[mutter/gbsneto/effects-paint-nodes: 169/172] clutter/paint-nodes: Add opacity overriding to ClutterActorNode

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 4b44c7c63cab6455e11aff94ffc09774520cd1c2
Author: Georges Basile Stavracas Neto <georges stavracas gmail com>
Date:   Sun Jul 5 16:27:08 2020 -0300

    clutter/paint-nodes: Add opacity overriding to ClutterActorNode
    
    Some effects, such as ShellBlurEffect and ClutterOffscreenEffect, need
    to make sure the actor is painted fully opaque. With ClutterActorNode,
    however, that is currently not possible.
    
    Add a new 'opacity' parameter to clutter_actor_node_new(). It follows
    the opacity override heuristic, where -1 means disable, and anything
    else is clamped to [0, 255].
    
    https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1340

 clutter/clutter/clutter-actor.c       |  2 +-
 clutter/clutter/clutter-effect.c      |  2 +-
 clutter/clutter/clutter-paint-nodes.c | 21 ++++++++++++++++++++-
 clutter/clutter/clutter-paint-nodes.h |  3 ++-
 4 files changed, 24 insertions(+), 4 deletions(-)
---
diff --git a/clutter/clutter/clutter-actor.c b/clutter/clutter/clutter-actor.c
index 68290b986d..b899459145 100644
--- a/clutter/clutter/clutter-actor.c
+++ b/clutter/clutter/clutter-actor.c
@@ -3801,7 +3801,7 @@ clutter_actor_paint (ClutterActor        *self,
   if (!CLUTTER_ACTOR_IS_MAPPED (self))
     return;
 
-  actor_node = clutter_actor_node_new (self);
+  actor_node = clutter_actor_node_new (self, -1);
   root_node = clutter_paint_node_ref (actor_node);
 
   if (priv->has_clip)
diff --git a/clutter/clutter/clutter-effect.c b/clutter/clutter/clutter-effect.c
index ec28aae997..2f947f1703 100644
--- a/clutter/clutter/clutter-effect.c
+++ b/clutter/clutter/clutter-effect.c
@@ -209,7 +209,7 @@ clutter_effect_real_paint_node (ClutterEffect           *effect,
 
   actor = clutter_actor_meta_get_actor (CLUTTER_ACTOR_META (effect));
 
-  actor_node = clutter_actor_node_new (actor);
+  actor_node = clutter_actor_node_new (actor, -1);
   clutter_paint_node_add_child (node, actor_node);
   clutter_paint_node_unref (actor_node);
 }
diff --git a/clutter/clutter/clutter-paint-nodes.c b/clutter/clutter/clutter-paint-nodes.c
index 01c9419ba9..2b5924858c 100644
--- a/clutter/clutter/clutter-paint-nodes.c
+++ b/clutter/clutter/clutter-paint-nodes.c
@@ -1115,6 +1115,8 @@ struct _ClutterActorNode
   ClutterPaintNode parent_instance;
 
   ClutterActor *actor;
+  int opacity_override;
+  int saved_opacity_override;
 };
 
 struct _ClutterActorNodeClass
@@ -1130,6 +1132,14 @@ clutter_actor_node_pre_draw (ClutterPaintNode    *node,
 {
   ClutterActorNode *actor_node = CLUTTER_ACTOR_NODE (node);
 
+  if (actor_node->opacity_override != -1)
+    {
+      actor_node->saved_opacity_override =
+        clutter_actor_get_opacity_override (actor_node->actor);
+      clutter_actor_set_opacity_override (actor_node->actor,
+                                          actor_node->opacity_override);
+    }
+
   CLUTTER_SET_PRIVATE_FLAGS (actor_node->actor, CLUTTER_IN_PAINT);
 
   return TRUE;
@@ -1151,6 +1161,12 @@ clutter_actor_node_post_draw (ClutterPaintNode    *node,
   ClutterActorNode *actor_node = CLUTTER_ACTOR_NODE (node);
 
   CLUTTER_UNSET_PRIVATE_FLAGS (actor_node->actor, CLUTTER_IN_PAINT);
+
+ if (actor_node->opacity_override != -1)
+    {
+      clutter_actor_set_opacity_override (actor_node->actor,
+                                          actor_node->saved_opacity_override);
+    }
 }
 
 static JsonNode *
@@ -1192,6 +1208,7 @@ clutter_actor_node_init (ClutterActorNode *self)
 /*
  * clutter_actor_node_new:
  * @actor: the actor to paint
+ * @opacity: opacity to draw the actor with, or -1 to use the actor's opacity
  *
  * Creates a new #ClutterActorNode.
  *
@@ -1203,7 +1220,8 @@ clutter_actor_node_init (ClutterActorNode *self)
  *   Use clutter_paint_node_unref() when done.
  */
 ClutterPaintNode *
-clutter_actor_node_new (ClutterActor *actor)
+clutter_actor_node_new (ClutterActor *actor,
+                        int           opacity)
 {
   ClutterActorNode *res;
 
@@ -1211,6 +1229,7 @@ clutter_actor_node_new (ClutterActor *actor)
 
   res = _clutter_paint_node_create (CLUTTER_TYPE_ACTOR_NODE);
   res->actor = actor;
+  res->opacity_override = CLAMP (opacity, -1, 255);
 
   return (ClutterPaintNode *) res;
 }
diff --git a/clutter/clutter/clutter-paint-nodes.h b/clutter/clutter/clutter-paint-nodes.h
index 2e81c2b5df..32b56a8d39 100644
--- a/clutter/clutter/clutter-paint-nodes.h
+++ b/clutter/clutter/clutter-paint-nodes.h
@@ -160,7 +160,8 @@ CLUTTER_EXPORT
 GType clutter_actor_node_get_type (void) G_GNUC_CONST;
 
 CLUTTER_EXPORT
-ClutterPaintNode * clutter_actor_node_new (ClutterActor *actor);
+ClutterPaintNode * clutter_actor_node_new (ClutterActor *actor,
+                                           int           opacity);
 
 #define CLUTTER_TYPE_ROOT_NODE                  (clutter_root_node_get_type ())
 #define CLUTTER_ROOT_NODE(obj)                  (G_TYPE_CHECK_INSTANCE_CAST ((obj), CLUTTER_TYPE_ROOT_NODE, 
ClutterRootNode))