497 overflow programming errors within your program. This is a very
10498 important feature, and hence I recommend that you make use of
10499 GStrings. GString itself has a simple public definition:</para>
10501 <programlisting role="C">
10504 gchar *str; /* Points to the string's current \0-terminated value. */
10505 gint len; /* Current length */
10509 <para>As you might expect, there are a number of operations you can do with
10512 <programlisting role="C">
10513 GString *g_string_new( gchar *init );
10516 <para>This constructs a GString, copying the string value of <literal>init</literal>
10517 into the GString and returning a pointer to it. NULL may be given as
10518 the argument for an initially empty GString.</para>
10520 <programlisting role="C">
10521 void g_string_free( GString *string,
10522 gint free_segment );
10525 <para>This frees the memory for the given GString. If <literal>free_segment</literal> is
10526 TRUE, then this also frees its character data.</para>
10528 <programlisting role="C">
10529 GString *g_string_assign( GString *lval,
10530 const gchar *rval );
10533 <para>This copies the characters from rval into lval, destroying the
10534 previous contents of lval. Note that lval will be lengthened as
10535 necessary to hold the string's contents, unlike the standard strcpy()
10538 <para>The rest of these functions should be relatively obvious (the _c
10539 versions accept a character instead of a string):</para>
10541 <programlisting role="C">
10542 GString *g_string_truncate( GString *string,
10545 GString *g_string_append( GString *string,
10548 GString *g_string_append_c( GString *string,
10551 GString *g_string_prepend( GString *string,
10554 GString *g_string_prepend_c( GString *string,
10557 void g_string_sprintf( GString *string,
10561 void g_string_sprintfa ( GString *string,
10568 <!-- ----------------------------------------------------------------- -->
10569 <sect1 id="sec-UtilityAndErrorFunctions">
10570 <title>Utility and Error Functions</title>
10572 <programlisting role="C">
10573 gchar *g_strdup( const gchar *str );
10576 <para>Replacement strdup function. Copies the original strings contents to
10577 newly allocated memory, and returns a pointer to it.</para>
10579 <programlisting role="C">
10580 gchar *g_strerror( gint errnum );
10583 <para>I recommend using this for all error messages. It's much nicer, and more
10584 portable than perror() or others. The output is usually of the form:</para>
10586 <programlisting role="C">
10587 program name:function that failed:file or further description:strerror
10590 <para>Here's an example of one such call used in our hello_world program:</para>
10592 <programlisting role="C">
10593 g_print("hello_world:open:%s:%s\n", filename, g_strerror(errno));
10596 <programlisting role="C">
10597 void g_error( gchar *format, ... );
10600 <para>Prints an error message. The format is just like printf, but it
10601 prepends "** ERROR **: " to your message, and exits the program.
10602 Use only for fatal errors.</para>
10604 <programlisting role="C">
10605 void g_warning( gchar *format, ... );
10608 <para>Same as above, but prepends "** WARNING **: ", and does not exit the
10611 <programlisting role="C">
10612 void g_message( gchar *format, ... );
10615 <para>Prints "message: " prepended to the string you pass in.</para>
10617 <programlisting role="C">
10618 void g_print( gchar *format, ... );
10621 <para>Replacement for printf().</para>
10623 <para>And our last function:</para>
10625 <programlisting role="C">
10626 gchar *g_strsignal( gint signum );
10629 <para>Prints out the name of the Unix system signal given the signal number.
10630 Useful in generic signal handling functions.</para>
10632 <para>All of the above are more or less just stolen from glib.h. If anyone cares
10633 to document any function, just send me an email!</para>
10638 <!-- ***************************************************************** -->
10639 <chapter id="ch-GTKRCFiles">
10640 <title>GTK's rc Files</title>
10642 <para>GTK has its own way of dealing with application defaults, by using rc
10643 files. These can be used to set the colors of just about any widget, and
10644 can also be used to tile pixmaps onto the background of some widgets. </para>
10646 <!-- ----------------------------------------------------------------- -->
10647 <sect1 id="sec-FunctionsForRCFiles">
10648 <title>Functions For rc Files</title>
10650 <para>When your application starts, you should include a call to:</para>
10652 <programlisting role="C">
10653 void gtk_rc_parse( char *filename );
10656 <para>Passing in the filename of your rc file. This will cause GTK to parse
10657 this file, and use the style settings for the widget types defined
10660 <para>If you wish to have a special set of widgets that can take on a
10661 different style from others, or any other logical division of widgets,
10662 use a call to:</para>
10664 <programlisting role="C">
10665 void gtk_widget_set_name( GtkWidget *widget,
10669 <para>Passing your newly created widget as the first argument, and the name
10670 you wish to give it as the second. This will allow you to change the
10671 attributes of this widget by name through the rc file.</para>
10673 <para>If we use a call something like this:</para>
10675 <programlisting role="C">
10676 button = gtk_button_new_with_label ("Special Button");
10677 gtk_widget_set_name (button, "special button");
10680 <para>Then this button is given the name "special button" and may be addressed by
10681 name in the rc file as "special button.GtkButton". [<--- Verify ME!]</para>
10683 <para>The example rc file below, sets the properties of the main window, and lets
10684 all children of that main window inherit the style described by the "main
10685 button" style. The code used in the application is:</para>
10687 <programlisting role="C">
10688 window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
10689 gtk_widget_set_name (window, "main window");
10692 <para>And then the style is defined in the rc file using:</para>
10694 <programlisting role="C">
10695 widget "main window.*GtkButton*" style "main_button"
10698 <para>Which sets all the Button widgets in the "main window" to the
10699 "main_buttons" style as defined in the rc file.</para>
10701 <para>As you can see, this is a fairly powerful and flexible system. Use your
10702 imagination as to how best to take advantage of this.</para>
10706 <!-- ----------------------------------------------------------------- -->
10707 <sect1 id="sec-GTKsRCFileFormat">
10708 <title>GTK's rc File Format</title>
10710 <para>The format of the GTK file is illustrated in the example below. This is
10711 the testgtkrc file from the GTK distribution, but I've added a
10712 few comments and things. You may wish to include this explanation in
10713 your application to allow the user to fine tune his application.</para>
10715 <para>There are several directives to change the attributes of a widget.</para>
10718 <listitem><simpara>fg - Sets the foreground color of a widget.</simpara>
10720 <listitem><simpara>bg - Sets the background color of a widget.</simpara>
10722 <listitem><simpara>bg_pixmap - Sets the background of a widget to a tiled pixmap.</simpara>
10724 <listitem><simpara>font - Sets the font to be used with the given widget.</simpara>
10728 <para>In addition to this, there are several states a widget can be in, and you
10729 can set different colors, pixmaps and fonts for each state. These states are:</para>
10732 <listitem><simpara>NORMAL - The normal state of a widget, without the mouse over top of
10733 it, and not being pressed, etc.</simpara>
10735 <listitem><simpara>PRELIGHT - When the mouse is over top of the widget, colors defined
10736 using this state will be in effect.</simpara>
10738 <listitem><simpara>ACTIVE - When the widget is pressed or clicked it will be active, and
10739 the attributes assigned by this tag will be in effect.</simpara>
10741 <listitem><simpara>INSENSITIVE - When a widget is set insensitive, and cannot be
10742 activated, it will take these attributes.</simpara>
10744 <listitem><simpara>SELECTED - When an object is selected, it takes these attributes.</simpara>
10748 <para>When using the "fg" and "bg" keywords to set the colors of widgets, the
10751 <programlisting role="C">
10752 fg[<STATE>] = { Red, Green, Blue }
10755 <para>Where STATE is one of the above states (PRELIGHT, ACTIVE, etc), and the Red,
10756 Green and Blue are values in the range of 0 - 1.0, { 1.0, 1.0, 1.0 } being
10757 white. They must be in float form, or they will register as 0, so a straight
10758 "1" will not work, it must be "1.0". A straight "0" is fine because it
10759 doesn't matter if it's not recognized. Unrecognized values are set to 0.</para>
10761 <para>bg_pixmap is very similar to the above, except the colors are replaced by a
10764 <para>pixmap_path is a list of paths separated by ":"'s. These paths will be
10765 searched for any pixmap you specify.</para>
10767 <para>The font directive is simply:</para>
10769 <programlisting role="C">
10770 font = "<font name>"
10773 <para>The only hard part is figuring out the font string. Using xfontsel or
10774 a similar utility should help.</para>
10776 <para>The "widget_class" sets the style of a class of widgets. These classes are
10777 listed in the widget overview on the class hierarchy.</para>
10779 <para>The "widget" directive sets a specifically named set of widgets to a
10780 given style, overriding any style set for the given widget class.
10781 These widgets are registered inside the application using the
10782 gtk_widget_set_name() call. This allows you to specify the attributes of a
10783 widget on a per widget basis, rather than setting the attributes of an
10784 entire widget class. I urge you to document any of these special widgets so
10785 users may customize them.</para>
10787 <para>When the keyword <literal>parent</> is used as an attribute, the widget will take on
10788 the attributes of its parent in the application.</para>
10790 <para>When defining a style, you may assign the attributes of a previously defined
10791 style to this new one.</para>
10793 <programlisting role="C">
10794 style "main_button" = "button"
10796 font = "-adobe-helvetica-medium-r-normal--*-100-*-*-*-*-*-*"
10797 bg[PRELIGHT] = { 0.75, 0, 0 }
10801 <para>This example takes the "button" style, and creates a new "main_button" style
10802 simply by changing the font and prelight background color of the "button"
10805 <para>Of course, many of these attributes don't apply to all widgets. It's a
10806 simple matter of common sense really. Anything that could apply, should.</para>
10810 <!-- ----------------------------------------------------------------- -->
10811 <sect1 id="sec-ExampleRCFile">
10812 <title>Example rc file</title>
10814 <programlisting role="C">
10815 # pixmap_path "<dir 1>:<dir 2>:<dir 3>:..."
10817 pixmap_path "/usr/include/X11R6/pixmaps:/home/imain/pixmaps"
10819 # style <name> [= <name>]
10824 # widget <widget_set> style <style_name>
10825 # widget_class <widget_class_set> style <style_name>
10827 # Here is a list of all the possible states. Note that some do not apply to
10830 # NORMAL - The normal state of a widget, without the mouse over top of
10831 # it, and not being pressed, etc.
10833 # PRELIGHT - When the mouse is over top of the widget, colors defined
10834 # using this state will be in effect.
10836 # ACTIVE - When the widget is pressed or clicked it will be active, and
10837 # the attributes assigned by this tag will be in effect.
10839 # INSENSITIVE - When a widget is set insensitive, and cannot be
10840 # activated, it will take these attributes.
10842 # SELECTED - When an object is selected, it takes these attributes.
10844 # Given these states, we can set the attributes of the widgets in each of
10845 # these states using the following directives.
10847 # fg - Sets the foreground color of a widget.
10848 # fg - Sets the background color of a widget.
10849 # bg_pixmap - Sets the background of a widget to a tiled pixmap.
10850 # font - Sets the font to be used with the given widget.
10853 # This sets a style called "button". The name is not really important, as
10854 # it is assigned to the actual widgets at the bottom of the file.
10858 #This sets the padding around the window to the pixmap specified.
10859 #bg_pixmap[<STATE>] = "<pixmap filename>"
10860 bg_pixmap[NORMAL] = "warning.xpm"
10865 #Sets the foreground color (font color) to red when in the "NORMAL"
10868 fg[NORMAL] = { 1.0, 0, 0 }
10870 #Sets the background pixmap of this widget to that of its parent.
10871 bg_pixmap[NORMAL] = "<parent>"
10876 # This shows all the possible states for a button. The only one that
10877 # doesn't apply is the SELECTED state.
10879 fg[PRELIGHT] = { 0, 1.0, 1.0 }
10880 bg[PRELIGHT] = { 0, 0, 1.0 }
10881 bg[ACTIVE] = { 1.0, 0, 0 }
10882 fg[ACTIVE] = { 0, 1.0, 0 }
10883 bg[NORMAL] = { 1.0, 1.0, 0 }
10884 fg[NORMAL] = { .99, 0, .99 }
10885 bg[INSENSITIVE] = { 1.0, 1.0, 1.0 }
10886 fg[INSENSITIVE] = { 1.0, 0, 1.0 }
10889 # In this example, we inherit the attributes of the "button" style and then
10890 # override the font and background color when prelit to create a new
10891 # "main_button" style.
10893 style "main_button" = "button"
10895 font = "-adobe-helvetica-medium-r-normal--*-100-*-*-*-*-*-*"
10896 bg[PRELIGHT] = { 0.75, 0, 0 }
10899 style "toggle_button" = "button"
10901 fg[NORMAL] = { 1.0, 0, 0 }
10902 fg[ACTIVE] = { 1.0, 0, 0 }
10904 # This sets the background pixmap of the toggle_button to that of its
10905 # parent widget (as defined in the application).
10906 bg_pixmap[NORMAL] = "<parent>"
10911 bg_pixmap[NORMAL] = "marble.xpm"
10912 fg[NORMAL] = { 1.0, 1.0, 1.0 }
10917 font = "-adobe-helvetica-medium-r-normal--*-80-*-*-*-*-*-*"
10920 # pixmap_path "~/.pixmaps"
10922 # These set the widget types to use the styles defined above.
10923 # The widget types are listed in the class hierarchy, but could probably be
10924 # just listed in this document for the users reference.
10926 widget_class "GtkWindow" style "window"
10927 widget_class "GtkDialog" style "window"
10928 widget_class "GtkFileSelection" style "window"
10929 widget_class "*Gtk*Scale" style "scale"
10930 widget_class "*GtkCheckButton*" style "toggle_button"
10931 widget_class "*GtkRadioButton*" style "toggle_button"
10932 widget_class "*GtkButton*" style "button"
10933 widget_class "*Ruler" style "ruler"
10934 widget_class "*GtkText" style "text"
10936 # This sets all the buttons that are children of the "main window" to
10937 # the main_button style. These must be documented to be taken advantage of.
10938 widget "main window.*GtkButton*" style "main_button"
10944 <!-- ***************************************************************** -->
10945 <chapter id="ch-WritingYourOwnWidgets">
10946 <title>Writing Your Own Widgets</title>
10948 <!-- ----------------------------------------------------------------- -->
10949 <sect1 id="sec-WidgetsOverview">
10950 <title>Overview</title>
10952 <para>Although the GTK distribution comes with many types of widgets that
10953 should cover most basic needs, there may come a time when you need to
10954 create your own new widget type. Since GTK uses widget inheritance
10955 extensively, and there is already a widget that is close to what you want,
10956 it is often possible to make a useful new widget type in
10957 just a few lines of code. But before starting work on a new widget, check
10958 around first to make sure that someone has not already written
10959 it. This will prevent duplication of effort and keep the number of
10960 GTK widgets out there to a minimum, which will help keep both the code
10961 and the interface of different applications consistent. As a flip side
10962 to this, once you finish your widget, announce it to the world so
10963 other people can benefit. The best place to do this is probably the
10964 <literal>gtk-list</literal>.</para>
10966 <para>Complete sources for the example widgets are available at the place you
10967 got this tutorial, or from:</para>
10969 <para><ulink url="http://www.gtk.org/~otaylor/gtk/tutorial/">http://www.gtk.org/~otaylor/gtk/tutorial/</ulink></para>
10974 <!-- ----------------------------------------------------------------- -->
10975 <sect1 id="sec-TheAnatomyOfAWidget">
10976 <title>The Anatomy Of A Widget</title>
10978 <para>In order to create a new widget, it is important to have an
10979 understanding of how GTK objects work. This section is just meant as a
10980 brief overview. See the reference documentation for the details. </para>
10982 <para>GTK widgets are implemented in an object oriented fashion. However,
10983 they are implemented in standard C. This greatly improves portability
10984 and stability over using current generation C++ compilers; however,
10985 it does mean that the widget writer has to pay attention to some of
10986 the implementation details. The information common to all instances of
10987 one class of widgets (e.g., to all Button widgets) is stored in the
10988 <emphasis>class structure</emphasis>. There is only one copy of this in
10989 which is stored information about the class's signals
10990 (which act like virtual functions in C). To support inheritance, the
10991 first field in the class structure must be a copy of the parent's
10992 class structure. The declaration of the class structure of GtkButtton
10995 <programlisting role="C">
10996 struct _GtkButtonClass
10998 GtkContainerClass parent_class;
11000 void (* pressed) (GtkButton *button);
11001 void (* released) (GtkButton *button);
11002 void (* clicked) (GtkButton *button);
11003 void (* enter) (GtkButton *button);
11004 void (* leave) (GtkButton *button);
11008 <para>When a button is treated as a container (for instance, when it is
11009 resized), its class structure can be cast to GtkContainerClass, and
11010 the relevant fields used to handle the signals.</para>
11012 <para>There is also a structure for each widget that is created on a
11013 per-instance basis. This structure has fields to store information that
11014 is different for each instance of the widget. We'll call this
11015 structure the <emphasis>object structure</emphasis>. For the Button class, it looks
11018 <programlisting role="C">
11021 GtkContainer container;
11025 guint in_button : 1;
11026 guint button_down : 1;
11030 <para>Note that, similar to the class structure, the first field is the
11031 object structure of the parent class, so that this structure can be
11032 cast to the parent class' object structure as needed.</para>
11036 <!-- ----------------------------------------------------------------- -->
11037 <sect1 id="sec-CreatingACompositeWidget">
11038 <title>Creating a Composite widget</title>
11040 <!-- ----------------------------------------------------------------- -->
11042 <title>Introduction</title>
11044 <para>One type of widget that you may be interested in creating is a
11045 widget that is merely an aggregate of other GTK widgets. This type of
11046 widget does nothing that couldn't be done without creating new
11047 widgets, but provides a convenient way of packaging user interface
11048 elements for reuse. The FileSelection and ColorSelection widgets in
11049 the standard distribution are examples of this type of widget.</para>
11051 <para>The example widget that we'll create in this section is the Tictactoe
11052 widget, a 3x3 array of toggle buttons which triggers a signal when all
11053 three buttons in a row, column, or on one of the diagonals are
11056 <para><emphasis>Note: the full source code for the Tictactoe example described
11057 below is in the <link linkend="sec-Tictactoe">Code Examples Appendix</link>
11061 <inlinemediaobject>
11063 <imagedata fileref="images/tictactoe.png" format="png">
11065 </inlinemediaobject>
11070 <!-- ----------------------------------------------------------------- -->
11072 <title>Choosing a parent class</title>
11074 <para>The parent class for a composite widget is typically the container
11075 class that holds all of the elements of the composite widget. For
11076 example, the parent class of the FileSelection widget is the
11077 Dialog class. Since our buttons will be arranged in a table, it
11078 is natural to make our parent class the Table class.</para>
11082 <!-- ----------------------------------------------------------------- -->
11084 <title>The header file</title>
11086 <para>Each GObject class has a header file which declares the object and
11087 class structures for that object, along with public functions.
11088 A couple of features are worth pointing out. To prevent duplicate
11089 definitions, we wrap the entire header file in:</para>
11091 <programlisting role="C">
11092 #ifndef __TICTACTOE_H__
11093 #define __TICTACTOE_H__
11097 #endif /* __TICTACTOE_H__ */
11100 <para>And to keep C++ programs that include the header file happy, in:</para>
11102 <programlisting role="C">
11103 #include <glib.h>
11112 <para>Along with the functions and structures, we declare five standard
11113 macros in our header file, <literal>TICTACTOE_TYPE</literal>,
11114 <literal>TICTACTOE(obj)</literal>,
11115 <literal>TICTACTOE_CLASS(klass)</literal>,
11116 <literal>IS_TICTACTOE(obj)</literal>, and
11117 <literal>IS_TICTACTOE_CLASS(klass)</literal>, which cast a
11118 pointer into a pointer to the object or class structure, and check
11119 if an object is a Tictactoe widget respectively.</para>
11123 <!-- ----------------------------------------------------------------- -->
11125 <title>The <literal>_get_type()</literal> function</title>
11127 <para>We now continue on to the implementation of our widget. A core
11128 function for every object is the function
11129 <literal>WIDGETNAME_get_type()</literal>. This function, when first called, tells
11130 Glib about the new class, and gets an ID that uniquely identifies
11131 the class. Upon subsequent calls, it just returns the ID.</para>
11133 <programlisting role="C">
11135 tictactoe_get_type (void)
11137 static GType ttt_type = 0;
11141 const GTypeInfo ttt_info =
11143 sizeof (TictactoeClass),
11144 NULL, /* base_init */
11145 NULL, /* base_finalize */
11146 (GClassInitFunc) tictactoe_class_init,
11147 NULL, /* class_finalize */
11148 NULL, /* class_data */
11149 sizeof (Tictactoe),
11150 0, /* n_preallocs */
11151 (GInstanceInitFunc) tictactoe_init,
11154 ttt_type = g_type_register_static (GTK_TYPE_TABLE,
11164 <para>The GTypeInfo structure has the following definition:</para>
11166 <programlisting role="C">
11169 /* interface types, classed types, instantiated types */
11170 guint16 class_size;
11172 GBaseInitFunc base_init;
11173 GBaseFinalizeFunc base_finalize;
11175 /* classed types, instantiated types */
11176 GClassInitFunc class_init;
11177 GClassFinalizeFunc class_finalize;
11178 gconstpointer class_data;
11180 /* instantiated types */
11181 guint16 instance_size;
11182 guint16 n_preallocs;
11183 GInstanceInitFunc instance_init;
11185 /* value handling */
11186 const GTypeValueTable *value_table;
11190 <para>The important fields of this structure are pretty self-explanatory.
11191 We'll ignore the <literal>base_init</literal> and
11192 <literal>base_finalize</literal> as well as the <literal>value_table</literal>
11193 fields here. Once Glib has a correctly filled in copy of
11194 this structure, it knows how to create objects of a particular type. </para>
11198 <!-- ----------------------------------------------------------------- -->
11200 <title>The <literal>_class_init()</literal> function</title>
11202 <para>The <literal>WIDGETNAME_class_init()</literal> function initializes the fields of
11203 the widget's class structure, and sets up any signals for the
11204 class. For our Tictactoe widget it looks like:</para>
11206 <programlisting role="C">
11213 static guint tictactoe_signals[LAST_SIGNAL] = { 0 };
11216 tictactoe_class_init (TictactoeClass *klass)
11218 tictactoe_signals[TICTACTOE_SIGNAL] =
11219 g_signal_new ("tictactoe",
11220 G_TYPE_FROM_CLASS (klass),
11221 G_SIGNAL_RUN_FIRST | G_SIGNAL_ACTION,
11222 G_STRUCT_OFFSET (TictactoeClass, tictactoe),
11224 g_cclosure_marshal_VOID__VOID, G_TYPE_NONE, 0);
11228 <para>Our widget has just one signal, the <literal>tictactoe</literal> signal that is
11229 invoked when a row, column, or diagonal is completely filled in. Not
11230 every composite widget needs signals, so if you are reading this for
11231 the first time, you may want to skip to the next section now, as
11232 things are going to get a bit complicated.</para>
11234 <para>The function:</para>
11236 <programlisting role="C">
11237 guint g_signal_new( const gchar *signal_name,
11239 GSignalFlags signal_flags,
11240 guint class_offset,
11241 GSignalAccumulator *accumulator,
11242 gpointer accu_data,
11243 GSignalCMarshaller *c_marshaller,
11249 <para>Creates a new signal. The parameters are:</para>
11252 <listitem><simpara> <literal>signal_name</literal>: The name of the signal.</simpara>
11255 <listitem><simpara> <literal>itype</literal>: The ID of the object that this signal applies
11256 to. (It will also apply to that objects descendants.)</simpara>
11259 <listitem><simpara> <literal>signal_flags</literal>: Whether the default handler runs before or after
11260 user handlers and other flags. Usually this will be one of
11261 <literal>G_SIGNAL_RUN_FIRST</literal> or <literal>G_SIGNAL_RUN_LAST</literal>,
11262 although there are other possibilities. The flag
11263 <literal>G_SIGNAL_ACTION</literal> specifies that no extra code needs to
11264 run that performs special pre or post emission adjustments. This means that
11265 the signal can also be emitted from object external code.</simpara>
11268 <listitem><simpara> <literal>class_offset</literal>: The offset within the class structure of
11269 a pointer to the default handler.</simpara>
11272 <listitem><simpara> <literal>accumulator</literal>: For most classes this can
11273 be set to NULL.</simpara></listitem>
11275 <listitem><simpara> <literal>accu_data</literal>: User data that will be handed
11276 to the accumulator function.</simpara></listitem>
11278 <listitem><simpara> <literal>c_marshaller</literal>: A function that is used to invoke the signal
11279 handler. For signal handlers that have no arguments other than the
11280 object that emitted the signal and user data, we can use the
11281 pre-supplied marshaller function <literal>g_cclosure_marshal_VOID__VOID</literal>.</simpara>
11284 <listitem><simpara> <literal>return_type</literal>: The type of the return value.</simpara>
11287 <listitem><simpara> <literal>n_params</literal>: The number of parameters of the signal handler
11288 (other than the two default ones mentioned above)</simpara>
11291 <listitem><simpara> <literal>...</literal>: The types of the parameters.</simpara>
11295 <para>When specifying types, the following standard types can be used:</para>
11297 <programlisting role="C">
11321 <para><literal>g_signal_new()</literal> returns a unique integer identifier for the
11322 signal, that we store in the <literal>tictactoe_signals</literal> array, which we
11323 index using an enumeration. (Conventionally, the enumeration elements
11324 are the signal name, uppercased, but here there would be a conflict
11325 with the <literal>TICTACTOE()</literal> macro, so we called it <literal>TICTACTOE_SIGNAL</literal>
11330 <!-- ----------------------------------------------------------------- -->
11332 <title>The <literal>_init()</literal> function</title>
11334 <para>Each class also needs a function to initialize the object
11335 structure. Usually, this function has the fairly limited role of
11336 setting the fields of the structure to default values. For composite
11337 widgets, however, this function also creates the component widgets.</para>
11339 <programlisting role="C">
11341 tictactoe_init (Tictactoe *ttt)
11345 gtk_table_resize (GTK_TABLE (ttt), 3, 3);
11346 gtk_table_set_homogeneous (GTK_TABLE (ttt), TRUE);
11348 for (i=0;i<3; i++)
11349 for (j=0;j<3; j++)
11351 ttt->buttons[i][j] = gtk_toggle_button_new ();
11352 gtk_table_attach_defaults (GTK_TABLE (ttt), ttt->buttons[i][j],
11354 g_signal_connect (ttt->buttons[i][j], "toggled",
11355 G_CALLBACK (tictactoe_toggle), ttt);
11356 gtk_widget_set_size_request (ttt->buttons[i][j], 20, 20);
11357 gtk_widget_show (ttt->buttons[i][j]);
11364 <!-- ----------------------------------------------------------------- -->
11366 <title>And the rest...</title>
11368 <para>There is one more function that every object (except for abstract
11369 classes like Bin that cannot be instantiated) needs to have - the
11370 function that the user calls to create an object of that type. This is
11371 conventionally called <literal>OBJECTNAME_new()</literal>. In some
11372 widgets, though not for the Tictactoe widgets, this function takes
11373 arguments, and does some setup based on the arguments. The other two
11374 functions are specific to the Tictactoe widget. </para>
11376 <para><literal>tictactoe_clear()</literal> is a public function that resets all the
11377 buttons in the widget to the up position. Note the use of
11378 <literal>g_signal_handlers_block_matched()</literal> to keep our signal handler for
11379 button toggles from being triggered unnecessarily.</para>
11381 <para><literal>tictactoe_toggle()</literal> is the signal handler that is invoked when the
11382 user clicks on a button. It checks to see if there are any winning
11383 combinations that involve the toggled button, and if so, emits
11384 the "tictactoe" signal.</para>
11386 <programlisting role="C">
11388 tictactoe_new (void)
11390 return GTK_WIDGET ( g_object_new (TICTACTOE_TYPE, NULL));
11394 tictactoe_clear (Tictactoe *ttt)
11398 for (i=0;i<3;i++)
11399 for (j=0;j<3;j++)
11401 g_signal_handlers_block_matched (G_OBJECT (ttt->buttons[i][j]),
11402 G_SIGNAL_MATCH_DATA,
11403 0, 0, NULL, NULL, ttt);
11404 gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (ttt->buttons[i][j]),
11406 g_signal_handlers_unblock_matched (G_OBJECT (ttt->buttons[i][j]),
11407 G_SIGNAL_MATCH_DATA,
11408 0, 0, NULL, NULL, ttt);
11413 tictactoe_toggle (GtkWidget *widget, Tictactoe *ttt)
11417 static int rwins[8][3] = { { 0, 0, 0 }, { 1, 1, 1 }, { 2, 2, 2 },
11418 { 0, 1, 2 }, { 0, 1, 2 }, { 0, 1, 2 },
11419 { 0, 1, 2 }, { 0, 1, 2 } };
11420 static int cwins[8][3] = { { 0, 1, 2 }, { 0, 1, 2 }, { 0, 1, 2 },
11421 { 0, 0, 0 }, { 1, 1, 1 }, { 2, 2, 2 },
11422 { 0, 1, 2 }, { 2, 1, 0 } };
11424 int success, found;
11426 for (k=0; k<8; k++)
11431 for (i=0;i<3;i++)
11433 success = success &&
11434 GTK_TOGGLE_BUTTON(ttt->buttons[rwins[k][i]][cwins[k][i]])->active;
11436 ttt->buttons[rwins[k][i]][cwins[k][i]] == widget;
11439 if (success && found)
11441 g_signal_emit (ttt,
11442 tictactoe_signals[TICTACTOE_SIGNAL], 0);
11449 <para>And finally, an example program using our Tictactoe widget:</para>
11451 <programlisting role="C">
11452 #include <gtk/gtk.h>
11453 #include "tictactoe.h"
11455 /* Invoked when a row, column or diagonal is completed */
11457 win (GtkWidget *widget, gpointer data)
11459 g_print ("Yay!\n");
11460 tictactoe_clear (TICTACTOE (widget));
11464 main (int argc, char *argv[])
11469 gtk_init (&argc, &argv);
11471 window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
11473 gtk_window_set_title (GTK_WINDOW (window), "Aspect Frame");
11475 g_signal_connect (window, "destroy",
11476 G_CALLBACK (exit), NULL);
11478 gtk_container_set_border_width (GTK_CONTAINER (window), 10);
11480 /* Create a new Tictactoe widget */
11481 ttt = tictactoe_new ();
11482 gtk_container_add (GTK_CONTAINER (window), ttt);
11483 gtk_widget_show (ttt);
11485 /* And attach to its "tictactoe" signal */
11486 g_signal_connect (ttt, "tictactoe",
11487 G_CALLBACK (win), NULL);
11489 gtk_widget_show (window);
11500 <!-- ----------------------------------------------------------------- -->
11501 <sect1 id="sec-CreatingAWidgetFromScratch">
11502 <title>Creating a widget from scratch</title>
11504 <!-- ----------------------------------------------------------------- -->
11506 <title>Introduction</title>
11508 <para>In this section, we'll learn more about how widgets display themselves
11509 on the screen and interact with events. As an example of this, we'll
11510 create an analog dial widget with a pointer that the user can drag to
11511 set the value.</para>
11514 <inlinemediaobject>
11516 <imagedata fileref="images/gtkdial.png" format="png">
11518 </inlinemediaobject>
11523 <!-- ----------------------------------------------------------------- -->
11525 <title>Displaying a widget on the screen</title>
11527 <para>There are several steps that are involved in displaying on the screen.
11528 After the widget is created with a call to <literal>WIDGETNAME_new()</literal>,
11529 several more functions are needed:</para>
11532 <listitem><simpara> <literal>WIDGETNAME_realize()</literal> is responsible for creating an X
11533 window for the widget if it has one.</simpara>
11535 <listitem><simpara> <literal>WIDGETNAME_map()</literal> is invoked after the user calls
11536 <literal>gtk_widget_show()</literal>. It is responsible for making sure the widget
11537 is actually drawn on the screen (<emphasis>mapped</emphasis>). For a container class,
11538 it must also make calls to <literal>map()</literal> functions of any child widgets.</simpara>
11540 <listitem><simpara> <literal>WIDGETNAME_draw()</literal> is invoked when <literal>gtk_widget_draw()</literal>
11541 is called for the widget or one of its ancestors. It makes the actual
11542 calls to the drawing functions to draw the widget on the screen. For
11543 container widgets, this function must make calls to
11544 <literal>gtk_widget_draw()</literal> for its child widgets.</simpara>
11546 <listitem><simpara> <literal>WIDGETNAME_expose()</literal> is a handler for expose events for the
11547 widget. It makes the necessary calls to the drawing functions to draw
11548 the exposed portion on the screen. For container widgets, this
11549 function must generate expose events for its child widgets which don't
11550 have their own windows. (If they have their own windows, then X will
11551 generate the necessary expose events.)</simpara>
11555 <para>You might notice that the last two functions are quite similar - each
11556 is responsible for drawing the widget on the screen. In fact many
11557 types of widgets don't really care about the difference between the
11558 two. The default <literal>draw()</literal> function in the widget class simply
11559 generates a synthetic expose event for the redrawn area. However, some
11560 types of widgets can save work by distinguishing between the two
11561 functions. For instance, if a widget has multiple X windows, then
11562 since expose events identify the exposed window, it can redraw only
11563 the affected window, which is not possible for calls to <literal>draw()</literal>.</para>
11565 <para>Container widgets, even if they don't care about the difference for
11566 themselves, can't simply use the default <literal>draw()</literal> function because
11567 their child widgets might care about the difference. However,
11568 it would be wasteful to duplicate the drawing code between the two
11569 functions. The convention is that such widgets have a function called
11570 <literal>WIDGETNAME_paint()</literal> that does the actual work of drawing the
11571 widget, that is then called by the <literal>draw()</literal> and <literal>expose()</literal>
11574 <para>In our example approach, since the dial widget is not a container
11575 widget, and only has a single window, we can take the simplest
11576 approach and use the default <literal>draw()</literal> function and only implement
11577 an <literal>expose()</literal> function.</para>
11581 <!-- ----------------------------------------------------------------- -->
11583 <title>The origins of the Dial Widget</title>
11585 <para>Just as all land animals are just variants on the first amphibian that
11586 crawled up out of the mud, GTK widgets tend to start off as variants
11587 of some other, previously written widget. Thus, although this section
11588 is entitled "Creating a Widget from Scratch", the Dial widget really
11589 began with the source code for the Range widget. This was picked as a
11590 starting point because it would be nice if our Dial had the same
11591 interface as the Scale widgets which are just specialized descendants
11592 of the Range widget. So, though the source code is presented below in
11593 finished form, it should not be implied that it was written, <emphasis>ab
11594 initio</emphasis> in this fashion. Also, if you aren't yet familiar with
11595 how scale widgets work from the application writer's point of view, it
11596 would be a good idea to look them over before continuing.</para>
11600 <!-- ----------------------------------------------------------------- -->
11602 <title>The Basics</title>
11604 <para>Quite a bit of our widget should look pretty familiar from the
11605 Tictactoe widget. First, we have a header file:</para>
11607 <programlisting role="C">
11608 /* GTK - The GIMP Toolkit
11609 * Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
11611 * This library is free software; you can redistribute it and/or
11612 * modify it under the terms of the GNU Library General Public
11613 * License as published by the Free Software Foundation; either
11614 * version 2 of the License, or (at your option) any later version.
11616 * This library is distributed in the hope that it will be useful,
11617 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11618 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11619 * Library General Public License for more details.
11621 * You should have received a copy of the GNU Library General Public
11622 * License along with this library; if not, write to the Free
11623 * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
11626 #ifndef __GTK_DIAL_H__
11627 #define __GTK_DIAL_H__
11629 #include <gdk/gdk.h>
11630 #include <gtk/gtkadjustment.h>
11631 #include <gtk/gtkwidget.h>
11636 #endif /* __cplusplus */
11639 #define GTK_DIAL(obj) GTK_CHECK_CAST (obj, gtk_dial_get_type (), GtkDial)
11640 #define GTK_DIAL_CLASS(klass) GTK_CHECK_CLASS_CAST (klass, gtk_dial_get_type (), GtkDialClass)
11641 #define GTK_IS_DIAL(obj) GTK_CHECK_TYPE (obj, gtk_dial_get_type ())
11644 typedef struct _GtkDial GtkDial;
11645 typedef struct _GtkDialClass GtkDialClass;
11651 /* update policy (GTK_UPDATE_[CONTINUOUS/DELAYED/DISCONTINUOUS]) */
11654 /* Button currently pressed or 0 if none */
11657 /* Dimensions of dial components */
11659 gint pointer_width;
11661 /* ID of update timer, or 0 if none */
11664 /* Current angle */
11667 /* Old values from adjustment stored so we know when something changes */
11672 /* The adjustment object that stores the data for this dial */
11673 GtkAdjustment *adjustment;
11676 struct _GtkDialClass
11678 GtkWidgetClass parent_class;
11682 GtkWidget* gtk_dial_new (GtkAdjustment *adjustment);
11683 GtkType gtk_dial_get_type (void);
11684 GtkAdjustment* gtk_dial_get_adjustment (GtkDial *dial);
11685 void gtk_dial_set_update_policy (GtkDial *dial,
11686 GtkUpdateType policy);
11688 void gtk_dial_set_adjustment (GtkDial *dial,
11689 GtkAdjustment *adjustment);
11692 #endif /* __cplusplus */
11695 #endif /* __GTK_DIAL_H__ */
11698 <para>Since there is quite a bit more going on in this widget than the last
11699 one, we have more fields in the data structure, but otherwise things
11700 are pretty similar.</para>
11702 <para>Next, after including header files and declaring a few constants,
11703 we have some functions to provide information about the widget
11704 and initialize it:</para>
11706 <programlisting role="C">
11707 #include <math.h>
11708 #include <stdio.h>
11709 #include <gtk/gtkmain.h>
11710 #include <gtk/gtksignal.h>
11712 #include "gtkdial.h"
11714 #define SCROLL_DELAY_LENGTH 300
11715 #define DIAL_DEFAULT_SIZE 100
11717 /* Forward declarations */
11719 [ omitted to save space ]
11723 static GtkWidgetClass *parent_class = NULL;
11726 gtk_dial_get_type ()
11728 static GtkType dial_type = 0;
11732 static const GtkTypeInfo dial_info =
11736 sizeof (GtkDialClass),
11737 (GtkClassInitFunc) gtk_dial_class_init,
11738 (GtkObjectInitFunc) gtk_dial_init,
11739 /* reserved_1 */ NULL,
11740 /* reserved_1 */ NULL,
11741 (GtkClassInitFunc) NULL
11744 dial_type = gtk_type_unique (GTK_TYPE_WIDGET, &dial_info);
11751 gtk_dial_class_init (GtkDialClass *class)
11753 GtkObjectClass *object_class;
11754 GtkWidgetClass *widget_class;
11756 object_class = (GtkObjectClass*) class;
11757 widget_class = (GtkWidgetClass*) class;
11759 parent_class = gtk_type_class (gtk_widget_get_type ());
11761 object_class->destroy = gtk_dial_destroy;
11763 widget_class->realize = gtk_dial_realize;
11764 widget_class->expose_event = gtk_dial_expose;
11765 widget_class->size_request = gtk_dial_size_request;
11766 widget_class->size_allocate = gtk_dial_size_allocate;
11767 widget_class->button_press_event = gtk_dial_button_press;
11768 widget_class->button_release_event = gtk_dial_button_release;
11769 widget_class->motion_notify_event = gtk_dial_motion_notify;
11773 gtk_dial_init (GtkDial *dial)
11776 dial->policy = GTK_UPDATE_CONTINUOUS;
11779 dial->pointer_width = 0;
11781 dial->old_value = 0.0;
11782 dial->old_lower = 0.0;
11783 dial->old_upper = 0.0;
11784 dial->adjustment = NULL;
11788 gtk_dial_new (GtkAdjustment *adjustment)
11792 dial = gtk_type_new (gtk_dial_get_type ());
11795 adjustment = gtk_adjustment_new (0.0, 0.0, 0.0, 0.0, 0.0, 0.0);
11797 gtk_dial_set_adjustment (dial, adjustment);
11799 return GTK_WIDGET (dial);
11803 gtk_dial_destroy (GtkObject *object)
11807 g_return_if_fail (object != NULL);
11808 g_return_if_fail (GTK_IS_DIAL (object));
11810 dial = GTK_DIAL (object);
11812 if (dial->adjustment)
11813 gtk_object_unref (GTK_OBJECT (dial->adjustment));
11815 if (GTK_OBJECT_CLASS (parent_class)->destroy)
11816 (* GTK_OBJECT_CLASS (parent_class)->destroy) (object);
11820 <para>Note that this <literal>init()</literal> function does less than for the Tictactoe
11821 widget, since this is not a composite widget, and the <literal>new()</literal>
11822 function does more, since it now has an argument. Also, note that when
11823 we store a pointer to the Adjustment object, we increment its
11824 reference count, (and correspondingly decrement it when we no longer
11825 use it) so that GTK can keep track of when it can be safely destroyed.</para>
11827 <para>Also, there are a few function to manipulate the widget's options:</para>
11829 <programlisting role="C">
11831 gtk_dial_get_adjustment (GtkDial *dial)
11833 g_return_val_if_fail (dial != NULL, NULL);
11834 g_return_val_if_fail (GTK_IS_DIAL (dial), NULL);
11836 return dial->adjustment;
11840 gtk_dial_set_update_policy (GtkDial *dial,
11841 GtkUpdateType policy)
11843 g_return_if_fail (dial != NULL);
11844 g_return_if_fail (GTK_IS_DIAL (dial));
11846 dial->policy = policy;
11850 gtk_dial_set_adjustment (GtkDial *dial,
11851 GtkAdjustment *adjustment)
11853 g_return_if_fail (dial != NULL);
11854 g_return_if_fail (GTK_IS_DIAL (dial));
11856 if (dial->adjustment)
11858 gtk_signal_disconnect_by_data (GTK_OBJECT (dial->adjustment), (gpointer) dial);
11859 gtk_object_unref (GTK_OBJECT (dial->adjustment));
11862 dial->adjustment = adjustment;
11863 gtk_object_ref (GTK_OBJECT (dial->adjustment));
11865 gtk_signal_connect (GTK_OBJECT (adjustment), "changed",
11866 (GtkSignalFunc) gtk_dial_adjustment_changed,
11868 gtk_signal_connect (GTK_OBJECT (adjustment), "value_changed",
11869 (GtkSignalFunc) gtk_dial_adjustment_value_changed,
11872 dial->old_value = adjustment->value;
11873 dial->old_lower = adjustment->lower;
11874 dial->old_upper = adjustment->upper;
11876 gtk_dial_update (dial);
11882 <!-- ----------------------------------------------------------------- -->
11884 <title><literal>gtk_dial_realize()</literal></title>
11886 <para>Now we come to some new types of functions. First, we have a function
11887 that does the work of creating the X window. Notice that a mask is
11888 passed to the function <literal>gdk_window_new()</literal> which specifies which fields of
11889 the GdkWindowAttr structure actually have data in them (the remaining
11890 fields will be given default values). Also worth noting is the way the
11891 event mask of the widget is created. We call
11892 <literal>gtk_widget_get_events()</literal> to retrieve the event mask that the user
11893 has specified for this widget (with <literal>gtk_widget_set_events()</literal>), and
11894 add the events that we are interested in ourselves.</para>
11896 <para>After creating the window, we set its style and background, and put a
11897 pointer to the widget in the user data field of the GdkWindow. This
11898 last step allows GTK to dispatch events for this window to the correct
11901 <programlisting role="C">
11903 gtk_dial_realize (GtkWidget *widget)
11906 GdkWindowAttr attributes;
11907 gint attributes_mask;
11909 g_return_if_fail (widget != NULL);
11910 g_return_if_fail (GTK_IS_DIAL (widget));
11912 gtk_widget_set_realized (widget, TRUE);
11913 dial = GTK_DIAL (widget);
11915 attributes.x = widget->allocation.x;
11916 attributes.y = widget->allocation.y;
11917 attributes.width = widget->allocation.width;
11918 attributes.height = widget->allocation.height;
11919 attributes.wclass = GDK_INPUT_OUTPUT;
11920 attributes.window_type = GDK_WINDOW_CHILD;
11921 attributes.event_mask = gtk_widget_get_events (widget) |
11922 GDK_EXPOSURE_MASK | GDK_BUTTON_PRESS_MASK |
11923 GDK_BUTTON_RELEASE_MASK | GDK_POINTER_MOTION_MASK |
11924 GDK_POINTER_MOTION_HINT_MASK;
11925 attributes.visual = gtk_widget_get_visual (widget);
11926 attributes.colormap = gtk_widget_get_colormap (widget);
11928 attributes_mask = GDK_WA_X | GDK_WA_Y | GDK_WA_VISUAL | GDK_WA_COLORMAP;
11929 widget->window = gdk_window_new (gtk_widget_get_parent_window (widget), &attributes, attributes_mask);
11931 widget->style = gtk_style_attach (widget->style, widget->window);
11933 gdk_window_set_user_data (widget->window, widget);
11935 gtk_style_set_background (widget->style, widget->window, GTK_STATE_ACTIVE);
11941 <!-- ----------------------------------------------------------------- -->
11943 <title>Size negotiation</title>
11945 <para>Before the first time that the window containing a widget is
11946 displayed, and whenever the layout of the window changes, GTK asks
11947 each child widget for its desired size. This request is handled by the
11948 function <literal>gtk_dial_size_request()</literal>. Since our widget isn't a
11949 container widget, and has no real constraints on its size, we just
11950 return a reasonable default value.</para>
11952 <programlisting role="C">
11954 gtk_dial_size_request (GtkWidget *widget,
11955 GtkRequisition *requisition)
11957 requisition->width = DIAL_DEFAULT_SIZE;
11958 requisition->height = DIAL_DEFAULT_SIZE;
11962 <para>After all the widgets have requested an ideal size, the layout of the
11963 window is computed and each child widget is notified of its actual
11964 size. Usually, this will be at least as large as the requested size,
11965 but if for instance the user has resized the window, it may
11966 occasionally be smaller than the requested size. The size notification
11967 is handled by the function <literal>gtk_dial_size_allocate()</literal>. Notice that
11968 as well as computing the sizes of some component pieces for future
11969 use, this routine also does the grunt work of moving the widget's X
11970 window into the new position and size.</para>
11972 <programlisting role="C">
11974 gtk_dial_size_allocate (GtkWidget *widget,
11975 GtkAllocation *allocation)
11979 g_return_if_fail (widget != NULL);
11980 g_return_if_fail (GTK_IS_DIAL (widget));
11981 g_return_if_fail (allocation != NULL);
11983 widget->allocation = *allocation;
11984 if (gtk_widget_get_realized (widget))
11986 dial = GTK_DIAL (widget);
11988 gdk_window_move_resize (widget->window,
11989 allocation->x, allocation->y,
11990 allocation->width, allocation->height);
11992 dial->radius = MAX(allocation->width,allocation->height) * 0.45;
11993 dial->pointer_width = dial->radius / 5;
12000 <!-- ----------------------------------------------------------------- -->
12002 <title><literal>gtk_dial_expose()</literal></title>
12004 <para>As mentioned above, all the drawing of this widget is done in the
12005 handler for expose events. There's not much to remark on here except
12006 the use of the function <literal>gtk_draw_polygon</literal> to draw the pointer with
12007 three dimensional shading according to the colors stored in the
12008 widget's style.</para>
12010 <programlisting role="C">
12012 gtk_dial_expose( GtkWidget *widget,
12013 GdkEventExpose *event )
12016 GdkPoint points[3];
12023 g_return_val_if_fail (widget != NULL, FALSE);
12024 g_return_val_if_fail (GTK_IS_DIAL (widget), FALSE);
12025 g_return_val_if_fail (event != NULL, FALSE);
12027 if (event->count > 0)
12030 dial = GTK_DIAL (widget);
12032 gdk_window_clear_area (widget->window,
12034 widget->allocation.width,
12035 widget->allocation.height);
12037 xc = widget->allocation.width/2;
12038 yc = widget->allocation.height/2;
12042 for (i=0; i<25; i++)
12044 theta = (i*M_PI/18. - M_PI/6.);
12048 tick_length = (i%6 == 0) ? dial->pointer_width : dial->pointer_width/2;
12050 gdk_draw_line (widget->window,
12051 widget->style->fg_gc[widget->state],
12052 xc + c*(dial->radius - tick_length),
12053 yc - s*(dial->radius - tick_length),
12054 xc + c*dial->radius,
12055 yc - s*dial->radius);
12060 s = sin(dial->angle);
12061 c = cos(dial->angle);
12064 points[0].x = xc + s*dial->pointer_width/2;
12065 points[0].y = yc + c*dial->pointer_width/2;
12066 points[1].x = xc + c*dial->radius;
12067 points[1].y = yc - s*dial->radius;
12068 points[2].x = xc - s*dial->pointer_width/2;
12069 points[2].y = yc - c*dial->pointer_width/2;
12071 gtk_draw_polygon (widget->style,
12084 <!-- ----------------------------------------------------------------- -->
12086 <title>Event handling</title>
12088 <para>The rest of the widget's code handles various types of events, and
12089 isn't too different from what would be found in many GTK
12090 applications. Two types of events can occur - either the user can
12091 click on the widget with the mouse and drag to move the pointer, or
12092 the value of the Adjustment object can change due to some external
12093 circumstance.</para>
12095 <para>When the user clicks on the widget, we check to see if the click was
12096 appropriately near the pointer, and if so, store the button that the
12097 user clicked with in the <literal>button</literal> field of the widget
12098 structure, and grab all mouse events with a call to
12099 <literal>gtk_grab_add()</literal>. Subsequent motion of the mouse causes the
12100 value of the control to be recomputed (by the function
12101 <literal>gtk_dial_update_mouse</literal>). Depending on the policy that has been
12102 set, "value_changed" events are either generated instantly
12103 (<literal>GTK_UPDATE_CONTINUOUS</literal>), after a delay in a timer added with
12104 <literal>g_timeout_add()</literal> (<literal>GTK_UPDATE_DELAYED</literal>), or only when the
12105 button is released (<literal>GTK_UPDATE_DISCONTINUOUS</literal>).</para>
12107 <programlisting role="C">
12109 gtk_dial_button_press( GtkWidget *widget,
12110 GdkEventButton *event )
12116 double d_perpendicular;
12118 g_return_val_if_fail (widget != NULL, FALSE);
12119 g_return_val_if_fail (GTK_IS_DIAL (widget), FALSE);
12120 g_return_val_if_fail (event != NULL, FALSE);
12122 dial = GTK_DIAL (widget);
12124 /* Determine if button press was within pointer region - we
12125 do this by computing the parallel and perpendicular distance of
12126 the point where the mouse was pressed from the line passing through
12129 dx = event->x - widget->allocation.width / 2;
12130 dy = widget->allocation.height / 2 - event->y;
12132 s = sin(dial->angle);
12133 c = cos(dial->angle);
12135 d_parallel = s*dy + c*dx;
12136 d_perpendicular = fabs(s*dx - c*dy);
12138 if (!dial->button &&
12139 (d_perpendicular < dial->pointer_width/2) &&
12140 (d_parallel > - dial->pointer_width))
12142 gtk_grab_add (widget);
12144 dial->button = event->button;
12146 gtk_dial_update_mouse (dial, event->x, event->y);
12153 gtk_dial_button_release( GtkWidget *widget,
12154 GdkEventButton *event )
12158 g_return_val_if_fail (widget != NULL, FALSE);
12159 g_return_val_if_fail (GTK_IS_DIAL (widget), FALSE);
12160 g_return_val_if_fail (event != NULL, FALSE);
12162 dial = GTK_DIAL (widget);
12164 if (dial->button == event->button)
12166 gtk_grab_remove (widget);
12170 if (dial->policy == GTK_UPDATE_DELAYED)
12171 g_source_remove (dial->timer);
12173 if ((dial->policy != GTK_UPDATE_CONTINUOUS) &&
12174 (dial->old_value != dial->adjustment->value))
12175 gtk_signal_emit_by_name (GTK_OBJECT (dial->adjustment), "value_changed");
12182 gtk_dial_motion_notify( GtkWidget *widget,
12183 GdkEventMotion *event )
12186 GdkModifierType mods;
12189 g_return_val_if_fail (widget != NULL, FALSE);
12190 g_return_val_if_fail (GTK_IS_DIAL (widget), FALSE);
12191 g_return_val_if_fail (event != NULL, FALSE);
12193 dial = GTK_DIAL (widget);
12195 if (dial->button != 0)
12200 if (event->is_hint || (event->window != widget->window))
12201 gdk_window_get_pointer (widget->window, &x, &y, &mods);
12203 switch (dial->button)
12206 mask = GDK_BUTTON1_MASK;
12209 mask = GDK_BUTTON2_MASK;
12212 mask = GDK_BUTTON3_MASK;
12220 gtk_dial_update_mouse (dial, x,y);
12227 gtk_dial_timer( GtkDial *dial )
12229 g_return_val_if_fail (dial != NULL, FALSE);
12230 g_return_val_if_fail (GTK_IS_DIAL (dial), FALSE);
12232 if (dial->policy == GTK_UPDATE_DELAYED)
12233 gtk_signal_emit_by_name (GTK_OBJECT (dial->adjustment), "value_changed");
12239 gtk_dial_update_mouse (GtkDial *dial, gint x, gint y)
12244 g_return_if_fail (dial != NULL);
12245 g_return_if_fail (GTK_IS_DIAL (dial));
12247 xc = GTK_WIDGET(dial)->allocation.width / 2;
12248 yc = GTK_WIDGET(dial)->allocation.height / 2;
12250 old_value = dial->adjustment->value;
12251 dial->angle = atan2(yc-y, x-xc);
12253 if (dial->angle < -M_PI/2.)
12254 dial->angle += 2*M_PI;
12256 if (dial->angle < -M_PI/6)
12257 dial->angle = -M_PI/6;
12259 if (dial->angle > 7.*M_PI/6.)
12260 dial->angle = 7.*M_PI/6.;
12262 dial->adjustment->value = dial->adjustment->lower + (7.*M_PI/6 - dial->angle) *
12263 (dial->adjustment->upper - dial->adjustment->lower) / (4.*M_PI/3.);
12265 if (dial->adjustment->value != old_value)
12267 if (dial->policy == GTK_UPDATE_CONTINUOUS)
12269 gtk_signal_emit_by_name (GTK_OBJECT (dial->adjustment), "value_changed");
12273 gtk_widget_draw (GTK_WIDGET(dial), NULL);
12275 if (dial->policy == GTK_UPDATE_DELAYED)
12278 g_source_remove (dial->timer);
12280 dial->timer = g_timeout_add (SCROLL_DELAY_LENGTH,
12281 (GtkFunction) gtk_dial_timer,
12289 <para>Changes to the Adjustment by external means are communicated to our
12290 widget by the "changed" and "value_changed" signals. The handlers
12291 for these functions call <literal>gtk_dial_update()</literal> to validate the
12292 arguments, compute the new pointer angle, and redraw the widget (by
12293 calling <literal>gtk_widget_draw()</literal>).</para>
12295 <programlisting role="C">
12297 gtk_dial_update (GtkDial *dial)
12301 g_return_if_fail (dial != NULL);
12302 g_return_if_fail (GTK_IS_DIAL (dial));
12304 new_value = dial->adjustment->value;
12306 if (new_value < dial->adjustment->lower)
12307 new_value = dial->adjustment->lower;
12309 if (new_value > dial->adjustment->upper)
12310 new_value = dial->adjustment->upper;
12312 if (new_value != dial->adjustment->value)
12314 dial->adjustment->value = new_value;
12315 gtk_signal_emit_by_name (GTK_OBJECT (dial->adjustment), "value_changed");
12318 dial->angle = 7.*M_PI/6. - (new_value - dial->adjustment->lower) * 4.*M_PI/3. /
12319 (dial->adjustment->upper - dial->adjustment->lower);
12321 gtk_widget_draw (GTK_WIDGET(dial), NULL);
12325 gtk_dial_adjustment_changed (GtkAdjustment *adjustment,
12330 g_return_if_fail (adjustment != NULL);
12331 g_return_if_fail (data != NULL);
12333 dial = GTK_DIAL (data);
12335 if ((dial->old_value != adjustment->value) ||
12336 (dial->old_lower != adjustment->lower) ||
12337 (dial->old_upper != adjustment->upper))
12339 gtk_dial_update (dial);
12341 dial->old_value = adjustment->value;
12342 dial->old_lower = adjustment->lower;
12343 dial->old_upper = adjustment->upper;
12348 gtk_dial_adjustment_value_changed (GtkAdjustment *adjustment,
12353 g_return_if_fail (adjustment != NULL);
12354 g_return_if_fail (data != NULL);
12356 dial = GTK_DIAL (data);
12358 if (dial->old_value != adjustment->value)
12360 gtk_dial_update (dial);
12362 dial->old_value = adjustment->value;
12369 <!-- ----------------------------------------------------------------- -->
12371 <title>Possible Enhancements</title>
12373 <para>The Dial widget as we've described it so far runs about 670 lines of
12374 code. Although that might sound like a fair bit, we've really
12375 accomplished quite a bit with that much code, especially since much of
12376 that length is headers and boilerplate. However, there are quite a few
12377 more enhancements that could be made to this widget:</para>
12380 <listitem><simpara> If you try this widget out, you'll find that there is some
12381 flashing as the pointer is dragged around. This is because the entire
12382 widget is erased every time the pointer is moved before being
12383 redrawn. Often, the best way to handle this problem is to draw to an
12384 offscreen pixmap, then copy the final results onto the screen in one
12385 step. (The ProgressBar widget draws itself in this fashion.)</simpara>
12388 <listitem><simpara> The user should be able to use the up and down arrow keys to
12389 increase and decrease the value.</simpara>
12392 <listitem><simpara> It would be nice if the widget had buttons to increase and
12393 decrease the value in small or large steps. Although it would be
12394 possible to use embedded Button widgets for this, we would also like
12395 the buttons to auto-repeat when held down, as the arrows on a
12396 scrollbar do. Most of the code to implement this type of behavior can
12397 be found in the Range widget.</simpara>
12400 <listitem><simpara> The Dial widget could be made into a container widget with a
12401 single child widget positioned at the bottom between the buttons
12402 mentioned above. The user could then add their choice of a label or
12403 entry widget to display the current value of the dial.</simpara>
12410 <!-- ----------------------------------------------------------------- -->
12411 <sect1 id="sec-LearningMore">
12412 <title>Learning More</title>
12414 <para>Only a small part of the many details involved in creating widgets
12415 could be described above. If you want to write your own widgets, the
12416 best source of examples is the GTK source itself. Ask yourself some
12417 questions about the widget you want to write: IS it a Container
12418 widget? Does it have its own window? Is it a modification of an
12419 existing widget? Then find a similar widget, and start making changes.
12425 <!-- ***************************************************************** -->
12426 <chapter id="ch-Scribble">
12427 <title>Scribble, A Simple Example Drawing Program</title>
12429 <!-- ----------------------------------------------------------------- -->
12430 <sect1 id="sec-ScribbleOverview">
12431 <title>Overview</title>
12433 <para>In this section, we will build a simple drawing program. In the
12434 process, we will examine how to handle mouse events, how to draw in a
12435 window, and how to do drawing better by using a backing pixmap. After
12436 creating the simple drawing program, we will extend it by adding
12437 support for XInput devices, such as drawing tablets. GTK provides
12438 support routines which makes getting extended information, such as
12439 pressure and tilt, from such devices quite easy.</para>
12442 <inlinemediaobject>
12444 <imagedata fileref="images/scribble.png" format="png">
12446 </inlinemediaobject>
12451 <!-- ----------------------------------------------------------------- -->
12452 <sect1 id="sec-EventHandling">
12453 <title>Event Handling</title>
12455 <para>The GTK signals we have already discussed are for high-level actions,
12456 such as a menu item being selected. However, sometimes it is useful to
12457 learn about lower-level occurrences, such as the mouse being moved, or
12458 a key being pressed. There are also GTK signals corresponding to these
12459 low-level <emphasis>events</emphasis>. The handlers for these signals have an
12460 extra parameter which is a pointer to a structure containing
12461 information about the event. For instance, motion event handlers are
12462 passed a pointer to a GdkEventMotion structure which looks (in part)
12465 <programlisting role="C">
12466 struct _GdkEventMotion
12479 <para><literal>type</literal> will be set to the event type, in this case
12480 <literal>GDK_MOTION_NOTIFY</literal>, window is the window in which the event
12481 occurred. <literal>x</literal> and <literal>y</literal> give the coordinates of the event.
12482 <literal>state</literal> specifies the modifier state when the event
12483 occurred (that is, it specifies which modifier keys and mouse buttons
12484 were pressed). It is the bitwise OR of some of the following:</para>
12486 <programlisting role="C">
12502 <para>As for other signals, to determine what happens when an event occurs
12503 we call <literal>gtk_signal_connect()</literal>. But we also need let GTK
12504 know which events we want to be notified about. To do this, we call
12505 the function:</para>
12507 <programlisting role="C">
12508 void gtk_widget_set_events (GtkWidget *widget,
12512 <para>The second field specifies the events we are interested in. It
12513 is the bitwise OR of constants that specify different types
12514 of events. For future reference the event types are:</para>
12516 <programlisting role="C">
12518 GDK_POINTER_MOTION_MASK
12519 GDK_POINTER_MOTION_HINT_MASK
12520 GDK_BUTTON_MOTION_MASK
12521 GDK_BUTTON1_MOTION_MASK
12522 GDK_BUTTON2_MOTION_MASK
12523 GDK_BUTTON3_MOTION_MASK
12524 GDK_BUTTON_PRESS_MASK
12525 GDK_BUTTON_RELEASE_MASK
12527 GDK_KEY_RELEASE_MASK
12528 GDK_ENTER_NOTIFY_MASK
12529 GDK_LEAVE_NOTIFY_MASK
12530 GDK_FOCUS_CHANGE_MASK
12532 GDK_PROPERTY_CHANGE_MASK
12533 GDK_PROXIMITY_IN_MASK
12534 GDK_PROXIMITY_OUT_MASK
12537 <para>There are a few subtle points that have to be observed when calling
12538 <literal>gtk_widget_set_events()</literal>. First, it must be called before the X window
12539 for a GTK widget is created. In practical terms, this means you
12540 should call it immediately after creating the widget. Second, the
12541 widget must have an associated X window. For efficiency, many widget
12542 types do not have their own window, but draw in their parent's window.
12543 These widgets are:</para>
12545 <programlisting role="C">
12565 <para>To capture events for these widgets, you need to use an EventBox
12566 widget. See the section on the <link linkend="sec-EventBox">EventBox</link> widget for details.</para>
12568 <para>For our drawing program, we want to know when the mouse button is
12569 pressed and when the mouse is moved, so we specify
12570 <literal>GDK_POINTER_MOTION_MASK</literal> and <literal>GDK_BUTTON_PRESS_MASK</literal>. We also
12571 want to know when we need to redraw our window, so we specify
12572 <literal>GDK_EXPOSURE_MASK</literal>. Although we want to be notified via a
12573 Configure event when our window size changes, we don't have to specify
12574 the corresponding <literal>GDK_STRUCTURE_MASK</literal> flag, because it is
12575 automatically specified for all windows.</para>
12577 <para>It turns out, however, that there is a problem with just specifying
12578 <literal>GDK_POINTER_MOTION_MASK</literal>. This will cause the server to add a new
12579 motion event to the event queue every time the user moves the mouse.
12580 Imagine that it takes us 0.1 seconds to handle a motion event, but the
12581 X server queues a new motion event every 0.05 seconds. We will soon
12582 get way behind the users drawing. If the user draws for 5 seconds,
12583 it will take us another 5 seconds to catch up after they release
12584 the mouse button! What we would like is to only get one motion
12585 event for each event we process. The way to do this is to
12586 specify <literal>GDK_POINTER_MOTION_HINT_MASK</literal>. </para>
12588 <para>When we specify <literal>GDK_POINTER_MOTION_HINT_MASK</literal>, the server sends
12589 us a motion event the first time the pointer moves after entering
12590 our window, or after a button press or release event. Subsequent
12591 motion events will be suppressed until we explicitly ask for
12592 the position of the pointer using the function:</para>
12594 <programlisting role="C">
12595 GdkWindow* gdk_window_get_pointer (GdkWindow *window,
12598 GdkModifierType *mask);
12601 <para>(There is another function, <literal>gtk_widget_get_pointer()</literal> which
12602 has a simpler interface, but turns out not to be very useful, since
12603 it only retrieves the position of the mouse, not whether the buttons
12604 are pressed.)</para>
12606 <para>The code to set the events for our window then looks like:</para>
12608 <programlisting role="C">
12609 gtk_signal_connect (GTK_OBJECT (drawing_area), "expose_event",
12610 (GtkSignalFunc) expose_event, NULL);
12611 gtk_signal_connect (GTK_OBJECT(drawing_area),"configure_event",
12612 (GtkSignalFunc) configure_event, NULL);
12613 gtk_signal_connect (GTK_OBJECT (drawing_area), "motion_notify_event",
12614 (GtkSignalFunc) motion_notify_event, NULL);
12615 gtk_signal_connect (GTK_OBJECT (drawing_area), "button_press_event",
12616 (GtkSignalFunc) button_press_event, NULL);
12618 gtk_widget_set_events (drawing_area, GDK_EXPOSURE_MASK
12619 | GDK_LEAVE_NOTIFY_MASK
12620 | GDK_BUTTON_PRESS_MASK
12621 | GDK_POINTER_MOTION_MASK
12622 | GDK_POINTER_MOTION_HINT_MASK);
12625 <para>We'll save the "expose_event" and "configure_event" handlers for
12626 later. The "motion_notify_event" and "button_press_event" handlers
12627 are pretty simple:</para>
12629 <programlisting role="C">
12631 button_press_event( GtkWidget *widget, GdkEventButton *event )
12633 if (event->button == 1 && pixmap != NULL)
12634 draw_brush (widget, event->x, event->y);
12640 motion_notify_event( GtkWidget *widget, GdkEventMotion *event )
12643 GdkModifierType state;
12645 if (event->is_hint)
12646 gdk_window_get_pointer (event->window, &x, &y, &state);
12651 state = event->state;
12654 if (state & GDK_BUTTON1_MASK && pixmap != NULL)
12655 draw_brush (widget, x, y);
12663 <!-- ----------------------------------------------------------------- -->
12664 <sect1 id="sec-TheDrawingAreaWidget">
12665 <title>The DrawingArea Widget, And Drawing</title>
12667 <para>We now turn to the process of drawing on the screen. The
12668 widget we use for this is the DrawingArea widget. A drawing area
12669 widget is essentially an X window and nothing more. It is a blank
12670 canvas in which we can draw whatever we like. A drawing area
12671 is created using the call:</para>
12673 <programlisting role="C">
12674 GtkWidget* gtk_drawing_area_new (void);
12677 <para>A default size for the widget can be specified by calling:</para>
12679 <programlisting role="C">
12680 void gtk_drawing_area_size (GtkDrawingArea *darea,
12685 <para>This default size can be overridden, as is true for all widgets,
12686 by calling <literal>gtk_widget_set_size_request()</literal>, and that, in turn, can
12687 be overridden if the user manually resizes the the window containing
12688 the drawing area.</para>
12690 <para>It should be noted that when we create a DrawingArea widget, we are
12691 <emphasis>completely</emphasis> responsible for drawing the contents. If our
12692 window is obscured then uncovered, we get an exposure event and must
12693 redraw what was previously hidden.</para>
12695 <para>Having to remember everything that was drawn on the screen so we
12696 can properly redraw it can, to say the least, be a nuisance. In
12697 addition, it can be visually distracting if portions of the
12698 window are cleared, then redrawn step by step. The solution to
12699 this problem is to use an offscreen <emphasis>backing pixmap</emphasis>.
12700 Instead of drawing directly to the screen, we draw to an image
12701 stored in server memory but not displayed, then when the image
12702 changes or new portions of the image are displayed, we copy the
12703 relevant portions onto the screen.</para>
12705 <para>To create an offscreen pixmap, we call the function:</para>
12707 <programlisting role="C">
12708 GdkPixmap* gdk_pixmap_new (GdkWindow *window,
12714 <para>The <literal>window</literal> parameter specifies a GDK window that this pixmap
12715 takes some of its properties from. <literal>width</literal> and <literal>height</literal>
12716 specify the size of the pixmap. <literal>depth</literal> specifies the <emphasis>color
12717 depth</emphasis>, that is the number of bits per pixel, for the new window.
12718 If the depth is specified as <literal>-1</literal>, it will match the depth
12719 of <literal>window</literal>.</para>
12721 <para>We create the pixmap in our "configure_event" handler. This event
12722 is generated whenever the window changes size, including when it
12723 is originally created.</para>
12725 <programlisting role="C">
12726 /* Backing pixmap for drawing area */
12727 static GdkPixmap *pixmap = NULL;
12729 /* Create a new backing pixmap of the appropriate size */
12731 configure_event( GtkWidget *widget, GdkEventConfigure *event )
12734 g_object_unref(pixmap);
12736 pixmap = gdk_pixmap_new(widget->window,
12737 widget->allocation.width,
12738 widget->allocation.height,
12740 gdk_draw_rectangle (pixmap,
12741 widget->style->white_gc,
12744 widget->allocation.width,
12745 widget->allocation.height);
12751 <para>The call to <literal>gdk_draw_rectangle()</literal> clears the pixmap
12752 initially to white. We'll say more about that in a moment.</para>
12754 <para>Our exposure event handler then simply copies the relevant portion
12755 of the pixmap onto the screen (we determine the area we need
12756 to redraw by using the event->area field of the exposure event):</para>
12758 <programlisting role="C">
12759 /* Redraw the screen from the backing pixmap */
12761 expose_event( GtkWidget *widget, GdkEventExpose *event )
12763 gdk_draw_drawable(widget->window,
12764 widget->style->fg_gc[gtk_widget_get_state (widget)],
12766 event->area.x, event->area.y,
12767 event->area.x, event->area.y,
12768 event->area.width, event->area.height);
12774 <para>We've now seen how to keep the screen up to date with our pixmap, but
12775 how do we actually draw interesting stuff on our pixmap? There are a
12776 large number of calls in GTK's GDK library for drawing on
12777 <emphasis>drawables</emphasis>. A drawable is simply something that can be drawn
12778 upon. It can be a window, a pixmap, or a bitmap (a black and white
12779 image). We've already seen two such calls above,
12780 <literal>gdk_draw_rectangle()</literal> and <literal>gdk_draw_drawable()</literal>. The
12781 complete list is:</para>
12783 <programlisting role="C">
12786 gdk_draw_rectangle ()
12788 gdk_draw_polygon ()
12791 gdk_draw_segments ()
12795 gdk_draw_layout_line ()
12797 gdk_draw_layout_line_with_colors ()
12798 gdk_draw_layout_with_colors ()
12799 gdk_draw_glyphs_transformed ()
12800 gdk_draw_glyphs_trapezoids ()
12803 <para>See the reference documentation or the header file
12804 <literal><gdk/gdkdrawable.h></literal> for further details on these functions.
12805 These functions all share the same first two arguments. The first
12806 argument is the drawable to draw upon, the second argument is a
12807 <emphasis>graphics context</emphasis> (GC).</para>
12809 <para>A graphics context encapsulates information about things such as
12810 foreground and background color and line width. GDK has a full set of
12811 functions for creating and modifying graphics contexts, but to keep
12812 things simple we'll just use predefined graphics contexts. Each widget
12813 has an associated style. (Which can be modified in a gtkrc file, see
12814 the section GTK's rc file.) This, among other things, stores a number
12815 of graphics contexts. Some examples of accessing these graphics
12816 contexts are:</para>
12818 <programlisting role="C">
12819 widget->style->white_gc
12820 widget->style->black_gc
12821 widget->style->fg_gc[GTK_STATE_NORMAL]
12822 widget->style->bg_gc[gtk_widget_get_state(widget)]
12825 <para>The fields <literal>fg_gc</literal>, <literal>bg_gc</literal>, <literal>dark_gc</literal>, and
12826 <literal>light_gc</literal> are indexed by a parameter of type
12827 <literal>GtkStateType</literal> which can take on the values:</para>
12829 <programlisting role="C">
12832 GTK_STATE_PRELIGHT,
12833 GTK_STATE_SELECTED,
12834 GTK_STATE_INSENSITIVE
12837 <para>For instance, for <literal>GTK_STATE_SELECTED</literal> the default foreground
12838 color is white and the default background color, dark blue.</para>
12840 <para>Our function <literal>draw_brush()</literal>, which does the actual drawing
12841 on the screen, is then:</para>
12843 <programlisting role="C">
12844 /* Draw a rectangle on the screen */
12846 draw_brush (GtkWidget *widget, gdouble x, gdouble y)
12848 GdkRectangle update_rect;
12850 update_rect.x = x - 5;
12851 update_rect.y = y - 5;
12852 update_rect.width = 10;
12853 update_rect.height = 10;
12854 gdk_draw_rectangle (pixmap,
12855 widget->style->black_gc,
12857 update_rect.x, update_rect.y,
12858 update_rect.width, update_rect.height);
12859 gtk_widget_queue_draw_area (widget,
12860 update_rect.x, update_rect.y,
12861 update_rect.width, update_rect.height);
12865 <para>After we draw the rectangle representing the brush onto the pixmap,
12866 we call the function:</para>
12868 <programlisting role="C">
12869 void gtk_widget_queue_draw_area (GtkWidget *widget,
12876 <para>which notifies X that the area given by the <literal>x</literal>,
12877 <literal>y</literal>, <literal>width</literal> and <literal>height</literal> parameters
12878 needs to be updated. X will eventually generate an expose event
12879 (possibly combining the areas passed in several calls to
12880 <literal>gtk_widget_queue_draw_area()</literal>) which will cause our expose event handler
12881 to copy the relevant portions to the screen.</para>
12883 <para>We have now covered the entire drawing program except for a few
12884 mundane details like creating the main window.</para>
12888 <!-- ----------------------------------------------------------------- -->
12889 <sect1 id="sec-AddingXInputSupport">
12890 <title>Adding XInput support</title>
12892 <para>It is now possible to buy quite inexpensive input devices such
12893 as drawing tablets, which allow drawing with a much greater
12894 ease of artistic expression than does a mouse. The simplest way
12895 to use such devices is simply as a replacement for the mouse,
12896 but that misses out many of the advantages of these devices,
12900 <listitem><simpara> Pressure sensitivity</simpara>
12902 <listitem><simpara> Tilt reporting</simpara>
12904 <listitem><simpara> Sub-pixel positioning</simpara>
12906 <listitem><simpara> Multiple inputs (for example, a stylus with a point and eraser)</simpara>
12910 <para>For information about the XInput extension, see the <ulink
12911 url="http://www.gtk.org/~otaylor/xinput/howto/index.html">XInput HOWTO</ulink>.</para>
12913 <para>If we examine the full definition of, for example, the GdkEventMotion
12914 structure, we see that it has fields to support extended device
12915 information.</para>
12917 <programlisting role="C">
12918 struct _GdkEventMotion
12930 GdkInputSource source;
12935 <para><literal>pressure</literal> gives the pressure as a floating point number between
12936 0 and 1. <literal>xtilt</literal> and <literal>ytilt</literal> can take on values between
12937 -1 and 1, corresponding to the degree of tilt in each direction.
12938 <literal>source</literal> and <literal>deviceid</literal> specify the device for which the
12939 event occurred in two different ways. <literal>source</literal> gives some simple
12940 information about the type of device. It can take the enumeration
12943 <programlisting role="C">
12950 <para><literal>deviceid</literal> specifies a unique numeric ID for the device. This can
12951 be used to find out further information about the device using the
12952 <literal>gdk_input_list_devices()</literal> call (see below). The special value
12953 <literal>GDK_CORE_POINTER</literal> is used for the core pointer device. (Usually
12956 <!-- ----------------------------------------------------------------- -->
12958 <title>Enabling extended device information</title>
12960 <para>To let GTK know about our interest in the extended device information,
12961 we merely have to add a single line to our program:</para>
12963 <programlisting role="C">
12964 gtk_widget_set_extension_events (drawing_area, GDK_EXTENSION_EVENTS_CURSOR);
12967 <para>By giving the value <literal>GDK_EXTENSION_EVENTS_CURSOR</literal> we say that
12968 we are interested in extension events, but only if we don't have
12969 to draw our own cursor. See the section <link
12970 linkend="sec-FurtherSophistications"> Further Sophistications </link> below
12971 for more information about drawing the cursor. We could also
12972 give the values <literal>GDK_EXTENSION_EVENTS_ALL</literal> if we were willing
12973 to draw our own cursor, or <literal>GDK_EXTENSION_EVENTS_NONE</literal> to revert
12974 back to the default condition.</para>
12976 <para>This is not completely the end of the story however. By default,
12977 no extension devices are enabled. We need a mechanism to allow
12978 users to enable and configure their extension devices. GTK provides
12979 the InputDialog widget to automate this process. The following
12980 procedure manages an InputDialog widget. It creates the dialog if
12981 it isn't present, and raises it to the top otherwise.</para>
12983 <programlisting role="C">
12985 input_dialog_destroy (GtkWidget *w, gpointer data)
12987 *((GtkWidget **)data) = NULL;
12991 create_input_dialog ()
12993 static GtkWidget *inputd = NULL;
12997 inputd = gtk_input_dialog_new();
12999 gtk_signal_connect (GTK_OBJECT(inputd), "destroy",
13000 (GtkSignalFunc)input_dialog_destroy, &inputd);
13001 gtk_signal_connect_object (GTK_OBJECT(GTK_INPUT_DIALOG(inputd)->close_button),
13003 (GtkSignalFunc)gtk_widget_hide,
13004 GTK_OBJECT(inputd));
13005 gtk_widget_hide ( GTK_INPUT_DIALOG(inputd)->save_button);
13007 gtk_widget_show (inputd);
13011 if (!gtk_widget_get_mapped(inputd))
13012 gtk_widget_show(inputd);
13014 gdk_window_raise(inputd->window);
13019 <para>(You might want to take note of the way we handle this dialog. By
13020 connecting to the "destroy" signal, we make sure that we don't keep a
13021 pointer to dialog around after it is destroyed - that could lead to a
13024 <para>The InputDialog has two buttons "Close" and "Save", which by default
13025 have no actions assigned to them. In the above function we make
13026 "Close" hide the dialog, hide the "Save" button, since we don't
13027 implement saving of XInput options in this program.</para>
13031 <!-- ----------------------------------------------------------------- -->
13033 <title>Using extended device information</title>
13035 <para>Once we've enabled the device, we can just use the extended
13036 device information in the extra fields of the event structures.
13037 In fact, it is always safe to use this information since these
13038 fields will have reasonable default values even when extended
13039 events are not enabled.</para>
13041 <para>Once change we do have to make is to call
13042 <literal>gdk_input_window_get_pointer()</literal> instead of
13043 <literal>gdk_window_get_pointer</literal>. This is necessary because
13044 <literal>gdk_window_get_pointer</literal> doesn't return the extended device
13045 information.</para>
13047 <programlisting role="C">
13048 void gdk_input_window_get_pointer( GdkWindow *window,
13055 GdkModifierType *mask);
13058 <para>When calling this function, we need to specify the device ID as
13059 well as the window. Usually, we'll get the device ID from the
13060 <literal>deviceid</literal> field of an event structure. Again, this function
13061 will return reasonable values when extension events are not
13062 enabled. (In this case, <literal>event->deviceid</literal> will have the value
13063 <literal>GDK_CORE_POINTER</literal>).</para>
13065 <para>So the basic structure of our button-press and motion event handlers
13066 doesn't change much - we just need to add code to deal with the
13067 extended information.</para>
13069 <programlisting role="C">
13071 button_press_event( GtkWidget *widget, GdkEventButton *event )
13073 print_button_press (event->deviceid);
13075 if (event->button == 1 && pixmap != NULL)
13076 draw_brush (widget, event->source, event->x, event->y, event->pressure);
13082 motion_notify_event( GtkWidget *widget, GdkEventMotion *event )
13086 GdkModifierType state;
13088 if (event->is_hint)
13089 gdk_input_window_get_pointer (event->window, event->deviceid,
13090 &x, &y, &pressure, NULL, NULL, &state);
13095 pressure = event->pressure;
13096 state = event->state;
13099 if (state & GDK_BUTTON1_MASK && pixmap != NULL)
13100 draw_brush (widget, event->source, x, y, pressure);
13106 <para>We also need to do something with the new information. Our new
13107 <literal>draw_brush()</literal> function draws with a different color for
13108 each <literal>event->source</literal> and changes the brush size depending
13109 on the pressure.</para>
13111 <programlisting role="C">
13112 /* Draw a rectangle on the screen, size depending on pressure,
13113 and color on the type of device */
13115 draw_brush (GtkWidget *widget, GdkInputSource source,
13116 gdouble x, gdouble y, gdouble pressure)
13119 GdkRectangle update_rect;
13123 case GDK_SOURCE_MOUSE:
13124 gc = widget->style->dark_gc[gtk_widget_get_state (widget)];
13126 case GDK_SOURCE_PEN:
13127 gc = widget->style->black_gc;
13129 case GDK_SOURCE_ERASER:
13130 gc = widget->style->white_gc;
13133 gc = widget->style->light_gc[gtk_widget_get_state (widget)];
13136 update_rect.x = x - 10 * pressure;
13137 update_rect.y = y - 10 * pressure;
13138 update_rect.width = 20 * pressure;
13139 update_rect.height = 20 * pressure;
13140 gdk_draw_rectangle (pixmap, gc, TRUE,
13141 update_rect.x, update_rect.y,
13142 update_rect.width, update_rect.height);
13143 gtk_widget_draw (widget, &update_rect);
13149 <!-- ----------------------------------------------------------------- -->
13151 <title>Finding out more about a device</title>
13153 <para>As an example of how to find out more about a device, our program
13154 will print the name of the device that generates each button
13155 press. To find out the name of a device, we call the function:</para>
13157 <programlisting role="C">
13158 GList *gdk_input_list_devices (void);
13161 <para>which returns a GList (a linked list type from the GLib library)
13162 of GdkDeviceInfo structures. The GdkDeviceInfo structure is defined
13165 <programlisting role="C">
13166 struct _GdkDeviceInfo
13170 GdkInputSource source;
13176 GdkDeviceKey *keys;
13180 <para>Most of these fields are configuration information that you can ignore
13181 unless you are implementing XInput configuration saving. The fieldwe
13182 are interested in here is <literal>name</literal> which is simply the name that X
13183 assigns to the device. The other field that isn't configuration
13184 information is <literal>has_cursor</literal>. If <literal>has_cursor</literal> is false, then we
13185 we need to draw our own cursor. But since we've specified
13186 <literal>GDK_EXTENSION_EVENTS_CURSOR</literal>, we don't have to worry about this.</para>
13188 <para>Our <literal>print_button_press()</literal> function simply iterates through
13189 the returned list until it finds a match, then prints out
13190 the name of the device.</para>
13192 <programlisting role="C">
13194 print_button_press (guint32 deviceid)
13198 /* gdk_input_list_devices returns an internal list, so we shouldn't
13199 free it afterwards */
13200 tmp_list = gdk_input_list_devices();
13204 GdkDeviceInfo *info = (GdkDeviceInfo *)tmp_list->data;
13206 if (info->deviceid == deviceid)
13208 printf("Button press on device '%s'\n", info->name);
13212 tmp_list = tmp_list->next;
13217 <para>That completes the changes to "XInputize" our program.</para>
13221 <!-- ----------------------------------------------------------------- -->
13222 <sect2 id="sec-FurtherSophistications">
13223 <title>Further sophistications</title>
13225 <para>Although our program now supports XInput quite well, it lacks some
13226 features we would want in a full-featured application. First, the user
13227 probably doesn't want to have to configure their device each time they
13228 run the program, so we should allow them to save the device
13229 configuration. This is done by iterating through the return of
13230 <literal>gdk_input_list_devices()</literal> and writing out the configuration to a
13233 <para>To restore the state next time the program is run, GDK provides
13234 functions to change device configuration:</para>
13236 <programlisting role="C">
13237 gdk_input_set_extension_events()
13238 gdk_input_set_source()
13239 gdk_input_set_mode()
13240 gdk_input_set_axes()
13241 gdk_input_set_key()
13244 <para>(The list returned from <literal>gdk_input_list_devices()</literal> should not be
13245 modified directly.) An example of doing this can be found in the
13246 drawing program gsumi. (Available from <ulink
13247 url="http://www.msc.cornell.edu/~otaylor/gsumi/">http://www.msc.cornell.edu/~otaylor/gsumi/</ulink>) Eventually, it
13248 would be nice to have a standard way of doing this for all
13249 applications. This probably belongs at a slightly higher level than
13250 GTK, perhaps in the GNOME library.</para>
13252 <para>Another major omission that we have mentioned above is the lack of
13253 cursor drawing. Platforms other than XFree86 currently do not allow
13254 simultaneously using a device as both the core pointer and directly by
13255 an application. See the <ulink
13256 url="http://www.msc.cornell.edu/~otaylor/xinput/XInput-HOWTO.html">XInput-HOWTO</ulink> for more information about this. This means that
13257 applications that want to support the widest audience need to draw
13258 their own cursor.</para>
13260 <para>An application that draws its own cursor needs to do two things:
13261 determine if the current device needs a cursor drawn or not, and
13262 determine if the current device is in proximity. (If the current
13263 device is a drawing tablet, it's a nice touch to make the cursor
13264 disappear when the stylus is lifted from the tablet. When the
13265 device is touching the stylus, that is called "in proximity.")
13266 The first is done by searching the device list, as we did
13267 to find out the device name. The second is achieved by selecting
13268 "proximity_out" events. An example of drawing one's own cursor is
13269 found in the "testinput" program found in the GTK distribution.</para>
13276 <!-- ***************************************************************** -->
13277 <chapter id="ch-Tips">
13278 <title>Tips For Writing GTK Applications</title>
13280 <para>This section is simply a gathering of wisdom, general style guidelines
13281 and hints to creating good GTK applications. Currently this section
13282 is very short, but I hope it will get longer in future editions of
13283 this tutorial.</para>
13285 <para>Use GNU autoconf and automake! They are your friends :) Automake
13286 examines C files, determines how they depend on each other, and
13287 generates a Makefile so the files can be compiled in the correct
13288 order. Autoconf permits automatic configuration of software
13289 installation, handling a large number of system quirks to increase
13290 portability. I am planning to make a quick intro on them here.</para>
13292 <para>When writing C code, use only C comments (beginning with "/*" and
13293 ending with "*/"), and don't use C++-style comments ("//"). Although
13294 many C compilers understand C++ comments, others don't, and the ANSI C
13295 standard does not require that C++-style comments be processed as
13300 <!-- ***************************************************************** -->
13301 <chapter id="ch-Contributing">
13302 <title>Contributing</title>
13304 <para>This document, like so much other great software out there, was
13305 created for free by volunteers. If you are at all knowledgeable about
13306 any aspect of GTK that does not already have documentation, please
13307 consider contributing to this document.</para>
13309 <para>If you do decide to contribute, please mail your text to Tony Gale,
13310 <literal><ulink url="mailto:gale@gtk.org">gale@gtk.org</ulink></literal>. Also, be aware that the entirety of this
13311 document is free, and any addition by you provide must also be
13312 free. That is, people may use any portion of your examples in their
13313 programs, and copies of this document may be distributed at will, etc.</para>
13315 <para>Thank you.</para>
13319 <!-- ***************************************************************** -->
13320 <chapter id="ch-Credits">
13321 <title>Credits</title>
13323 <para>We would like to thank the following for their contributions to this text.</para>
13326 <listitem><simpara>Bawer Dagdeviren, <literal><ulink url="mailto:chamele0n@geocities.com">chamele0n@geocities.com</ulink></literal> for the menus tutorial.</simpara>
13329 <listitem><simpara>Raph Levien, <literal><ulink url="mailto:raph@acm.org">raph@acm.org</ulink></literal>
13330 for hello world ala GTK, widget packing, and general all around wisdom.
13331 He's also generously donated a home for this tutorial.</simpara>
13334 <listitem><simpara>Peter Mattis, <literal><ulink url="mailto:petm@xcf.berkeley.edu">petm@xcf.berkeley.edu</ulink></literal> for the simplest GTK program..
13335 and the ability to make it :)</simpara>
13338 <listitem><simpara>Werner Koch <literal><ulink url="mailto:werner.koch@guug.de">werner.koch@guug.de</ulink></literal> for converting the original plain text to
13339 SGML, and the widget class hierarchy.</simpara>
13342 <listitem><simpara>Mark Crichton <literal><ulink
13343 url="mailto:crichton@expert.cc.purdue.edu">crichton@expert.cc.purdue.edu</ulink></literal> for the menu factory code,
13344 and the table packing tutorial.</simpara>
13347 <listitem><simpara>Owen Taylor <literal><ulink url="mailto:owt1@cornell.edu">owt1@cornell.edu</ulink></literal> for the EventBox widget section (and the
13348 patch to the distro). He's also responsible for the selections code
13349 and tutorial, as well as the sections on writing your own GTK widgets,
13350 and the example application. Thanks a lot Owen for all you help!</simpara>
13353 <listitem><simpara>Mark VanderBoom <literal><ulink url="mailto:mvboom42@calvin.edu">mvboom42@calvin.edu</ulink></literal> for his wonderful work on the
13354 Notebook, Progress Bar, Dialogs, and File selection widgets. Thanks a
13355 lot Mark! You've been a great help.</simpara>
13358 <listitem><simpara>Tim Janik <literal><ulink url="mailto:timj@gtk.org">timj@gtk.org</ulink></literal> for his great job on the Lists
13359 Widget. His excellent work on automatically extracting the widget tree
13360 and signal information from GTK. Thanks Tim :)</simpara>
13363 <listitem><simpara>Rajat Datta <literal><ulink url="mailto:rajat@ix.netcom.com">rajat@ix.netcom.com</ulink>
13364 </literal> for the excellent job on the Pixmap
13365 tutorial.</simpara>
13368 <listitem><simpara>Michael K. Johnson <literal><ulink url="mailto:johnsonm@redhat.com">johnsonm@redhat.com</ulink></literal> for info and code for popup menus.</simpara>
13371 <listitem><simpara>David Huggins-Daines <literal><ulink
13372 url="mailto:bn711@freenet.carleton.ca">bn711@freenet.carleton.ca</ulink></literal> for the Range Widgets and Tree
13373 Widget sections.</simpara>
13376 <listitem><simpara>Stefan Mars <literal><ulink url="mailto:mars@lysator.liu.se">mars@lysator.liu.se</ulink></literal> for the CList section.</simpara>
13379 <listitem><simpara>David A. Wheeler <literal><ulink url="mailto:dwheeler@ida.org">dwheeler@ida.org</ulink></literal> for portions of the text on GLib
13380 and various tutorial fixups and improvements.
13381 The GLib text was in turn based on material developed by Damon Chaplin
13382 <literal><ulink url="mailto:DAChaplin@msn.com">DAChaplin@msn.com</ulink></literal></simpara>
13385 <listitem><simpara>David King for style checking the entire document.</simpara>
13389 <para>And to all of you who commented on and helped refine this document.</para>
13391 <para>Thanks.</para>
13395 <!-- ***************************************************************** -->
13396 <chapter id="ch-Copyright">
13397 <title>Tutorial Copyright and Permissions Notice</title>
13399 <para>The GTK Tutorial is Copyright (C) 1997 Ian Main. </para>
13401 <para>Copyright (C) 1998-2002 Tony Gale.</para>
13403 <para>Permission is granted to make and distribute verbatim copies of this
13404 manual provided the copyright notice and this permission notice are
13405 preserved on all copies.</para>
13407 <para>Permission is granted to copy and distribute modified versions of
13408 this document under the conditions for verbatim copying, provided that
13409 this copyright notice is included exactly as in the original,
13410 and that the entire resulting derived work is distributed under
13411 the terms of a permission notice identical to this one.</para>
13413 <para>Permission is granted to copy and distribute translations of this
13414 document into another language, under the above conditions for modified
13417 <para>If you are intending to incorporate this document into a published
13418 work, please contact the maintainer, and we will make an effort
13419 to ensure that you have the most up to date information available.</para>
13421 <para>There is no guarantee that this document lives up to its intended
13422 purpose. This is simply provided as a free resource. As such,
13423 the authors and maintainers of the information provided within can
13424 not make any guarantee that the information is even accurate.</para>
13428 <!-- ***************************************************************** -->
13429 <!-- ***************************************************************** -->
13431 <!-- ***************************************************************** -->
13432 <appendix id="app-GTKSignals">
13433 <title>GTK Signals</title>
13435 <para>As GTK is an object oriented widget set, it has a hierarchy of
13436 inheritance. This inheritance mechanism applies for
13437 signals. Therefore, you should refer to the widget hierarchy tree when
13438 using the signals listed in this section.</para>
13440 <!-- ----------------------------------------------------------------- -->
13441 <sect1 id="sec-GtkObject">
13442 <title>GtkObject</title>
13444 <programlisting role="C">
13445 void GtkObject::destroy (GtkObject *,
13451 <!-- ----------------------------------------------------------------- -->
13452 <sect1 id="sec-GtkWidget">
13453 <title>GtkWidget</title>
13455 <programlisting role="C">
13456 void GtkWidget::show (GtkWidget *,
13458 void GtkWidget::hide (GtkWidget *,
13460 void GtkWidget::map (GtkWidget *,
13462 void GtkWidget::unmap (GtkWidget *,
13464 void GtkWidget::realize (GtkWidget *,
13466 void GtkWidget::unrealize (GtkWidget *,
13468 void GtkWidget::draw (GtkWidget *,
13471 void GtkWidget::draw-focus (GtkWidget *,
13473 void GtkWidget::draw-default (GtkWidget *,
13475 void GtkWidget::size-request (GtkWidget *,
13478 void GtkWidget::size-allocate (GtkWidget *,
13481 void GtkWidget::state-changed (GtkWidget *,
13484 void GtkWidget::parent-set (GtkWidget *,
13487 void GtkWidget::style-set (GtkWidget *,
13490 void GtkWidget::add-accelerator (GtkWidget *,
13497 void GtkWidget::remove-accelerator (GtkWidget *,
13502 gboolean GtkWidget::event (GtkWidget *,
13505 gboolean GtkWidget::button-press-event (GtkWidget *,
13508 gboolean GtkWidget::button-release-event (GtkWidget *,
13511 gboolean GtkWidget::motion-notify-event (GtkWidget *,
13514 gboolean GtkWidget::delete-event (GtkWidget *,
13517 gboolean GtkWidget::destroy-event (GtkWidget *,
13520 gboolean GtkWidget::expose-event (GtkWidget *,
13523 gboolean GtkWidget::key-press-event (GtkWidget *,
13526 gboolean GtkWidget::key-release-event (GtkWidget *,
13529 gboolean GtkWidget::enter-notify-event (GtkWidget *,
13532 gboolean GtkWidget::leave-notify-event (GtkWidget *,
13535 gboolean GtkWidget::configure-event (GtkWidget *,
13538 gboolean GtkWidget::focus-in-event (GtkWidget *,
13541 gboolean GtkWidget::focus-out-event (GtkWidget *,
13544 gboolean GtkWidget::map-event (GtkWidget *,
13547 gboolean GtkWidget::unmap-event (GtkWidget *,
13550 gboolean GtkWidget::property-notify-event (GtkWidget *,
13553 gboolean GtkWidget::selection-clear-event (GtkWidget *,
13556 gboolean GtkWidget::selection-request-event (GtkWidget *,
13559 gboolean GtkWidget::selection-notify-event (GtkWidget *,
13562 void GtkWidget::selection-get (GtkWidget *,
13563 GtkSelectionData *,
13566 void GtkWidget::selection-received (GtkWidget *,
13567 GtkSelectionData *,
13570 gboolean GtkWidget::proximity-in-event (GtkWidget *,
13573 gboolean GtkWidget::proximity-out-event (GtkWidget *,
13576 void GtkWidget::drag-begin (GtkWidget *,
13579 void GtkWidget::drag-end (GtkWidget *,
13582 void GtkWidget::drag-data-delete (GtkWidget *,
13585 void GtkWidget::drag-leave (GtkWidget *,
13589 gboolean GtkWidget::drag-motion (GtkWidget *,
13595 gboolean GtkWidget::drag-drop (GtkWidget *,
13601 void GtkWidget::drag-data-get (GtkWidget *,
13603 GtkSelectionData *,
13607 void GtkWidget::drag-data-received (GtkWidget *,
13611 GtkSelectionData *,
13615 gboolean GtkWidget::client-event (GtkWidget *,
13618 gboolean GtkWidget::no-expose-event (GtkWidget *,
13621 gboolean GtkWidget::visibility-notify-event (GtkWidget *,
13624 void GtkWidget::debug-msg (GtkWidget *,
13631 <!-- ----------------------------------------------------------------- -->
13632 <sect1 id="sec-GtkData">
13633 <title>GtkData</title>
13635 <programlisting role="C">
13636 void GtkData::disconnect (GtkData *,
13642 <!-- ----------------------------------------------------------------- -->
13643 <sect1 id="sec-GtkContainer">
13644 <title>GtkContainer</title>
13646 <programlisting role="C">
13647 void GtkContainer::add (GtkContainer *,
13650 void GtkContainer::remove (GtkContainer *,
13653 void GtkContainer::check-resize (GtkContainer *,
13655 GtkDirectionType GtkContainer::focus (GtkContainer *,
13658 void GtkContainer::set-focus-child (GtkContainer *,
13665 <!-- ----------------------------------------------------------------- -->
13666 <sect1 id="sec-GtkCalendar">
13667 <title>GtkCalendar</title>
13669 <programlisting role="C">
13670 void GtkCalendar::month-changed (GtkCalendar *,
13672 void GtkCalendar::day-selected (GtkCalendar *,
13674 void GtkCalendar::day-selected-double-click (GtkCalendar *,
13676 void GtkCalendar::prev-month (GtkCalendar *,
13678 void GtkCalendar::next-month (GtkCalendar *,
13680 void GtkCalendar::prev-year (GtkCalendar *,
13682 void GtkCalendar::next-year (GtkCalendar *,
13688 <!-- ----------------------------------------------------------------- -->
13689 <sect1 id="sec-GtkEditable">
13690 <title>GtkEditable</title>
13692 <programlisting role="C">
13693 void GtkEditable::changed (GtkEditable *,
13695 void GtkEditable::insert-text (GtkEditable *,
13700 void GtkEditable::delete-text (GtkEditable *,
13704 void GtkEditable::activate (GtkEditable *,
13706 void GtkEditable::set-editable (GtkEditable *,
13709 void GtkEditable::move-cursor (GtkEditable *,
13713 void GtkEditable::move-word (GtkEditable *,
13716 void GtkEditable::move-page (GtkEditable *,
13720 void GtkEditable::move-to-row (GtkEditable *,
13723 void GtkEditable::move-to-column (GtkEditable *,
13726 void GtkEditable::kill-char (GtkEditable *,
13729 void GtkEditable::kill-word (GtkEditable *,
13732 void GtkEditable::kill-line (GtkEditable *,
13735 void GtkEditable::cut-clipboard (GtkEditable *,
13737 void GtkEditable::copy-clipboard (GtkEditable *,
13739 void GtkEditable::paste-clipboard (GtkEditable *,
13745 <!-- ----------------------------------------------------------------- -->
13746 <sect1 id="sec-GtkNotebook">
13747 <title>GtkNotebook</title>
13749 <programlisting role="C">
13750 void GtkNotebook::switch-page (GtkNotebook *,
13758 <!-- ----------------------------------------------------------------- -->
13759 <sect1 id="sec-GtkList">
13760 <title>GtkList</title>
13762 <programlisting role="C">
13763 void GtkList::selection-changed (GtkList *,
13765 void GtkList::select-child (GtkList *,
13768 void GtkList::unselect-child (GtkList *,
13775 <!-- ----------------------------------------------------------------- -->
13776 <sect1 id="sec-GtkMenuShell">
13777 <title>GtkMenuShell</title>
13779 <programlisting role="C">
13780 void GtkMenuShell::deactivate (GtkMenuShell *,
13782 void GtkMenuShell::selection-done (GtkMenuShell *,
13784 void GtkMenuShell::move-current (GtkMenuShell *,
13785 GtkMenuDirectionType,
13787 void GtkMenuShell::activate-current (GtkMenuShell *,
13790 void GtkMenuShell::cancel (GtkMenuShell *,
13796 <!-- ----------------------------------------------------------------- -->
13797 <sect1 id="sec-GtkToolbar">
13798 <title>GtkToolbar</title>
13800 <programlisting role="C">
13801 void GtkToolbar::orientation-changed (GtkToolbar *,
13804 void GtkToolbar::style-changed (GtkToolbar *,
13811 <!-- ----------------------------------------------------------------- -->
13812 <sect1 id="sec-GtkButton">
13813 <title>GtkButton</title>
13815 <programlisting role="C">
13816 void GtkButton::pressed (GtkButton *,
13818 void GtkButton::released (GtkButton *,
13820 void GtkButton::clicked (GtkButton *,
13822 void GtkButton::enter (GtkButton *,
13824 void GtkButton::leave (GtkButton *,
13830 <!-- ----------------------------------------------------------------- -->
13831 <sect1 id="sec-GtkItem">
13832 <title>GtkItem</title>
13834 <programlisting role="C">
13835 void GtkItem::select (GtkItem *,
13837 void GtkItem::deselect (GtkItem *,
13839 void GtkItem::toggle (GtkItem *,
13845 <!-- ----------------------------------------------------------------- -->
13846 <sect1 id="sec-GtkWindow">
13847 <title>GtkWindow</title>
13849 <programlisting role="C">
13850 void GtkWindow::set-focus (GtkWindow *,
13857 <!-- ----------------------------------------------------------------- -->
13858 <sect1 id="sec-GtkHandleBox">
13859 <title>GtkHandleBox</title>
13861 <programlisting role="C">
13862 void GtkHandleBox::child-attached (GtkHandleBox *,
13865 void GtkHandleBox::child-detached (GtkHandleBox *,
13872 <!-- ----------------------------------------------------------------- -->
13873 <sect1 id="sec-GtkToggleButton">
13874 <title>GtkToggleButton</title>
13876 <programlisting role="C">
13877 void GtkToggleButton::toggled (GtkToggleButton *,
13883 <!-- ----------------------------------------------------------------- -->
13884 <sect1 id="sec-GtkMenuItem">
13885 <title>GtkMenuItem</title>
13887 <programlisting role="C">
13888 void GtkMenuItem::activate (GtkMenuItem *,
13890 void GtkMenuItem::activate-item (GtkMenuItem *,
13896 <!-- ----------------------------------------------------------------- -->
13897 <sect1 id="sec-GtkCheckMenuItem">
13898 <title>GtkCheckMenuItem</title>
13900 <programlisting role="C">
13901 void GtkCheckMenuItem::toggled (GtkCheckMenuItem *,
13907 <!-- ----------------------------------------------------------------- -->
13908 <sect1 id="sec-GtkInputDialog">
13909 <title>GtkInputDialog</title>
13911 <programlisting role="C">
13912 void GtkInputDialog::enable-device (GtkInputDialog *,
13915 void GtkInputDialog::disable-device (GtkInputDialog *,
13922 <!-- ----------------------------------------------------------------- -->
13923 <sect1 id="sec-GtkColorSelection">
13924 <title>GtkColorSelection</title>
13926 <programlisting role="C">
13927 void GtkColorSelection::color-changed (GtkColorSelection *,
13933 <!-- ----------------------------------------------------------------- -->
13934 <sect1 id="sec-GtkStatusBar">
13935 <title>GtkStatusBar</title>
13937 <programlisting role="C">
13938 void GtkStatusbar::text-pushed (GtkStatusbar *,
13942 void GtkStatusbar::text-popped (GtkStatusbar *,
13950 <!-- ----------------------------------------------------------------- -->
13951 <sect1 id="sec-GtkAdjustment">
13952 <title>GtkAdjustment</title>
13954 <programlisting role="C">
13955 void GtkAdjustment::changed (GtkAdjustment *,
13957 void GtkAdjustment::value-changed (GtkAdjustment *,
13964 <!-- ***************************************************************** -->
13965 <appendix id="app-GDKEventTypes">
13966 <title>GDK Event Types</title>
13968 <para>The following data types are passed into event handlers by GTK+. For
13969 each data type listed, the signals that use this data type are listed.</para>
13972 <listitem><simpara> GdkEvent</simpara>
13974 <listitem><simpara>drag_end_event</simpara>
13979 <listitem><simpara> GdkEventType<</simpara>
13982 <listitem><simpara> GdkEventAny</simpara>
13984 <listitem><simpara>delete_event</simpara>
13986 <listitem><simpara>destroy_event</simpara>
13988 <listitem><simpara>map_event</simpara>
13990 <listitem><simpara>unmap_event</simpara>
13992 <listitem><simpara>no_expose_event</simpara>
13997 <listitem><simpara> GdkEventExpose</simpara>
13999 <listitem><simpara>expose_event</simpara>
14004 <listitem><simpara> GdkEventNoExpose</simpara>
14007 <listitem><simpara> GdkEventVisibility</simpara>
14010 <listitem><simpara> GdkEventMotion</simpara>
14012 <listitem><simpara>motion_notify_event</simpara>
14016 <listitem><simpara> GdkEventButton</simpara>
14018 <listitem><simpara>button_press_event</simpara>
14020 <listitem><simpara>button_release_event</simpara>
14025 <listitem><simpara> GdkEventKey</simpara>
14027 <listitem><simpara>key_press_event</simpara>
14029 <listitem><simpara>key_release_event</simpara>
14034 <listitem><simpara> GdkEventCrossing</simpara>
14036 <listitem><simpara>enter_notify_event</simpara>
14038 <listitem><simpara>leave_notify_event</simpara>
14043 <listitem><simpara> GdkEventFocus</simpara>
14045 <listitem><simpara>focus_in_event</simpara>
14047 <listitem><simpara>focus_out_event</simpara>
14052 <listitem><simpara> GdkEventConfigure</simpara>
14054 <listitem><simpara>configure_event</simpara>
14059 <listitem><simpara> GdkEventProperty</simpara>
14061 <listitem><simpara>property_notify_event</simpara>
14066 <listitem><simpara> GdkEventSelection</simpara>
14068 <listitem><simpara>selection_clear_event</simpara>
14070 <listitem><simpara>selection_request_event</simpara>
14072 <listitem><simpara>selection_notify_event</simpara>
14077 <listitem><simpara> GdkEventProximity</simpara>
14079 <listitem><simpara>proximity_in_event</simpara>
14081 <listitem><simpara>proximity_out_event</simpara>
14086 <listitem><simpara> GdkEventDragBegin</simpara>
14088 <listitem><simpara>drag_begin_event</simpara>
14093 <listitem><simpara> GdkEventDragRequest</simpara>
14095 <listitem><simpara>drag_request_event</simpara>
14100 <listitem><simpara> GdkEventDropEnter</simpara>
14102 <listitem><simpara>drop_enter_event</simpara>
14107 <listitem><simpara> GdkEventDropLeave</simpara>
14109 <listitem><simpara>drop_leave_event</simpara>
14114 <listitem><simpara> GdkEventDropDataAvailable</simpara>
14116 <listitem><simpara>drop_data_available_event</simpara>
14121 <listitem><simpara> GdkEventClient</simpara>
14123 <listitem><simpara>client_event</simpara>
14128 <listitem><simpara> GdkEventOther</simpara>
14130 <listitem><simpara>other_event</simpara>
14136 <para>The data type <literal>GdkEventType</literal> is a special data type that is used by
14137 all the other data types as an indicator of the data type being passed
14138 to the signal handler. As you will see below, each of the event data
14139 structures has a member of this type. It is defined as an enumeration
14140 type as follows:</para>
14142 <programlisting role="C">
14149 GDK_MOTION_NOTIFY = 3,
14150 GDK_BUTTON_PRESS = 4,
14151 GDK_2BUTTON_PRESS = 5,
14152 GDK_3BUTTON_PRESS = 6,
14153 GDK_BUTTON_RELEASE = 7,
14155 GDK_KEY_RELEASE = 9,
14156 GDK_ENTER_NOTIFY = 10,
14157 GDK_LEAVE_NOTIFY = 11,
14158 GDK_FOCUS_CHANGE = 12,
14159 GDK_CONFIGURE = 13,
14162 GDK_PROPERTY_NOTIFY = 16,
14163 GDK_SELECTION_CLEAR = 17,
14164 GDK_SELECTION_REQUEST = 18,
14165 GDK_SELECTION_NOTIFY = 19,
14166 GDK_PROXIMITY_IN = 20,
14167 GDK_PROXIMITY_OUT = 21,
14168 GDK_DRAG_BEGIN = 22,
14169 GDK_DRAG_REQUEST = 23,
14170 GDK_DROP_ENTER = 24,
14171 GDK_DROP_LEAVE = 25,
14172 GDK_DROP_DATA_AVAIL = 26,
14173 GDK_CLIENT_EVENT = 27,
14174 GDK_VISIBILITY_NOTIFY = 28,
14175 GDK_NO_EXPOSE = 29,
14176 GDK_OTHER_EVENT = 9999 /* Deprecated, use filters instead */
14180 <para>The other event type that is different from the others is
14181 <literal>GdkEvent</literal> itself. This is a union of all the other
14182 data types, which allows it to be cast to a specific
14183 event data type within a signal handler.</para>
14185 <!-- Just a big list for now, needs expanding upon - TRG -->
14186 <para>So, the event data types are defined as follows:</para>
14188 <programlisting role="C">
14189 struct _GdkEventAny
14196 struct _GdkEventExpose
14202 gint count; /* If non-zero, how many more events follow. */
14205 struct _GdkEventNoExpose
14210 /* XXX: does anyone need the X major_code or minor_code fields? */
14213 struct _GdkEventVisibility
14218 GdkVisibilityState state;
14221 struct _GdkEventMotion
14234 GdkInputSource source;
14236 gdouble x_root, y_root;
14239 struct _GdkEventButton
14252 GdkInputSource source;
14254 gdouble x_root, y_root;
14257 struct _GdkEventKey
14269 struct _GdkEventCrossing
14274 GdkWindow *subwindow;
14275 GdkNotifyType detail;
14278 struct _GdkEventFocus
14286 struct _GdkEventConfigure
14296 struct _GdkEventProperty
14306 struct _GdkEventSelection
14318 /* This event type will be used pretty rarely. It only is important
14319 for XInput aware programs that are drawing their own cursor */
14321 struct _GdkEventProximity
14327 GdkInputSource source;
14331 struct _GdkEventDragRequest
14339 guint protocol_version:4;
14341 guint willaccept:1;
14342 guint delete_data:1; /* Do *not* delete if link is sent, only
14349 guint8 isdrop; /* This gdk event can be generated by a couple of
14350 X events - this lets the app know whether the
14351 drop really occurred or we just set the data */
14353 GdkPoint drop_coords;
14358 struct _GdkEventDragBegin
14365 guint protocol_version:4;
14372 struct _GdkEventDropEnter
14380 guint protocol_version:4;
14382 guint extended_typelist:1;
14389 struct _GdkEventDropLeave
14397 guint protocol_version:4;
14404 struct _GdkEventDropDataAvailable
14412 guint protocol_version:4;
14418 gchar *data_type; /* MIME type */
14419 gulong data_numbytes;
14425 struct _GdkEventClient
14430 GdkAtom message_type;
14431 gushort data_format;
14439 struct _GdkEventOther
14450 <!-- ***************************************************************** -->
14451 <appendix id="app-CodeExamples">
14452 <title>Code Examples</title>
14454 <para>Below are the code examples that are used in the above text
14455 which are not included in complete form elsewhere.</para>
14457 <!-- ----------------------------------------------------------------- -->
14458 <sect1 id="sec-Tictactoe">
14459 <title>Tictactoe</title>
14460 <!-- ----------------------------------------------------------------- -->
14462 <title>tictactoe.h</title>
14464 <programlisting role="C">
14465 <!-- example-start tictactoe tictactoe.h -->
14466 /* GTK - The GIMP Toolkit
14467 * Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
14469 * This library is free software; you can redistribute it and/or
14470 * modify it under the terms of the GNU Library General Public
14471 * License as published by the Free Software Foundation; either
14472 * version 2 of the License, or (at your option) any later version.
14474 * This library is distributed in the hope that it will be useful,
14475 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14476 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14477 * Library General Public License for more details.
14479 * You should have received a copy of the GNU Library General Public
14480 * License along with this library; if not, write to the
14481 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
14482 * Boston, MA 02111-1307, USA.
14484 #ifndef __TICTACTOE_H__
14485 #define __TICTACTOE_H__
14488 #include <glib.h>
14489 #include <glib-object.h>
14490 #include <gtk/gtktable.h>
14495 #define TICTACTOE_TYPE (tictactoe_get_type ())
14496 #define TICTACTOE(obj) (G_TYPE_CHECK_INSTANCE_CAST ((obj), TICTACTOE_TYPE, Tictactoe))
14497 #define TICTACTOE_CLASS(klass) (G_TYPE_CHECK_CLASS_CAST ((klass), TICTACTOE_TYPE, TictactoeClass))
14498 #define IS_TICTACTOE(obj) (G_TYPE_CHECK_INSTANCE_TYPE ((obj), TICTACTOE_TYPE))
14499 #define IS_TICTACTOE_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), TICTACTOE_TYPE))
14502 typedef struct _Tictactoe Tictactoe;
14503 typedef struct _TictactoeClass TictactoeClass;
14509 GtkWidget *buttons[3][3];
14512 struct _TictactoeClass
14514 GtkTableClass parent_class;
14516 void (* tictactoe) (Tictactoe *ttt);
14519 GType tictactoe_get_type (void);
14520 GtkWidget* tictactoe_new (void);
14521 void tictactoe_clear (Tictactoe *ttt);
14525 #endif /* __TICTACTOE_H__ */
14527 <!-- example-end -->
14532 <!-- ----------------------------------------------------------------- -->
14534 <title>tictactoe.c</title>
14536 <programlisting role="C">
14537 <!-- example-start tictactoe tictactoe.c -->
14539 /* GTK - The GIMP Toolkit
14540 * Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
14542 * This library is free software; you can redistribute it and/or
14543 * modify it under the terms of the GNU Library General Public
14544 * License as published by the Free Software Foundation; either
14545 * version 2 of the License, or (at your option) any later version.
14547 * This library is distributed in the hope that it will be useful,
14548 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14549 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14550 * Library General Public License for more details.
14552 * You should have received a copy of the GNU Library General Public
14553 * License along with this library; if not, write to the
14554 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
14555 * Boston, MA 02111-1307, USA.
14557 #include <gtk/gtksignal.h>
14558 #include <gtk/gtktable.h>
14559 #include <gtk/gtktogglebutton.h>
14560 #include "tictactoe.h"
14567 static void tictactoe_class_init (TictactoeClass *klass);
14568 static void tictactoe_init (Tictactoe *ttt);
14569 static void tictactoe_toggle (GtkWidget *widget, Tictactoe *ttt);
14571 static guint tictactoe_signals[LAST_SIGNAL] = { 0 };
14574 tictactoe_get_type (void)
14576 static GType ttt_type = 0;
14580 const GTypeInfo ttt_info =
14582 sizeof (TictactoeClass),
14583 NULL, /* base_init */
14584 NULL, /* base_finalize */
14585 (GClassInitFunc) tictactoe_class_init,
14586 NULL, /* class_finalize */
14587 NULL, /* class_data */
14588 sizeof (Tictactoe),
14590 (GInstanceInitFunc) tictactoe_init,
14593 ttt_type = g_type_register_static (GTK_TYPE_TABLE, "Tictactoe", &ttt_info, 0);
14600 tictactoe_class_init (TictactoeClass *klass)
14603 tictactoe_signals[TICTACTOE_SIGNAL] = g_signal_new ("tictactoe",
14604 G_TYPE_FROM_CLASS (klass),
14605 G_SIGNAL_RUN_FIRST | G_SIGNAL_ACTION,
14606 G_STRUCT_OFFSET (TictactoeClass, tictactoe),
14609 g_cclosure_marshal_VOID__VOID,
14616 tictactoe_init (Tictactoe *ttt)
14620 gtk_table_resize (GTK_TABLE (ttt), 3, 3);
14621 gtk_table_set_homogeneous (GTK_TABLE (ttt), TRUE);
14623 for (i=0;i<3; i++)
14624 for (j=0;j<3; j++) {
14625 ttt->buttons[i][j] = gtk_toggle_button_new ();
14626 gtk_table_attach_defaults (GTK_TABLE (ttt), ttt->buttons[i][j],
14628 g_signal_connect (ttt->buttons[i][j], "toggled",
14629 G_CALLBACK (tictactoe_toggle), (gpointer) ttt);
14630 gtk_widget_set_size_request (ttt->buttons[i][j], 20, 20);
14631 gtk_widget_show (ttt->buttons[i][j]);
14638 return GTK_WIDGET (g_object_new (tictactoe_get_type (), NULL));
14642 tictactoe_clear (Tictactoe *ttt)
14646 for (i = 0; i<3; i++)
14647 for (j = 0; j<3; j++)
14649 g_signal_handlers_block_matched (G_OBJECT (ttt->buttons[i][j]),
14650 G_SIGNAL_MATCH_DATA,
14651 0, 0, NULL, NULL, ttt);
14652 gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (ttt->buttons[i][j]),
14654 g_signal_handlers_unblock_matched (G_OBJECT (ttt->buttons[i][j]),
14655 G_SIGNAL_MATCH_DATA,
14656 0, 0, NULL, NULL, ttt);
14661 tictactoe_toggle (GtkWidget *widget, Tictactoe *ttt)
14665 static int rwins[8][3] = { { 0, 0, 0 }, { 1, 1, 1 }, { 2, 2, 2 },
14666 { 0, 1, 2 }, { 0, 1, 2 }, { 0, 1, 2 },
14667 { 0, 1, 2 }, { 0, 1, 2 } };
14668 static int cwins[8][3] = { { 0, 1, 2 }, { 0, 1, 2 }, { 0, 1, 2 },
14669 { 0, 0, 0 }, { 1, 1, 1 }, { 2, 2, 2 },
14670 { 0, 1, 2 }, { 2, 1, 0 } };
14672 int success, found;
14674 for (k = 0; k<8; k++)
14679 for (i = 0; i<3; i++)
14681 success = success &&
14682 GTK_TOGGLE_BUTTON (ttt->buttons[rwins[k][i]][cwins[k][i]])->active;
14684 ttt->buttons[rwins[k][i]][cwins[k][i]] == widget;
14687 if (success && found)
14689 g_signal_emit (ttt,
14690 tictactoe_signals[TICTACTOE_SIGNAL], 0);
14696 <!-- example-end -->
14701 <!-- ----------------------------------------------------------------- -->
14703 <title>ttt_test.c</title>
14705 <programlisting role="C">
14706 <!-- example-start tictactoe ttt_test.c -->
14708 #include <stdlib.h>
14709 #include <gtk/gtk.h>
14710 #include "tictactoe.h"
14712 void win( GtkWidget *widget,
14715 g_print ("Yay!\n");
14716 tictactoe_clear (TICTACTOE (widget));
14719 int main( int argc,
14725 gtk_init (&argc, &argv);
14727 window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
14729 gtk_window_set_title (GTK_WINDOW (window), "Aspect Frame");
14731 g_signal_connect (window, "destroy",
14732 G_CALLBACK (exit), NULL);
14734 gtk_container_set_border_width (GTK_CONTAINER (window), 10);
14736 ttt = tictactoe_new ();
14738 gtk_container_add (GTK_CONTAINER (window), ttt);
14739 gtk_widget_show (ttt);
14741 /* And attach to its "tictactoe" signal */
14742 g_signal_connect (ttt, "tictactoe",
14743 G_CALLBACK (win), NULL);
14745 gtk_widget_show (window);
14752 <!-- example-end -->
14758 <!-- ----------------------------------------------------------------- -->
14759 <sect1 id="sec-GtkDial">
14760 <title>GtkDial</title>
14762 <!-- ----------------------------------------------------------------- -->
14764 <title>gtkdial.h</title>
14766 <programlisting role="C">
14767 <!-- example-start gtkdial gtkdial.h -->
14769 /* GTK - The GIMP Toolkit
14770 * Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
14772 * This library is free software; you can redistribute it and/or
14773 * modify it under the terms of the GNU Library General Public
14774 * License as published by the Free Software Foundation; either
14775 * version 2 of the License, or (at your option) any later version.
14777 * This library is distributed in the hope that it will be useful,
14778 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14779 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14780 * Library General Public License for more details.
14782 * You should have received a copy of the GNU Library General Public
14783 * License along with this library; if not, write to the
14784 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
14785 * Boston, MA 02111-1307, USA.
14787 #ifndef __GTK_DIAL_H__
14788 #define __GTK_DIAL_H__
14791 #include <gdk/gdk.h>
14792 #include <gtk/gtkadjustment.h>
14793 #include <gtk/gtkwidget.h>
14798 #endif /* __cplusplus */
14801 #define GTK_DIAL(obj) GTK_CHECK_CAST (obj, gtk_dial_get_type (), GtkDial)
14802 #define GTK_DIAL_CLASS(klass) GTK_CHECK_CLASS_CAST (klass, gtk_dial_get_type (), GtkDialClass)
14803 #define GTK_IS_DIAL(obj) GTK_CHECK_TYPE (obj, gtk_dial_get_type ())
14806 typedef struct _GtkDial GtkDial;
14807 typedef struct _GtkDialClass GtkDialClass;
14813 /* update policy (GTK_UPDATE_[CONTINUOUS/DELAYED/DISCONTINUOUS]) */
14816 /* Button currently pressed or 0 if none */
14819 /* Dimensions of dial components */
14821 gint pointer_width;
14823 /* ID of update timer, or 0 if none */
14826 /* Current angle */
14830 /* Old values from adjustment stored so we know when something changes */
14835 /* The adjustment object that stores the data for this dial */
14836 GtkAdjustment *adjustment;
14839 struct _GtkDialClass
14841 GtkWidgetClass parent_class;
14845 GtkWidget* gtk_dial_new (GtkAdjustment *adjustment);
14846 GtkType gtk_dial_get_type (void);
14847 GtkAdjustment* gtk_dial_get_adjustment (GtkDial *dial);
14848 void gtk_dial_set_update_policy (GtkDial *dial,
14849 GtkUpdateType policy);
14851 void gtk_dial_set_adjustment (GtkDial *dial,
14852 GtkAdjustment *adjustment);
14855 #endif /* __cplusplus */
14858 #endif /* __GTK_DIAL_H__ */
14859 <!-- example-end -->
14864 <!-- ----------------------------------------------------------------- -->
14866 <title>gtkdial.c</title>
14868 <programlisting role="C">
14869 <!-- example-start gtkdial gtkdial.c -->
14871 /* GTK - The GIMP Toolkit
14872 * Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
14874 * This library is free software; you can redistribute it and/or
14875 * modify it under the terms of the GNU Library General Public
14876 * License as published by the Free Software Foundation; either
14877 * version 2 of the License, or (at your option) any later version.
14879 * This library is distributed in the hope that it will be useful,
14880 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14881 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14882 * Library General Public License for more details.
14884 * You should have received a copy of the GNU Library General Public
14885 * License along with this library; if not, write to the
14886 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
14887 * Boston, MA 02111-1307, USA.
14889 #include <math.h>
14890 #include <stdio.h>
14891 #include <gtk/gtkmain.h>
14892 #include <gtk/gtksignal.h>
14894 #include "gtkdial.h"
14896 #define SCROLL_DELAY_LENGTH 300
14897 #define DIAL_DEFAULT_SIZE 100
14899 /* Forward declarations */
14901 static void gtk_dial_class_init (GtkDialClass *klass);
14902 static void gtk_dial_init (GtkDial *dial);
14903 static void gtk_dial_destroy (GtkObject *object);
14904 static void gtk_dial_realize (GtkWidget *widget);
14905 static void gtk_dial_size_request (GtkWidget *widget,
14906 GtkRequisition *requisition);
14907 static void gtk_dial_size_allocate (GtkWidget *widget,
14908 GtkAllocation *allocation);
14909 static gboolean gtk_dial_expose (GtkWidget *widget,
14910 GdkEventExpose *event);
14911 static gboolean gtk_dial_button_press (GtkWidget *widget,
14912 GdkEventButton *event);
14913 static gboolean gtk_dial_button_release (GtkWidget *widget,
14914 GdkEventButton *event);
14915 static gboolean gtk_dial_motion_notify (GtkWidget *widget,
14916 GdkEventMotion *event);
14917 static gboolean gtk_dial_timer (GtkDial *dial);
14919 static void gtk_dial_update_mouse (GtkDial *dial, gint x, gint y);
14920 static void gtk_dial_update (GtkDial *dial);
14921 static void gtk_dial_adjustment_changed (GtkAdjustment *adjustment,
14923 static void gtk_dial_adjustment_value_changed (GtkAdjustment *adjustment,
14928 static GtkWidgetClass *parent_class = NULL;
14931 gtk_dial_get_type ()
14933 static GType dial_type = 0;
14937 const GTypeInfo dial_info =
14939 sizeof (GtkDialClass),
14942 (GClassInitFunc) gtk_dial_class_init,
14947 (GInstanceInitFunc) gtk_dial_init,
14950 dial_type = g_type_register_static (GTK_TYPE_WIDGET, "GtkDial", &dial_info, 0);
14957 gtk_dial_class_init (GtkDialClass *class)
14959 GtkObjectClass *object_class;
14960 GtkWidgetClass *widget_class;
14962 object_class = (GtkObjectClass*) class;
14963 widget_class = (GtkWidgetClass*) class;
14965 parent_class = gtk_type_class (gtk_widget_get_type ());
14967 object_class->destroy = gtk_dial_destroy;
14969 widget_class->realize = gtk_dial_realize;
14970 widget_class->expose_event = gtk_dial_expose;
14971 widget_class->size_request = gtk_dial_size_request;
14972 widget_class->size_allocate = gtk_dial_size_allocate;
14973 widget_class->button_press_event = gtk_dial_button_press;
14974 widget_class->button_release_event = gtk_dial_button_release;
14975 widget_class->motion_notify_event = gtk_dial_motion_notify;
14979 gtk_dial_init (GtkDial *dial)
14981 dial->button = 0;
14982 dial->policy = GTK_UPDATE_CONTINUOUS;
14983 dial->timer = 0;
14984 dial->radius = 0;
14985 dial->pointer_width = 0;
14986 dial->angle = 0.0;
14987 dial->old_value = 0.0;
14988 dial->old_lower = 0.0;
14989 dial->old_upper = 0.0;
14990 dial->adjustment = NULL;
14994 gtk_dial_new (GtkAdjustment *adjustment)
14998 dial = g_object_new (gtk_dial_get_type (), NULL);
15001 adjustment = gtk_adjustment_new (0.0, 0.0, 0.0, 0.0, 0.0, 0.0);
15003 gtk_dial_set_adjustment (dial, adjustment);
15005 return GTK_WIDGET (dial);
15009 gtk_dial_destroy (GtkObject *object)
15013 g_return_if_fail (object != NULL);
15014 g_return_if_fail (GTK_IS_DIAL (object));
15016 dial = GTK_DIAL (object);
15018 if (dial->adjustment)
15020 g_object_unref (GTK_OBJECT (dial->adjustment));
15021 dial->adjustment = NULL;
15024 if (GTK_OBJECT_CLASS (parent_class)->destroy)
15025 (* GTK_OBJECT_CLASS (parent_class)->destroy) (object);
15029 gtk_dial_get_adjustment (GtkDial *dial)
15031 g_return_val_if_fail (dial != NULL, NULL);
15032 g_return_val_if_fail (GTK_IS_DIAL (dial), NULL);
15034 return dial->adjustment;
15038 gtk_dial_set_update_policy (GtkDial *dial,
15039 GtkUpdateType policy)
15041 g_return_if_fail (dial != NULL);
15042 g_return_if_fail (GTK_IS_DIAL (dial));
15044 dial->policy = policy;
15048 gtk_dial_set_adjustment (GtkDial *dial,
15049 GtkAdjustment *adjustment)
15051 g_return_if_fail (dial != NULL);
15052 g_return_if_fail (GTK_IS_DIAL (dial));
15054 if (dial->adjustment)
15056 g_signal_handlers_disconnect_by_func (GTK_OBJECT (dial->adjustment), NULL, (gpointer) dial);
15057 g_object_unref (GTK_OBJECT (dial->adjustment));
15060 dial->adjustment = adjustment;
15061 g_object_ref (GTK_OBJECT (dial->adjustment));
15063 g_signal_connect (GTK_OBJECT (adjustment), "changed",
15064 G_CALLBACK (gtk_dial_adjustment_changed),
15066 g_signal_connect (GTK_OBJECT (adjustment), "value_changed",
15067 G_CALLBACK (gtk_dial_adjustment_value_changed),
15070 dial->old_value = adjustment->value;
15071 dial->old_lower = adjustment->lower;
15072 dial->old_upper = adjustment->upper;
15074 gtk_dial_update (dial);
15078 gtk_dial_realize (GtkWidget *widget)
15081 GdkWindowAttr attributes;
15082 gint attributes_mask;
15084 g_return_if_fail (widget != NULL);
15085 g_return_if_fail (GTK_IS_DIAL (widget));
15087 gtk_widget_set_realized (widget, TRUE);
15088 dial = GTK_DIAL (widget);
15090 attributes.x = widget->allocation.x;
15091 attributes.y = widget->allocation.y;
15092 attributes.width = widget->allocation.width;
15093 attributes.height = widget->allocation.height;
15094 attributes.wclass = GDK_INPUT_OUTPUT;
15095 attributes.window_type = GDK_WINDOW_CHILD;
15096 attributes.event_mask = gtk_widget_get_events (widget) |
15097 GDK_EXPOSURE_MASK | GDK_BUTTON_PRESS_MASK |
15098 GDK_BUTTON_RELEASE_MASK | GDK_POINTER_MOTION_MASK |
15099 GDK_POINTER_MOTION_HINT_MASK;
15100 attributes.visual = gtk_widget_get_visual (widget);
15101 attributes.colormap = gtk_widget_get_colormap (widget);
15103 attributes_mask = GDK_WA_X | GDK_WA_Y | GDK_WA_VISUAL | GDK_WA_COLORMAP;
15104 widget->window = gdk_window_new (widget->parent->window, &attributes, attributes_mask);
15106 widget->style = gtk_style_attach (widget->style, widget->window);
15108 gdk_window_set_user_data (widget->window, widget);
15110 gtk_style_set_background (widget->style, widget->window, GTK_STATE_ACTIVE);
15114 gtk_dial_size_request (GtkWidget *widget,
15115 GtkRequisition *requisition)
15117 requisition->width = DIAL_DEFAULT_SIZE;
15118 requisition->height = DIAL_DEFAULT_SIZE;
15122 gtk_dial_size_allocate (GtkWidget *widget,
15123 GtkAllocation *allocation)
15127 g_return_if_fail (widget != NULL);
15128 g_return_if_fail (GTK_IS_DIAL (widget));
15129 g_return_if_fail (allocation != NULL);
15131 widget->allocation = *allocation;
15132 dial = GTK_DIAL (widget);
15134 if (gtk_widget_get_realized (widget))
15137 gdk_window_move_resize (widget->window,
15138 allocation->x, allocation->y,
15139 allocation->width, allocation->height);
15142 dial->radius = MIN (allocation->width, allocation->height) * 0.45;
15143 dial->pointer_width = dial->radius / 5;
15147 gtk_dial_expose( GtkWidget *widget,
15148 GdkEventExpose *event )
15151 GdkPoint points[6];
15153 gdouble theta, last, increment;
15154 GtkStyle *blankstyle;
15160 g_return_val_if_fail (widget != NULL, FALSE);
15161 g_return_val_if_fail (GTK_IS_DIAL (widget), FALSE);
15162 g_return_val_if_fail (event != NULL, FALSE);
15164 if (event->count > 0)
15167 dial = GTK_DIAL (widget);
15169 /* gdk_window_clear_area (widget->window,
15171 widget->allocation.width,
15172 widget->allocation.height);
15174 xc = widget->allocation.width / 2;
15175 yc = widget->allocation.height / 2;
15177 upper = dial->adjustment->upper;
15178 lower = dial->adjustment->lower;
15180 /* Erase old pointer */
15182 s = sin (dial->last_angle);
15183 c = cos (dial->last_angle);
15184 dial->last_angle = dial->angle;
15186 points[0].x = xc + s*dial->pointer_width/2;
15187 points[0].y = yc + c*dial->pointer_width/2;
15188 points[1].x = xc + c*dial->radius;
15189 points[1].y = yc - s*dial->radius;
15190 points[2].x = xc - s*dial->pointer_width/2;
15191 points[2].y = yc - c*dial->pointer_width/2;
15192 points[3].x = xc - c*dial->radius/10;
15193 points[3].y = yc + s*dial->radius/10;
15194 points[4].x = points[0].x;
15195 points[4].y = points[0].y;
15197 blankstyle = gtk_style_new ();
15198 blankstyle->bg_gc[GTK_STATE_NORMAL] =
15199 widget->style->bg_gc[GTK_STATE_NORMAL];
15200 blankstyle->dark_gc[GTK_STATE_NORMAL] =
15201 widget->style->bg_gc[GTK_STATE_NORMAL];
15202 blankstyle->light_gc[GTK_STATE_NORMAL] =
15203 widget->style->bg_gc[GTK_STATE_NORMAL];
15204 blankstyle->black_gc =
15205 widget->style->bg_gc[GTK_STATE_NORMAL];
15207 gtk_paint_polygon (blankstyle,
15217 g_object_unref (blankstyle);
15222 if ((upper - lower) == 0)
15225 increment = (100*M_PI) / (dial->radius*dial->radius);
15227 inc = (upper - lower);
15229 while (inc < 100) inc *= 10;
15230 while (inc >= 1000) inc /= 10;
15233 for (i = 0; i <= inc; i++)
15235 theta = ((gfloat)i*M_PI / (18*inc/24.) - M_PI/6.);
15237 if ((theta - last) < (increment))
15244 tick_length = (i%(inc/10) == 0) ? dial->pointer_width : dial->pointer_width / 2;
15246 gdk_draw_line (widget->window,
15247 widget->style->fg_gc[widget->state],
15248 xc + c*(dial->radius - tick_length),
15249 yc - s*(dial->radius - tick_length),
15250 xc + c*dial->radius,
15251 yc - s*dial->radius);
15256 s = sin (dial->angle);
15257 c = cos (dial->angle);
15258 dial->last_angle = dial->angle;
15260 points[0].x = xc + s*dial->pointer_width/2;
15261 points[0].y = yc + c*dial->pointer_width/2;
15262 points[1].x = xc + c*dial->radius;
15263 points[1].y = yc - s*dial->radius;
15264 points[2].x = xc - s*dial->pointer_width/2;
15265 points[2].y = yc - c*dial->pointer_width/2;
15266 points[3].x = xc - c*dial->radius/10;
15267 points[3].y = yc + s*dial->radius/10;
15268 points[4].x = points[0].x;
15269 points[4].y = points[0].y;
15272 gtk_paint_polygon (widget->style,
15286 gtk_dial_button_press( GtkWidget *widget,
15287 GdkEventButton *event )
15293 double d_perpendicular;
15295 g_return_val_if_fail (widget != NULL, FALSE);
15296 g_return_val_if_fail (GTK_IS_DIAL (widget), FALSE);
15297 g_return_val_if_fail (event != NULL, FALSE);
15299 dial = GTK_DIAL (widget);
15301 /* Determine if button press was within pointer region - we
15302 do this by computing the parallel and perpendicular distance of
15303 the point where the mouse was pressed from the line passing through
15306 dx = event->x - widget->allocation.width / 2;
15307 dy = widget->allocation.height / 2 - event->y;
15309 s = sin (dial->angle);
15310 c = cos (dial->angle);
15312 d_parallel = s*dy + c*dx;
15313 d_perpendicular = fabs (s*dx - c*dy);
15315 if (!dial->button &&
15316 (d_perpendicular < dial->pointer_width/2) &&
15317 (d_parallel > - dial->pointer_width))
15319 gtk_grab_add (widget);
15321 dial->button = event->button;
15323 gtk_dial_update_mouse (dial, event->x, event->y);
15330 gtk_dial_button_release( GtkWidget *widget,
15331 GdkEventButton *event )
15335 g_return_val_if_fail (widget != NULL, FALSE);
15336 g_return_val_if_fail (GTK_IS_DIAL (widget), FALSE);
15337 g_return_val_if_fail (event != NULL, FALSE);
15339 dial = GTK_DIAL (widget);
15341 if (dial->button == event->button)
15343 gtk_grab_remove (widget);
15345 dial->button = 0;
15347 if (dial->policy == GTK_UPDATE_DELAYED)
15348 g_source_remove (dial->timer);
15350 if ((dial->policy != GTK_UPDATE_CONTINUOUS) &&
15351 (dial->old_value != dial->adjustment->value))
15352 g_signal_emit_by_name (GTK_OBJECT (dial->adjustment), "value_changed");
15359 gtk_dial_motion_notify( GtkWidget *widget,
15360 GdkEventMotion *event )
15363 GdkModifierType mods;
15366 g_return_val_if_fail (widget != NULL, FALSE);
15367 g_return_val_if_fail (GTK_IS_DIAL (widget), FALSE);
15368 g_return_val_if_fail (event != NULL, FALSE);
15370 dial = GTK_DIAL (widget);
15372 if (dial->button != 0)
15377 if (event->is_hint || (event->window != widget->window))
15378 gdk_window_get_pointer (widget->window, &x, &y, &mods);
15380 switch (dial->button)
15383 mask = GDK_BUTTON1_MASK;
15386 mask = GDK_BUTTON2_MASK;
15389 mask = GDK_BUTTON3_MASK;
15396 if (mods & mask)
15397 gtk_dial_update_mouse (dial, x,y);
15404 gtk_dial_timer( GtkDial *dial )
15406 g_return_val_if_fail (dial != NULL, FALSE);
15407 g_return_val_if_fail (GTK_IS_DIAL (dial), FALSE);
15409 if (dial->policy == GTK_UPDATE_DELAYED)
15410 g_signal_emit_by_name (GTK_OBJECT (dial->adjustment), "value_changed");
15416 gtk_dial_update_mouse( GtkDial *dial, gint x, gint y )
15421 g_return_if_fail (dial != NULL);
15422 g_return_if_fail (GTK_IS_DIAL (dial));
15424 xc = GTK_WIDGET(dial)->allocation.width / 2;
15425 yc = GTK_WIDGET(dial)->allocation.height / 2;
15427 old_value = dial->adjustment->value;
15428 dial->angle = atan2(yc-y, x-xc);
15430 if (dial->angle < -M_PI/2.)
15431 dial->angle += 2*M_PI;
15433 if (dial->angle < -M_PI/6)
15434 dial->angle = -M_PI/6;
15436 if (dial->angle > 7.*M_PI/6.)
15437 dial->angle = 7.*M_PI/6.;
15439 dial->adjustment->value = dial->adjustment->lower + (7.*M_PI/6 - dial->angle) *
15440 (dial->adjustment->upper - dial->adjustment->lower) / (4.*M_PI/3.);
15442 if (dial->adjustment->value != old_value)
15444 if (dial->policy == GTK_UPDATE_CONTINUOUS)
15446 g_signal_emit_by_name (GTK_OBJECT (dial->adjustment), "value_changed");
15450 gtk_widget_queue_draw (GTK_WIDGET (dial));
15452 if (dial->policy == GTK_UPDATE_DELAYED)
15454 if (dial->timer)
15455 g_source_remove (dial->timer);
15457 dial->timer = g_timeout_add (SCROLL_DELAY_LENGTH,
15458 (GtkFunction) gtk_dial_timer,
15466 gtk_dial_update (GtkDial *dial)
15470 g_return_if_fail (dial != NULL);
15471 g_return_if_fail (GTK_IS_DIAL (dial));
15473 new_value = dial->adjustment->value;
15475 if (new_value < dial->adjustment->lower)
15476 new_value = dial->adjustment->lower;
15478 if (new_value > dial->adjustment->upper)
15479 new_value = dial->adjustment->upper;
15481 if (new_value != dial->adjustment->value)
15483 dial->adjustment->value = new_value;
15484 g_signal_emit_by_name (GTK_OBJECT (dial->adjustment), "value_changed");
15487 dial->angle = 7.*M_PI/6. - (new_value - dial->adjustment->lower) * 4.*M_PI/3. /
15488 (dial->adjustment->upper - dial->adjustment->lower);
15490 gtk_widget_queue_draw (GTK_WIDGET (dial));
15494 gtk_dial_adjustment_changed (GtkAdjustment *adjustment,
15499 g_return_if_fail (adjustment != NULL);
15500 g_return_if_fail (data != NULL);
15502 dial = GTK_DIAL (data);
15504 if ((dial->old_value != adjustment->value) ||
15505 (dial->old_lower != adjustment->lower) ||
15506 (dial->old_upper != adjustment->upper))
15508 gtk_dial_update (dial);
15510 dial->old_value = adjustment->value;
15511 dial->old_lower = adjustment->lower;
15512 dial->old_upper = adjustment->upper;
15517 gtk_dial_adjustment_value_changed (GtkAdjustment *adjustment,
15522 g_return_if_fail (adjustment != NULL);
15523 g_return_if_fail (data != NULL);
15525 dial = GTK_DIAL (data);
15527 if (dial->old_value != adjustment->value)
15529 gtk_dial_update (dial);
15531 dial->old_value = adjustment->value;
15534 <!-- example-end -->
15539 <!-- ----------------------------------------------------------------- -->
15541 <title>dial_test.c</title>
15543 <programlisting role="C">
15544 <!-- example-start gtkdial dial_test.c -->
15546 #include <stdio.h>
15547 #include <stdlib.h>
15548 #include <gtk/gtk.h>
15549 #include "gtkdial.h"
15551 void value_changed( GtkAdjustment *adjustment,
15556 sprintf(buffer,"%4.2f",adjustment->value);
15557 gtk_label_set_text (GTK_LABEL (label), buffer);
15560 int main( int argc,
15564 GtkAdjustment *adjustment;
15570 gtk_init (&argc, &argv);
15572 window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
15574 gtk_window_set_title (GTK_WINDOW (window), "Dial");
15576 g_signal_connect (window, "destroy",
15577 G_CALLBACK (exit), NULL);
15579 gtk_container_set_border_width (GTK_CONTAINER (window), 10);
15581 vbox = gtk_vbox_new (FALSE, 5);
15582 gtk_container_add (GTK_CONTAINER (window), vbox);
15583 gtk_widget_show (vbox);
15585 frame = gtk_frame_new (NULL);
15586 gtk_frame_set_shadow_type (GTK_FRAME (frame), GTK_SHADOW_IN);
15587 gtk_container_add (GTK_CONTAINER (vbox), frame);
15588 gtk_widget_show (frame);
15590 adjustment = gtk_adjustment_new (0, 0, 100, 0.01, 0.1, 0);
15592 dial = gtk_dial_new (adjustment);
15593 gtk_dial_set_update_policy (GTK_DIAL (dial), GTK_UPDATE_DELAYED);
15594 /* gtk_widget_set_size_request (dial, 100, 100); */
15596 gtk_container_add (GTK_CONTAINER (frame), dial);
15597 gtk_widget_show (dial);
15599 label = gtk_label_new ("0.00");
15600 gtk_box_pack_end (GTK_BOX (vbox), label, 0, 0, 0);
15601 gtk_widget_show (label);
15603 g_signal_connect (adjustment, "value_changed",
15604 G_CALLBACK (value_changed), (gpointer) label);
15606 gtk_widget_show (window);
15612 <!-- example-end -->
15618 <!-- ----------------------------------------------------------------- -->
15619 <sect1 id="sec-Scribble">
15620 <title>Scribble</title>
15622 <!-- ----------------------------------------------------------------- -->
15624 <title>scribble-simple.c</title>
15626 <programlisting role="C">
15627 <!-- example-start scribble-simple scribble-simple.c -->
15629 /* GTK - The GIMP Toolkit
15630 * Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
15632 * This library is free software; you can redistribute it and/or
15633 * modify it under the terms of the GNU Library General Public
15634 * License as published by the Free Software Foundation; either
15635 * version 2 of the License, or (at your option) any later version.
15637 * This library is distributed in the hope that it will be useful,
15638 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15639 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15640 * Library General Public License for more details.
15642 * You should have received a copy of the GNU Library General Public
15643 * License along with this library; if not, write to the
15644 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
15645 * Boston, MA 02111-1307, USA.
15648 #include <stdlib.h>
15649 #include <gtk/gtk.h>
15651 /* Backing pixmap for drawing area */
15652 static GdkPixmap *pixmap = NULL;
15654 /* Create a new backing pixmap of the appropriate size */
15655 static gboolean configure_event( GtkWidget *widget,
15656 GdkEventConfigure *event )
15659 g_object_unref (pixmap);
15661 pixmap = gdk_pixmap_new (widget->window,
15662 widget->allocation.width,
15663 widget->allocation.height,
15665 gdk_draw_rectangle (pixmap,
15666 widget->style->white_gc,
15669 widget->allocation.width,
15670 widget->allocation.height);
15675 /* Redraw the screen from the backing pixmap */
15676 static gboolean expose_event( GtkWidget *widget,
15677 GdkEventExpose *event )
15679 gdk_draw_drawable (widget->window,
15680 widget->style->fg_gc[gtk_widget_get_state (widget)],
15682 event->area.x, event->area.y,
15683 event->area.x, event->area.y,
15684 event->area.width, event->area.height);
15689 /* Draw a rectangle on the screen */
15690 static void draw_brush( GtkWidget *widget,
15694 GdkRectangle update_rect;
15696 update_rect.x = x - 5;
15697 update_rect.y = y - 5;
15698 update_rect.width = 10;
15699 update_rect.height = 10;
15700 gdk_draw_rectangle (pixmap,
15701 widget->style->black_gc,
15703 update_rect.x, update_rect.y,
15704 update_rect.width, update_rect.height);
15705 gtk_widget_queue_draw_area (widget,
15706 update_rect.x, update_rect.y,
15707 update_rect.width, update_rect.height);
15710 static gboolean button_press_event( GtkWidget *widget,
15711 GdkEventButton *event )
15713 if (event->button == 1 && pixmap != NULL)
15714 draw_brush (widget, event->x, event->y);
15719 static gboolean motion_notify_event( GtkWidget *widget,
15720 GdkEventMotion *event )
15723 GdkModifierType state;
15725 if (event->is_hint)
15726 gdk_window_get_pointer (event->window, &x, &y, &state);
15731 state = event->state;
15734 if (state & GDK_BUTTON1_MASK && pixmap != NULL)
15735 draw_brush (widget, x, y);
15745 int main( int argc,
15749 GtkWidget *drawing_area;
15754 gtk_init (&argc, &argv);
15756 window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
15757 gtk_widget_set_name (window, "Test Input");
15759 vbox = gtk_vbox_new (FALSE, 0);
15760 gtk_container_add (GTK_CONTAINER (window), vbox);
15761 gtk_widget_show (vbox);
15763 g_signal_connect (window, "destroy",
15764 G_CALLBACK (quit), NULL);
15766 /* Create the drawing area */
15768 drawing_area = gtk_drawing_area_new ();
15769 gtk_widget_set_size_request (GTK_WIDGET (drawing_area), 200, 200);
15770 gtk_box_pack_start (GTK_BOX (vbox), drawing_area, TRUE, TRUE, 0);
15772 gtk_widget_show (drawing_area);
15774 /* Signals used to handle backing pixmap */
15776 g_signal_connect (drawing_area, "expose_event",
15777 G_CALLBACK (expose_event), NULL);
15778 g_signal_connect (drawing_area, "configure_event",
15779 G_CALLBACK (configure_event), NULL);
15781 /* Event signals */
15783 g_signal_connect (drawing_area, "motion_notify_event",
15784 G_CALLBACK (motion_notify_event), NULL);
15785 g_signal_connect (drawing_area, "button_press_event",
15786 G_CALLBACK (button_press_event), NULL);
15788 gtk_widget_set_events (drawing_area, GDK_EXPOSURE_MASK
15789 | GDK_LEAVE_NOTIFY_MASK
15790 | GDK_BUTTON_PRESS_MASK
15791 | GDK_POINTER_MOTION_MASK
15792 | GDK_POINTER_MOTION_HINT_MASK);
15794 /* .. And a quit button */
15795 button = gtk_button_new_with_label ("Quit");
15796 gtk_box_pack_start (GTK_BOX (vbox), button, FALSE, FALSE, 0);
15798 g_signal_connect_swapped (button, "clicked",
15799 G_CALLBACK (gtk_widget_destroy),
15801 gtk_widget_show (button);
15803 gtk_widget_show (window);
15809 <!-- example-end -->
15814 <!-- ----------------------------------------------------------------- -->
15816 <title>scribble-xinput.c</title>
15818 <programlisting role="C">
15819 <!-- example-start scribble-xinput scribble-xinput.c -->
15821 /* GTK - The GIMP Toolkit
15822 * Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
15824 * This library is free software; you can redistribute it and/or
15825 * modify it under the terms of the GNU Library General Public
15826 * License as published by the Free Software Foundation; either
15827 * version 2 of the License, or (at your option) any later version.
15829 * This library is distributed in the hope that it will be useful,
15830 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15831 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15832 * Library General Public License for more details.
15834 * You should have received a copy of the GNU Library General Public
15835 * License along with this library; if not, write to the
15836 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
15837 * Boston, MA 02111-1307, USA.
15840 #include <gtk/gtk.h>
15842 /* Backing pixmap for drawing area */
15843 static GdkPixmap *pixmap = NULL;
15845 /* Create a new backing pixmap of the appropriate size */
15847 configure_event (GtkWidget *widget, GdkEventConfigure *event)
15850 g_object_unref (pixmap);
15852 pixmap = gdk_pixmap_new (widget->window,
15853 widget->allocation.width,
15854 widget->allocation.height,
15856 gdk_draw_rectangle (pixmap,
15857 widget->style->white_gc,
15860 widget->allocation.width,
15861 widget->allocation.height);
15866 /* Redraw the screen from the backing pixmap */
15868 expose_event (GtkWidget *widget, GdkEventExpose *event)
15870 gdk_draw_drawable (widget->window,
15871 widget->style->fg_gc[gtk_widget_get_state (widget)],
15873 event->area.x, event->area.y,
15874 event->area.x, event->area.y,
15875 event->area.width, event->area.height);
15880 /* Draw a rectangle on the screen, size depending on pressure,
15881 and color on the type of device */
15883 draw_brush (GtkWidget *widget, GdkInputSource source,
15884 gdouble x, gdouble y, gdouble pressure)
15887 GdkRectangle update_rect;
15891 case GDK_SOURCE_MOUSE:
15892 gc = widget->style->dark_gc[gtk_widget_get_state (widget)];
15894 case GDK_SOURCE_PEN:
15895 gc = widget->style->black_gc;
15897 case GDK_SOURCE_ERASER:
15898 gc = widget->style->white_gc;
15901 gc = widget->style->light_gc[gtk_widget_get_state (widget)];
15904 update_rect.x = x - 10 * pressure;
15905 update_rect.y = y - 10 * pressure;
15906 update_rect.width = 20 * pressure;
15907 update_rect.height = 20 * pressure;
15908 gdk_draw_rectangle (pixmap, gc, TRUE,
15909 update_rect.x, update_rect.y,
15910 update_rect.width, update_rect.height);
15911 gtk_widget_queue_draw_area (widget,
15912 update_rect.x, update_rect.y,
15913 update_rect.width, update_rect.height);
15917 print_button_press (GdkDevice *device)
15919 g_print ("Button press on device '%s'\n", device->name);
15923 button_press_event (GtkWidget *widget, GdkEventButton *event)
15925 print_button_press (event->device);
15927 if (event->button == 1 && pixmap != NULL) {
15929 gdk_event_get_axis ((GdkEvent *)event, GDK_AXIS_PRESSURE, &pressure);
15930 draw_brush (widget, event->device->source, event->x, event->y, pressure);
15937 motion_notify_event (GtkWidget *widget, GdkEventMotion *event)
15941 GdkModifierType state;
15943 if (event->is_hint)
15945 gdk_device_get_state (event->device, event->window, NULL, &state);
15946 gdk_event_get_axis ((GdkEvent *)event, GDK_AXIS_X, &x);
15947 gdk_event_get_axis ((GdkEvent *)event, GDK_AXIS_Y, &y);
15948 gdk_event_get_axis ((GdkEvent *)event, GDK_AXIS_PRESSURE, &pressure);
15954 gdk_event_get_axis ((GdkEvent *)event, GDK_AXIS_PRESSURE, &pressure);
15955 state = event->state;
15958 if (state & GDK_BUTTON1_MASK && pixmap != NULL)
15959 draw_brush (widget, event->device->source, x, y, pressure);
15965 input_dialog_destroy (GtkWidget *w, gpointer data)
15967 *((GtkWidget **)data) = NULL;
15971 create_input_dialog ()
15973 static GtkWidget *inputd = NULL;
15977 inputd = gtk_input_dialog_new();
15979 g_signal_connect (inputd, "destroy",
15980 G_CALLBACK (input_dialog_destroy), (gpointer) &inputd);
15981 g_signal_connect_swapped (GTK_INPUT_DIALOG (inputd)->close_button,
15983 G_CALLBACK (gtk_widget_hide),
15985 gtk_widget_hide (GTK_INPUT_DIALOG (inputd)->save_button);
15987 gtk_widget_show (inputd);
15991 if (!gtk_widget_get_mapped (inputd))
15992 gtk_widget_show (inputd);
15994 gdk_window_raise (inputd->window);
15999 main (int argc, char *argv[])
16002 GtkWidget *drawing_area;
16007 gtk_init (&argc, &argv);
16009 window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
16010 gtk_widget_set_name (window, "Test Input");
16012 vbox = gtk_vbox_new (FALSE, 0);
16013 gtk_container_add (GTK_CONTAINER (window), vbox);
16014 gtk_widget_show (vbox);
16016 g_signal_connect (window, "destroy",
16017 G_CALLBACK (gtk_main_quit), NULL);
16019 /* Create the drawing area */
16021 drawing_area = gtk_drawing_area_new ();
16022 gtk_widget_set_size_request (GTK_WIDGET (drawing_area), 200, 200);
16023 gtk_box_pack_start (GTK_BOX (vbox), drawing_area, TRUE, TRUE, 0);
16025 gtk_widget_show (drawing_area);
16027 /* Signals used to handle backing pixmap */
16029 g_signal_connect (drawing_area, "expose_event",
16030 G_CALLBACK (expose_event), NULL);
16031 g_signal_connect (drawing_area, "configure_event",
16032 G_CALLBACK (configure_event), NULL);
16034 /* Event signals */
16036 g_signal_connect (drawing_area, "motion_notify_event",
16037 G_CALLBACK (motion_notify_event), NULL);
16038 g_signal_connect (drawing_area, "button_press_event",
16039 G_CALLBACK (button_press_event), NULL);
16041 gtk_widget_set_events (drawing_area, GDK_EXPOSURE_MASK
16042 | GDK_LEAVE_NOTIFY_MASK
16043 | GDK_BUTTON_PRESS_MASK
16044 | GDK_POINTER_MOTION_MASK
16045 | GDK_POINTER_MOTION_HINT_MASK);
16047 /* The following call enables tracking and processing of extension
16048 events for the drawing area */
16049 gtk_widget_set_extension_events (drawing_area, GDK_EXTENSION_EVENTS_CURSOR);
16051 /* .. And some buttons */
16052 button = gtk_button_new_with_label ("Input Dialog");
16053 gtk_box_pack_start (GTK_BOX (vbox), button, FALSE, FALSE, 0);
16055 g_signal_connect (button, "clicked",
16056 G_CALLBACK (create_input_dialog), NULL);
16057 gtk_widget_show (button);
16059 button = gtk_button_new_with_label ("Quit");
16060 gtk_box_pack_start (GTK_BOX (vbox), button, FALSE, FALSE, 0);
16062 g_signal_connect_swapped (button, "clicked",
16063 G_CALLBACK (gtk_widget_destroy),
16065 gtk_widget_show (button);
16067 gtk_widget_show (window);
16073 <!-- example-end -->