drag: Add a default drag-motion behaviour

The DragAction should, by default, drag the actor to which it has been
applied, instead of delegating what to do to the developer. If custom
code need to override it, g_signal_stop_emission_by_name() can be called
to stop the default handler to ever running.

diff --git a/clutter/clutter-drag-action.c b/clutter/clutter-drag-action.c
index ae51e81..7b3c5df 100644 (file)
--- a/clutter/clutter-drag-action.c
+++ b/clutter/clutter-drag-action.c
@@ -349,6 +349,22 @@ clutter_drag_action_set_actor (ClutterActorMeta *meta,
 }
 
 static void
+clutter_drag_action_real_drag_motion (ClutterDragAction *action,
+                                      ClutterActor      *actor,
+                                      gfloat             delta_x,
+                                      gfloat             delta_y)
+{
+  ClutterActor *drag_handle;
+
+  if (action->priv->drag_handle != NULL)
+    drag_handle = action->priv->drag_handle;
+  else
+    drag_handle = actor;
+
+  clutter_actor_move_by (drag_handle, delta_x, delta_y);
+}
+
+static void
 clutter_drag_action_set_property (GObject      *gobject,
                                   guint         prop_id,
                                   const GValue *value,
@@ -443,6 +459,8 @@ clutter_drag_action_class_init (ClutterDragActionClass *klass)
 
   meta_class->set_actor = clutter_drag_action_set_actor;
 
+  klass->drag_motion = clutter_drag_action_real_drag_motion;
+
   /**
    * ClutterDragAction:drag-threshold:
    *
@@ -551,6 +569,13 @@ clutter_drag_action_class_init (ClutterDragActionClass *klass)
    * stage coordinates of the latest motion event you can use
    * clutter_drag_action_get_motion_coords().
    *
+   * The default handler of the signal will call clutter_actor_move_by()
+   * either on @actor or, if set, of #ClutterDragAction:drag-handle using
+   * the @delta_x and @delta_y components of the dragging motion. If you
+   * want to override the default behaviour, you can connect to this
+   * signal and call g_signal_stop_emission_by_name() from within your
+   * callback.
+   *
    * Since: 1.4
    */
   drag_signals[DRAG_MOTION] =

diff --git a/tests/interactive/test-drag.c b/tests/interactive/test-drag.c
index e8c479c..2aa1d1d 100644 (file)
--- a/tests/interactive/test-drag.c
+++ b/tests/interactive/test-drag.c
@@ -36,21 +36,6 @@ on_drag_begin (ClutterDragAction   *action,
 }
 
 static void
-on_drag_motion (ClutterDragAction   *action,
-                ClutterActor        *actor,
-                gfloat               delta_x,
-                gfloat               delta_y,
-                ClutterModifierType  modifiers)
-{
-  ClutterActor *drag_handle;
-
-  drag_handle = clutter_drag_action_get_drag_handle (action);
-  g_assert (drag_handle != NULL);
-
-  clutter_actor_move_by (drag_handle, delta_x, delta_y);
-}
-
-static void
 on_drag_end (ClutterDragAction   *action,
              ClutterActor        *actor,
              gfloat               event_x,
@@ -176,7 +161,6 @@ test_drag_main (int argc, char *argv[])
                                      get_drag_axis (drag_axis));
 
   g_signal_connect (action, "drag-begin", G_CALLBACK (on_drag_begin), NULL);
-  g_signal_connect (action, "drag-motion", G_CALLBACK (on_drag_motion), NULL);
   g_signal_connect (action, "drag-end", G_CALLBACK (on_drag_end), NULL);
 
   clutter_actor_add_action (handle, action);