clutter-actor-meta: Add an internal 'priority' property

This adds a priority property to all ClutterActorMetas. The
ClutterMetaGroup keeps the list sorted so that higher priority metas
remain at the beginning of the list. The priority is a signed integer
with the default as zero. An actor meta can therefore be put before
all default metas with a positive number, or after with a negative
number.

There are constants to set an 'internal' priority. The intention is
that applications wouldn't be allowed to use these values so that we
can keep special internal metas to that are before or after all
application metas.

The property isn't a real GObject property because for now it is
completely internal and only used to implement the 'transparency'
property of ClutterActor. ClutterMetaGroup doesn't currently resort
the list if the property changes so if we wanted to make it public we
should either make it construct-only or make the meta group listen for
changes on the property and resort accordingly.

The methods in ClutterActor that get the list of metas now use a new
function that filters out internal metas from the meta
group. Similarly for clearing the metas, the internal metas are left
in.

clutter/clutter-actor-meta-private.h

@@ -50,6 +50,20 @@ struct _ClutterMetaGroupClass
   GObjectClass parent_class;
 };
 
+/* Each actor meta has a priority with zero as a default. A higher
+   number means higher priority. Higher priority metas stay at the
+   beginning of the list. The priority can be negative to give lower
+   priority than the default. */
+
+#define CLUTTER_ACTOR_META_PRIORITY_DEFAULT 0
+
+/* Any value greater than this is considered an 'internal' priority
+   and if we expose the priority property publicly then an application
+   would not be able to use these values. */
+
+#define CLUTTER_ACTOR_META_PRIORITY_INTERNAL_HIGH (G_MAXINT / 2)
+#define CLUTTER_ACTOR_META_PRIORITY_INTERNAL_LOW (G_MININT / 2)
+
 GType _clutter_meta_group_get_type (void) G_GNUC_CONST;
 
 void                  _clutter_meta_group_add_meta    (ClutterMetaGroup *group,
@@ -61,12 +75,24 @@ void                  _clutter_meta_group_clear_metas (ClutterMetaGroup *group);
 ClutterActorMeta *    _clutter_meta_group_get_meta    (ClutterMetaGroup *group,
                                                        const gchar      *name);
 
+GList *
+_clutter_meta_group_get_metas_no_internal (ClutterMetaGroup *group);
+
+void
+_clutter_meta_group_clear_metas_no_internal (ClutterMetaGroup *group);
+
 /* ActorMeta */
 void                  _clutter_actor_meta_set_actor   (ClutterActorMeta *meta,
                                                        ClutterActor     *actor);
 
 const gchar *           _clutter_actor_meta_get_debug_name        (ClutterActorMeta *meta);
 
+void                  _clutter_actor_meta_set_priority (ClutterActorMeta *meta,
+                                                        gint priority);
+int                   _clutter_actor_meta_get_priority (ClutterActorMeta *meta);
+
+gboolean              _clutter_actor_meta_is_internal  (ClutterActorMeta *meta);
+
 G_END_DECLS
 
 #endif /* __CLUTTER_ACTOR_META_PRIVATE_H__ */

clutter/clutter-actor-meta.c

@@ -58,6 +58,8 @@ struct _ClutterActorMetaPrivate
   gchar *name;
 
   guint is_enabled : 1;
+
+  gint priority;
 };
 
 enum
@@ -237,6 +239,8 @@ clutter_actor_meta_init (ClutterActorMeta *self)
                                             ClutterActorMetaPrivate);
 
   self->priv->is_enabled = TRUE;
+
+  self->priv->priority = CLUTTER_ACTOR_META_PRIORITY_DEFAULT;
 }
 
 /**
@@ -367,6 +371,40 @@ clutter_actor_meta_get_actor (ClutterActorMeta *meta)
   return meta->priv->actor;
 }
 
+void
+_clutter_actor_meta_set_priority (ClutterActorMeta *meta,
+                                  gint priority)
+{
+  g_return_if_fail (CLUTTER_IS_ACTOR_META (meta));
+
+  /* This property shouldn't be modified after the actor meta is in
+     use because ClutterMetaGroup doesn't resort the list when it
+     changes. If we made the priority public then we could either make
+     the priority a construct-only property or listen for
+     notifications on the property from the ClutterMetaGroup and
+     resort. */
+  g_return_if_fail (meta->priv->actor == NULL);
+
+  meta->priv->priority = priority;
+}
+
+gint
+_clutter_actor_meta_get_priority (ClutterActorMeta *meta)
+{
+  g_return_val_if_fail (CLUTTER_IS_ACTOR_META (meta), 0);
+
+  return meta->priv->priority;
+}
+
+gboolean
+_clutter_actor_meta_is_internal (ClutterActorMeta *meta)
+{
+  gint priority = meta->priv->priority;
+
+  return (priority <= CLUTTER_ACTOR_META_PRIORITY_INTERNAL_LOW ||
+          priority >= CLUTTER_ACTOR_META_PRIORITY_INTERNAL_HIGH);
+}
+
 /*
  * ClutterMetaGroup: a collection of ClutterActorMeta instances
  */
@@ -408,6 +446,8 @@ void
 _clutter_meta_group_add_meta (ClutterMetaGroup *group,
                               ClutterActorMeta *meta)
 {
+  GList *prev = NULL, *l;
+
   if (meta->priv->actor != NULL)
     {
       g_warning ("The meta of type '%s' with name '%s' is "
@@ -422,7 +462,22 @@ _clutter_meta_group_add_meta (ClutterMetaGroup *group,
       return;
     }
 
-  group->meta = g_list_append (group->meta, meta);
+  /* Find a meta that has lower priority and insert before that */
+  for (l = group->meta; l; l = l->next)
+    if (_clutter_actor_meta_get_priority (l->data) <
+        _clutter_actor_meta_get_priority (meta))
+      break;
+    else
+      prev = l;
+
+  if (prev == NULL)
+    group->meta = g_list_prepend (group->meta, meta);
+  else
+    {
+      prev->next = g_list_prepend (prev->next, meta);
+      prev->next->prev = prev;
+    }
+
   g_object_ref_sink (meta);
 
   _clutter_actor_meta_set_actor (meta, group->actor);
@@ -473,6 +528,30 @@ _clutter_meta_group_peek_metas (ClutterMetaGroup *group)
   return group->meta;
 }
 
+/*
+ * _clutter_meta_group_get_metas_no_internal:
+ * @group: a #ClutterMetaGroup
+ *
+ * Returns a new allocated list containing all of the metas that don't
+ * have an internal priority.
+ *
+ * Return value: A GList containing non-internal metas. Free with
+ * g_list_free.
+ */
+GList *
+_clutter_meta_group_get_metas_no_internal (ClutterMetaGroup *group)
+{
+  GList *ret = NULL;
+  GList *l;
+
+  /* Build a new list filtering out the internal metas */
+  for (l = group->meta; l; l = l->next)
+    if (!_clutter_actor_meta_is_internal (l->data))
+      ret = g_list_prepend (ret, l->data);
+
+  return g_list_reverse (ret);
+}
+
 /*
  * _clutter_meta_group_clear_metas:
  * @group: a #ClutterMetaGroup
@@ -490,6 +569,42 @@ _clutter_meta_group_clear_metas (ClutterMetaGroup *group)
   group->meta = NULL;
 }
 
+/*
+ * _clutter_meta_group_clear_metas_no_internal:
+ * @group: a #ClutterMetaGroup
+ *
+ * Clears @group of all #ClutterActorMeta instances that don't have an
+ * internal priority and releases the reference on them
+ */
+void
+_clutter_meta_group_clear_metas_no_internal (ClutterMetaGroup *group)
+{
+  GList *internal_list = NULL;
+  GList *l, *next;
+
+  for (l = group->meta; l; l = next)
+    {
+      next = l->next;
+
+      if (_clutter_actor_meta_is_internal (l->data))
+        {
+          if (internal_list)
+            internal_list->prev = l;
+          l->next = internal_list;
+          l->prev = NULL;
+          internal_list = l;
+        }
+      else
+        {
+          _clutter_actor_meta_set_actor (l->data, NULL);
+          g_object_unref (l->data);
+          g_list_free_1 (l);
+        }
+    }
+
+  group->meta = g_list_reverse (internal_list);
+}
+
 /*
  * _clutter_meta_group_get_meta:
  * @group: a #ClutterMetaGroup

clutter/clutter-actor.c

@@ -11239,16 +11239,12 @@ clutter_actor_remove_action_by_name (ClutterActor *self,
 GList *
 clutter_actor_get_actions (ClutterActor *self)
 {
-  const GList *actions;
-
   g_return_val_if_fail (CLUTTER_IS_ACTOR (self), NULL);
 
   if (self->priv->actions == NULL)
     return NULL;
 
-  actions = _clutter_meta_group_peek_metas (self->priv->actions);
-
-  return g_list_copy ((GList *) actions);
+  return _clutter_meta_group_get_metas_no_internal (self->priv->actions);
 }
 
 /**
@@ -11294,7 +11290,7 @@ clutter_actor_clear_actions (ClutterActor *self)
   if (self->priv->actions == NULL)
     return;
 
-  _clutter_meta_group_clear_metas (self->priv->actions);
+  _clutter_meta_group_clear_metas_no_internal (self->priv->actions);
 }
 
 /**
@@ -11447,16 +11443,12 @@ clutter_actor_remove_constraint_by_name (ClutterActor *self,
 GList *
 clutter_actor_get_constraints (ClutterActor *self)
 {
-  const GList *constraints;
-
   g_return_val_if_fail (CLUTTER_IS_ACTOR (self), NULL);
 
   if (self->priv->constraints == NULL)
     return NULL;
 
-  constraints = _clutter_meta_group_peek_metas (self->priv->constraints);
-
-  return g_list_copy ((GList *) constraints);
+  return _clutter_meta_group_get_metas_no_internal (self->priv->constraints);
 }
 
 /**
@@ -11502,7 +11494,7 @@ clutter_actor_clear_constraints (ClutterActor *self)
   if (self->priv->constraints == NULL)
     return;
 
-  _clutter_meta_group_clear_metas (self->priv->constraints);
+  _clutter_meta_group_clear_metas_no_internal (self->priv->constraints);
 }
 
 /**
@@ -11704,7 +11696,6 @@ GList *
 clutter_actor_get_effects (ClutterActor *self)
 {
   ClutterActorPrivate *priv;
-  const GList *effects;
 
   g_return_val_if_fail (CLUTTER_IS_ACTOR (self), NULL);
 
@@ -11713,9 +11704,7 @@ clutter_actor_get_effects (ClutterActor *self)
   if (priv->effects == NULL)
     return NULL;
 
-  effects = _clutter_meta_group_peek_metas (priv->effects);
-
-  return g_list_copy ((GList *) effects);
+  return _clutter_meta_group_get_metas_no_internal (priv->effects);
 }
 
 /**
@@ -11761,7 +11750,7 @@ clutter_actor_clear_effects (ClutterActor *self)
   if (self->priv->effects == NULL)
     return;
 
-  _clutter_meta_group_clear_metas (self->priv->effects);
+  _clutter_meta_group_clear_metas_no_internal (self->priv->effects);
 }
 
 /**