[mutter] backend: Pre-emptively create idle monitors based on clutter events

[Jasper St. Pierre <jstpierre src gnome org>]

commit 659360d54340ce01047d84a21b2d01d78969a408
Author: Jasper St. Pierre <jstpierre mecheye net>
Date:   Thu Sep 4 12:06:03 2014 -0700

    backend: Pre-emptively create idle monitors based on clutter events
    
    Rather than have the DBus code control this, move this into
    MetaBackend. This also lets us destroy idle monitors when appropriate,
    rather than leaking them forever.

 src/backends/meta-backend.c |   78 ++++++++++++++++++++++++++++++++++---------
 1 files changed, 62 insertions(+), 16 deletions(-)
---
diff --git a/src/backends/meta-backend.c b/src/backends/meta-backend.c
index a912d5a..370e79a 100644
--- a/src/backends/meta-backend.c
+++ b/src/backends/meta-backend.c
@@ -98,6 +98,47 @@ on_monitors_changed (MetaMonitorManager *monitors,
 }
 
 static void
+create_device_monitor (MetaBackend *backend,
+                       int          device_id)
+{
+  g_assert (backend->device_monitors[device_id] == NULL);
+
+  backend->device_monitors[device_id] = meta_backend_create_idle_monitor (backend, device_id);
+  backend->device_id_max = MAX (backend->device_id_max, device_id);
+}
+
+static void
+destroy_device_monitor (MetaBackend *backend,
+                        int          device_id)
+{
+  g_clear_object (&backend->device_monitors[device_id]);
+  if (device_id == backend->device_id_max)
+    backend->device_id_max--;
+}
+
+static void
+on_device_added (ClutterDeviceManager *device_manager,
+                 ClutterInputDevice   *device,
+                 gpointer              user_data)
+{
+  MetaBackend *backend = META_BACKEND (user_data);
+  int device_id = clutter_input_device_get_device_id (device);
+
+  create_idle_monitor (backend, device_id);
+}
+
+static void
+on_device_removed (ClutterDeviceManager *device_manager,
+                   ClutterInputDevice   *device,
+                   gpointer              user_data)
+{
+  MetaBackend *backend = META_BACKEND (user_data);
+  int device_id = clutter_input_device_get_device_id (device);
+
+  destroy_idle_monitor (backend, device_id);
+}
+
+static void
 meta_backend_real_post_init (MetaBackend *backend)
 {
   MetaBackendPrivate *priv = meta_backend_get_instance_private (backend);
@@ -113,6 +154,27 @@ meta_backend_real_post_init (MetaBackend *backend)
   meta_backend_sync_screen_size (backend);
 
   priv->cursor_renderer = META_BACKEND_GET_CLASS (backend)->create_cursor_renderer (backend);
+
+  {
+    ClutterDeviceManager *manager;
+    GSList *devices, *l;
+
+    manager = clutter_device_manager_get_default ();
+    g_signal_connect_object (manager, "device-added",
+                             G_CALLBACK (on_device_added), backend, 0);
+    g_signal_connect_object (manager, "device-removed",
+                             G_CALLBACK (on_device_removed), backend, 0);
+
+    devices = clutter_device_manager_list_devices (backend);
+
+    for (l = devices; l != NULL; l = l->next)
+      {
+        ClutterDevice *device = l->data;
+        on_device_added (manager, device, backend);
+      }
+
+    g_slist_free (devices);
+  }
 }
 
 static MetaCursorRenderer *
@@ -182,16 +244,6 @@ meta_backend_init (MetaBackend *backend)
   _backend = backend;
 }
 
-/* FIXME -- destroy device monitors at some point */
-G_GNUC_UNUSED static void
-destroy_device_monitor (MetaBackend *backend,
-                        int          device_id)
-{
-  g_clear_object (&backend->device_monitors[device_id]);
-  if (device_id == backend->device_id_max)
-    backend->device_id_max--;
-}
-
 static MetaIdleMonitor *
 meta_backend_create_idle_monitor (MetaBackend *backend,
                                   int          device_id)
@@ -214,12 +266,6 @@ meta_backend_get_idle_monitor (MetaBackend *backend,
 {
   g_return_val_if_fail (device_id >= 0 && device_id < 256, NULL);
 
-  if (!backend->device_monitors[device_id])
-    {
-      backend->device_monitors[device_id] = meta_backend_create_idle_monitor (backend, device_id);
-      backend->device_id_max = MAX (backend->device_id_max, device_id);
-    }
-
   return backend->device_monitors[device_id];
 }