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#include <gtk/gtk.h>
static gboolean
da_expose (GtkWidget *widget,
GdkEventExpose *event,
gpointer user_data)
{
GtkOffscreenWindow *offscreen = (GtkOffscreenWindow *)user_data;
GdkPixmap *pixmap;
cairo_t *cr;
if (gtk_widget_is_drawable (widget))
{
pixmap = gtk_offscreen_window_get_pixmap (offscreen);
cr = gdk_cairo_create (gtk_widget_get_window (widget));
gdk_cairo_set_source_pixmap (cr, pixmap, 50, 50);
cairo_paint (cr);
cairo_destroy (cr);
}
return FALSE;
}
static gboolean
offscreen_damage (GtkWidget *widget,
GdkEventExpose *event,
GtkWidget *da)
{
gtk_widget_queue_draw (da);
return TRUE;
}
static gboolean
da_button_press (GtkWidget *area, GdkEventButton *event, GtkWidget *button)
{
gtk_widget_set_size_request (button, 150, 60);
return TRUE;
}
int
main (int argc, char **argv)
{
GtkWidget *window;
GtkWidget *button;
GtkWidget *offscreen;
GtkWidget *da;
gtk_init (&argc, &argv);
offscreen = gtk_offscreen_window_new ();
button = gtk_button_new_with_label ("Test");
gtk_widget_set_size_request (button, 50, 50);
gtk_container_add (GTK_CONTAINER (offscreen), button);
gtk_widget_show (button);
gtk_widget_show (offscreen);
/* Queue exposures and ensure they are handled so
* that the result is uptodate for the first
* expose of the window. If you want to get further
* changes, also track damage on the offscreen
* as done above.
*/
gtk_widget_queue_draw (offscreen);
window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
g_signal_connect (window, "delete-event",
G_CALLBACK (gtk_main_quit), window);
da = gtk_drawing_area_new ();
gtk_container_add (GTK_CONTAINER (window), da);
g_signal_connect (da,
"expose-event",
G_CALLBACK (da_expose),
offscreen);
g_signal_connect (offscreen,
"damage-event",
G_CALLBACK (offscreen_damage),
da);
gtk_widget_add_events (da, GDK_BUTTON_PRESS_MASK);
g_signal_connect (da, "button_press_event", G_CALLBACK (da_button_press),
button);
gtk_widget_show_all (window);
gtk_main();
return 0;
}
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