1 <!-- ##### SECTION Title ##### -->
4 <!-- ##### SECTION Short_Description ##### -->
5 The base class of the Gtk type hierarchy.
7 <!-- ##### SECTION Long_Description ##### -->
9 <title>Description</title>
11 #GtkObject is the base class for all widgets, and for a few
12 non-widget objects such as #GtkAdjustment. #GtkObject predates
13 #GObject; non-widgets that derive from #GtkObject rather than
14 #GObject do so for backward compatibility reasons.
17 The most interesting difference between #GtkObject and #GObject is the
18 "floating" reference count. A #GObject is created with a reference count of 1,
19 owned by the creator of the #GObject. (The owner of a reference is the code
20 section that has the right to call g_object_unref() in order to remove that
21 reference.) A #GtkObject is created with a reference count of 1 also, but it
22 isn't owned by anyone; calling g_object_unref() on the newly-created #GtkObject
23 is incorrect. Instead, the initial reference count of a #GtkObject is "floating."
24 The floating reference can be removed by anyone at any time, by calling
25 gtk_object_sink(). gtk_object_sink() does nothing if an object is already
26 sunk (has no floating reference).
29 When you add a widget to its parent container, the parent container
32 g_object_ref (G_OBJECT (child_widget));
33 gtk_object_sink (GTK_OBJECT (child_widget));
35 This means that the container now owns a reference to the child widget (since
36 it called g_object_ref()), and the child widget has no floating reference.
39 The purpose of the floating reference is to keep the child widget alive
40 until you add it to a parent container:
42 button = gtk_button_new ();
43 /* button has one floating reference to keep it alive */
44 gtk_container_add (GTK_CONTAINER (container), button);
45 /* button has one non-floating reference owned by the container */
49 #GtkWindow is a special case, because GTK+ itself will ref/sink it on creation.
50 That is, after calling gtk_window_new(), the #GtkWindow will have one
51 reference which is owned by GTK+, and no floating references.
55 One more factor comes into play: the "destroy" signal, emitted by the
56 gtk_object_destroy() method. The "destroy" signal asks all code owning a
57 reference to an object to release said reference. So, for example, if you call
58 gtk_object_destroy() on a #GtkWindow, GTK+ will release the reference count that
59 it owns; if you call gtk_object_destroy() on a #GtkButton, then the button will
60 be removed from its parent container and the parent container will release its
61 reference to the button. Because these references are released, calling
62 gtk_object_destroy() should result in freeing all memory associated with an
63 object, unless some buggy code fails to release its references in response to
64 the "destroy" signal. Freeing memory (referred to as
65 <firstterm>finalization</firstterm> only happens if the reference count reaches
70 Some simple rules for handling #GtkObject:
73 Never call g_object_unref() unless you have previously called g_object_ref(),
74 even if you created the #GtkObject. (Note: this is <emphasis>not</emphasis>
75 true for #GObject; for #GObject, the creator of the object owns a reference.)
78 Call gtk_object_destroy() to get rid of most objects in most cases.
79 In particular, widgets are almost always destroyed in this way.
81 <listitem><para> Because of the floating reference count, you don't need to
82 worry about reference counting for widgets and toplevel windows, unless you
83 explicitly call g_object_ref() yourself. </para></listitem>
89 <!-- ##### SECTION See_Also ##### -->
94 <!-- ##### STRUCT GtkObject ##### -->
96 The object itself. You should never use these members directly-
97 instead you the accessing macros.
101 <!-- ##### MACRO GTK_OBJECT_TYPE ##### -->
103 Get the type of an object.
107 <!-- # Unused Parameters # -->
108 @obj: the object whose type we wish to get.
111 <!-- ##### MACRO GTK_OBJECT_TYPE_NAME ##### -->
119 <!-- ##### ENUM GtkObjectFlags ##### -->
121 Tells about the state of the object.
125 @GTK_FLOATING: whether the object is orphaned. Objects that take
126 strong hold of an object may gtk_object_sink() it, after obtaining
127 there own references, if they believe they are nearly primary
128 ownership of the object.
129 GTK_CONNECTED: refers to whether are signals are connected to this
131 @GTK_RESERVED_1: reserved for future use
132 @GTK_RESERVED_2: reserved for future use
134 <!-- ##### MACRO GTK_OBJECT_FLAGS ##### -->
136 Get the #GtkObjectFlags for an object without directly
137 accessing its members.
140 @obj: the object whose flags are returned.
143 <!-- ##### MACRO GTK_OBJECT_FLOATING ##### -->
145 Evaluates to %TRUE if the object still has its floating reference count.
146 See the overview documentation for #GtkObject.
149 @obj: the object to examine.
152 <!-- ##### MACRO GTK_OBJECT_CONNECTED ##### -->
154 Test whether a GtkObject has had a signal connected to it.
157 @obj: the object to examine.
160 <!-- ##### MACRO GTK_OBJECT_SET_FLAGS ##### -->
162 Turn on certain object flags. (Private)
165 @obj: the object to affect.
166 @flag: the flags to set.
169 <!-- ##### MACRO GTK_OBJECT_UNSET_FLAGS ##### -->
171 Turn off certain object flags. (Private)
174 @obj: the object to affect.
175 @flag: the flags to unset.
178 <!-- ##### ENUM GtkArgFlags ##### -->
180 Possible flags indicating how an argument should be treated.
181 Deprecated in favor of #GParamSpec features.
184 @GTK_ARG_READABLE: the argument is readable. (i.e. can be queried)
185 @GTK_ARG_WRITABLE: the argument is writable. (i.e. settable)
186 @GTK_ARG_CONSTRUCT: the argument needs construction.
187 @GTK_ARG_CONSTRUCT_ONLY: the argument needs construction (and will
188 be set once during object creation), but is otherwise cannot be
189 set. Hence this flag is not allowed with #GTK_ARG_WRITABLE,
190 and is redundant with #GTK_ARG_CONSTRUCT.
191 @GTK_ARG_CHILD_ARG: an argument type that applies to (and may be different for)
192 each child. Used by #GtkContainer.
194 <!-- ##### FUNCTION gtk_object_new ##### -->
196 Construct an object given its arguments, enumerated in the call to the
197 function. Deprecated in favor of g_object_new().
200 @type: the type identifying this object. Returned by gtk_type_unique()
201 although (for a properly-written object it should be accessible through
203 @first_property_name:
204 @Varargs: the first argument's value, followed by any number of
205 name/argument-value pairs, terminated with NULL.
206 @Returns: the new GtkObject.
207 <!-- # Unused Parameters # -->
208 @first_arg_name: name of the first argument to set when constructing
212 <!-- ##### FUNCTION gtk_object_sink ##### -->
214 Removes the floating reference from a #GtkObject, if it exists;
215 otherwise does nothing. See the #GtkObject overview documentation at
219 @object: the object to sink.
222 <!-- ##### FUNCTION gtk_object_ref ##### -->
224 Increase the reference count of the object, simply calls
225 g_object_ref() internally.
226 Deprecated in favor of g_object_ref().
229 @object: the object to reference.
230 @Returns: the object which was referenced
233 <!-- ##### FUNCTION gtk_object_unref ##### -->
235 Decrease the reference count of an object. When its reference count drops to 0,
236 the object is finalized (i.e. its memory is freed). Deprecated in favor of
237 g_object_unref(). Simply calls g_object_unref() internally.
240 @object: the object to dereference.
243 <!-- ##### FUNCTION gtk_object_weakref ##### -->
245 Adds a weak reference callback to an object. Deprecated in favor of
246 g_object_weak_ref(). Weak references are used for notification when an object is
247 finalized. They are called "weak references" because they allow you to safely
248 hold a pointer to an object without calling g_object_ref() (g_object_ref() adds
249 a strong reference, that is, forces the object to stay alive).
252 @object: object to weakly reference.
253 @notify: callback to invoke before the object is freed.
254 @data: extra data to pass to #notify.
257 <!-- ##### FUNCTION gtk_object_weakunref ##### -->
259 Removes a weak reference callback to an object.
262 @object: object stop weakly referencing.
263 @notify: callback to search for.
264 @data: data to search for.
267 <!-- ##### FUNCTION gtk_object_destroy ##### -->
269 Emits the "destroy" signal notifying all reference holders that they should
270 release the #GtkObject. See the overview documentation at the top of the
271 page for more details.
274 The memory for the object itself won't be deleted until
275 its reference count actually drops to 0; gtk_object_destroy() merely asks
276 reference holders to release their references, it does not free the object.
279 @object: the object to destroy.
282 <!-- ##### FUNCTION gtk_object_get ##### -->
284 Get properties of an object. Deprecated in favor of g_object_get(). It takes an
285 object, then a list of name/return location pairs in a list, followed by NULL.
288 @object: a #GtkObject
289 @first_property_name: name of first property to get the value for
290 @Varargs: list of name-return location pairs.
293 <!-- ##### FUNCTION gtk_object_set ##### -->
295 Set properties on an object. Deprecated in favor of g_object_set().
298 It takes an object, then a list of name/value pairs
299 in a list, followed by NULL.
304 void set_box_properties(GtkBox* box)
306 gtk_object_set(GTK_OBJECT(box), "homogeneous", TRUE,
314 @object: the object whose arguments should be set.
315 @first_property_name: name of the first property to set
316 @Varargs: the value of the first argument, followed optionally
317 by more name/value pairs, followed by NULL.
320 <!-- ##### FUNCTION gtk_object_set_data ##### -->
322 Deprecated in favor of g_object_set_data().
323 Each object carries around a table of associations from
324 strings to pointers. This function lets you set an association.
327 If the object already had an association with that name,
328 the old association will be destroyed.
331 @object: object containing the associations.
332 @key: name of the key.
333 @data: data to associate with that key.
336 <!-- ##### FUNCTION gtk_object_set_data_full ##### -->
338 Deprecated in favor of g_object_set_data_full().
339 Like gtk_object_set_data() except it adds notification
340 for when the association is destroyed, either by
341 gtk_object_remove_data() or when the object is destroyed.
344 @object: object containing the associations.
345 @key: name of the key.
346 @data: data to associate with that key.
347 @destroy: function to call when the association is destroyed.
350 <!-- ##### FUNCTION gtk_object_remove_data ##### -->
352 Deprecated in favor of setting object data to %NULL using g_object_set_data().
353 Removes a specified datum from the object's data associations (the object_data).
354 Subsequent calls to gtk_object_get_data() will return NULL.
357 If you specified a destroy handler with gtk_object_set_data_full(),
361 @object: the object maintaining the association.
362 @key: name of the key for that association.
365 <!-- ##### FUNCTION gtk_object_get_data ##### -->
367 Deprecated in favor of g_object_get_data().
368 Get a named field from the object's table of associations (the object_data).
371 @object: the object maintaining the associations.
372 @key: name of the key for that association.
373 @Returns: the data if found, or NULL if no such data exists.
376 <!-- ##### FUNCTION gtk_object_remove_no_notify ##### -->
378 Deprecated in favor of g_object_steal_data().
379 Remove a specified datum from the object's data associations (the object_data),
380 without invoking the association's destroy handler.
383 Just like gtk_object_remove_data() except that any destroy handler
385 Therefore this only affects data set using gtk_object_set_data_full().
388 @object: the object maintaining the association.
389 @key: name of the key for that association.
392 <!-- ##### FUNCTION gtk_object_set_user_data ##### -->
394 Deprecated in favor of g_object_set_data().
395 For convenience, every object offers a generic user data
396 pointer. The function set it.
399 This function is equivalent to:
402 gtk_object_set_data(object, "user_data", data);
407 @object: the object whose user data should be set.
408 @data: the new value for the user data.
411 <!-- ##### FUNCTION gtk_object_get_user_data ##### -->
413 Deprecated in favor of g_object_get_data().
414 Get the object's user data pointer.
417 This is intended to be a pointer for your convenience in
418 writing applications.
422 @Returns: the user data field for object.
425 <!-- ##### FUNCTION gtk_object_add_arg_type ##### -->
427 Deprecated in favor of the #GObject property system including #GParamSpec.
428 Add a new type of argument to an object class.
429 Usually this is called when registering a new type of object.
432 @arg_name: fully qualify object name, for example GtkObject::user_data.
433 @arg_type: type of the argument.
434 @arg_flags: bitwise-OR of the #GtkArgFlags enum. (Whether the argument is
435 settable or gettable, whether it is set when the object is constructed.)
436 @arg_id: an internal number, passed in from here to the "set_arg" and
437 "get_arg" handlers of the object.
440 <!-- ##### FUNCTION gtk_object_set_data_by_id ##### -->
442 Deprecated in favor of g_object_set_qdata().
443 Just like gtk_object_set_data() except that it takes
444 a #GQuark instead of a string, so it is slightly faster.
447 Use gtk_object_data_try_key() and gtk_object_data_force_id()
448 to get an id from a string.
451 @object: object containing the associations.
452 @data_id: quark of the key.
453 @data: data to associate with that key.
456 <!-- ##### FUNCTION gtk_object_set_data_by_id_full ##### -->
458 Deprecated in favor of g_object_set_qdata_full().
459 Just like gtk_object_set_data_full() except that it takes
460 a #GQuark instead of a string, so it is slightly faster.
463 Use gtk_object_data_try_key() and gtk_object_data_force_id()
464 to get an id from a string.
467 @object: object containing the associations.
468 @data_id: quark of the key.
469 @data: data to associate with that key.
470 @destroy: function to call when the association is destroyed.
473 <!-- ##### FUNCTION gtk_object_get_data_by_id ##### -->
475 Deprecated in favor of g_object_get_qdata().
476 Just like gtk_object_get_data() except that it takes
477 a #GQuark instead of a string, so it is slightly faster.
480 Use gtk_object_data_try_key() and gtk_object_data_force_id()
481 to get an id from a string.
484 @object: object containing the associations.
485 @data_id: quark of the key.
486 @Returns: the data if found, or NULL if no such data exists.
489 <!-- ##### FUNCTION gtk_object_remove_data_by_id ##### -->
491 Deprecated in favor of g_object_set_qdata() called with data of %NULL.
492 Just like gtk_object_remove_data() except that it takes
493 a #GQuark instead of a string, so it is slightly faster.
496 Remove a specified datum from the object's data associations.
497 Subsequent calls to gtk_object_get_data() will return NULL.
500 Use gtk_object_data_try_key() and gtk_object_data_force_id()
501 to get an id from a string.
504 @object: object containing the associations.
505 @data_id: quark of the key.
508 <!-- ##### FUNCTION gtk_object_remove_no_notify_by_id ##### -->
510 Deprecated in favor of g_object_steal_qdata().
511 Just like gtk_object_remove_no_notify() except that it takes
512 a #GQuark instead of a string, so it is slightly faster.
515 Use gtk_object_data_try_key() and gtk_object_data_force_id()
516 to get an id from a string.
519 @object: object containing the associations.
521 <!-- # Unused Parameters # -->
522 @data_id: quark of the key.
525 <!-- ##### MACRO gtk_object_data_try_key ##### -->
527 Useless deprecated macro. Ignore it.
532 <!-- ##### MACRO gtk_object_data_force_id ##### -->
534 Useless deprecated macro. Ignore it.
539 <!-- ##### SIGNAL GtkObject::destroy ##### -->
541 Signals that all holders of a reference to the #GtkObject should release
542 the reference that they hold. May result in finalization of the object
543 if all references are released.
546 @object: the object which received the signal.
548 <!-- ##### ARG GtkObject:user-data ##### -->
550 A pointer for convenience when programming applications.