actor: Don't use propagated_one_redraw to determine effect dirty state

Previously ClutterActor was using priv->propagated_one_redraw to
determine whether to pass CLUTTER_EFFECT_PAINT_ACTOR_DIRTY to the
paint method of the effect. This isn't a good idea because the
propagated_one_redraw flag is cleared whenever clutter_actor_paint is
called, even if the actor isn't actually painted because of the zero
opacity shortcut. Instead of this, ClutterActor now has a separate
flag called is_dirty that gets set whenever queue_redraw_full is
called or whenever the queue redraw signal is bubbled up from a child
actor. The flag is only cleared in clutter_actor_paint if the effects
are actually run. Therefore it will stay set even if the opacity is
zero or if the parent actor decides not to paint the child.

Previously there were two places set propagated_one_redraw to FALSE -
once if the opacity is zero and once just before we emit the paint
signal.  Now that propagated_one_redraw is only used to determine
whether to pass on the queue redraw signal it seems to make sense to
just clear it in one place right at the start of clutter_actor_paint.

https://bugzilla.gnome.org/show_bug.cgi?id=651784

clutter/clutter-actor.c

@@ -415,6 +415,11 @@ struct _ClutterActorPrivate
   guint last_paint_volume_valid     : 1;
   guint in_clone_paint              : 1;
   guint transform_valid             : 1;
+  /* This is TRUE if anything has queued a redraw since we were last
+     painted. In this case effect_to_redraw will point to an effect
+     the redraw was queued from or it will be NULL if the redraw was
+     queued without an effect. */
+  guint is_dirty                    : 1;
 
   gfloat clip[4];
 
@@ -485,7 +490,9 @@ struct _ClutterActorPrivate
      redraw can be queued to start from a particular effect. This is
      used by parametrised effects that can cache an image of the
      actor. If a parameter of the effect changes then it only needs to
-     redraw the cached image, not the actual actor */
+     redraw the cached image, not the actual actor. The pointer is
+     only valid if is_dirty == TRUE. If the pointer is NULL then the
+     whole actor is dirty. */
   ClutterEffect *effect_to_redraw;
 
   ClutterPaintVolume paint_volume;
@@ -1910,6 +1917,14 @@ clutter_actor_real_queue_redraw (ClutterActor *self,
   if (CLUTTER_ACTOR_IN_DESTRUCTION (self))
     return;
 
+  /* If the queue redraw is coming from a child then the actor has
+     become dirty and any queued effect is no longer valid */
+  if (self != origin)
+    {
+      self->priv->is_dirty = TRUE;
+      self->priv->effect_to_redraw = NULL;
+    }
+
   /* If the actor isn't visible, we still had to emit the signal
    * to allow for a ClutterClone, but the appearance of the parent
    * won't change so we don't have to propagate up the hierarchy.
@@ -1934,14 +1949,6 @@ clutter_actor_real_queue_redraw (ClutterActor *self,
 
   self->priv->propagated_one_redraw = TRUE;
 
-  /* If the queue redraw is coming from a child actor then we'll
-     assume the queued effect is no longer valid. If this actor has
-     had a redraw queued then that will mean it will instead redraw
-     the whole actor. If it hasn't had a redraw queued then it will
-     stay that way */
-  if (self != origin)
-    self->priv->effect_to_redraw = NULL;
-
   /* notify parents, if they are all visible eventually we'll
    * queue redraw on the stage, which queues the redraw idle.
    */
@@ -2779,6 +2786,9 @@ clutter_actor_paint (ClutterActor *self)
 
   pick_mode = _clutter_context_get_pick_mode ();
 
+  if (pick_mode == CLUTTER_PICK_NONE)
+    priv->propagated_one_redraw = FALSE;
+
   /* It's an important optimization that we consider painting of
    * actors with 0 opacity to be a NOP... */
   if (pick_mode == CLUTTER_PICK_NONE &&
@@ -2787,10 +2797,7 @@ clutter_actor_paint (ClutterActor *self)
       /* Use the override opacity if its been set */
       ((priv->opacity_override >= 0) ?
        priv->opacity_override : priv->opacity) == 0)
-    {
+    return;
-      priv->propagated_one_redraw = FALSE;
-      return;
-    }
 
   /* if we aren't paintable (not in a toplevel with all
    * parents paintable) then do nothing.
@@ -2906,6 +2913,11 @@ clutter_actor_paint (ClutterActor *self)
     _clutter_actor_draw_paint_volume (self);
 
 done:
+  /* If we make it here then the actor has run through a complete
+     paint run including all the effects so it's no longer dirty */
+  if (pick_mode == CLUTTER_PICK_NONE)
+    priv->is_dirty = FALSE;
+
   if (clip_set)
     cogl_clip_pop();
 
@@ -2949,11 +2961,7 @@ clutter_actor_continue_paint (ClutterActor *self)
   if (priv->next_effect_to_paint == NULL)
     {
       if (_clutter_context_get_pick_mode () == CLUTTER_PICK_NONE)
-        {
+        g_signal_emit (self, actor_signals[PAINT], 0);
-          priv->propagated_one_redraw = FALSE;
-
-          g_signal_emit (self, actor_signals[PAINT], 0);
-        }
       else
         {
           ClutterColor col = { 0, };
@@ -2981,7 +2989,7 @@ clutter_actor_continue_paint (ClutterActor *self)
 
       if (_clutter_context_get_pick_mode () == CLUTTER_PICK_NONE)
         {
-          if (priv->propagated_one_redraw)
+          if (priv->is_dirty)
             {
               /* If there's an effect queued with this redraw then all
                  effects up to that one will be considered dirty. It
@@ -5392,7 +5400,6 @@ _clutter_actor_queue_redraw_full (ClutterActor       *self,
   ClutterPaintVolume *pv;
   gboolean should_free_pv;
   ClutterActor *stage;
-  gboolean was_dirty;
 
   /* Here's an outline of the actor queue redraw mechanism:
    *
@@ -5515,8 +5522,6 @@ _clutter_actor_queue_redraw_full (ClutterActor       *self,
       should_free_pv = FALSE;
     }
 
-  was_dirty = priv->queue_redraw_entry != NULL;
-
   self->priv->queue_redraw_entry =
     _clutter_stage_queue_actor_redraw (CLUTTER_STAGE (stage),
                                        priv->queue_redraw_entry,
@@ -5528,7 +5533,7 @@ _clutter_actor_queue_redraw_full (ClutterActor       *self,
 
   /* If this is the first redraw queued then we can directly use the
      effect parameter */
-  if (!was_dirty)
+  if (!priv->is_dirty)
     priv->effect_to_redraw = effect;
   /* Otherwise we need to merge it with the existing effect parameter */
   else if (effect)
@@ -5561,6 +5566,8 @@ _clutter_actor_queue_redraw_full (ClutterActor       *self,
     /* If no effect is specified then we need to redraw the whole
        actor */
     priv->effect_to_redraw = NULL;
+
+  priv->is_dirty = TRUE;
 }
 
 /**