[mutter] window-actor: Base the paint volume on our children, not our shape

[Jasper St. Pierre <jstpierre src gnome org>]

commit 6fbd21001b04c5183111111e50948f48aa1be44a
Author: Jasper St. Pierre <jstpierre mecheye net>
Date:   Wed Jul 30 17:09:02 2014 +0200

    window-actor: Base the paint volume on our children, not our shape
    
    This was wrong for subsurfaces that extend beyond the parent's shape,
    since the paint volume would be wrong in this case. Instead of using the
    shape region which can be out of date and wrong, just use the union of
    our children's volumes, which is a lot easier to manage.

 src/compositor/meta-window-actor.c |   33 ++++++++++++++++-----------------
 1 files changed, 16 insertions(+), 17 deletions(-)
---
diff --git a/src/compositor/meta-window-actor.c b/src/compositor/meta-window-actor.c
index 5415ac3..66a7e3c 100644
--- a/src/compositor/meta-window-actor.c
+++ b/src/compositor/meta-window-actor.c
@@ -710,25 +710,16 @@ meta_window_actor_get_paint_volume (ClutterActor       *actor,
 {
   MetaWindowActor *self = META_WINDOW_ACTOR (actor);
   MetaWindowActorPrivate *priv = self->priv;
-  cairo_rectangle_int_t unobscured_bounds, bounds;
   gboolean appears_focused = meta_window_appears_focused (priv->window);
-  ClutterVertex origin;
 
   /* The paint volume is computed before paint functions are called
    * so our bounds might not be updated yet. Force an update. */
   meta_window_actor_handle_updates (self);
 
-  meta_window_actor_get_shape_bounds (self, &bounds);
-
-  if (priv->surface)
-    {
-      if (meta_surface_actor_get_unobscured_bounds (priv->surface, &unobscured_bounds))
-        gdk_rectangle_intersect (&bounds, &unobscured_bounds, &bounds);
-    }
-
   if (appears_focused ? priv->focused_shadow : priv->unfocused_shadow)
     {
       cairo_rectangle_int_t shadow_bounds;
+      ClutterActorBox shadow_box;
 
       /* We could compute an full clip region as we do for the window
        * texture, but the shadow is relatively cheap to draw, and
@@ -738,16 +729,24 @@ meta_window_actor_get_paint_volume (ClutterActor       *actor,
        */
 
       meta_window_actor_get_shadow_bounds (self, appears_focused, &shadow_bounds);
-      gdk_rectangle_union (&bounds, &shadow_bounds, &bounds);
+      shadow_box.x1 = shadow_bounds.x;
+      shadow_box.x2 = shadow_bounds.x + shadow_bounds.width;
+      shadow_box.y1 = shadow_bounds.y;
+      shadow_box.y2 = shadow_bounds.y + shadow_bounds.height;
+
+      clutter_paint_volume_union_box (volume, &shadow_box);
     }
 
-  origin.x = bounds.x;
-  origin.y = bounds.y;
-  origin.z = 0.0f;
-  clutter_paint_volume_set_origin (volume, &origin);
+  if (priv->surface)
+    {
+      const ClutterPaintVolume *child_volume;
 
-  clutter_paint_volume_set_width (volume, bounds.width);
-  clutter_paint_volume_set_height (volume, bounds.height);
+      child_volume = clutter_actor_get_transformed_paint_volume (CLUTTER_ACTOR (priv->surface), actor);
+      if (!child_volume)
+        return FALSE;
+
+      clutter_paint_volume_union (volume, child_volume);
+    }
 
   return TRUE;
 }