From cd2ee4421670e40e0eee8519af42b7477c7d8eed Mon Sep 17 00:00:00 2001
From: Georges Basile Stavracas Neto <georges.stavracas@gmail.com>
Date: Thu, 17 Oct 2019 21:02:34 +0200
Subject: [PATCH] clutter/actor: Always paint using paint nodes

Make ClutterActor paint using ClutterTransformNode, ClutterClip
node, and ClutterActorNode. Essencially, the actor node is a
replacement for clutter_actor_continue_paint().

An interesting aspect of this commit is that the order of the
operations is reversed to be preserved.

Before being able to remove the dummy node hack, we'll need to
make ClutterEffects compatible with paint nodes first -- and
naturally, that's enough content for its own merge request.

https://gitlab.gnome.org/GNOME/mutter/merge_requests/872
---
 clutter/clutter/clutter-actor.c | 93 +++++++++++++++------------------
 1 file changed, 42 insertions(+), 51 deletions(-)

diff --git a/clutter/clutter/clutter-actor.c b/clutter/clutter/clutter-actor.c
index 207a5ef30..101f4bf0f 100644
--- a/clutter/clutter/clutter-actor.c
+++ b/clutter/clutter/clutter-actor.c
@@ -3876,10 +3876,11 @@ clutter_actor_paint_node (ClutterActor     *actor,
 void
 clutter_actor_paint (ClutterActor *self)
 {
+  g_autoptr (ClutterPaintNode) actor_node = NULL;
+  g_autoptr (ClutterPaintNode) root_node = NULL;
   ClutterActorPrivate *priv;
   ClutterActorBox clip;
   gboolean clip_set = FALSE;
-  ClutterStage *stage;
 
   g_return_if_fail (CLUTTER_IS_ACTOR (self));
 
@@ -3906,22 +3907,51 @@ clutter_actor_paint (ClutterActor *self)
 
   clutter_actor_ensure_resource_scale (self);
 
-  stage = (ClutterStage *) _clutter_actor_get_stage_internal (self);
-
   /* mark that we are in the paint process */
   CLUTTER_SET_PRIVATE_FLAGS (self, CLUTTER_IN_PAINT);
 
-  cogl_push_matrix ();
+  actor_node = clutter_actor_node_new (self);
+  root_node = clutter_paint_node_ref (actor_node);
+
+  if (priv->has_clip)
+    {
+      clip.x1 = priv->clip.origin.x;
+      clip.y1 = priv->clip.origin.y;
+      clip.x2 = priv->clip.origin.x + priv->clip.size.width;
+      clip.y2 = priv->clip.origin.y + priv->clip.size.height;
+      clip_set = TRUE;
+    }
+  else if (priv->clip_to_allocation)
+    {
+      clip.x1 = 0.f;
+      clip.y1 = 0.f;
+      clip.x2 = priv->allocation.x2 - priv->allocation.x1;
+      clip.y2 = priv->allocation.y2 - priv->allocation.y1;
+      clip_set = TRUE;
+    }
+
+  if (clip_set)
+    {
+      ClutterPaintNode *clip_node;
+
+      clip_node = clutter_clip_node_new ();
+      clutter_paint_node_add_rectangle (clip_node, &clip);
+      clutter_paint_node_add_child (clip_node, root_node);
+
+      root_node = g_steal_pointer (&clip_node);
+    }
 
   if (priv->enable_model_view_transform)
     {
-      CoglMatrix matrix;
+      ClutterPaintNode *transform_node;
+      CoglMatrix transform;
 
-      /* XXX: It could be better to cache the modelview with the actor
-       * instead of progressively building up the transformations on
-       * the matrix stack every time we paint. */
-      cogl_get_modelview_matrix (&matrix);
-      _clutter_actor_apply_modelview_transform (self, &matrix);
+      clutter_actor_get_transform (self, &transform);
+
+      transform_node = clutter_transform_node_new (&transform);
+      clutter_paint_node_add_child (transform_node, root_node);
+
+      root_node = g_steal_pointer (&transform_node);
 
 #ifdef CLUTTER_ENABLE_DEBUG
       /* Catch when out-of-band transforms have been made by actors not as part
@@ -3933,7 +3963,7 @@ clutter_actor_paint (ClutterActor *self)
           _clutter_actor_get_relative_transformation_matrix (self, NULL,
                                                              &expected_matrix);
 
-          if (!cogl_matrix_equal (&matrix, &expected_matrix))
+          if (!cogl_matrix_equal (&transform, &expected_matrix))
             {
               GString *buf = g_string_sized_new (1024);
               ClutterActor *parent;
@@ -3960,36 +3990,6 @@ clutter_actor_paint (ClutterActor *self)
             }
         }
 #endif /* CLUTTER_ENABLE_DEBUG */
-
-      cogl_set_modelview_matrix (&matrix);
-    }
-
-  if (priv->has_clip)
-    {
-      clip.x1 = priv->clip.origin.x;
-      clip.y1 = priv->clip.origin.y;
-      clip.x2 = priv->clip.origin.x + priv->clip.size.width;
-      clip.y2 = priv->clip.origin.y + priv->clip.size.height;
-      clip_set = TRUE;
-    }
-  else if (priv->clip_to_allocation)
-    {
-      clip.x1 = 0.f;
-      clip.y1 = 0.f;
-      clip.x2 = priv->allocation.x2 - priv->allocation.x1;
-      clip.y2 = priv->allocation.y2 - priv->allocation.y1;
-      clip_set = TRUE;
-    }
-
-  if (clip_set)
-    {
-      CoglFramebuffer *fb = _clutter_stage_get_active_framebuffer (stage);
-
-      cogl_framebuffer_push_rectangle_clip (fb,
-                                            clip.x1,
-                                            clip.y1,
-                                            clip.x2,
-                                            clip.y2);
     }
 
   /* We check whether we need to add the flatten effect before
@@ -4054,7 +4054,7 @@ clutter_actor_paint (ClutterActor *self)
     priv->next_effect_to_paint =
       _clutter_meta_group_peek_metas (priv->effects);
 
-  clutter_actor_continue_paint (self);
+  clutter_paint_node_paint (root_node);
 
   if (G_UNLIKELY (clutter_paint_debug_flags & CLUTTER_DEBUG_PAINT_VOLUMES))
     _clutter_actor_draw_paint_volume (self);
@@ -4064,15 +4064,6 @@ clutter_actor_paint (ClutterActor *self)
   priv->is_dirty = FALSE;
 
 done:
-  if (clip_set)
-    {
-      CoglFramebuffer *fb = _clutter_stage_get_active_framebuffer (stage);
-
-      cogl_framebuffer_pop_clip (fb);
-    }
-
-  cogl_pop_matrix ();
-
   /* paint sequence complete */
   CLUTTER_UNSET_PRIVATE_FLAGS (self, CLUTTER_IN_PAINT);
 }