[mutter] backends: Center pointer on primary monitor on startup

[Carlos Garnacho <carlosg src gnome org>]

commit c6e6ed87c537deee99998694d2b593228bc91efa
Author: Carlos Garnacho <carlosg gnome org>
Date:   Fri Mar 27 15:50:59 2015 +0100

    backends: Center pointer on primary monitor on startup
    
    This seems nicer/tidier than the current X11 (center on the span of all
    monitors) or native (so close to the activities corner it's hard not
    to trigger it) platform behaviors.
    
    This code also takes over the native-specific pointer warping that
    happens when the pointer was over a removed output.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=746896

 src/backends/meta-backend.c               |   27 +++++++++++++++++++++++
 src/backends/native/meta-backend-native.c |   34 -----------------------------
 2 files changed, 27 insertions(+), 34 deletions(-)
---
diff --git a/src/backends/meta-backend.c b/src/backends/meta-backend.c
index f55a4a0..4a88c89 100644
--- a/src/backends/meta-backend.c
+++ b/src/backends/meta-backend.c
@@ -93,11 +93,36 @@ meta_backend_sync_screen_size (MetaBackend *backend)
 }
 
 static void
+center_pointer (MetaBackend *backend)
+{
+  MetaBackendPrivate *priv = meta_backend_get_instance_private (backend);
+  MetaMonitorInfo *monitors, *primary;
+  guint n_monitors;
+
+  monitors = meta_monitor_manager_get_monitor_infos (priv->monitor_manager, &n_monitors);
+  primary = &monitors[meta_monitor_manager_get_primary_index (priv->monitor_manager)];
+  meta_backend_warp_pointer (backend,
+                             primary->rect.x + primary->rect.width / 2,
+                             primary->rect.y + primary->rect.height / 2);
+}
+
+static void
 on_monitors_changed (MetaMonitorManager *monitors,
                      gpointer user_data)
 {
   MetaBackend *backend = META_BACKEND (user_data);
+  ClutterDeviceManager *manager = clutter_device_manager_get_default ();
+  ClutterInputDevice *device = clutter_device_manager_get_core_device (manager, CLUTTER_POINTER_DEVICE);
+  ClutterPoint point;
+
   meta_backend_sync_screen_size (backend);
+
+  if (clutter_input_device_get_coords (device, NULL, &point))
+    {
+      /* If we're outside all monitors, warp the pointer back inside */
+      if (meta_monitor_manager_get_monitor_at_point (monitors, point.x, point.y) < 0)
+        center_pointer (backend);
+    }
 }
 
 static MetaIdleMonitor *
@@ -283,6 +308,8 @@ meta_backend_real_post_init (MetaBackend *backend)
   }
 
   priv->input_settings = meta_input_settings_create ();
+
+  center_pointer (backend);
 }
 
 static MetaCursorRenderer *
diff --git a/src/backends/native/meta-backend-native.c b/src/backends/native/meta-backend-native.c
index 9f2cb9b..b33c936 100644
--- a/src/backends/native/meta-backend-native.c
+++ b/src/backends/native/meta-backend-native.c
@@ -153,48 +153,14 @@ pointer_constrain_callback (ClutterInputDevice *device,
 }
 
 static void
-on_monitors_changed (MetaMonitorManager *monitor_manager,
-                     MetaBackend        *backend)
-{
-  ClutterDeviceManager *manager = clutter_device_manager_get_default ();
-  ClutterInputDevice *device = clutter_device_manager_get_core_device (manager, CLUTTER_POINTER_DEVICE);
-  MetaMonitorInfo *monitors, *primary;
-  unsigned int n_monitors;
-  ClutterPoint point;
-
-  if (!clutter_input_device_get_coords (device, NULL, &point))
-    return;
-
-  monitors = meta_monitor_manager_get_monitor_infos (monitor_manager, &n_monitors);
-
-  /* if we're inside a monitor, we're fine */
-  if (meta_monitor_manager_get_monitor_at_point (monitor_manager, point.x, point.y) >= 0)
-    return;
-
-  /* warp the pointer to the primary monitor so it isn't lost */
-  primary = &monitors[meta_monitor_manager_get_primary_index (monitor_manager)];
-  meta_backend_warp_pointer (backend,
-                             primary->rect.x + primary->rect.width / 2,
-                             primary->rect.y + primary->rect.height / 2);
-}
-
-static void
 meta_backend_native_post_init (MetaBackend *backend)
 {
-  MetaMonitorManager *monitor_manager;
   ClutterDeviceManager *manager = clutter_device_manager_get_default ();
 
   META_BACKEND_CLASS (meta_backend_native_parent_class)->post_init (backend);
 
   clutter_evdev_set_pointer_constrain_callback (manager, pointer_constrain_callback,
                                                 NULL, NULL);
-
-  monitor_manager = meta_backend_get_monitor_manager (backend);
-  g_signal_connect_object (monitor_manager, "monitors-changed",
-                           G_CALLBACK (on_monitors_changed), backend, G_CONNECT_AFTER);
-
-  /* make sure the pointer is in the visible area after init */
-  on_monitors_changed (monitor_manager, backend);
 }
 
 static MetaIdleMonitor *