Bug 631599 - Allow to use arbitrary surfaces for offscreen windows

Add signal GdkWindow::create-surface which allows to use any
surface type as storage for offscreen windows.

Test the new signal in tests/gdkoffscreenbox.c

1 files changed, 28 insertions, 10 deletions

diff --git a/gdk/gdkoffscreenwindow.c b/gdk/gdkoffscreenwindow.c
index 0cea577379..55d1fad827 100644
--- a/gdk/gdkoffscreenwindow.c
+++ b/gdk/gdkoffscreenwindow.c
@@ -113,17 +113,11 @@ get_surface (GdkOffscreenWindow *offscreen)
   if (! offscreen->surface)
     {
       GdkWindowObject *private = (GdkWindowObject *) offscreen->wrapper;
-      cairo_surface_t *similar;
 
-      similar = _gdk_drawable_ref_cairo_surface ((GdkWindow *)private->parent);
-
-      offscreen->surface = cairo_surface_create_similar (similar,
-                                                         /* FIXME: use visual */
-                                                         CAIRO_CONTENT_COLOR,
-                                                         private->width,
-                                                         private->height);
-
-      cairo_surface_destroy (similar);
+      g_signal_emit_by_name (private, "create-surface",
+                             private->width,
+                             private->height,
+                             &offscreen->surface);
     }
 
   return offscreen->surface;
@@ -155,6 +149,30 @@ gdk_offscreen_window_ref_cairo_surface (GdkDrawable *drawable)
   return cairo_surface_reference (get_surface (offscreen));
 }
 
+cairo_surface_t *
+_gdk_offscreen_window_create_surface (GdkWindow *offscreen,
+                                      gint       width,
+                                      gint       height)
+{
+  GdkWindowObject *private = (GdkWindowObject *) offscreen;
+  cairo_surface_t *similar;
+  cairo_surface_t *surface;
+
+  g_return_val_if_fail (GDK_IS_OFFSCREEN_WINDOW (private->impl), NULL);
+
+  similar = _gdk_drawable_ref_cairo_surface ((GdkWindow *)private->parent);
+
+  surface = cairo_surface_create_similar (similar,
+                                          /* FIXME: use visual */
+                                          CAIRO_CONTENT_COLOR,
+                                          width,
+                                          height);
+
+  cairo_surface_destroy (similar);
+
+  return surface;
+}
+
 void
 _gdk_offscreen_window_new (GdkWindow     *window,
 			   GdkWindowAttr *attributes,