Document GdkScreen.

[~andy/gtk] / docs / reference / gtk / tmpl / gtkimage.sgml

<!-- ##### SECTION Title ##### -->
GtkImage

<!-- ##### SECTION Short_Description ##### -->
A widget displaying an image

<!-- ##### SECTION Long_Description ##### -->
<para>
The #GtkImage widget displays an image. Various kinds of object 
can be displayed as an image; most typically, you would load a 
#GdkPixbuf ("pixel buffer") from a file, and then display that. 
There's a convenience function to do this, gtk_image_new_from_file(),
used as follows:
<informalexample><programlisting>
  GtkWidget *image;
  image = gtk_image_new_from_file ("myfile.png");
</programlisting></informalexample>
If the file isn't loaded successfully, the image will contain a
"broken image" icon similar to that used in many web browsers.
If you want to handle errors in loading the file yourself, 
for example by displaying an error message, then load the image with
gdk_pixbuf_new_from_file(), then create the #GtkImage with 
gtk_image_new_from_pixbuf().
</para>
<para>
The image file may contain an animation, if so the #GtkImage will 
display an animation (#GdkPixbufAnimation) instead of a static image.
</para>
<para>
#GtkImage is a subclass of #GtkMisc, which implies that you can 
align it (center, left, right) and add padding to it, using 
#GtkMisc methods.
</para>
<para>
#GtkImage is a "no window" widget (has no #GdkWindow of its own), 
so by default does not receive events. If you want to receive events
on the image, such as button clicks, place the image inside a 
#GtkEventBox, then connect to the event signals on the event box.
<example>
<title>Handling button press events on a 
<structname>GtkImage</structname>.</title>
<programlisting>
  static void
  button_press_callback (GtkWidget      *event_box, 
                         GdkEventButton *event,
                         gpointer        data)
  {
    g_print ("Event box clicked at coordinates &percent;d,&percent;d\n", 
             event->x, event->y);

    /* Returning TRUE means we handled the event, so the signal 
     * emission should be stopped (don't call any further 
     * callbacks that may be connected). Return FALSE
     * to continue invoking callbacks.
     */
    return TRUE;
  }

  static GtkWidget*
  create_image (void)
  {
    GtkWidget *image;
    GtkWidget *event_box;

    image = gtk_image_new_from_file ("myfile.png");

    event_box = gtk_event_box_new (<!>);

    gtk_container_add (GTK_CONTAINER (event_box), image);

    g_signal_connect (G_OBJECT (event_box), 
                      "button_press_event",
                      G_CALLBACK (button_press_callback),
                      image);

    return image;
  }
</programlisting>
</example>
</para>
<para>
When handling events on the event box, keep in mind that coordinates
in the image may be different from event box coordinates due to 
the alignment and padding settings on the image (see #GtkMisc). 
The simplest way to solve this is to set the alignment to 0.0
(left/top), and set the padding to zero. Then the origin of 
the image will be the same as the origin of the event box.
</para>

<para>
Sometimes an application will want to avoid depending on external data
files, such as image files. GTK+ comes with a program to avoid this,
called <application>gdk-pixbuf-csource</application>. This program
allows you to convert an image into a C variable declaration, which
can then be loaded into a #GdkPixbuf using
gdk_pixbuf_new_from_inline().
</para>

<!-- ##### SECTION See_Also ##### -->
<para>
#GdkPixbuf
</para>

<!-- ##### STRUCT GtkImage ##### -->
<para>
This struct contain private data only and should be accessed by the functions
below.
</para>


<!-- ##### ENUM GtkImageType ##### -->
<para>
Describes the image data representation used by a #GtkImage. If you
want to get the image from the widget, you can only get the
currently-stored representation. e.g.  if the
gtk_image_get_storage_type() returns #GTK_IMAGE_PIXBUF, then you can
call gtk_image_get_pixbuf() but not gtk_image_get_stock().  For empty
images, you can request any storage type (call any of the "get"
functions), but they will all return %NULL values.
</para>

@GTK_IMAGE_EMPTY: there is no image displayed by the widget
@GTK_IMAGE_PIXMAP: the widget contains a #GdkPixmap
@GTK_IMAGE_IMAGE: the widget contains a #GdkImage
@GTK_IMAGE_PIXBUF: the widget contains a #GdkPixbuf
@GTK_IMAGE_STOCK: the widget contains a stock icon name
@GTK_IMAGE_ICON_SET: the widget contains a #GtkIconSet
@GTK_IMAGE_ANIMATION: the widget contains a #GdkPixbufAnimation

<!-- ##### FUNCTION gtk_image_get_icon_set ##### -->
<para>

</para>

@image: 
@icon_set: 
@size: 


<!-- ##### FUNCTION gtk_image_get_image ##### -->
<para>

</para>

@image: 
@gdk_image: 
@mask: 


<!-- ##### FUNCTION gtk_image_get_pixbuf ##### -->
<para>

</para>

@image: 
@Returns: 


<!-- ##### FUNCTION gtk_image_get_pixmap ##### -->
<para>

</para>

@image: 
@pixmap: 
@mask: 


<!-- ##### FUNCTION gtk_image_get_stock ##### -->
<para>

</para>

@image: 
@stock_id: 
@size: 


<!-- ##### FUNCTION gtk_image_get_animation ##### -->
<para>

</para>

@image: 
@Returns: 


<!-- ##### FUNCTION gtk_image_get_storage_type ##### -->
<para>

</para>

@image: 
@Returns: 


<!-- ##### FUNCTION gtk_image_new_from_file ##### -->
<para>

</para>

@filename: 
@Returns: 


<!-- ##### FUNCTION gtk_image_new_from_icon_set ##### -->
<para>

</para>

@icon_set: 
@size: 
@Returns: 


<!-- ##### FUNCTION gtk_image_new_from_image ##### -->
<para>

</para>

@image: 
@mask: 
@Returns: 


<!-- ##### FUNCTION gtk_image_new_from_pixbuf ##### -->
<para>

</para>

@pixbuf: 
@Returns: 


<!-- ##### FUNCTION gtk_image_new_from_pixmap ##### -->
<para>

</para>

@pixmap: 
@mask: 
@Returns: 


<!-- ##### FUNCTION gtk_image_new_from_stock ##### -->
<para>

</para>

@stock_id: 
@size: 
@Returns: 


<!-- ##### FUNCTION gtk_image_new_from_animation ##### -->
<para>

</para>

@animation: 
@Returns: 


<!-- ##### FUNCTION gtk_image_set_from_file ##### -->
<para>

</para>

@image: 
@filename: 


<!-- ##### FUNCTION gtk_image_set_from_icon_set ##### -->
<para>

</para>

@image: 
@icon_set: 
@size: 


<!-- ##### FUNCTION gtk_image_set_from_image ##### -->
<para>

</para>

@image: 
@gdk_image: 
@mask: 


<!-- ##### FUNCTION gtk_image_set_from_pixbuf ##### -->
<para>

</para>

@image: 
@pixbuf: 


<!-- ##### FUNCTION gtk_image_set_from_pixmap ##### -->
<para>

</para>

@image: 
@pixmap: 
@mask: 


<!-- ##### FUNCTION gtk_image_set_from_stock ##### -->
<para>

</para>

@image: 
@stock_id: 
@size: 


<!-- ##### FUNCTION gtk_image_set_from_animation ##### -->
<para>

</para>

@image: 
@animation: 


<!-- ##### FUNCTION gtk_image_new ##### -->
<para>

</para>

@Returns: the #GtkImage
<!-- # Unused Parameters # -->
@val: 
@mask: a #GdkBitmap that indicates which parts of the image should be transparent.


<!-- ##### FUNCTION gtk_image_set ##### -->
<para>
Sets the #GtkImage.
</para>

@image: a #GdkPixmap
@val: 
@mask: a #GdkBitmap that indicates which parts of the image should be transparent.


<!-- ##### FUNCTION gtk_image_get ##### -->
<para>
Gets the #GtkImage.
</para>

@image: a #GdkPixmap
@val: 
@mask: a #GdkBitmap that indicates which parts of the image should be transparent.


<!-- ##### ARG GtkImage:pixbuf ##### -->
<para>

</para>

<!-- ##### ARG GtkImage:pixmap ##### -->
<para>

</para>

<!-- ##### ARG GtkImage:image ##### -->
<para>

</para>

<!-- ##### ARG GtkImage:mask ##### -->
<para>

</para>

<!-- ##### ARG GtkImage:file ##### -->
<para>

</para>

<!-- ##### ARG GtkImage:stock ##### -->
<para>

</para>

<!-- ##### ARG GtkImage:icon-set ##### -->
<para>

</para>

<!-- ##### ARG GtkImage:icon-size ##### -->
<para>

</para>

<!-- ##### ARG GtkImage:pixbuf-animation ##### -->
<para>

</para>

<!-- ##### ARG GtkImage:storage-type ##### -->
<para>

</para>