effect: Allow any effect to override the paint volume

An Effect implementation might override the paint volume of the actor to
which it is applied to. The get_paint_volume() virtual function should
be added to the Effect class vtable so that any effect can get the
current paint volume and update it.

The clutter_actor_get_paint_volume() function becomes context aware, and
does the right thing if called from within a ClutterEffect pre_paint()
or post_paint() implementation, by allowing all effects in the chain up
to the caller to modify the paint volume.

clutter/clutter-actor.c

@@ -493,6 +493,8 @@ struct _ClutterActorPrivate
   ClutterMetaGroup *actions;
   ClutterMetaGroup *constraints;
   ClutterMetaGroup *effects;
+
+  ClutterActorMeta *current_effect;
 };
 
 enum
@@ -2338,14 +2340,20 @@ _clutter_actor_effects_pre_paint (ClutterActor *self)
   const GList *effects, *l;
   gboolean was_pre_painted = FALSE;
 
+  priv->current_effect = NULL;
+
   effects = _clutter_meta_group_peek_metas (priv->effects);
   for (l = effects; l != NULL; l = l->next)
     {
       ClutterEffect *effect = l->data;
 
+      priv->current_effect = l->data;
+
       was_pre_painted |= _clutter_effect_pre_paint (effect);
     }
 
+  priv->current_effect = NULL;
+
   return was_pre_painted;
 }
 
@@ -2355,14 +2363,20 @@ _clutter_actor_effects_post_paint (ClutterActor *self)
   ClutterActorPrivate *priv = self->priv;
   const GList *effects, *l;
 
+  priv->current_effect = NULL;
+
   /* we walk the list backwards, to unwind the post-paint order */
   effects = _clutter_meta_group_peek_metas (priv->effects);
   for (l = g_list_last ((GList *) effects); l != NULL; l = l->prev)
     {
       ClutterEffect *effect = l->data;
 
+      priv->current_effect = l->data;
+
       _clutter_effect_post_paint (effect);
     }
+
+  priv->current_effect = NULL;
 }
 
 /* Recursively applies the transforms associated with this actor and
@@ -3259,11 +3273,13 @@ clutter_actor_real_get_paint_volume (ClutterActor       *self,
                                      ClutterPaintVolume *volume)
 {
   ClutterActorPrivate *priv = self->priv;
+  gfloat width, height;
 
   /* the default origin is set to { 0, 0, 0 } */
+  clutter_actor_box_get_size (&priv->allocation, &width, &height);
+  clutter_paint_volume_set_width (volume, width);
+  clutter_paint_volume_set_height (volume, height);
 
-  clutter_paint_volume_set_width (volume, priv->allocation.x2 - priv->allocation.x1);
-  clutter_paint_volume_set_height (volume, priv->allocation.y2 - priv->allocation.y1);
   clutter_paint_volume_set_depth (volume, priv->z);
 }
 
@@ -11682,6 +11698,7 @@ _clutter_paint_volume_get_box (ClutterPaintVolume *pv,
 ClutterPaintVolume *
 clutter_actor_get_paint_volume (ClutterActor *self)
 {
+  ClutterActorPrivate *priv;
   ClutterPaintVolume *pv;
 
   g_return_val_if_fail (CLUTTER_IS_ACTOR (self), NULL);
@@ -11689,6 +11706,39 @@ clutter_actor_get_paint_volume (ClutterActor *self)
   pv = _clutter_paint_volume_new (self);
   CLUTTER_ACTOR_GET_CLASS (self)->get_paint_volume (self, pv);
 
+  priv = self->priv;
+
+  /* since effects can modify the paint volume, we allow them to actually
+   * do this by making get_paint_volume() "context sensitive"
+   */
+  if (priv->effects != NULL)
+    {
+      if (priv->current_effect != NULL)
+        {
+          const GList *effects, *l;
+
+          /* if we are being called from within the paint sequence of
+           * an actor, get the paint volume up to the current effect
+           */
+          effects = _clutter_meta_group_peek_metas (priv->effects);
+          for (l = effects;
+               l != NULL || (l != NULL && l->data != priv->current_effect);
+               l = l->next)
+            {
+              _clutter_effect_get_paint_volume (l->data, pv);
+            }
+        }
+      else
+        {
+          const GList *effects, *l;
+
+          /* otherwise, get the cumulative volume */
+          effects = _clutter_meta_group_peek_metas (priv->effects);
+          for (l = effects; l != NULL; l = l->next)
+            _clutter_effect_get_paint_volume (l->data, pv);
+        }
+    }
+
   return pv;
 }
 

clutter/clutter-effect.c

@@ -191,11 +191,18 @@ clutter_effect_real_post_paint (ClutterEffect *effect)
 {
 }
 
+static void
+clutter_effect_real_get_paint_volume (ClutterEffect      *effect,
+                                      ClutterPaintVolume *volume)
+{
+}
+
 static void
 clutter_effect_class_init (ClutterEffectClass *klass)
 {
   klass->pre_paint = clutter_effect_real_pre_paint;
   klass->post_paint = clutter_effect_real_post_paint;
+  klass->get_paint_volume = clutter_effect_real_get_paint_volume;
 }
 
 static void
@@ -218,3 +225,13 @@ _clutter_effect_post_paint (ClutterEffect *effect)
 
   CLUTTER_EFFECT_GET_CLASS (effect)->post_paint (effect);
 }
+
+void
+_clutter_effect_get_paint_volume (ClutterEffect      *effect,
+                                  ClutterPaintVolume *volume)
+{
+  g_return_if_fail (CLUTTER_IS_EFFECT (effect));
+  g_return_if_fail (volume != NULL);
+
+  CLUTTER_EFFECT_GET_CLASS (effect)->get_paint_volume (effect, volume);
+}

clutter/clutter-effect.h

@@ -72,16 +72,21 @@ struct _ClutterEffectClass
   ClutterActorMetaClass parent_class;
 
   /*< public >*/
-  gboolean (* pre_paint)  (ClutterEffect *effect);
-  void     (* post_paint) (ClutterEffect *effect);
+  gboolean (* pre_paint)        (ClutterEffect      *effect);
+  void     (* post_paint)       (ClutterEffect      *effect);
+
+  void     (* get_paint_volume) (ClutterEffect      *effect,
+                                 ClutterPaintVolume *volume);
 
   /*< private >*/
+  void (* _clutter_effect0) (void);
   void (* _clutter_effect1) (void);
   void (* _clutter_effect2) (void);
   void (* _clutter_effect3) (void);
   void (* _clutter_effect4) (void);
   void (* _clutter_effect5) (void);
   void (* _clutter_effect6) (void);
+  void (* _clutter_effect7) (void);
 };
 
 GType clutter_effect_get_type (void) G_GNUC_CONST;

clutter/clutter-private.h

@@ -384,8 +384,10 @@ void _clutter_run_repaint_functions (void);
 
 gint32 _clutter_backend_get_units_serial (ClutterBackend *backend);
 
-gboolean _clutter_effect_pre_paint  (ClutterEffect *effect);
-void     _clutter_effect_post_paint (ClutterEffect *effect);
+gboolean _clutter_effect_pre_paint        (ClutterEffect      *effect);
+void     _clutter_effect_post_paint       (ClutterEffect      *effect);
+void     _clutter_effect_get_paint_volume (ClutterEffect      *effect,
+                                           ClutterPaintVolume *volume);
 
 void _clutter_constraint_update_allocation (ClutterConstraint *constraint,
                                             ClutterActor      *actor,