xinput_hierarchy_changed_event_listener.h revision 5d1f7b1de12d16ceb2c938c56701a3e8bfa558f7 
1// Copyright (c) 2012 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef CHROME_BROWSER_CHROMEOS_EVENTS_XINPUT_HIERARCHY_CHANGED_EVENT_LISTENER_H_
6#define CHROME_BROWSER_CHROMEOS_EVENTS_XINPUT_HIERARCHY_CHANGED_EVENT_LISTENER_H_
7
8#include "base/memory/singleton.h"
9#include "base/message_loop/message_loop.h"
10#include "base/observer_list.h"
11#include "chrome/browser/chromeos/device_hierarchy_observer.h"
12
13typedef union _XEvent XEvent;
14
15namespace chromeos {
16
17// XInputHierarchyChangedEventListener listens for an XI_HierarchyChanged event,
18// which is sent to Chrome when X detects a system or USB keyboard (or mouse),
19// then tells X to change the current XKB keyboard layout. Start by just calling
20// instance() to get it going.
21class XInputHierarchyChangedEventListener
22    : public base::MessageLoopForUI::Observer {
23 public:
24  static XInputHierarchyChangedEventListener* GetInstance();
25
26  void Stop();
27
28  void AddObserver(DeviceHierarchyObserver* observer);
29  void RemoveObserver(DeviceHierarchyObserver* observer);
30
31 private:
32  // Defines the delete on exit Singleton traits we like.  Best to have this
33  // and const/dest private as recommended for Singletons.
34  friend struct DefaultSingletonTraits<XInputHierarchyChangedEventListener>;
35
36  XInputHierarchyChangedEventListener();
37  virtual ~XInputHierarchyChangedEventListener();
38
39  // MessageLoopForUI::Observer overrides.
40  virtual base::EventStatus WillProcessEvent(
41      const base::NativeEvent& event) OVERRIDE;
42  virtual void DidProcessEvent(const base::NativeEvent& event) OVERRIDE;
43
44  // Returns true if the event was processed, false otherwise.
45  virtual bool ProcessedXEvent(XEvent* xevent);
46
47  // Notify observers that a device has been added/removed.
48  void NotifyDeviceHierarchyChanged();
49
50  bool stopped_;
51  int xiopcode_;
52
53  ObserverList<DeviceHierarchyObserver> observer_list_;
54
55  DISALLOW_COPY_AND_ASSIGN(XInputHierarchyChangedEventListener);
56};
57
58}  // namespace chromeos
59
60#endif  // CHROME_BROWSER_CHROMEOS_EVENTS_XINPUT_HIERARCHY_CHANGED_EVENT_LISTENER_H_
61