Explicitly create the clutter context and backend

This changes the setup phase of clutter to not be result of calling an
init function that sets up a few global singletons, via global singleton
setup vfuncs.

The way it worked was that mutter first did some initial setup
(connecting to the X11 server), then set a "custom backend" setup vfunc
global, before calling clutter_init().

During the clutter_init() call, the context and backend was setup by
calling the global singleton getters, which implicitly created the
backend and context on-demand.

This has now changed to mutter explicitly creating a `ClutterContext`
(which is actually a `ClutterMainContext`, but with the name shortened to
be consistent with `CoglContext` and `MetaContext`), calling it with a
backend constructor vfunc and user data pointer.

This function now explicitly creates the backend, without having to go
via the previously set global vfunc.

This changes the behavior of some "get_default()" like functions, which
will now fail if called after mutter has shut down, as when it does so,
it now destroys the backends and contexts, not only its own, but the
clutter ones too.

The "ownership" of the clutter backend is also moved to
`ClutterContext`, and MetaBackend is changed to fetch it via the clutter
context.

This also removed the unused option parsing that existed in clutter.

In some places, NULL checks for fetching the clutter context, or
backend, and fetching the cogl context from the clutter backend, had to
be added.

The reason for this is that some code that handles EGL contexts attempts
to restore the cogl EGL context tracking so that the right EGL context
is used by cogl the next time. This makes no sense to do before Cogl and
Clutter are even initialized, which was the case. It wasn't noticed
because the relevant singletons were initialized on demand via their
"getters".

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2002>

clutter/clutter/clutter-backend-private.h

@@ -96,8 +96,6 @@ struct _ClutterBackendClass
   void (* settings_changed)   (ClutterBackend *backend);
 };
 
-ClutterBackend *        _clutter_create_backend                         (void);
-
 ClutterStageWindow *    _clutter_backend_create_stage                   (ClutterBackend         *backend,
                                                                          ClutterStage           *wrapper,
                                                                          GError                **error);

clutter/clutter/clutter-backend.c

@@ -353,8 +353,7 @@ clutter_backend_real_create_context (ClutterBackend  *backend,
       if (internal_error != NULL)
         g_propagate_error (error, internal_error);
       else
-        g_set_error_literal (error, CLUTTER_INIT_ERROR,
-                             CLUTTER_INIT_ERROR_BACKEND,
+        g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_FAILED,
                              "Unable to initialize the Clutter backend: no available drivers found.");
 
       return FALSE;
@@ -391,28 +390,6 @@ clutter_backend_real_get_features (ClutterBackend *backend)
   return flags;
 }
 
-static ClutterBackend * (* custom_backend_func) (void);
-
-void
-clutter_set_custom_backend_func (ClutterBackend *(* func) (void))
-{
-  custom_backend_func = func;
-}
-
-ClutterBackend *
-_clutter_create_backend (void)
-{
-  ClutterBackend *retval;
-
-  g_return_val_if_fail (custom_backend_func, NULL);
-
-  retval = custom_backend_func ();
-  if (!retval)
-    g_error ("Failed to create custom backend.");
-
-  return retval;
-}
-
 static void
 clutter_backend_class_init (ClutterBackendClass *klass)
 {

clutter/clutter/clutter-feature.c

@@ -70,10 +70,9 @@ clutter_features_from_cogl (void)
 }
 
 gboolean
-_clutter_feature_init (GError **error)
+clutter_feature_init (ClutterMainContext  *context,
+                      GError             **error)
 {
-  ClutterMainContext *context;
-
   CLUTTER_NOTE (MISC, "checking features");
 
   if (!__features)
@@ -86,8 +85,6 @@ _clutter_feature_init (GError **error)
   if (__features->features_set)
     return TRUE;
 
-  context = _clutter_context_get_default ();
-
   /* makes sure we have a GL context; if we have, this is a no-op */
   if (!_clutter_backend_create_context (context->backend, error))
     return FALSE;

clutter/clutter/clutter-main.c

@@ -489,38 +489,11 @@ _clutter_context_is_initialized (void)
 ClutterMainContext *
 _clutter_context_get_default (void)
 {
-  if (G_UNLIKELY (ClutterCntx == NULL))
-    {
-      ClutterMainContext *ctx;
-
-      ClutterCntx = ctx = g_new0 (ClutterMainContext, 1);
-
-      ctx->is_initialized = FALSE;
-
-      /* create the windowing system backend */
-      ctx->backend = _clutter_create_backend ();
-
-      /* create the default settings object, and store a back pointer to
-       * the backend singleton
-       */
-      ctx->settings = clutter_settings_get_default ();
-      _clutter_settings_set_backend (ctx->settings, ctx->backend);
-
-      ctx->events_queue = g_async_queue_new ();
-
-      ctx->last_repaint_id = 1;
-    }
-
+  g_assert (ClutterCntx);
   return ClutterCntx;
 }
 
-GQuark
-clutter_init_error_quark (void)
-{
-  return g_quark_from_static_string ("clutter-init-error-quark");
-}
-
-static ClutterInitError
+static gboolean
 clutter_init_real (ClutterMainContext  *clutter_context,
                    GError             **error)
 {
@@ -532,7 +505,7 @@ clutter_init_real (ClutterMainContext  *clutter_context,
   backend = clutter_context->backend;
 
   if (!_clutter_backend_finish_init (backend, error))
-    return CLUTTER_INIT_ERROR_BACKEND;
+    return FALSE;
 
   /* If we are displaying the regions that would get redrawn with clipped
    * redraws enabled we actually have to disable the clipped redrawing
@@ -554,8 +527,8 @@ clutter_init_real (ClutterMainContext  *clutter_context,
   /* this will take care of initializing Cogl's state and
    * query the GL machinery for features
    */
-  if (!_clutter_feature_init (error))
-    return CLUTTER_INIT_ERROR_BACKEND;
+  if (!clutter_feature_init (clutter_context, error))
+    return FALSE;
 
   clutter_text_direction = clutter_get_text_direction ();
 
@@ -567,9 +540,9 @@ clutter_init_real (ClutterMainContext  *clutter_context,
     cally_accessibility_init ();
 
   /* Initialize types required for paint nodes */
-  _clutter_paint_node_init_types ();
+  clutter_paint_node_init_types (clutter_context->backend);
 
-  return CLUTTER_INIT_SUCCESS;
+  return TRUE;
 }
 
 static void
@@ -626,27 +599,57 @@ init_clutter_debug (ClutterMainContext *clutter_context)
     clutter_disable_mipmap_text = TRUE;
 }
 
-/**
- * clutter_init: (skip)
- */
-ClutterInitError
-clutter_init (GError **error)
+ClutterContext *
+clutter_context_new (ClutterBackendConstructor   backend_constructor,
+                     gpointer                    user_data,
+                     GError                    **error)
 {
   ClutterMainContext *clutter_context;
 
-  if (clutter_is_initialized)
-    return CLUTTER_INIT_SUCCESS;
+  if (ClutterCntx)
+    {
+      g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED,
+                   "Currently only creating one clutter context is supported");
+      return NULL;
+    }
 
-  clutter_base_init ();
-
-  clutter_context = _clutter_context_get_default ();
+  clutter_graphene_init ();
 
+  clutter_context = g_new0 (ClutterMainContext, 1);
   init_clutter_debug (clutter_context);
-
   clutter_context->frame_rate = clutter_default_fps;
   clutter_context->show_fps = clutter_show_fps;
+  clutter_context->is_initialized = FALSE;
 
-  return clutter_init_real (clutter_context, error);
+  clutter_context->backend = backend_constructor (user_data);
+  clutter_context->settings = clutter_settings_get_default ();
+  _clutter_settings_set_backend (clutter_context->settings,
+                                 clutter_context->backend);
+
+  clutter_context->events_queue = g_async_queue_new ();
+  clutter_context->last_repaint_id = 1;
+
+  if (!clutter_init_real (clutter_context, error))
+    return NULL;
+
+  ClutterCntx = clutter_context;
+
+  return clutter_context;
+}
+
+void
+clutter_context_free (ClutterMainContext *clutter_context)
+{
+  g_clear_pointer (&clutter_context->events_queue, g_async_queue_unref);
+  g_clear_pointer (&clutter_context->backend, clutter_backend_destroy);
+  ClutterCntx = NULL;
+  g_free (clutter_context);
+}
+
+ClutterBackend *
+clutter_context_get_backend (ClutterContext *clutter_context)
+{
+  return clutter_context->backend;
 }
 
 gboolean
@@ -1506,24 +1509,6 @@ _clutter_process_event (ClutterEvent *event)
   context->current_event = g_slist_delete_link (context->current_event, context->current_event);
 }
 
-void
-clutter_base_init (void)
-{
-  static gboolean initialised = FALSE;
-
-  if (!initialised)
-    {
-      initialised = TRUE;
-
-#if !GLIB_CHECK_VERSION (2, 35, 1)
-      /* initialise GLib type system */
-      g_type_init ();
-#endif
-
-      clutter_graphene_init ();
-    }
-}
-
 /**
  * clutter_get_default_frame_rate:
  *

clutter/clutter/clutter-main.h

@@ -77,37 +77,6 @@ typedef enum
   CLUTTER_DEBUG_PAINT_MAX_RENDER_TIME           = 1 << 10,
 } ClutterDrawDebugFlag;
 
-/**
- * CLUTTER_INIT_ERROR:
- *
- * #GError domain for #ClutterInitError
- */
-#define CLUTTER_INIT_ERROR      (clutter_init_error_quark ())
-
-/**
- * ClutterInitError:
- * @CLUTTER_INIT_SUCCESS: Initialisation successful
- * @CLUTTER_INIT_ERROR_UNKNOWN: Unknown error
- * @CLUTTER_INIT_ERROR_THREADS: Thread initialisation failed
- * @CLUTTER_INIT_ERROR_BACKEND: Backend initialisation failed
- * @CLUTTER_INIT_ERROR_INTERNAL: Internal error
- *
- * Error conditions returned by clutter_init().
- *
- * Since: 0.2
- */
-typedef enum
-{
-  CLUTTER_INIT_SUCCESS        =  1,
-  CLUTTER_INIT_ERROR_UNKNOWN  =  0,
-  CLUTTER_INIT_ERROR_THREADS  = -1,
-  CLUTTER_INIT_ERROR_BACKEND  = -2,
-  CLUTTER_INIT_ERROR_INTERNAL = -3
-} ClutterInitError;
-
-CLUTTER_EXPORT
-GQuark clutter_init_error_quark (void);
-
 /**
  * CLUTTER_PRIORITY_REDRAW:
  *
@@ -121,17 +90,6 @@ GQuark clutter_init_error_quark (void);
  */
 #define CLUTTER_PRIORITY_REDRAW         (G_PRIORITY_HIGH_IDLE + 50)
 
-/* Initialisation */
-CLUTTER_EXPORT
-void                    clutter_base_init                       (void);
-CLUTTER_EXPORT
-ClutterInitError        clutter_init                            (GError **error) G_GNUC_WARN_UNUSED_RESULT;
-
-CLUTTER_EXPORT
-GOptionGroup *          clutter_get_option_group                (void);
-CLUTTER_EXPORT
-GOptionGroup *          clutter_get_option_group_without_init   (void);
-
 CLUTTER_EXPORT
 void                    clutter_do_event                        (ClutterEvent *event);
 

clutter/clutter/clutter-mutter.h

@@ -38,6 +38,32 @@
 #include "clutter-stage-view-private.h"
 #include "clutter.h"
 
+typedef struct _ClutterMainContext ClutterContext;
+
+typedef ClutterBackend * (* ClutterBackendConstructor) (gpointer user_data);
+
+/**
+ * clutter_context_new: (skip)
+ */
+CLUTTER_EXPORT
+ClutterContext * clutter_context_new (ClutterBackendConstructor   backend_constructor,
+                                      gpointer                    user_data,
+                                      GError                    **error);
+
+/**
+ * clutter_context_free: (skip)
+ */
+CLUTTER_EXPORT
+void clutter_context_free (ClutterContext *clutter_context);
+
+/**
+ * clutter_context_get_backend:
+ *
+ * Returns: (transfer none): The corresponding %ClutterBackend
+ */
+CLUTTER_EXPORT
+ClutterBackend * clutter_context_get_backend (ClutterContext *clutter_context);
+
 CLUTTER_EXPORT
 GList * clutter_stage_peek_stage_views (ClutterStage *stage);
 
@@ -45,9 +71,6 @@ CLUTTER_EXPORT
 gboolean clutter_actor_is_effectively_on_stage_view (ClutterActor     *self,
                                                      ClutterStageView *view);
 
-CLUTTER_EXPORT
-void clutter_set_custom_backend_func (ClutterBackend *(* func) (void));
-
 CLUTTER_EXPORT
 int64_t clutter_stage_get_frame_counter (ClutterStage *stage);
 

clutter/clutter/clutter-paint-node-private.h

@@ -27,6 +27,7 @@
 
 #include <glib-object.h>
 #include <json-glib/json-glib.h>
+#include <clutter/clutter-backend.h>
 #include <clutter/clutter-paint-context.h>
 #include <clutter/clutter-paint-node.h>
 
@@ -109,7 +110,7 @@ void                    _clutter_paint_operation_paint_path             (const C
 void                    _clutter_paint_operation_clip_path              (const ClutterPaintOperation *op);
 void                    _clutter_paint_operation_paint_primitive        (const ClutterPaintOperation *op);
 
-void                    _clutter_paint_node_init_types                  (void);
+void                    clutter_paint_node_init_types                   (ClutterBackend *clutter_backend);
 gpointer                _clutter_paint_node_create                      (GType gtype);
 
 ClutterPaintNode *      _clutter_transform_node_new                     (const graphene_matrix_t     *matrix);

clutter/clutter/clutter-paint-nodes.c

@@ -51,30 +51,30 @@ static CoglPipeline *default_color_pipeline   = NULL;
 static CoglPipeline *default_texture_pipeline = NULL;
 
 /*< private >
- * _clutter_paint_node_init_types:
+ * clutter_paint_node_init_types:
  *
  * Initializes the required types for ClutterPaintNode subclasses
  */
 void
-_clutter_paint_node_init_types (void)
+clutter_paint_node_init_types (ClutterBackend *clutter_backend)
 {
-  CoglContext *ctx;
+  CoglContext *cogl_context;
   CoglColor cogl_color;
   GType node_type G_GNUC_UNUSED;
 
   if (G_LIKELY (default_color_pipeline != NULL))
     return;
 
-  ctx = clutter_backend_get_cogl_context (clutter_get_default_backend ());
+  cogl_context = clutter_backend_get_cogl_context (clutter_backend);
 
   node_type = clutter_paint_node_get_type ();
 
   cogl_color_init_from_4f (&cogl_color, 1.0, 1.0, 1.0, 1.0);
 
-  default_color_pipeline = cogl_pipeline_new (ctx);
+  default_color_pipeline = cogl_pipeline_new (cogl_context);
   cogl_pipeline_set_color (default_color_pipeline, &cogl_color);
 
-  default_texture_pipeline = cogl_pipeline_new (ctx);
+  default_texture_pipeline = cogl_pipeline_new (cogl_context);
   cogl_pipeline_set_layer_null_texture (default_texture_pipeline, 0);
   cogl_pipeline_set_color (default_texture_pipeline, &cogl_color);
   cogl_pipeline_set_layer_wrap_mode (default_texture_pipeline, 0,

clutter/clutter/clutter-private.h

@@ -154,7 +154,6 @@ struct _ClutterMainContext
 
   /* boolean flags */
   guint is_initialized          : 1;
-  guint options_parsed          : 1;
   guint show_fps                : 1;
 };
 
@@ -176,7 +175,8 @@ CLUTTER_EXPORT
 gboolean                _clutter_context_is_initialized                 (void);
 gboolean                _clutter_context_get_show_fps                   (void);
 
-gboolean      _clutter_feature_init (GError **error);
+gboolean clutter_feature_init (ClutterMainContext  *clutter_context,
+                               GError             **error);
 
 /* Diagnostic mode */
 gboolean        _clutter_diagnostic_enabled     (void);

src/backends/meta-backend.c

@@ -162,7 +162,7 @@ struct _MetaBackendPrivate
   WacomDeviceDatabase *wacom_db;
 #endif
 
-  ClutterBackend *clutter_backend;
+  ClutterContext *clutter_context;
   ClutterSeat *default_seat;
   ClutterActor *stage;
 
@@ -257,7 +257,7 @@ meta_backend_dispose (GObject *object)
   g_clear_pointer (&priv->stage, clutter_actor_destroy);
   g_clear_pointer (&priv->idle_manager, meta_idle_manager_free);
   g_clear_object (&priv->renderer);
-  g_clear_pointer (&priv->clutter_backend, clutter_backend_destroy);
+  g_clear_pointer (&priv->clutter_context, clutter_context_free);
   g_clear_list (&priv->gpus, g_object_unref);
 
   G_OBJECT_CLASS (meta_backend_parent_class)->dispose (object);
@@ -1037,11 +1037,11 @@ static GSourceFuncs clutter_source_funcs = {
 };
 
 static ClutterBackend *
-meta_get_clutter_backend (void)
+meta_clutter_backend_constructor (gpointer user_data)
 {
-  MetaBackend *backend = meta_get_backend ();
+  MetaBackend *backend = META_BACKEND (user_data);
 
-  return meta_backend_get_clutter_backend (backend);
+  return META_BACKEND_GET_CLASS (backend)->create_clutter_backend (backend);
 }
 
 static ClutterSeat *
@@ -1059,9 +1059,10 @@ init_clutter (MetaBackend  *backend,
   MetaBackendSource *backend_source;
   GSource *source;
 
-  clutter_set_custom_backend_func (meta_get_clutter_backend);
-
-  if (clutter_init (error) != CLUTTER_INIT_SUCCESS)
+  priv->clutter_context = clutter_context_new (meta_clutter_backend_constructor,
+                                               backend,
+                                               error);
+  if (!priv->clutter_context)
     return FALSE;
 
   priv->default_seat = meta_backend_create_default_seat (backend, error);
@@ -1526,14 +1527,13 @@ ClutterBackend *
 meta_backend_get_clutter_backend (MetaBackend *backend)
 {
   MetaBackendPrivate *priv = meta_backend_get_instance_private (backend);
+  ClutterContext *clutter_context;
 
-  if (!priv->clutter_backend)
-    {
-      priv->clutter_backend =
-        META_BACKEND_GET_CLASS (backend)->create_clutter_backend (backend);
-    }
+  clutter_context = priv->clutter_context;
+  if (!clutter_context)
+    return NULL;
 
-  return priv->clutter_backend;
+  return clutter_context_get_backend (clutter_context);
 }
 
 void

src/backends/native/meta-renderer-native.c

@@ -485,7 +485,11 @@ cogl_context_from_renderer_native (MetaRendererNative *renderer_native)
 {
   MetaRenderer *renderer = META_RENDERER (renderer_native);
   MetaBackend *backend = meta_renderer_get_backend (renderer);
-  ClutterBackend *clutter_backend = meta_backend_get_clutter_backend (backend);
+  ClutterBackend *clutter_backend;
+
+  clutter_backend = meta_backend_get_clutter_backend (backend);
+  if (!clutter_backend)
+    return NULL;
 
   return clutter_backend_get_cogl_context (clutter_backend);
 }

src/backends/x11/meta-backend-x11.c

@@ -867,7 +867,6 @@ meta_backend_x11_initable_init (GInitable    *initable,
 
   priv->xdisplay = xdisplay;
   priv->xcb = XGetXCBConnection (priv->xdisplay);
-  meta_clutter_x11_set_display (xdisplay);
 
   init_xkb_state (x11);
 

src/backends/x11/meta-clutter-backend-x11.c

@@ -28,6 +28,7 @@
 
 #include "backends/meta-backend-private.h"
 #include "backends/meta-renderer.h"
+#include "backends/x11/meta-backend-x11.h"
 #include "backends/x11/meta-clutter-backend-x11.h"
 #include "backends/x11/meta-keymap-x11.h"
 #include "backends/x11/meta-seat-x11.h"
@@ -76,7 +77,6 @@ static const gchar *atom_names[] = {
 
 /* various flags corresponding to pre init setup calls */
 static gboolean clutter_enable_stereo = FALSE;
-static Display  *_foreign_dpy = NULL;
 
 /* options */
 static gboolean clutter_synchronise = FALSE;
@@ -117,47 +117,13 @@ meta_clutter_backend_x11_finish_init (ClutterBackend  *clutter_backend,
 {
   MetaClutterBackendX11 *clutter_backend_x11 =
     META_CLUTTER_BACKEND_X11 (clutter_backend);
+  MetaClutterBackendX11Private *priv =
+    meta_clutter_backend_x11_get_instance_private (clutter_backend_x11);
+  MetaBackendX11 *backend_x11 = META_BACKEND_X11 (priv->backend);
   Atom atoms[N_ATOM_NAMES];
   Screen *xscreen;
 
-  if (_foreign_dpy)
-    backend_x11->xdisplay = _foreign_dpy;
-
-  /* Only open connection if not already set by prior call to
-   * clutter_x11_set_display()
-   */
-  if (clutter_backend_x11->xdisplay == NULL)
-    {
-      const char *display_name;
-
-      display_name = g_getenv ("DISPLAY");
-      if (display_name && *display_name != '\0')
-	{
-	  g_debug ("XOpenDisplay on '%s'", display_name);
-
-          clutter_backend_x11->xdisplay = XOpenDisplay (display_name);
-          if (clutter_backend_x11->xdisplay == NULL)
-            {
-              g_set_error (error, CLUTTER_INIT_ERROR,
-                           CLUTTER_INIT_ERROR_BACKEND,
-                           "Unable to open display '%s'",
-                           display_name);
-              return FALSE;
-            }
-	}
-      else
-	{
-	  g_set_error_literal (error, CLUTTER_INIT_ERROR,
-                               CLUTTER_INIT_ERROR_BACKEND,
-                               "Unable to open display. You have to set the "
-                               "DISPLAY environment variable, or use the "
-                               "--display command line argument");
-	  return FALSE;
-	}
-    }
-
-
-  g_debug ("Getting the X screen");
+  clutter_backend_x11->xdisplay = meta_backend_x11_get_xdisplay (backend_x11);
 
   /* add event filter for Cogl events */
   meta_clutter_backend_x11_add_filter (clutter_backend_x11,
@@ -297,8 +263,7 @@ check_onscreen_template (CoglRenderer         *renderer,
     }
   else
     {
-      g_set_error_literal (error, CLUTTER_INIT_ERROR,
-                           CLUTTER_INIT_ERROR_BACKEND,
+      g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_FAILED,
                            internal_error != NULL
                            ? internal_error->message
                            : "Creation of a CoglDisplay failed");
@@ -543,19 +508,6 @@ meta_clutter_x11_get_default_display (void)
   return META_CLUTTER_BACKEND_X11 (clutter_backend)->xdisplay;
 }
 
-void
-meta_clutter_x11_set_display (Display *xdisplay)
-{
-  if (_clutter_context_is_initialized ())
-    {
-      g_warning ("%s() can only be used before calling clutter_init()",
-                 G_STRFUNC);
-      return;
-    }
-
-  _foreign_dpy= xdisplay;
-}
-
 int
 meta_clutter_x11_get_default_screen (void)
 {

src/backends/x11/meta-clutter-backend-x11.h

@@ -82,7 +82,6 @@ gint meta_clutter_x11_untrap_x_errors (void);
 Display *meta_clutter_x11_get_default_display (void);
 int meta_clutter_x11_get_default_screen (void);
 Window meta_clutter_x11_get_root_window (void);
-void meta_clutter_x11_set_display (Display * xdpy);
 
 void meta_clutter_backend_x11_add_filter (MetaClutterBackendX11 *clutter_backend_x11,
                                           MetaX11FilterFunc      func,

src/backends/x11/meta-renderer-x11.c

@@ -30,6 +30,7 @@
 #include "backends/meta-logical-monitor.h"
 #include "backends/meta-renderer-view.h"
 #include "backends/meta-renderer.h"
+#include "backends/x11/meta-backend-x11.h"
 #include "backends/x11/meta-clutter-backend-x11.h"
 #include "backends/x11/meta-renderer-x11.h"
 #include "cogl/cogl-xlib.h"
@@ -81,8 +82,10 @@ get_x11_cogl_winsys_vtable (CoglRenderer *renderer)
 static CoglRenderer *
 meta_renderer_x11_create_cogl_renderer (MetaRenderer *renderer)
 {
+  MetaBackend *backend = meta_renderer_get_backend (renderer);
+  MetaBackendX11 *backend_x11 = META_BACKEND_X11 (backend);
+  Display *xdisplay = meta_backend_x11_get_xdisplay (backend_x11);
   CoglRenderer *cogl_renderer;
-  Display *xdisplay = meta_clutter_x11_get_default_display ();
 
   cogl_renderer = cogl_renderer_new ();
   cogl_renderer_set_custom_winsys (cogl_renderer, get_x11_cogl_winsys_vtable,