[clutter/clutter-1.16] offscreen-effect: limit offscreen fbo size to the stage's size

[Emmanuele Bassi <ebassi src gnome org>]

commit 9c6f3793e832e03ec72c63cd11f28601bf760f5b
Author: Lionel Landwerlin <llandwerlin gmail com>
Date:   Sat May 4 17:37:33 2013 +0100

    offscreen-effect: limit offscreen fbo size to the stage's size
    
    When using a ClutterOffscreenEffect, the size of the offscreen buffer
    allocated to perform the effect is currently computed using the paint
    volume of the actor it's attached to and in the case the paint volume
    cannot be computed, the effect falls back to using the stage's size.
    
    If you scale an actor enough so its paint volume is much bigger that
    the size of the stage, you can end up running out of memory (which
    leads to your application crashing).
    
    https://bugzilla.gnome.org/show_bug.cgi?id=699675

 clutter/clutter-offscreen-effect.c |   23 ++++++++++++++++-------
 1 files changed, 16 insertions(+), 7 deletions(-)
---
diff --git a/clutter/clutter-offscreen-effect.c b/clutter/clutter-offscreen-effect.c
index 8d8c852..5394fb8 100644
--- a/clutter/clutter-offscreen-effect.c
+++ b/clutter/clutter-offscreen-effect.c
@@ -223,9 +223,11 @@ clutter_offscreen_effect_pre_paint (ClutterEffect *effect)
   ClutterOffscreenEffect *self = CLUTTER_OFFSCREEN_EFFECT (effect);
   ClutterOffscreenEffectPrivate *priv = self->priv;
   ClutterActorBox box;
+  ClutterActor *stage;
   CoglMatrix projection;
   CoglColor transparent;
-  gfloat fbo_width, fbo_height;
+  gfloat stage_width, stage_height;
+  gfloat fbo_width = -1, fbo_height = -1;
   gfloat width, height;
   gfloat xexpand, yexpand;
   int texture_width, texture_height;
@@ -236,6 +238,9 @@ clutter_offscreen_effect_pre_paint (ClutterEffect *effect)
   if (priv->actor == NULL)
     return FALSE;
 
+  stage = _clutter_actor_get_stage_internal (priv->actor);
+  clutter_actor_get_size (stage, &stage_width, &stage_height);
+
   /* The paint box is the bounding box of the actor's paint volume in
    * stage coordinates. This will give us the size for the framebuffer
    * we need to redirect its rendering offscreen and its position will
@@ -244,17 +249,21 @@ clutter_offscreen_effect_pre_paint (ClutterEffect *effect)
     {
       clutter_actor_box_get_size (&box, &fbo_width, &fbo_height);
       clutter_actor_box_get_origin (&box, &priv->x_offset, &priv->y_offset);
+
+      fbo_width = MIN (fbo_width, stage_width);
+      fbo_height = MIN (fbo_height, stage_height);
     }
   else
     {
-      /* If we can't get a valid paint box then we fallback to
-       * creating a full stage size fbo. */
-      ClutterActor *stage = _clutter_actor_get_stage_internal (priv->actor);
-      clutter_actor_get_size (stage, &fbo_width, &fbo_height);
-      priv->x_offset = 0.0f;
-      priv->y_offset = 0.0f;
+      fbo_width = stage_width;
+      fbo_height = stage_height;
     }
 
+  if (fbo_width == stage_width)
+    priv->x_offset = 0.0f;
+  if (fbo_height == stage_height)
+    priv->y_offset = 0.0f;
+
   /* First assert that the framebuffer is the right size... */
   if (!update_fbo (effect, fbo_width, fbo_height))
     return FALSE;