From 55c957267ef241767ebd3891d49f06deb2ff4aa9 Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Mon, 2 Mar 2015 12:11:30 +0000
Subject: [PATCH] stage-cogl: Use swap buffers with damage

cogl provides an interface to pass along damage with the swap buffers
request. This is useful for the display servers and hardware to minimise
the work done in updating the screen and also reducing the work done by
external listeners (such as vnc, drm/udl and PRIME).

Bugzilla: https://bugzilla.gnome.org/show_bug.cgi?id=745512
---
 clutter/cogl/clutter-stage-cogl.c | 52 ++++++++++++++++++-------------
 1 file changed, 31 insertions(+), 21 deletions(-)

diff --git a/clutter/cogl/clutter-stage-cogl.c b/clutter/cogl/clutter-stage-cogl.c
index ee612d4df..378797d70 100644
--- a/clutter/cogl/clutter-stage-cogl.c
+++ b/clutter/cogl/clutter-stage-cogl.c
@@ -405,6 +405,7 @@ clutter_stage_cogl_redraw (ClutterStageWindow *stage_window)
   gboolean has_buffer_age;
   ClutterActor *wrapper;
   cairo_rectangle_int_t *clip_region;
+  int damage[4], ndamage;
   gboolean force_swap;
   int window_scale;
 
@@ -591,35 +592,43 @@ clutter_stage_cogl_redraw (ClutterStageWindow *stage_window)
       cogl_object_unref (prim);
     }
 
+  /* XXX: It seems there will be a race here in that the stage
+   * window may be resized before the cogl_onscreen_swap_region
+   * is handled and so we may copy the wrong region. I can't
+   * really see how we can handle this with the current state of X
+   * but at least in this case a full redraw should be queued by
+   * the resize anyway so it should only exhibit temporary
+   * artefacts.
+   */
+  if (use_clipped_redraw || force_swap)
+    {
+      damage[0] = clip_region->x * window_scale;
+      damage[1] = clip_region->y * window_scale;
+      damage[2] = clip_region->width * window_scale;
+      damage[3] = clip_region->height * window_scale;
+      ndamage = 1;
+    }
+  else
+    {
+      damage[0] = 0;
+      damage[1] = 0;
+      damage[2] = geom.width;
+      damage[3] = geom.height;
+      ndamage = -1;
+    }
+
   /* push on the screen */
   if (use_clipped_redraw && !force_swap)
     {
-      cairo_rectangle_int_t *clip = clip_region;
-      int copy_area[4];
-
-      /* XXX: It seems there will be a race here in that the stage
-       * window may be resized before the cogl_onscreen_swap_region
-       * is handled and so we may copy the wrong region. I can't
-       * really see how we can handle this with the current state of X
-       * but at least in this case a full redraw should be queued by
-       * the resize anyway so it should only exhibit temporary
-       * artefacts.
-       */
-
-      copy_area[0] = clip->x * window_scale;
-      copy_area[1] = clip->y * window_scale;
-      copy_area[2] = clip->width * window_scale;
-      copy_area[3] = clip->height * window_scale;
-
       CLUTTER_NOTE (BACKEND,
                     "cogl_onscreen_swap_region (onscreen: %p, "
                                                 "x: %d, y: %d, "
                                                 "width: %d, height: %d)",
                     stage_cogl->onscreen,
-                    copy_area[0], copy_area[1], copy_area[2], copy_area[3]);
+                    damage[0], damage[1], damage[2], damage[3]);
 
-
-      cogl_onscreen_swap_region (stage_cogl->onscreen, copy_area, 1);
+      cogl_onscreen_swap_region (stage_cogl->onscreen,
+				 damage, ndamage);
     }
   else
     {
@@ -632,7 +641,8 @@ clutter_stage_cogl_redraw (ClutterStageWindow *stage_window)
       if (clutter_feature_available (CLUTTER_FEATURE_SWAP_EVENTS))
         stage_cogl->pending_swaps++;
 
-      cogl_onscreen_swap_buffers (stage_cogl->onscreen);
+      cogl_onscreen_swap_buffers_with_damage (stage_cogl->onscreen,
+					      damage, ndamage);
     }
 
   /* reset the redraw clipping for the next paint... */