chromeos/audio/audio_devices_pref_handler.h

   1 // Copyright (c) 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 CHROMEOS_AUDIO_AUDIO_DEVICES_PREF_HANDLER_H_
   6 #define CHROMEOS_AUDIO_AUDIO_DEVICES_PREF_HANDLER_H_
   7
   8 #include "base/basictypes.h"
   9 #include "base/memory/ref_counted.h"
  10 #include "chromeos/audio/audio_pref_observer.h"
  11 #include "chromeos/chromeos_export.h"
  12
  13 class PrefService;
  14
  15 namespace chromeos {
  16
  17 struct AudioDevice;
  18
  19 // Interface that handles audio preference related work, reads and writes
  20 // audio preferences, and notifies AudioPrefObserver for audio preference
  21 // changes.
  22 class CHROMEOS_EXPORT AudioDevicesPrefHandler
  23     : public base::RefCountedThreadSafe<AudioDevicesPrefHandler> {
  24  public:
  25   // Integer because C++ does not allow static const double in header files.
  26   static const int kDefaultOutputVolumePercent = 75;
  27   static const int kDefaultHdmiOutputVolumePercent = 100;
  28
  29   // Gets the audio output volume value from prefs for a device. Since we can
  30   // only have either a gain or a volume for a device (depending on whether it
  31   // is input or output), we don't really care which value it is.
  32   virtual double GetOutputVolumeValue(const AudioDevice* device) = 0;
  33   virtual double GetInputGainValue(const AudioDevice* device) = 0;
  34   // Sets the audio volume or gain value to prefs for a device.
  35   virtual void SetVolumeGainValue(const AudioDevice& device, double value) = 0;
  36
  37   // Reads the audio mute value from prefs for a device.
  38   virtual bool GetMuteValue(const AudioDevice& device) = 0;
  39   // Sets the audio mute value to prefs for a device.
  40   virtual void SetMuteValue(const AudioDevice& device, bool mute_on) = 0;
  41
  42   // Reads the audio output allowed value from prefs.
  43   virtual bool GetAudioOutputAllowedValue() = 0;
  44
  45   // Adds an audio preference observer.
  46   virtual void AddAudioPrefObserver(AudioPrefObserver* observer) = 0;
  47   // Removes an audio preference observer.
  48   virtual void RemoveAudioPrefObserver(AudioPrefObserver* observer) = 0;
  49
  50  protected:
  51   virtual ~AudioDevicesPrefHandler() {}
  52
  53  private:
  54   friend class base::RefCountedThreadSafe<AudioDevicesPrefHandler>;
  55 };
  56
  57 }  // namespace chromeos
  58
  59 #endif  // CHROMEOS_AUDIO_AUDIO_DEVICES_PREF_HANDLER_H_