[clutter] evdev: Pass a motion delta to pointer constrain callback

[Jonas Ådahl <jadahl src gnome org>]

commit 8181ef15d6d203e82de9f2f10827563515612c2a
Author: Jonas Ådahl <jadahl gmail com>
Date:   Tue Jul 7 10:23:12 2015 +0800

    evdev: Pass a motion delta to pointer constrain callback
    
    The constrain callback cannot rely on the pointer position of the
    corresponding ClutterInputDevice to get the actual delta of the motion
    event that is to be constrained since it is only updated when an event is
    dispatched. So change the API to pass the previous pointer position when
    constraining.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=752752

 README.in                                    |    7 +++++++
 clutter/evdev/clutter-device-manager-evdev.c |    5 ++++-
 clutter/evdev/clutter-evdev.h                |    2 ++
 3 files changed, 13 insertions(+), 1 deletions(-)
---
diff --git a/README.in b/README.in
index 5eb8e0d..65fd6cc 100644
--- a/README.in
+++ b/README.in
@@ -289,6 +289,13 @@ Relevant information for developers with existing Clutter applications
 wanting to port to newer releases (see NEWS for general information on new
 features).
 
+Release Notes for Clutter 1.26
+-------------------------------------------------------------------------------
+
+• The evdev backend specific ClutterPointerConstrainCallback type was changed
+  to include not only the target position but also the previous position. This
+  is an API change, and will require a version check in any caller code.
+
 Release Notes for Clutter 1.24
 -------------------------------------------------------------------------------
 
diff --git a/clutter/evdev/clutter-device-manager-evdev.c b/clutter/evdev/clutter-device-manager-evdev.c
index 53aa848..df9cd19 100644
--- a/clutter/evdev/clutter-device-manager-evdev.c
+++ b/clutter/evdev/clutter-device-manager-evdev.c
@@ -452,7 +452,10 @@ new_absolute_motion_event (ClutterInputDevice *input_device,
   if (manager_evdev->priv->constrain_callback)
     {
       manager_evdev->priv->constrain_callback (seat->core_pointer,
-                                               us2ms (time_us), &x, &y,
+                                               us2ms (time_us),
+                                               seat->pointer_x,
+                                               seat->pointer_y,
+                                               &x, &y,
                                               manager_evdev->priv->constrain_data);
     }
   else
diff --git a/clutter/evdev/clutter-evdev.h b/clutter/evdev/clutter-evdev.h
index dca093d..be8748f 100644
--- a/clutter/evdev/clutter-evdev.h
+++ b/clutter/evdev/clutter-evdev.h
@@ -82,6 +82,8 @@ void  clutter_evdev_reclaim_devices (void);
  */
 typedef void (*ClutterPointerConstrainCallback) (ClutterInputDevice *device,
                                                 guint32             time,
+                                                float               prev_x,
+                                                float               prev_y,
                                                 float              *x,
                                                 float              *y,
                                                 gpointer            user_data);