device-manager: Add private interface to manipulate platform event data

This normally belonged to the ClutterBackend, however there's device
managers (eg. evdev) that are somewhat detached from the backend, so
need to bridge this somehow.

This allows device managers to implement these bits that were usually
responsibility of the ClutterBackend.

https://bugzilla.gnome.org/show_bug.cgi?id=758238

2 files changed, 29 insertions, 0 deletions

diff --git a/clutter/clutter-device-manager-private.h b/clutter/clutter-device-manager-private.h
index 3e09288e1..9c42450ae 100644
--- a/clutter/clutter-device-manager-private.h
+++ b/clutter/clutter-device-manager-private.h
@@ -145,6 +145,26 @@ struct _ClutterInputDeviceClass
                                  guint              *evdev_keycode);
 };
 
+/* Platform-dependent interface */
+typedef struct _ClutterEventExtender ClutterEventExtender;
+typedef struct _ClutterEventExtenderInterface ClutterEventExtenderInterface;
+
+#define CLUTTER_TYPE_EVENT_EXTENDER         (clutter_event_extender_get_type ())
+#define CLUTTER_EVENT_EXTENDER(o)           (G_TYPE_CHECK_INSTANCE_CAST ((o), CLUTTER_TYPE_EVENT_EXTENDER, ClutterEventExtender))
+#define CLUTTER_IS_EVENT_EXTENDER(o)	     (G_TYPE_CHECK_INSTANCE_TYPE ((o), CLUTTER_TYPE_EVENT_EXTENDER))
+#define CLUTTER_EVENT_EXTENDER_GET_IFACE(o) (G_TYPE_INSTANCE_GET_INTERFACE ((o), CLUTTER_TYPE_EVENT_EXTENDER, ClutterEventExtenderInterface))
+
+struct _ClutterEventExtenderInterface
+{
+  void (* copy_event_data) (ClutterEventExtender *event_extender,
+                            const ClutterEvent   *src,
+                            ClutterEvent         *dest);
+  void (* free_event_data) (ClutterEventExtender *event_extender,
+                            ClutterEvent         *event);
+};
+
+GType           clutter_event_extender_get_type        (void) G_GNUC_CONST;
+
 /* device manager */
 void            _clutter_device_manager_add_device              (ClutterDeviceManager *device_manager,
                                                                  ClutterInputDevice   *device);
diff --git a/clutter/clutter-device-manager.c b/clutter/clutter-device-manager.c
index 32a6e8a4a..597b0d1ad 100644
--- a/clutter/clutter-device-manager.c
+++ b/clutter/clutter-device-manager.c
@@ -79,6 +79,15 @@ G_DEFINE_ABSTRACT_TYPE_WITH_PRIVATE (ClutterDeviceManager,
                                      clutter_device_manager,
                                      G_TYPE_OBJECT)
 
+G_DEFINE_INTERFACE (ClutterEventExtender,
+                    clutter_event_extender,
+                    CLUTTER_TYPE_DEVICE_MANAGER)
+
+static void
+clutter_event_extender_default_init (ClutterEventExtenderInterface *iface)
+{
+}
+
 static void
 clutter_device_manager_set_property (GObject      *gobject,
                                      guint         prop_id,