[mutter] clutter: Add API for filtering relative motion events

[Carlos Garnacho <carlosg src gnome org>]

commit 8f691c28f30a5605471b81a5fb933e1b1222c06a
Author: Jonas Ådahl <jadahl gmail com>
Date:   Fri Feb 3 13:02:50 2017 +0800

    clutter: Add API for filtering relative motion events
    
    Add an API that allows the owner of the clutter context to alter the
    relative motion events (so far relative pointer events).
    
    https://bugzilla.gnome.org/show_bug.cgi?id=778119

 .../clutter/evdev/clutter-device-manager-evdev.c   |   36 ++++++++++++++++++++
 .../clutter/evdev/clutter-device-manager-evdev.h   |    7 ++++
 clutter/clutter/evdev/clutter-evdev.h              |   12 ++++++
 clutter/clutter/evdev/clutter-seat-evdev.c         |    7 ++++
 4 files changed, 62 insertions(+), 0 deletions(-)
---
diff --git a/clutter/clutter/evdev/clutter-device-manager-evdev.c 
b/clutter/clutter/evdev/clutter-device-manager-evdev.c
index 47df1a6..e3269b9 100644
--- a/clutter/clutter/evdev/clutter-device-manager-evdev.c
+++ b/clutter/clutter/evdev/clutter-device-manager-evdev.c
@@ -102,6 +102,9 @@ struct _ClutterDeviceManagerEvdevPrivate
   gpointer                        constrain_data;
   GDestroyNotify                  constrain_data_notify;
 
+  ClutterRelativeMotionFilter relative_motion_filter;
+  gpointer relative_motion_filter_user_data;
+
   ClutterStageManager *stage_manager;
   guint stage_added_handler;
   guint stage_removed_handler;
@@ -264,6 +267,22 @@ _clutter_device_manager_evdev_constrain_pointer (ClutterDeviceManagerEvdev *mana
     }
 }
 
+void
+_clutter_device_manager_evdev_filter_relative_motion (ClutterDeviceManagerEvdev *manager_evdev,
+                                                      ClutterInputDevice        *device,
+                                                      float                      x,
+                                                      float                      y,
+                                                      float                     *dx,
+                                                      float                     *dy)
+{
+  ClutterDeviceManagerEvdevPrivate *priv = manager_evdev->priv;
+
+  if (!priv->relative_motion_filter)
+    return;
+
+  priv->relative_motion_filter (device, x, y, dx, dy,
+                                priv->relative_motion_filter_user_data);
+}
 
 static ClutterEvent *
 new_absolute_motion_event (ClutterInputDevice *input_device,
@@ -2661,6 +2680,23 @@ clutter_evdev_set_pointer_constrain_callback (ClutterDeviceManager            *e
   priv->constrain_data_notify = user_data_notify;
 }
 
+void
+clutter_evdev_set_relative_motion_filter (ClutterDeviceManager       *evdev,
+                                          ClutterRelativeMotionFilter filter,
+                                          gpointer                    user_data)
+{
+  ClutterDeviceManagerEvdev *manager_evdev;
+  ClutterDeviceManagerEvdevPrivate *priv;
+
+  g_return_if_fail (CLUTTER_IS_DEVICE_MANAGER_EVDEV (evdev));
+
+  manager_evdev = CLUTTER_DEVICE_MANAGER_EVDEV (evdev);
+  priv = manager_evdev->priv;
+
+  priv->relative_motion_filter = filter;
+  priv->relative_motion_filter_user_data = user_data;
+}
+
 /**
  * clutter_evdev_set_keyboard_repeat:
  * @evdev: the #ClutterDeviceManager created by the evdev backend
diff --git a/clutter/clutter/evdev/clutter-device-manager-evdev.h 
b/clutter/clutter/evdev/clutter-device-manager-evdev.h
index c2dbe31..2b87a44 100644
--- a/clutter/clutter/evdev/clutter-device-manager-evdev.h
+++ b/clutter/clutter/evdev/clutter-device-manager-evdev.h
@@ -76,6 +76,13 @@ void _clutter_device_manager_evdev_constrain_pointer (ClutterDeviceManagerEvdev
                                                       float                     *new_x,
                                                       float                     *new_y);
 
+void _clutter_device_manager_evdev_filter_relative_motion (ClutterDeviceManagerEvdev *manager_evdev,
+                                                           ClutterInputDevice        *device,
+                                                           float                      x,
+                                                           float                      y,
+                                                           float                     *dx,
+                                                           float                     *dy);
+
 void _clutter_device_manager_evdev_dispatch (ClutterDeviceManagerEvdev *manager_evdev);
 
 static inline guint64
diff --git a/clutter/clutter/evdev/clutter-evdev.h b/clutter/clutter/evdev/clutter-evdev.h
index e17ec12..b64b136 100644
--- a/clutter/clutter/evdev/clutter-evdev.h
+++ b/clutter/clutter/evdev/clutter-evdev.h
@@ -97,6 +97,18 @@ void  clutter_evdev_set_pointer_constrain_callback (ClutterDeviceManager
                                                    gpointer                         user_data,
                                                    GDestroyNotify                   user_data_notify);
 
+typedef void (*ClutterRelativeMotionFilter) (ClutterInputDevice *device,
+                                             float               x,
+                                             float               y,
+                                             float              *dx,
+                                             float              *dy,
+                                             gpointer            user_data);
+
+CLUTTER_AVAILABLE_IN_MUTTER
+void clutter_evdev_set_relative_motion_filter (ClutterDeviceManager       *evdev,
+                                               ClutterRelativeMotionFilter filter,
+                                               gpointer                    user_data);
+
 CLUTTER_AVAILABLE_IN_1_16
 void               clutter_evdev_set_keyboard_map   (ClutterDeviceManager *evdev,
                                                     struct xkb_keymap    *keymap);
diff --git a/clutter/clutter/evdev/clutter-seat-evdev.c b/clutter/clutter/evdev/clutter-seat-evdev.c
index a15f17c..f6fdf9b 100644
--- a/clutter/clutter/evdev/clutter-seat-evdev.c
+++ b/clutter/clutter/evdev/clutter-seat-evdev.c
@@ -405,6 +405,13 @@ clutter_seat_evdev_notify_relative_motion (ClutterSeatEvdev   *seat,
   if (!_clutter_input_device_get_stage (input_device))
     return;
 
+  _clutter_device_manager_evdev_filter_relative_motion (seat->manager_evdev,
+                                                        input_device,
+                                                        seat->pointer_x,
+                                                        seat->pointer_y,
+                                                        &dx,
+                                                        &dy);
+
   new_x = seat->pointer_x + dx;
   new_y = seat->pointer_y + dy;
   event = new_absolute_motion_event (seat, input_device,