Add gdk_window_set_invalidate_handler

This lets you register callbacks for when child widgets invalidate
areas of the window read it and/or change it.

For instance, this lets you do rendering effects and keeping offscreen
caches uptodate.

1 files changed, 20 insertions, 0 deletions

diff --git a/gdk/gdkwindow.h b/gdk/gdkwindow.h
index b898a394c1..73e6f86494 100644
--- a/gdk/gdkwindow.h
+++ b/gdk/gdkwindow.h
@@ -679,6 +679,26 @@ gboolean gdk_window_set_static_gravities (GdkWindow *window,
 
 /* GdkWindow */
 
+/**
+ * GdkWindowInvalidateHandlerFunc:
+ * @window: a #GdkWindow
+ * @region: a #cairo_region_t
+ *
+ * Whenever some area of the window is invalidated (directly in the
+ * window or in a child window) this gets called with @region in
+ * the coordinate space of @window. You can use @region to just
+ * keep track of the dirty region, or you can actually change
+ * @region in case you are doing display tricks like showing
+ * a child in multiple places.
+ *
+ * Since: 3.10
+ */
+typedef void (*GdkWindowInvalidateHandlerFunc)  (GdkWindow *window,
+						 cairo_region_t *region);
+GDK_AVAILABLE_IN_3_10
+void gdk_window_set_invalidate_handler (GdkWindow *window,
+					GdkWindowInvalidateHandlerFunc handler);
+
 GDK_AVAILABLE_IN_ALL
 gboolean      gdk_window_has_native         (GdkWindow       *window);
 GDK_AVAILABLE_IN_ALL