[clutter] backend: Provide a default create_stage()

[Emmanuele Bassi <ebassi src gnome org>]

commit 828ca2982f0f7b6974283921d59c65929385da8f
Author: Emmanuele Bassi <ebassi linux intel com>
Date:   Fri Nov 4 19:00:49 2011 +0000

    backend: Provide a default create_stage()
    
    We can now safely create a ClutterStageWindow in the shared code path,
    instead of deferring to the backend.

 clutter/clutter-backend.c |   32 ++++++++++++++++++++++++++++++++
 1 files changed, 32 insertions(+), 0 deletions(-)
---
diff --git a/clutter/clutter-backend.c b/clutter/clutter-backend.c
index 9cabfad..4f9e1e1 100644
--- a/clutter/clutter-backend.c
+++ b/clutter/clutter-backend.c
@@ -389,6 +389,37 @@ clutter_backend_real_get_features (ClutterBackend *backend)
   return flags;
 }
 
+static ClutterStageWindow *
+clutter_backend_real_create_stage (ClutterBackend  *backend,
+                                   ClutterStage    *wrapper,
+                                   GError         **error)
+{
+  ClutterBackendClass *klass;
+
+  if (!clutter_feature_available (CLUTTER_FEATURE_STAGE_MULTIPLE))
+    {
+      ClutterStageManager *manager = clutter_stage_manager_get_default ();
+
+      if (clutter_stage_manager_get_default_stage (manager) != NULL)
+        {
+          g_set_error (error, CLUTTER_INIT_ERROR,
+                       CLUTTER_INIT_ERROR_BACKEND,
+                       _("The backend of type '%s' does not support "
+                         "creating multiple stages"),
+                       G_OBJECT_TYPE_NAME (backend));
+          return NULL;
+        }
+    }
+
+  klass = CLUTTER_BACKEND_GET_CLASS (backend);
+  g_assert (klass->stage_window_type != G_TYPE_INVALID);
+
+  return g_object_new (klass->stage_window_type,
+                       "backend", backend,
+                       "wrapper", wrapper,
+                       NULL);
+}
+
 static void
 clutter_backend_real_redraw (ClutterBackend *backend,
                              ClutterStage   *stage)
@@ -576,6 +607,7 @@ clutter_backend_class_init (ClutterBackendClass *klass)
   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->create_stage = clutter_backend_real_create_stage;
   klass->redraw = clutter_backend_real_redraw;
 }