backend: Provide a default get_features() implementation

Continue gutting ClutterBackendCogl; get_features() is the last bit that
still does something, but now we can use the Cogl API.

clutter/clutter-backend.c

@@ -356,6 +356,39 @@ clutter_backend_real_ensure_context (ClutterBackend *backend,
   cogl_set_framebuffer (framebuffer);
 }
 
+static ClutterFeatureFlags
+clutter_backend_real_get_features (ClutterBackend *backend)
+{
+  ClutterFeatureFlags flags = 0;
+
+  if (cogl_clutter_winsys_has_feature (COGL_WINSYS_FEATURE_MULTIPLE_ONSCREEN))
+    {
+      CLUTTER_NOTE (BACKEND, "Cogl supports multiple onscreen framebuffers");
+      flags |= CLUTTER_FEATURE_STAGE_MULTIPLE;
+    }
+  else
+    {
+      CLUTTER_NOTE (BACKEND, "Cogl only supports one onscreen framebuffer");
+      flags |= CLUTTER_FEATURE_STAGE_STATIC;
+    }
+
+  if (cogl_clutter_winsys_has_feature (COGL_WINSYS_FEATURE_SWAP_THROTTLE))
+    {
+      CLUTTER_NOTE (BACKEND, "Cogl supports swap buffers throttling");
+      flags |= CLUTTER_FEATURE_SYNC_TO_VBLANK;
+    }
+  else
+    CLUTTER_NOTE (BACKEND, "Cogl doesn't support swap buffers throttling");
+
+  if (cogl_clutter_winsys_has_feature (COGL_WINSYS_FEATURE_SWAP_BUFFERS_EVENT))
+    {
+      CLUTTER_NOTE (BACKEND, "Cogl supports swap buffers complete events");
+      flags |= CLUTTER_FEATURE_SWAP_EVENTS;
+    }
+
+  return flags;
+}
+
 static void
 clutter_backend_real_redraw (ClutterBackend *backend,
                              ClutterStage   *stage)
@@ -540,6 +573,7 @@ clutter_backend_class_init (ClutterBackendClass *klass)
   klass->translate_event = clutter_backend_real_translate_event;
   klass->create_context = clutter_backend_real_create_context;
   klass->ensure_context = clutter_backend_real_ensure_context;
+  klass->get_features = clutter_backend_real_get_features;
   klass->redraw = clutter_backend_real_redraw;
 }
 

clutter/cogl/clutter-backend-cogl.c

@@ -129,46 +129,6 @@ clutter_backend_cogl_constructor (GType                  gtype,
   return g_object_ref (backend_singleton);
 }
 
-static ClutterFeatureFlags
-clutter_backend_cogl_get_features (ClutterBackend *backend)
-{
-  ClutterBackendCogl *backend_cogl = CLUTTER_BACKEND_COGL (backend);
-  ClutterFeatureFlags flags = 0;
-
-  if (cogl_clutter_winsys_has_feature (COGL_WINSYS_FEATURE_MULTIPLE_ONSCREEN))
-    {
-      CLUTTER_NOTE (BACKEND, "Cogl supports multiple onscreen framebuffers");
-      flags |= CLUTTER_FEATURE_STAGE_MULTIPLE;
-    }
-  else
-    {
-      CLUTTER_NOTE (BACKEND, "Cogl only supports one onscreen framebuffer");
-      flags |= CLUTTER_FEATURE_STAGE_STATIC;
-    }
-
-  if (cogl_clutter_winsys_has_feature (COGL_WINSYS_FEATURE_SWAP_THROTTLE))
-    {
-      CLUTTER_NOTE (BACKEND, "Cogl supports swap buffers throttling");
-      flags |= CLUTTER_FEATURE_SYNC_TO_VBLANK;
-    }
-  else
-    CLUTTER_NOTE (BACKEND, "Cogl doesn't support swap buffers throttling");
-
-  if (cogl_clutter_winsys_has_feature (COGL_WINSYS_FEATURE_SWAP_BUFFERS_EVENT))
-    {
-      CLUTTER_NOTE (BACKEND, "Cogl supports swap buffers complete events");
-      flags |= CLUTTER_FEATURE_SWAP_EVENTS;
-    }
-
-  if (cogl_clutter_winsys_has_feature (COGL_WINSYS_FEATURE_SWAP_REGION))
-    {
-      CLUTTER_NOTE (BACKEND, "Cogl supports swapping buffer regions");
-      backend_cogl->can_blit_sub_buffer = TRUE;
-    }
-
-  return flags;
-}
-
 static void
 _clutter_backend_cogl_class_init (ClutterBackendCoglClass *klass)
 {
@@ -181,7 +141,6 @@ _clutter_backend_cogl_class_init (ClutterBackendCoglClass *klass)
 
   backend_class->pre_parse = clutter_backend_cogl_pre_parse;
   backend_class->post_parse = clutter_backend_cogl_post_parse;
-  backend_class->get_features = clutter_backend_cogl_get_features;
 }
 
 static void

clutter/cogl/clutter-stage-cogl.c

@@ -316,11 +316,10 @@ static void
 clutter_stage_cogl_redraw (ClutterStageWindow *stage_window)
 {
   ClutterStageCogl *stage_cogl = CLUTTER_STAGE_COGL (stage_window);
-  ClutterActor *wrapper;
-  ClutterBackend *backend;
-  ClutterBackendCogl *backend_cogl;
   gboolean may_use_clipped_redraw;
   gboolean use_clipped_redraw;
+  gboolean can_blit_sub_buffer;
+  ClutterActor *wrapper;
 
   CLUTTER_STATIC_TIMER (painting_timer,
                         "Redrawing", /* parent */
@@ -343,19 +342,19 @@ clutter_stage_cogl_redraw (ClutterStageWindow *stage_window)
   if (!stage_cogl->onscreen)
     return;
 
-  backend = clutter_get_default_backend ();
-  backend_cogl = CLUTTER_BACKEND_COGL (backend);
-
   CLUTTER_TIMER_START (_clutter_uprof_context, painting_timer);
 
+  can_blit_sub_buffer =
+    cogl_clutter_winsys_has_feature (COGL_WINSYS_FEATURE_SWAP_REGION);
+
   may_use_clipped_redraw = FALSE;
   if (_clutter_stage_window_can_clip_redraws (stage_window) &&
-      G_LIKELY (backend_cogl->can_blit_sub_buffer) &&
+      can_blit_sub_buffer &&
       /* NB: a zero width redraw clip == full stage redraw */
       stage_cogl->bounding_redraw_clip.width != 0 &&
       /* some drivers struggle to get going and produce some junk
        * frames when starting up... */
-      G_LIKELY (stage_cogl->frame_count > 3))
+      stage_cogl->frame_count > 3)
     {
       may_use_clipped_redraw = TRUE;
     }

clutter/gdk/clutter-backend-gdk.c

@@ -218,11 +218,13 @@ clutter_backend_gdk_dispose (GObject *gobject)
 static ClutterFeatureFlags
 clutter_backend_gdk_get_features (ClutterBackend *backend)
 {
-  ClutterFeatureFlags flags = CLUTTER_FEATURE_STAGE_USER_RESIZE | CLUTTER_FEATURE_STAGE_CURSOR;
+  ClutterBackendClass *parent_class;
 
-  flags |= CLUTTER_BACKEND_CLASS (clutter_backend_gdk_parent_class)->get_features (backend);
+  parent_class = CLUTTER_BACKEND_CLASS (clutter_backend_gdk_parent_class);
 
-  return flags;
+  return parent_class->get_features (backend)
+        | CLUTTER_FEATURE_STAGE_USER_RESIZE
+        | CLUTTER_FEATURE_STAGE_CURSOR;
 }
 
 static void

clutter/win32/clutter-backend-win32.c

@@ -183,34 +183,12 @@ ClutterFeatureFlags
 clutter_backend_win32_get_features (ClutterBackend *backend)
 {
   ClutterBackendClass *parent_class;
-  ClutterFeatureFlags flags;
 
   parent_class = CLUTTER_BACKEND_CLASS (clutter_backend_win32_parent_class);
 
-  flags = CLUTTER_FEATURE_STAGE_USER_RESIZE | CLUTTER_FEATURE_STAGE_CURSOR;
+  return parent_class->get_features (backend)
-
+    | CLUTTER_FEATURE_STAGE_USER_RESIZE
-  if (cogl_clutter_winsys_has_feature (COGL_WINSYS_FEATURE_MULTIPLE_ONSCREEN))
+    | CLUTTER_FEATURE_STAGE_CURSOR;
-    {
-      CLUTTER_NOTE (BACKEND, "Cogl supports multiple onscreen framebuffers");
-      flags |= CLUTTER_FEATURE_STAGE_MULTIPLE;
-    }
-  else
-    {
-      CLUTTER_NOTE (BACKEND, "Cogl only supports one onscreen framebuffer");
-      flags |= CLUTTER_FEATURE_STAGE_STATIC;
-    }
-
-  if (cogl_clutter_winsys_has_feature (COGL_WINSYS_FEATURE_SWAP_THROTTLE))
-    {
-      CLUTTER_NOTE (BACKEND, "Cogl supports swap buffers throttling");
-      flags |= CLUTTER_FEATURE_SYNC_TO_VBLANK;
-    }
-  else
-    CLUTTER_NOTE (BACKEND, "Cogl doesn't support swap buffers throttling");
-
-  CLUTTER_NOTE (BACKEND, "backend features checked");
-
-  return flags;
 }
 
 static ClutterStageWindow *