system_key_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_SYSTEM_KEY_EVENT_LISTENER_H_
6#define CHROME_BROWSER_CHROMEOS_EVENTS_SYSTEM_KEY_EVENT_LISTENER_H_
7
8#include "base/memory/singleton.h"
9#include "base/message_loop/message_loop.h"
10
11typedef union _XEvent XEvent;
12
13namespace chromeos {
14
15class SystemKeyEventListener : public base::MessageLoopForUI::Observer {
16 public:
17  // Observer for caps lock state changes.
18  class CapsLockObserver {
19   public:
20    virtual void OnCapsLockChange(bool enabled) = 0;
21
22   protected:
23    CapsLockObserver() {}
24    virtual ~CapsLockObserver() {}
25
26    DISALLOW_COPY_AND_ASSIGN(CapsLockObserver);
27  };
28
29  // Observer for modifier keys' state changes.
30  class ModifiersObserver {
31   public:
32    enum {
33      SHIFT_PRESSED = 1,
34      CTRL_PRESSED = 1 << 1,
35      ALT_PRESSED = 1 << 2,
36    };
37
38    // |pressed_modifiers| is a bitmask of SHIFT_PRESSED, CTRL_PRESSED and
39    // ALT_PRESSED.
40    virtual void OnModifiersChange(int pressed_modifiers) = 0;
41
42   protected:
43    ModifiersObserver() {}
44    virtual ~ModifiersObserver() {}
45
46    DISALLOW_COPY_AND_ASSIGN(ModifiersObserver);
47  };
48
49  static void Initialize();
50  static void Shutdown();
51  // GetInstance returns NULL if not initialized or if already shutdown.
52  static SystemKeyEventListener* GetInstance();
53
54  void Stop();
55
56  void AddCapsLockObserver(CapsLockObserver* observer);
57  void AddModifiersObserver(ModifiersObserver* observer);
58  void RemoveCapsLockObserver(CapsLockObserver* observer);
59  void RemoveModifiersObserver(ModifiersObserver* observer);
60
61 private:
62  // Defines the delete on exit Singleton traits we like.  Best to have this
63  // and const/dest private as recommended for Singletons.
64  friend struct DefaultSingletonTraits<SystemKeyEventListener>;
65  friend class SystemKeyEventListenerTest;
66
67  SystemKeyEventListener();
68  virtual ~SystemKeyEventListener();
69
70  // MessageLoopForUI::Observer overrides.
71  virtual base::EventStatus WillProcessEvent(
72      const base::NativeEvent& event) OVERRIDE;
73  virtual void DidProcessEvent(const base::NativeEvent& event) OVERRIDE;
74
75  void OnCapsLock(bool enabled);
76  void OnModifiers(int state);
77
78  // Returns true if the event was processed, false otherwise.
79  virtual bool ProcessedXEvent(XEvent* xevent);
80
81  bool stopped_;
82
83  unsigned int num_lock_mask_;
84  bool caps_lock_is_on_;
85  int pressed_modifiers_;
86  ObserverList<CapsLockObserver> caps_lock_observers_;
87  ObserverList<ModifiersObserver> modifiers_observers_;
88
89  // Base X ID for events from the XKB extension.
90  int xkb_event_base_;
91
92  DISALLOW_COPY_AND_ASSIGN(SystemKeyEventListener);
93};
94
95}  // namespace chromeos
96
97#endif  // CHROME_BROWSER_CHROMEOS_EVENTS_SYSTEM_KEY_EVENT_LISTENER_H_
98