aura: Re-enable XInput2 events.

ui/base/x/events_x.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/base/events.h"
 
 #include <X11/extensions/XInput2.h>
 
 #include "base/logging.h"
 #include "ui/base/keycodes/keyboard_code_conversion_x.h"
@@ skipping 229 matching lines @@
 gfx::Point EventLocationFromNative(const base::NativeEvent& native_event) {
   switch (native_event->type) {
     case ButtonPress:
     case ButtonRelease:
       return gfx::Point(native_event->xbutton.x, native_event->xbutton.y);
     case MotionNotify:
       return gfx::Point(native_event->xmotion.x, native_event->xmotion.y);
     case GenericEvent: {
       XIDeviceEvent* xievent =
           static_cast<XIDeviceEvent*>(native_event->xcookie.data);
-      return gfx::Point(static_cast<int>(xievent->event_x),
-                        static_cast<int>(xievent->event_y));
+
+      if (xievent->sourceid == xievent->deviceid) {
+        // This event is coming from a slave device. Read the position from the
+        // valuators, because the events reported for a slave device seems to be
+        // behind the master device by one event. See more on crbug.com/103981.
+        // The position in the valuators is in the global screen coordinates.
+        // But it is necessary to convert it into the window's coordinates.
+        // Prepare to be revolted.

[sadrul, 2011/11/21 01:30:29]

It's not all that bad, really.

+        double x = xievent->valuators.values[0] - (xievent->root_x -
+                                                   xievent->event_x);
+        double y = xievent->valuators.values[1] - (xievent->root_y -
+                                                   xievent->event_y);
+        return gfx::Point(static_cast<int>(x), static_cast<int>(y));
+      } else {
+        return gfx::Point(static_cast<int>(xievent->event_x),
+                          static_cast<int>(xievent->event_y));
+      }
     }
   }
   return gfx::Point();
 }
 
 KeyboardCode KeyboardCodeFromNative(const base::NativeEvent& native_event) {
   return KeyboardCodeFromXKeyEvent(native_event);
 }
 
 bool IsMouseEvent(const base::NativeEvent& native_event) {
@@ skipping 86 matching lines @@
   unsigned int deviceid =
       static_cast<XIDeviceEvent*>(native_event->xcookie.data)->sourceid;
   // Force is normalized to fall into [0, 1]
   if (!ui::TouchFactory::GetInstance()->NormalizeTouchParam(
       deviceid, ui::TouchFactory::TP_PRESSURE, &force))
     force = 0.0;
   return force;
 }
 
 }  // namespace ui