media/base/keyboard_event_counter.h

   1 // Copyright 2013 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 MEDIA_BASE_KEYBOARD_EVENT_COUNTER_H_
   6 #define MEDIA_BASE_KEYBOARD_EVENT_COUNTER_H_
   7
   8 #include <set>
   9
  10 #include "base/synchronization/lock.h"
  11 #include "media/base/media_export.h"
  12 #include "ui/events/event_constants.h"
  13 #include "ui/events/keycodes/keyboard_codes.h"
  14
  15 namespace media {
  16
  17 // This class tracks the total number of keypresses based on the OnKeyboardEvent
  18 // calls it receives from the client.
  19 // Multiple key down events for the same key are counted as one keypress until
  20 // the same key is released.
  21 class MEDIA_EXPORT KeyboardEventCounter {
  22  public:
  23   KeyboardEventCounter();
  24   ~KeyboardEventCounter();
  25
  26   // Resets the count to 0. Must be called on the same thread as
  27   // OnKeyboardEvent.
  28   void Reset();
  29
  30   // Returns the total number of keypresses since its creation or last Reset()
  31   // call. Can be called on any thread.
  32   size_t GetKeyPressCount() const;
  33
  34   // The client should call this method on key down or key up events.
  35   // Must be called on a single thread.
  36   void OnKeyboardEvent(ui::EventType event, ui::KeyboardCode key_code);
  37
  38  private:
  39   // The set of keys currently held down.
  40   std::set<ui::KeyboardCode> pressed_keys_;
  41
  42   size_t total_key_presses_;
  43
  44   DISALLOW_COPY_AND_ASSIGN(KeyboardEventCounter);
  45 };
  46
  47 }  // namespace media
  48
  49 #endif  // MEDIA_BASE_KEYBOARD_EVENT_COUNTER_H_