[mutter] clutter/actor: Use paint context when culling to check render target

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

commit 138907c4808608c90a321b96fecdcca75e55691f
Author: Jonas Ådahl <jadahl gmail com>
Date:   Thu Nov 21 16:26:35 2019 +0100

    clutter/actor: Use paint context when culling to check render target
    
    Rendering off stage we never cull, and previously this was checked by
    comparing the "active framebuffer" of the stage, to the current
    framebuffer in the cogl stack. Replace this by checking whether the
    current paint context is currently drawing on stage or not.
    
    https://gitlab.gnome.org/GNOME/mutter/merge_requests/935

 clutter/clutter/clutter-actor.c                 | 12 +++++++-----
 clutter/clutter/clutter-paint-context-private.h |  2 ++
 clutter/clutter/clutter-paint-context.c         | 16 ++++++++++++++++
 3 files changed, 25 insertions(+), 5 deletions(-)
---
diff --git a/clutter/clutter/clutter-actor.c b/clutter/clutter/clutter-actor.c
index 53f4c11f5..9d23a357c 100644
--- a/clutter/clutter/clutter-actor.c
+++ b/clutter/clutter/clutter-actor.c
@@ -643,6 +643,7 @@
 #include "clutter-main.h"
 #include "clutter-marshal.h"
 #include "clutter-mutter.h"
+#include "clutter-paint-context-private.h"
 #include "clutter-paint-nodes.h"
 #include "clutter-paint-node-private.h"
 #include "clutter-paint-volume-private.h"
@@ -3594,8 +3595,9 @@ in_clone_paint (void)
  * means there's no point in trying to cull descendants of the current
  * node. */
 static gboolean
-cull_actor (ClutterActor      *self,
-            ClutterCullResult *result_out)
+cull_actor (ClutterActor        *self,
+            ClutterPaintContext *paint_context,
+            ClutterCullResult   *result_out)
 {
   ClutterActorPrivate *priv = self->priv;
   ClutterStage *stage;
@@ -3622,10 +3624,10 @@ cull_actor (ClutterActor      *self,
       return FALSE;
     }
 
-  if (cogl_get_draw_framebuffer () != _clutter_stage_get_active_framebuffer (stage))
+  if (clutter_paint_context_is_drawing_off_stage (paint_context))
     {
       CLUTTER_NOTE (CLIPPING, "Bail from cull_actor without culling (%s): "
-                    "Current framebuffer doesn't correspond to stage",
+                    "Drawing off stage",
                     _clutter_actor_get_debug_name (self));
       return FALSE;
     }
@@ -4058,7 +4060,7 @@ clutter_actor_paint (ClutterActor        *self,
                      CLUTTER_DEBUG_DISABLE_CLIPPED_REDRAWS)))
         _clutter_actor_update_last_paint_volume (self);
 
-      success = cull_actor (self, &result);
+      success = cull_actor (self, paint_context, &result);
 
       if (G_UNLIKELY (clutter_paint_debug_flags & CLUTTER_DEBUG_REDRAWS))
         _clutter_actor_paint_cull_result (self, success, result, actor_node);
diff --git a/clutter/clutter/clutter-paint-context-private.h b/clutter/clutter/clutter-paint-context-private.h
index 8d8986ca1..bb9118019 100644
--- a/clutter/clutter/clutter-paint-context-private.h
+++ b/clutter/clutter/clutter-paint-context-private.h
@@ -27,4 +27,6 @@ void clutter_paint_context_push_framebuffer (ClutterPaintContext *paint_context,
 
 void clutter_paint_context_pop_framebuffer (ClutterPaintContext *paint_context);
 
+gboolean clutter_paint_context_is_drawing_off_stage (ClutterPaintContext *paint_context);
+
 #endif /* CLUTTER_PAINT_CONTEXT_PRIVATE_H */
diff --git a/clutter/clutter/clutter-paint-context.c b/clutter/clutter/clutter-paint-context.c
index 51f73b9a5..fe0b6a6a0 100644
--- a/clutter/clutter/clutter-paint-context.c
+++ b/clutter/clutter/clutter-paint-context.c
@@ -137,3 +137,19 @@ clutter_paint_context_get_stage_view (ClutterPaintContext *paint_context)
 {
   return paint_context->view;
 }
+
+/**
+ * clutter_paint_context_is_drawing_off_stage: (skip)
+ *
+ * Return %TRUE if the paint context is currently drawing off stage.
+ * This happens if there are any framebuffers pushed, and the base framebuffer
+ * comes from the stage view.
+ */
+gboolean
+clutter_paint_context_is_drawing_off_stage (ClutterPaintContext *paint_context)
+{
+  if (g_list_length (paint_context->framebuffers) > 1)
+    return TRUE;
+
+  return !paint_context->view;
+}