[mutter/gnome-3-36] clutter/stage-cogl: Fix painting the redraw clip with the damage region

[verdre <jonasd src gnome org>]

commit b80b465a653db0b04de7b0e384760333a39cf6bf
Author: Jonas Dreßler <verdre v0yd nl>
Date:   Fri Mar 6 10:33:30 2020 +0000

    clutter/stage-cogl: Fix painting the redraw clip with the damage region
    
    The redraw clip that's painted together with the damage region has to be
    copied earlier than we do right now. That's because if
    PAINT_DAMAGE_REGION is enabled, buffer age is disabled and thus
    use_clipped_redraw is FALSE. That means the redraw_clip is updated and
    set to the full view-rect. If we copy the queued_redraw_clip after that,
    it's also going to be set to the full view-rect. So copy the redraw clip
    a bit earlier to make sure we're actually passing the real redraw clip
    to paint_damage_region().
    
    Also keep the queued_redraw_clip around a bit longer so it can actually
    be used by paint_damage_region() and isn't freed before that.
    
    While at it, move paint_damage_region() from swap_framebuffer() into
    clutter_stage_cogl_redraw_view() so we don't have to pass things to
    swap_framebuffer() only for debugging.
    
    Fixes https://gitlab.gnome.org/GNOME/mutter/-/issues/1104
    
    https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1208
    
    
    (cherry picked from commit 793a9d45e14909b5c27219a7c41352c99b07f077)

 clutter/clutter/cogl/clutter-stage-cogl.c | 24 +++++++++++++-----------
 1 file changed, 13 insertions(+), 11 deletions(-)
---
diff --git a/clutter/clutter/cogl/clutter-stage-cogl.c b/clutter/clutter/cogl/clutter-stage-cogl.c
index 28b33455f..9031f5291 100644
--- a/clutter/clutter/cogl/clutter-stage-cogl.c
+++ b/clutter/clutter/cogl/clutter-stage-cogl.c
@@ -403,15 +403,11 @@ static gboolean
 swap_framebuffer (ClutterStageWindow *stage_window,
                   ClutterStageView   *view,
                   cairo_region_t     *swap_region,
-                  gboolean            swap_with_damage,
-                  cairo_region_t     *queued_redraw_clip)
+                  gboolean            swap_with_damage)
 {
   CoglFramebuffer *framebuffer = clutter_stage_view_get_onscreen (view);
   int *damage, n_rects, i;
 
-  if (G_UNLIKELY ((clutter_paint_debug_flags & CLUTTER_DEBUG_PAINT_DAMAGE_REGION)))
-    paint_damage_region (stage_window, view, swap_region, queued_redraw_clip);
-
   n_rects = cairo_region_num_rectangles (swap_region);
   damage = g_newa (int, n_rects * 4);
   for (i = 0; i < n_rects; i++)
@@ -648,7 +644,7 @@ clutter_stage_cogl_redraw_view (ClutterStageWindow *stage_window,
   gboolean swap_with_damage;
   ClutterActor *wrapper;
   cairo_region_t *redraw_clip;
-  cairo_region_t *queued_redraw_clip;
+  cairo_region_t *queued_redraw_clip = NULL;
   cairo_region_t *fb_clip_region;
   cairo_region_t *swap_region;
   cairo_rectangle_int_t redraw_rect;
@@ -672,6 +668,8 @@ clutter_stage_cogl_redraw_view (ClutterStageWindow *stage_window,
   has_buffer_age = cogl_is_onscreen (fb) && is_buffer_age_enabled ();
 
   redraw_clip = clutter_stage_view_take_redraw_clip (view);
+  if (G_UNLIKELY (clutter_paint_debug_flags & CLUTTER_DEBUG_PAINT_DAMAGE_REGION))
+    queued_redraw_clip = cairo_region_copy (redraw_clip);
 
   /* NB: a NULL redraw clip == full stage redraw */
   if (!redraw_clip)
@@ -739,8 +737,6 @@ clutter_stage_cogl_redraw_view (ClutterStageWindow *stage_window,
       redraw_clip = cairo_region_create_rectangle (&view_rect);
     }
 
-  queued_redraw_clip = cairo_region_copy (redraw_clip);
-
   if (may_use_clipped_redraw &&
       G_LIKELY (!(clutter_paint_debug_flags & CLUTTER_DEBUG_DISABLE_CLIPPED_REDRAWS)))
     use_clipped_redraw = TRUE;
@@ -950,7 +946,6 @@ clutter_stage_cogl_redraw_view (ClutterStageWindow *stage_window,
     }
 
   g_clear_pointer (&redraw_clip, cairo_region_destroy);
-  g_clear_pointer (&queued_redraw_clip, cairo_region_destroy);
   g_clear_pointer (&fb_clip_region, cairo_region_destroy);
 
   if (do_swap_buffer)
@@ -971,11 +966,17 @@ clutter_stage_cogl_redraw_view (ClutterStageWindow *stage_window,
           swap_region = transformed_swap_region;
         }
 
+      if (queued_redraw_clip)
+        {
+          paint_damage_region (stage_window, view,
+                               swap_region, queued_redraw_clip);
+          cairo_region_destroy (queued_redraw_clip);
+        }
+
       res = swap_framebuffer (stage_window,
                               view,
                               swap_region,
-                              swap_with_damage,
-                              queued_redraw_clip);
+                              swap_with_damage);
 
       cairo_region_destroy (swap_region);
 
@@ -983,6 +984,7 @@ clutter_stage_cogl_redraw_view (ClutterStageWindow *stage_window,
     }
   else
     {
+      g_clear_pointer (&queued_redraw_clip, cairo_region_destroy);
       return FALSE;
     }
 }