[mutter] clutter/stage: Find devices to update after finish queue redraw

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

commit 3944daf3c001a7fdf9be316718f91f1a4f9adb64
Author: Jonas Ådahl <jadahl gmail com>
Date:   Sat Apr 4 01:20:08 2020 +0200

    clutter/stage: Find devices to update after finish queue redraw
    
    Devices are updated (repicked) as part of the stage update phase, as
    their stacking, position and transform might have changed since since
    the last update.
    
    The redraw clip was used to avoid unnecessary updating of devices, if
    the device in question had it's position outside of the redraw clip. If
    the device coordinate was outside of the redraw clip, what was
    underneith the device couldn't have changed.
    
    What it failed to do, however, was to update devices if a relayout had
    happened in the same update, as it checked the state whether a layout
    had happened before attempting to do a relayout, effectively delaying
    the device updating to the next update.
    
    This commit changes the behavior to always update the device given the
    complete redraw clip caused by all possible relayouts of the same update
    as the device update happens in.
    
    https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1285

 clutter/clutter/clutter-stage.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)
---
diff --git a/clutter/clutter/clutter-stage.c b/clutter/clutter/clutter-stage.c
index aabf302ff9..d50fd37f07 100644
--- a/clutter/clutter/clutter-stage.c
+++ b/clutter/clutter/clutter-stage.c
@@ -1402,11 +1402,8 @@ gboolean
 _clutter_stage_do_update (ClutterStage *stage)
 {
   ClutterStagePrivate *priv = stage->priv;
-  gboolean stage_was_relayout = priv->stage_was_relayout;
   GSList *devices = NULL;
 
-  priv->stage_was_relayout = FALSE;
-
   priv->needs_update = FALSE;
 
   /* if the stage is being destroyed, or if the destruction already
@@ -1430,12 +1427,16 @@ _clutter_stage_do_update (ClutterStage *stage)
   if (!priv->redraw_pending)
     return FALSE;
 
-  if (stage_was_relayout)
-    devices = clutter_stage_find_updated_devices (stage);
-
   update_actor_stage_views (stage);
 
   clutter_stage_maybe_finish_queue_redraws (stage);
+
+  if (priv->stage_was_relayout)
+    {
+      priv->stage_was_relayout = FALSE;
+      devices = clutter_stage_find_updated_devices (stage);
+    }
+
   clutter_stage_do_redraw (stage);
 
   /* reset the guard, so that new redraws are possible */