[mutter] clutter/view: Make it possible to assign a temporary direct scanout

[Jonas Ådahl <jadahl src gnome org>]

commit 753066598ff83fa9bdbd1be23d1e22663ae59297
Author: Jonas Ådahl <jadahl gmail com>
Date:   Thu Sep 12 11:28:50 2019 +0200

    clutter/view: Make it possible to assign a temporary direct scanout
    
    Make it possible to cause the next frame to scan out directly from the
    passed CoglScannout. This makes it possible to completely bypass
    compositing for the following frame.
    
    https://gitlab.gnome.org/GNOME/mutter/merge_requests/798

 clutter/clutter/clutter-mutter.h             |  4 ++++
 clutter/clutter/clutter-stage-view-private.h |  2 ++
 clutter/clutter/clutter-stage-view.c         | 24 ++++++++++++++++++++++++
 clutter/clutter/cogl/clutter-stage-cogl.c    | 28 +++++++++++++++++++++++++++-
 cogl/cogl/cogl-onscreen.h                    |  2 +-
 5 files changed, 58 insertions(+), 2 deletions(-)
---
diff --git a/clutter/clutter/clutter-mutter.h b/clutter/clutter/clutter-mutter.h
index e51ccba98..5c652a4e3 100644
--- a/clutter/clutter/clutter-mutter.h
+++ b/clutter/clutter/clutter-mutter.h
@@ -57,6 +57,10 @@ void clutter_stage_thaw_updates (ClutterStage *stage);
 CLUTTER_EXPORT
 void clutter_stage_update_resource_scales (ClutterStage *stage);
 
+CLUTTER_EXPORT
+void clutter_stage_view_assign_next_scanout (ClutterStageView *stage_view,
+                                             CoglScanout      *scanout);
+
 CLUTTER_EXPORT
 gboolean clutter_actor_has_damage (ClutterActor *actor);
 
diff --git a/clutter/clutter/clutter-stage-view-private.h b/clutter/clutter/clutter-stage-view-private.h
index 3b0d419fc..2e5ad4c53 100644
--- a/clutter/clutter/clutter-stage-view-private.h
+++ b/clutter/clutter/clutter-stage-view-private.h
@@ -43,4 +43,6 @@ const cairo_region_t * clutter_stage_view_peek_redraw_clip (ClutterStageView *vi
 
 cairo_region_t * clutter_stage_view_take_redraw_clip (ClutterStageView *view);
 
+CoglScanout * clutter_stage_view_take_scanout (ClutterStageView *view);
+
 #endif /* __CLUTTER_STAGE_VIEW_PRIVATE_H__ */
diff --git a/clutter/clutter/clutter-stage-view.c b/clutter/clutter/clutter-stage-view.c
index d93cf573f..b7413be7c 100644
--- a/clutter/clutter/clutter-stage-view.c
+++ b/clutter/clutter/clutter-stage-view.c
@@ -24,6 +24,8 @@
 #include <math.h>
 
 #include "clutter/clutter-private.h"
+#include "clutter/clutter-mutter.h"
+#include "cogl/cogl.h"
 
 enum
 {
@@ -52,6 +54,8 @@ typedef struct _ClutterStageViewPrivate
   CoglOffscreen *shadowfb;
   CoglPipeline *shadowfb_pipeline;
 
+  CoglScanout *next_scanout;
+
   gboolean has_redraw_clip;
   cairo_region_t *redraw_clip;
 
@@ -407,6 +411,26 @@ clutter_stage_default_get_offscreen_transformation_matrix (ClutterStageView *vie
   cogl_matrix_init_identity (matrix);
 }
 
+void
+clutter_stage_view_assign_next_scanout (ClutterStageView *view,
+                                        CoglScanout      *scanout)
+{
+  ClutterStageViewPrivate *priv =
+    clutter_stage_view_get_instance_private (view);
+
+  g_clear_object (&priv->next_scanout);
+  priv->next_scanout = scanout;
+}
+
+CoglScanout *
+clutter_stage_view_take_scanout (ClutterStageView *view)
+{
+  ClutterStageViewPrivate *priv =
+    clutter_stage_view_get_instance_private (view);
+
+  return g_steal_pointer (&priv->next_scanout);
+}
+
 static void
 clutter_stage_view_get_property (GObject    *object,
                                  guint       prop_id,
diff --git a/clutter/clutter/cogl/clutter-stage-cogl.c b/clutter/clutter/cogl/clutter-stage-cogl.c
index d48e97641..533d68154 100644
--- a/clutter/clutter/cogl/clutter-stage-cogl.c
+++ b/clutter/clutter/cogl/clutter-stage-cogl.c
@@ -959,6 +959,20 @@ clutter_stage_cogl_redraw_view (ClutterStageWindow *stage_window,
     }
 }
 
+static void
+clutter_stage_cogl_scanout_view (ClutterStageCogl *stage_cogl,
+                                 ClutterStageView *view,
+                                 CoglScanout      *scanout)
+{
+  CoglFramebuffer *framebuffer = clutter_stage_view_get_framebuffer (view);
+  CoglOnscreen *onscreen;
+
+  g_return_if_fail (cogl_is_onscreen (framebuffer));
+
+  onscreen = COGL_ONSCREEN (framebuffer);
+  cogl_onscreen_direct_scanout (onscreen, scanout);
+}
+
 static void
 clutter_stage_cogl_redraw (ClutterStageWindow *stage_window)
 {
@@ -971,11 +985,23 @@ clutter_stage_cogl_redraw (ClutterStageWindow *stage_window)
   for (l = _clutter_stage_window_get_views (stage_window); l; l = l->next)
     {
       ClutterStageView *view = l->data;
+      g_autoptr (CoglScanout) scanout = NULL;
 
       if (!clutter_stage_view_has_redraw_clip (view))
         continue;
 
-      swap_event |= clutter_stage_cogl_redraw_view (stage_window, view);
+      scanout = clutter_stage_view_take_scanout (view);
+      if (scanout)
+        {
+          clutter_stage_cogl_scanout_view (stage_cogl,
+                                           view,
+                                           scanout);
+          swap_event = TRUE;
+        }
+      else
+        {
+          swap_event |= clutter_stage_cogl_redraw_view (stage_window, view);
+        }
     }
 
   _clutter_stage_emit_after_paint (stage_cogl->wrapper);
diff --git a/cogl/cogl/cogl-onscreen.h b/cogl/cogl/cogl-onscreen.h
index fd95edd82..845470350 100644
--- a/cogl/cogl/cogl-onscreen.h
+++ b/cogl/cogl/cogl-onscreen.h
@@ -289,7 +289,7 @@ cogl_onscreen_swap_buffers_with_damage (CoglOnscreen *onscreen,
 /**
  * cogl_onscreen_direct_scanout: (skip)
  */
-void
+COGL_EXPORT void
 cogl_onscreen_direct_scanout (CoglOnscreen *onscreen,
                               CoglScanout  *scanout);