Emit GdkDevice::changed when the slave device being used changes

When the slave device changes, the master takes the shape of the
new one, modifying its axes, this signal is more useful to catch
this situation than the n-axes property

2 files changed, 30 insertions, 0 deletions

diff --git a/gdk/gdkdevice.c b/gdk/gdkdevice.c
index 4e9b3d24e8..dc66f3bddd 100644
--- a/gdk/gdkdevice.c
+++ b/gdk/gdkdevice.c
@@ -64,6 +64,14 @@ struct _GdkDevicePrivate
   GArray *axes;
 };
 
+enum {
+  CHANGED,
+  LAST_SIGNAL
+};
+
+static guint signals [LAST_SIGNAL] = { 0 };
+
+
 static void gdk_device_dispose      (GObject      *object);
 static void gdk_device_set_property (GObject      *object,
                                      guint         prop_id,
@@ -238,6 +246,26 @@ gdk_device_class_init (GdkDeviceClass *klass)
                                                       0, G_MAXUINT, 0,
                                                       G_PARAM_READABLE | G_PARAM_STATIC_STRINGS));
 
+  /**
+   * GdkDevice::changed:
+   * @device: the #GdkDevice that changed.
+   *
+   * The ::changed signal is emitted either when the #GdkDevice
+   * has changed the number of either axes or keys. For example
+   * In X this will normally happen when the slave device routing
+   * events through the master device changes (for example, user
+   * switches from the USB mouse to a tablet), in that case the
+   * master device will change to reflect the new slave device
+   * axes and keys.
+   */
+  signals[CHANGED] =
+    g_signal_new (g_intern_static_string ("changed"),
+                  G_TYPE_FROM_CLASS (object_class),
+                  G_SIGNAL_RUN_LAST,
+                  NULL, NULL, NULL,
+                  g_cclosure_marshal_VOID__VOID,
+                  G_TYPE_NONE, 0);
+
   g_type_class_add_private (object_class, sizeof (GdkDevicePrivate));
 }
 
diff --git a/gdk/x11/gdkdevicemanager-xi2.c b/gdk/x11/gdkdevicemanager-xi2.c
index 1cc2fc2a27..bdfeac9953 100644
--- a/gdk/x11/gdkdevicemanager-xi2.c
+++ b/gdk/x11/gdkdevicemanager-xi2.c
@@ -499,6 +499,8 @@ handle_device_changed (GdkDeviceManagerXI2  *device_manager,
 
   _gdk_device_reset_axes (device);
   translate_device_classes (display, device, ev->classes, ev->num_classes);
+
+  g_signal_emit_by_name (G_OBJECT (device), "changed");
 }
 
 static GdkCrossingMode