backend: Take over seat ownership from the clutter backend

Having the clutter backend owning and managing creates complication for
implementing graceful shutdown, so move it to the real backend.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1775>

clutter/clutter/clutter-backend-private.h

@@ -73,7 +73,6 @@ struct _ClutterBackendClass
   ClutterStageWindow *  (* create_stage)       (ClutterBackend  *backend,
                                                 ClutterStage    *wrapper,
                                                 GError         **error);
-  void                  (* init_events)        (ClutterBackend  *backend);
   void                  (* init_features)      (ClutterBackend  *backend);
   void                  (* add_options)        (ClutterBackend  *backend,
                                                 GOptionGroup    *group);
@@ -116,7 +115,6 @@ gboolean                _clutter_backend_pre_parse                      (Clutter
 gboolean                _clutter_backend_post_parse                     (ClutterBackend         *backend,
                                                                          GError                **error);
 
-void                    _clutter_backend_init_events                    (ClutterBackend         *backend);
 CLUTTER_EXPORT
 gboolean                _clutter_backend_translate_event                (ClutterBackend         *backend,
                                                                          gpointer                native,

clutter/clutter/clutter-backend.c

@@ -445,12 +445,6 @@ _clutter_create_backend (void)
   return retval;
 }
 
-static void
-clutter_backend_real_init_events (ClutterBackend *backend)
-{
-  g_error ("Unknown input backend");
-}
-
 static void
 clutter_backend_class_init (ClutterBackendClass *klass)
 {
@@ -513,7 +507,6 @@ clutter_backend_class_init (ClutterBackendClass *klass)
   klass->resolution_changed = clutter_backend_real_resolution_changed;
   klass->font_changed = clutter_backend_real_font_changed;
 
-  klass->init_events = clutter_backend_real_init_events;
   klass->create_context = clutter_backend_real_create_context;
   klass->get_features = clutter_backend_real_get_features;
 }
@@ -652,17 +645,6 @@ _clutter_backend_get_features (ClutterBackend *backend)
   return 0;
 }
 
-void
-_clutter_backend_init_events (ClutterBackend *backend)
-{
-  ClutterBackendClass *klass;
-
-  g_assert (CLUTTER_IS_BACKEND (backend));
-
-  klass = CLUTTER_BACKEND_GET_CLASS (backend);
-  klass->init_events (backend);
-}
-
 gfloat
 _clutter_backend_get_units_per_em (ClutterBackend       *backend,
                                    PangoFontDescription *font_desc)

clutter/clutter/clutter-main.c

@@ -608,9 +608,6 @@ clutter_init_real (GError **error)
 
   clutter_text_direction = clutter_get_text_direction ();
 
-  /* Initiate event collection */
-  _clutter_backend_init_events (ctx->backend);
-
   clutter_is_initialized = TRUE;
   ctx->is_initialized = TRUE;
 

src/backends/meta-backend-private.h

@@ -71,6 +71,9 @@ struct _MetaBackendClass
                                       GError     **error);
   MetaInputSettings * (* get_input_settings) (MetaBackend *backend);
 
+  ClutterSeat * (* create_default_seat) (MetaBackend  *backend,
+                                         GError      **error);
+
   gboolean (* grab_device) (MetaBackend *backend,
                             int          device_id,
                             uint32_t     timestamp);
@@ -122,6 +125,8 @@ void meta_backend_init_wayland (MetaBackend *backend);
 
 ClutterBackend * meta_backend_get_clutter_backend (MetaBackend *backend);
 
+ClutterSeat * meta_backend_get_default_seat (MetaBackend *bakcend);
+
 MetaIdleMonitor * meta_backend_get_idle_monitor (MetaBackend        *backend,
                                                  ClutterInputDevice *device);
 void meta_backend_foreach_device_monitor (MetaBackend *backend,

src/backends/meta-backend.c

@@ -149,6 +149,7 @@ struct _MetaBackendPrivate
 #endif
 
   ClutterBackend *clutter_backend;
+  ClutterSeat *default_seat;
   ClutterActor *stage;
 
   GList *gpus;
@@ -244,6 +245,7 @@ meta_backend_dispose (GObject *object)
   g_clear_object (&priv->profiler);
 #endif
 
+  g_clear_object (&priv->default_seat);
   g_clear_object (&priv->clutter_backend);
 
   G_OBJECT_CLASS (meta_backend_parent_class)->dispose (object);
@@ -1047,10 +1049,18 @@ meta_get_clutter_backend (void)
   return meta_backend_get_clutter_backend (backend);
 }
 
+static ClutterSeat *
+meta_backend_create_default_seat (MetaBackend  *backend,
+                                  GError      **error)
+{
+  return META_BACKEND_GET_CLASS (backend)->create_default_seat (backend, error);
+}
+
 static gboolean
 init_clutter (MetaBackend  *backend,
               GError      **error)
 {
+  MetaBackendPrivate *priv = meta_backend_get_instance_private (backend);
   MetaBackendSource *backend_source;
   GSource *source;
 
@@ -1063,6 +1073,10 @@ init_clutter (MetaBackend  *backend,
       return FALSE;
     }
 
+  priv->default_seat = meta_backend_create_default_seat (backend, error);
+  if (!priv->default_seat)
+    return FALSE;
+
   source = g_source_new (&clutter_source_funcs, sizeof (MetaBackendSource));
   backend_source = (MetaBackendSource *) source;
   backend_source->backend = backend;
@@ -1393,6 +1407,14 @@ meta_backend_get_stage (MetaBackend *backend)
   return priv->stage;
 }
 
+ClutterSeat *
+meta_backend_get_default_seat (MetaBackend *backend)
+{
+  MetaBackendPrivate *priv = meta_backend_get_instance_private (backend);
+
+  return priv->default_seat;
+}
+
 static gboolean
 update_last_device (MetaBackend *backend)
 {

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

@@ -126,6 +126,29 @@ meta_backend_native_create_clutter_backend (MetaBackend *backend)
   return g_object_new (META_TYPE_CLUTTER_BACKEND_NATIVE, NULL);
 }
 
+static ClutterSeat *
+meta_backend_native_create_default_seat (MetaBackend  *backend,
+                                         GError      **error)
+{
+  MetaBackendNative *backend_native = META_BACKEND_NATIVE (backend);
+  ClutterBackend *clutter_backend = meta_backend_get_clutter_backend (backend);
+  const char *seat_id;
+  MetaSeatNativeFlag flags;
+
+  seat_id = meta_backend_native_get_seat_id (backend_native);
+
+  if (meta_backend_native_is_headless (backend_native))
+    flags = META_SEAT_NATIVE_FLAG_NO_LIBINPUT;
+  else
+    flags = META_SEAT_NATIVE_FLAG_NONE;
+
+  return CLUTTER_SEAT (g_object_new (META_TYPE_SEAT_NATIVE,
+                                     "backend", clutter_backend,
+                                     "seat-id", seat_id,
+                                     "flags", flags,
+                                     NULL));
+}
+
 #ifdef HAVE_REMOTE_DESKTOP
 static void
 maybe_disable_screen_cast_dma_bufs (MetaBackendNative *native)
@@ -597,6 +620,7 @@ meta_backend_native_class_init (MetaBackendNativeClass *klass)
   object_class->dispose = meta_backend_native_dispose;
 
   backend_class->create_clutter_backend = meta_backend_native_create_clutter_backend;
+  backend_class->create_default_seat = meta_backend_native_create_default_seat;
 
   backend_class->post_init = meta_backend_native_post_init;
 

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

@@ -54,8 +54,6 @@
 struct _MetaClutterBackendNative
 {
   ClutterBackend parent;
-
-  MetaSeatNative *main_seat;
 };
 
 G_DEFINE_TYPE (MetaClutterBackendNative, meta_clutter_backend_native,
@@ -82,37 +80,12 @@ meta_clutter_backend_native_create_stage (ClutterBackend  *clutter_backend,
                        NULL);
 }
 
-static void
-meta_clutter_backend_native_init_events (ClutterBackend *clutter_backend)
-{
-  MetaClutterBackendNative *clutter_backend_native =
-    META_CLUTTER_BACKEND_NATIVE (clutter_backend);
-  MetaBackend *backend = meta_get_backend ();
-  MetaBackendNative *backend_native = META_BACKEND_NATIVE (backend);
-  const char *seat_id;
-  MetaSeatNativeFlag flags;
-
-  seat_id = meta_backend_native_get_seat_id (backend_native);
-
-  if (meta_backend_native_is_headless (backend_native))
-    flags = META_SEAT_NATIVE_FLAG_NO_LIBINPUT;
-  else
-    flags = META_SEAT_NATIVE_FLAG_NONE;
-
-  clutter_backend_native->main_seat = g_object_new (META_TYPE_SEAT_NATIVE,
-                                                    "backend", clutter_backend,
-                                                    "seat-id", seat_id,
-                                                    "flags", flags,
-                                                    NULL);
-}
-
 static ClutterSeat *
 meta_clutter_backend_native_get_default_seat (ClutterBackend *clutter_backend)
 {
-  MetaClutterBackendNative *clutter_backend_native =
+  MetaBackend *backend = meta_get_backend ();
-    META_CLUTTER_BACKEND_NATIVE (clutter_backend);
 
-  return CLUTTER_SEAT (clutter_backend_native->main_seat);
+  return meta_backend_get_default_seat (backend);
 }
 
 static gboolean
@@ -121,17 +94,6 @@ meta_clutter_backend_native_is_display_server (ClutterBackend *clutter_backend)
   return TRUE;
 }
 
-static void
-meta_clutter_backend_native_finalize (GObject *object)
-{
-  MetaClutterBackendNative *clutter_backend_native =
-    META_CLUTTER_BACKEND_NATIVE (object);
-
-  g_clear_object (&clutter_backend_native->main_seat);
-
-  G_OBJECT_CLASS (meta_clutter_backend_native_parent_class)->finalize (object);
-}
-
 static void
 meta_clutter_backend_native_init (MetaClutterBackendNative *clutter_backend_nativen)
 {
@@ -140,14 +102,10 @@ meta_clutter_backend_native_init (MetaClutterBackendNative *clutter_backend_nati
 static void
 meta_clutter_backend_native_class_init (MetaClutterBackendNativeClass *klass)
 {
-  GObjectClass *object_class = G_OBJECT_CLASS (klass);
   ClutterBackendClass *clutter_backend_class = CLUTTER_BACKEND_CLASS (klass);
 
-  object_class->finalize = meta_clutter_backend_native_finalize;
-
   clutter_backend_class->get_renderer = meta_clutter_backend_native_get_renderer;
   clutter_backend_class->create_stage = meta_clutter_backend_native_create_stage;
-  clutter_backend_class->init_events = meta_clutter_backend_native_init_events;
   clutter_backend_class->get_default_seat = meta_clutter_backend_native_get_default_seat;
   clutter_backend_class->is_display_server = meta_clutter_backend_native_is_display_server;
 }

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

@@ -624,6 +624,42 @@ meta_backend_x11_create_clutter_backend (MetaBackend *backend)
   return g_object_new (META_TYPE_CLUTTER_BACKEND_X11, NULL);
 }
 
+static ClutterSeat *
+meta_backend_x11_create_default_seat (MetaBackend  *backend,
+                                      GError      **error)
+{
+  MetaBackendX11 *x11 = META_BACKEND_X11 (backend);
+  MetaBackendX11Private *priv = meta_backend_x11_get_instance_private (x11);
+  int event_base, first_event, first_error;
+  int major, minor;
+  MetaSeatX11 *seat_x11;
+
+  if (!XQueryExtension (priv->xdisplay,
+                        "XInputExtension",
+                        &event_base,
+                        &first_event,
+                        &first_error))
+    {
+      g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED,
+                   "Failed to query XInputExtension");
+      return NULL;
+    }
+
+  major = 2;
+  minor = 3;
+  if (XIQueryVersion (priv->xdisplay, &major, &minor) == BadRequest)
+    {
+      g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED,
+                   "Incompatible XInputExtension version");
+      return NULL;
+    }
+
+  seat_x11 = meta_seat_x11_new (event_base,
+                                META_VIRTUAL_CORE_POINTER_ID,
+                                META_VIRTUAL_CORE_KEYBOARD_ID);
+  return CLUTTER_SEAT (seat_x11);
+}
+
 static gboolean
 meta_backend_x11_grab_device (MetaBackend *backend,
                               int          device_id,
@@ -894,6 +930,7 @@ meta_backend_x11_class_init (MetaBackendX11Class *klass)
   object_class->dispose = meta_backend_x11_dispose;
   object_class->finalize = meta_backend_x11_finalize;
   backend_class->create_clutter_backend = meta_backend_x11_create_clutter_backend;
+  backend_class->create_default_seat = meta_backend_x11_create_default_seat;
   backend_class->post_init = meta_backend_x11_post_init;
   backend_class->grab_device = meta_backend_x11_grab_device;
   backend_class->ungrab_device = meta_backend_x11_ungrab_device;

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

@@ -41,7 +41,6 @@
 struct _MetaClutterBackendX11
 {
   ClutterBackendX11 parent;
-  MetaSeatX11 *core_seat;
 };
 
 G_DEFINE_TYPE (MetaClutterBackendX11, meta_clutter_backend_x11,
@@ -82,10 +81,10 @@ meta_clutter_backend_x11_translate_event (ClutterBackend *clutter_backend,
                                           gpointer        native,
                                           ClutterEvent   *event)
 {
-  MetaClutterBackendX11 *clutter_backend_x11 =
+  MetaBackend *backend = meta_get_backend ();
-    META_CLUTTER_BACKEND_X11 (clutter_backend);
   MetaStageX11 *stage_x11;
   ClutterBackendClass *clutter_backend_class;
+  ClutterSeat *seat;
 
   clutter_backend_class =
     CLUTTER_BACKEND_CLASS (meta_clutter_backend_x11_parent_class);
@@ -97,49 +96,19 @@ meta_clutter_backend_x11_translate_event (ClutterBackend *clutter_backend,
   if (meta_stage_x11_translate_event (stage_x11, native, event))
     return TRUE;
 
-  if (meta_seat_x11_translate_event (clutter_backend_x11->core_seat,
+  seat = meta_backend_get_default_seat (backend);
-                                     native, event))
+  if (meta_seat_x11_translate_event (META_SEAT_X11 (seat), native, event))
     return TRUE;
 
   return FALSE;
 }
 
-static void
-meta_clutter_backend_x11_init_events (ClutterBackend *backend)
-{
-  MetaClutterBackendX11 *backend_x11 = META_CLUTTER_BACKEND_X11 (backend);
-  int event_base, first_event, first_error;
-
-  if (XQueryExtension (clutter_x11_get_default_display (),
-                       "XInputExtension",
-                       &event_base,
-                       &first_event,
-                       &first_error))
-    {
-      int major = 2;
-      int minor = 3;
-
-      if (XIQueryVersion (clutter_x11_get_default_display (),
-                          &major, &minor) != BadRequest)
-        {
-          backend_x11->core_seat =
-            meta_seat_x11_new (event_base,
-                               META_VIRTUAL_CORE_POINTER_ID,
-                               META_VIRTUAL_CORE_KEYBOARD_ID);
-        }
-    }
-
-  if (!backend_x11->core_seat)
-    g_error ("No XInput 2.3 support");
-}
-
 static ClutterSeat *
 meta_clutter_backend_x11_get_default_seat (ClutterBackend *clutter_backend)
 {
-  MetaClutterBackendX11 *clutter_backend_x11 =
+  MetaBackend *backend = meta_get_backend ();
-    META_CLUTTER_BACKEND_X11 (clutter_backend);
 
-  return CLUTTER_SEAT (clutter_backend_x11->core_seat);
+  return meta_backend_get_default_seat (backend);
 }
 
 static gboolean
@@ -161,7 +130,6 @@ meta_clutter_backend_x11_class_init (MetaClutterBackendX11Class *klass)
   clutter_backend_class->get_renderer = meta_clutter_backend_x11_get_renderer;
   clutter_backend_class->create_stage = meta_clutter_backend_x11_create_stage;
   clutter_backend_class->translate_event = meta_clutter_backend_x11_translate_event;
-  clutter_backend_class->init_events = meta_clutter_backend_x11_init_events;
   clutter_backend_class->get_default_seat = meta_clutter_backend_x11_get_default_seat;
   clutter_backend_class->is_display_server = meta_clutter_backend_x11_is_display_server;
 }