[clutter] actor: Provide a better default pick() behaviour

[Emmanuele Bassi <ebassi src gnome org>]

commit 629ded568e30a845337e41f04b04b5fcc20a82d4
Author: Emmanuele Bassi <ebassi linux intel com>
Date:   Tue Jan 17 16:13:55 2012 +0000

    actor: Provide a better default pick() behaviour
    
    The default pick() behaviour does not take into consideration the
    children of a ClutterActor because the existing containter actors
    usually override pick(), chain up, and then paint their children.
    
    With ClutterActor now a concrete class, though, we need a way to pick
    its children without requiring a sub-class; we could simply iterate over
    the children inside the default pick() implementation, but this would
    lead to double painting, which is not acceptable.
    
    A moderately gross hack is to check if the Actor instance did override
    the pick() implementation, and if it is not the case, paint the children
    in pick mode.

 clutter/clutter-actor.c |   17 +++++++++++++++++
 1 files changed, 17 insertions(+), 0 deletions(-)
---
diff --git a/clutter/clutter-actor.c b/clutter/clutter-actor.c
index 9ec6ceb..c51d8c0 100644
--- a/clutter/clutter-actor.c
+++ b/clutter/clutter-actor.c
@@ -1703,6 +1703,23 @@ clutter_actor_real_pick (ClutterActor       *self,
 
       cogl_rectangle (0, 0, width, height);
     }
+
+  /* XXX - this thoroughly sucks, but we need to maintain compatibility
+   * with existing container classes that override the pick() virtual
+   * and chain up to the default implementation - otherwise we'll end up
+   * painting our children twice.
+   *
+   * this has to go away for 2.0; hopefully along the pick() itself.
+   */
+  if (CLUTTER_ACTOR_GET_CLASS (self)->pick == clutter_actor_real_pick)
+    {
+      ClutterActor *iter;
+
+      for (iter = self->priv->first_child;
+           iter != NULL;
+           iter = iter->priv->next_sibling)
+        clutter_actor_paint (iter);
+    }
 }
 
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