touch: Allow grabbing/ungrabbing touch devices for XInput2.

views/touchui/touch_factory.h

+// 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.
+
+#ifndef VIEWS_TOUCHUI_TOUCH_FACTORY_H_
+#define VIEWS_TOUCHUI_TOUCH_FACTORY_H_
+#pragma once
+
+#include <bitset>
+#include <vector>
+#include <X11/Xlib.h>

[sky, 2011/01/19 19:34:54]

Is it possible to forward declare the types you need so that folks don't end up
including X11? app/x11_util.h forward declares some X types.

[sadrul, 2011/01/19 20:10:17]

Indeed! I wasn't sure if we wanted to typedef Window to unsigned long, since
there are multiple variations in X11/X.h, but looks like in app/x11_util.h, XID
is typedef'ed to unsigned long. Did the same for Window here. Thanks for the
pointer!

+
+#include "base/singleton.h"
+
+namespace views {
+
+// Functions related to determining touch devices.
+class TouchFactory {
+ public:
+  // Returns the TouchFactory singleton.
+   static TouchFactory* GetInstance();

[sky, 2011/01/19 19:34:54]

you've got an extra space here.

[sadrul, 2011/01/19 20:10:17]

Done.

+
+  // Keep a list of touch devices so that it is possible to determine if a
+  // pointer event is a touch-event or a mouse-event.
+  void SetTouchDeviceList(const std::vector<unsigned int>& devices);
+
+  // Is the device a touch-device?
+  bool IsTouchDevice(unsigned int deviceid);
+
+  // Grab the touch devices for the specified window on the specified display.
+  // Returns if grab was successful for all touch devices.
+  bool GrabTouchDevices(Display* display, ::Window window);
+
+  // Ungrab the touch devices. Returns if ungrab was successful for all touch
+  // devices.
+  bool UngrabTouchDevices(Display* display);
+
+ private:
+  TouchFactory();

[sky, 2011/01/19 19:34:54]

I think you forget an implementation of this.

[sadrul, 2011/01/19 20:10:17]

It is there in touch_factory.cc

+
+  // Requirement for Signleton
+  friend struct DefaultSingletonTraits<TouchFactory>;
+
+  // A quick lookup table for determining if a device is a touch device.
+  std::bitset<128> touch_device_lookup_;

[sky, 2011/01/19 19:34:54]

Are you sure you want to use both a bitset and vector here? Why not just a map?
I can't imagine this is called in performance intensive places where it really
matters.

[sadrul, 2011/01/19 20:10:17]

The lookup table is used for each pointer event (i.e. move/press/release events
from mouse, touch devices). For a simple gesture, there can be hundreds of such
events, and a lookup table would be useful to speed things up.

We could get rid of touch_device_list_, since it's currently only used for
grabbing/ungrabbing devices (which happens for popup windows, e.g. menus). But
without it, we would have to go over the lookup table to decide which devices to
grab on, and that seems a bit awkward.

Ultimately, it is possible that we can do away with both the list and the lookup
table, and have a single device-id for the touch device. But that is TBD until
more experiments with devices. I can leave a note here accordingly if that
sounds good to you?

[sky, 2011/01/19 23:15:31]

Sounds good.

+
+  // The list of touch devices.
+  std::vector<int> touch_device_list_;
+
+  DISALLOW_COPY_AND_ASSIGN(TouchFactory);
+};
+
+}  // namespace views
+
+#endif  // VIEWS_TOUCHUI_TOUCH_FACTORY_H_