From 615b0f46ae487f291f92d6373a8d4bf438f705d8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jonas=20=C3=85dahl?= <jadahl@gmail.com>
Date: Tue, 17 Mar 2015 10:58:35 +0800
Subject: [PATCH] evdev: Keep track of the pointer coordinate ourself

When multiple relative motion events are received and queued, we can't
base the relative => absolute motion conversion off of the stage pointer
position, since that is only updated when the queue is processed at
the beginning of each frame. The effect of trying to use the stage
pointer position was that subsequent motion events were effectively
dropped.

To improve things, switch to keeping track of the pointer position
ourselves in the evdev backend and adding to that.

This has the side effect of making the internal function
_clutter_input_device_set_coords not effect the internal coordinate
state of the evdev stage, but AFAICS there is nothing depending on that
so that should be fine.

https://bugzilla.gnome.org/show_bug.cgi?id=746328
---
 clutter/evdev/clutter-device-manager-evdev.c | 30 +++++++++++---------
 1 file changed, 17 insertions(+), 13 deletions(-)

diff --git a/clutter/evdev/clutter-device-manager-evdev.c b/clutter/evdev/clutter-device-manager-evdev.c
index b03878d19..523b538bd 100644
--- a/clutter/evdev/clutter-device-manager-evdev.c
+++ b/clutter/evdev/clutter-device-manager-evdev.c
@@ -97,6 +97,9 @@ struct _ClutterSeatEvdev
   guint32 repeat_count;
   guint32 repeat_timer;
   ClutterInputDevice *repeat_device;
+
+  gfloat pointer_x;
+  gfloat pointer_y;
 };
 
 struct _ClutterEventFilter
@@ -395,6 +398,9 @@ notify_absolute_motion (ClutterInputDevice *input_device,
 
   _clutter_input_device_set_stage (seat->core_pointer, stage);
 
+  seat->pointer_x = x;
+  seat->pointer_y = y;
+
   queue_event (event);
 }
 
@@ -407,7 +413,6 @@ notify_relative_motion (ClutterInputDevice *input_device,
   gfloat new_x, new_y;
   ClutterInputDeviceEvdev *device_evdev;
   ClutterSeatEvdev *seat;
-  ClutterPoint point;
 
   /* We can drop the event on the floor if no stage has been
    * associated with the device yet. */
@@ -417,9 +422,8 @@ notify_relative_motion (ClutterInputDevice *input_device,
   device_evdev = CLUTTER_INPUT_DEVICE_EVDEV (input_device);
   seat = _clutter_input_device_evdev_get_seat (device_evdev);
 
-  clutter_input_device_get_coords (seat->core_pointer, NULL, &point);
-  new_x = point.x + dx;
-  new_y = point.y + dy;
+  new_x = seat->pointer_x + dx;
+  new_y = seat->pointer_y + dy;
 
   notify_absolute_motion (input_device, time_, new_x, new_y);
 }
@@ -434,7 +438,6 @@ notify_scroll (ClutterInputDevice *input_device,
   ClutterSeatEvdev *seat;
   ClutterStage *stage;
   ClutterEvent *event = NULL;
-  ClutterPoint point;
   gdouble scroll_factor;
 
   /* We can drop the event on the floor if no stage has been
@@ -462,9 +465,8 @@ notify_scroll (ClutterInputDevice *input_device,
                                   scroll_factor * dx,
                                   scroll_factor * dy);
 
-  clutter_input_device_get_coords (seat->core_pointer, NULL, &point);
-  event->scroll.x = point.x;
-  event->scroll.y = point.y;
+  event->scroll.x = seat->pointer_x;
+  event->scroll.y = seat->pointer_y;
   clutter_event_set_device (event, seat->core_pointer);
   clutter_event_set_source_device (event, input_device);
 
@@ -481,7 +483,6 @@ notify_button (ClutterInputDevice *input_device,
   ClutterSeatEvdev *seat;
   ClutterStage *stage;
   ClutterEvent *event = NULL;
-  ClutterPoint point;
   gint button_nr;
   static gint maskmap[8] =
     {
@@ -542,9 +543,8 @@ notify_button (ClutterInputDevice *input_device,
   event->button.device = seat->core_pointer;
   _clutter_xkb_translate_state (event, seat->xkb, seat->button_state);
   event->button.button = button_nr;
-  clutter_input_device_get_coords (seat->core_pointer, NULL, &point);
-  event->button.x = point.x;
-  event->button.y = point.y;
+  event->button.x = seat->pointer_x;
+  event->button.y = seat->pointer_y;
   clutter_event_set_device (event, seat->core_pointer);
   clutter_event_set_source_device (event, input_device);
 
@@ -741,7 +741,11 @@ clutter_seat_evdev_new (ClutterDeviceManagerEvdev *manager_evdev)
   device = _clutter_input_device_evdev_new_virtual (
     manager, seat, CLUTTER_POINTER_DEVICE);
   _clutter_input_device_set_stage (device, priv->stage);
-  _clutter_input_device_set_coords (device, NULL, INITIAL_POINTER_X, INITIAL_POINTER_Y, NULL);
+  seat->pointer_x = INITIAL_POINTER_X;
+  seat->pointer_y = INITIAL_POINTER_Y;
+  _clutter_input_device_set_coords (device, NULL,
+                                    seat->pointer_x, seat->pointer_y,
+                                    NULL);
   _clutter_device_manager_add_device (manager, device);
   seat->core_pointer = device;