actor: Always use get_paint_volume override for active effects

If an effect is active and it overrides the paint volume, we should
always recompute the paint volume when requested and not use the
cache, since the paint volume override can change from call to
call depending on what phase of painting we are in. For instance,
if we are part way through painting effects and request the
paint volume, the paint volume should only go up to the current
effect, but in a later call to compute repaint regions, the
paint volume needs to expand to accomadate the effect.

This still involves a lot of recomputation in the case of effects -
in a later clutter version it would be worth adding an API to
allow effects to explicitly recompute and return a new the paint
volume up to the current effect as opposed to recomputing
the cached one.


(cherry picked from commit 5d19aee23a)

clutter/clutter/clutter-actor.c

@@ -17521,6 +17521,32 @@ _clutter_actor_get_paint_volume_real (ClutterActor *self,
   return TRUE;
 }
 
+static gboolean
+_clutter_actor_has_active_paint_volume_override_effects (ClutterActor *self)
+{
+  const GList *l;
+
+  if (self->priv->effects == NULL)
+    return FALSE;
+
+  /* We just need to all effects current effect to see
+   * if anyone wants to override the paint volume. If so, then
+   * we need to recompute, since the paint volume returned can
+   * change from call to call. */
+  for (l = _clutter_meta_group_peek_metas (self->priv->effects);
+       l != NULL;
+       l = l->next)
+    {
+      ClutterEffect *effect = l->data;
+
+      if (clutter_actor_meta_get_enabled (CLUTTER_ACTOR_META (effect)) &&
+          _clutter_effect_has_custom_paint_volume (effect))
+        return TRUE;
+    }
+
+  return FALSE;
+}
+
 /* The public clutter_actor_get_paint_volume API returns a const
  * pointer since we return a pointer directly to the cached
  * PaintVolume associated with the actor and don't want the user to
@@ -17537,7 +17563,13 @@ _clutter_actor_get_paint_volume_mutable (ClutterActor *self)
 
   if (priv->paint_volume_valid)
     {
-      if (!priv->needs_paint_volume_update)
+      /* If effects are applied, the actor paint volume
+       * needs to be recomputed on each paint, since those
+       * paint volumes could change over the duration of the
+       * effect. */
+      if (!priv->needs_paint_volume_update &&
+          priv->current_effect == NULL &&
+          !_clutter_actor_has_active_paint_volume_override_effects (self))
         return &priv->paint_volume;
       clutter_paint_volume_free (&priv->paint_volume);
     }

clutter/clutter/clutter-effect-private.h

@@ -9,6 +9,7 @@ gboolean        _clutter_effect_pre_paint               (ClutterEffect
 void            _clutter_effect_post_paint              (ClutterEffect           *effect);
 gboolean        _clutter_effect_get_paint_volume        (ClutterEffect           *effect,
                                                          ClutterPaintVolume      *volume);
+gboolean        _clutter_effect_has_custom_paint_volume (ClutterEffect           *effect);
 void            _clutter_effect_paint                   (ClutterEffect           *effect,
                                                          ClutterEffectPaintFlags  flags);
 void            _clutter_effect_pick                    (ClutterEffect           *effect,

clutter/clutter/clutter-effect.c

@@ -308,6 +308,14 @@ _clutter_effect_get_paint_volume (ClutterEffect      *effect,
   return CLUTTER_EFFECT_GET_CLASS (effect)->get_paint_volume (effect, volume);
 }
 
+gboolean
+_clutter_effect_has_custom_paint_volume (ClutterEffect *effect)
+{
+  g_return_val_if_fail (CLUTTER_IS_EFFECT (effect), FALSE);
+
+  return CLUTTER_EFFECT_GET_CLASS (effect)->get_paint_volume != clutter_effect_real_get_paint_volume;
+}
+
 /**
  * clutter_effect_queue_repaint:
  * @effect: A #ClutterEffect which needs redrawing