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// Copyright (c) 2013 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.
#include "base/memory/ref_counted.h"
#include "chromeos/audio/audio_pref_observer.h"
#include "chromeos/chromeos_export.h"
class PrefService;
namespace chromeos {
struct AudioDevice;
// Used to represent an audio device's state. This state should be updated
// to AUDIO_STATE_ACTIVE when it is selected as active or set to
// AUDIO_STATE_INACTIVE when selected to a different device. When the audio
// device is unplugged, its last active/inactive state should be stored.
// The default value of device state will be AUDIO_STATE_NOT_AVAILABLE if
// the device is not found in the pref settings.
// Note that these states enum can't be renumbered or it would break existing
// preference.
enum AudioDeviceState {
// Interface that handles audio preference related work, reads and writes
// audio preferences, and notifies AudioPrefObserver for audio preference
// changes.
class CHROMEOS_EXPORT AudioDevicesPrefHandler
: public base::RefCountedThreadSafe<AudioDevicesPrefHandler> {
// Integer because C++ does not allow static const double in header files.
static const int kDefaultOutputVolumePercent = 75;
static const int kDefaultHdmiOutputVolumePercent = 100;
// Gets the audio output volume value from prefs for a device. Since we can
// only have either a gain or a volume for a device (depending on whether it
// is input or output), we don't really care which value it is.
virtual double GetOutputVolumeValue(const AudioDevice* device) = 0;
virtual double GetInputGainValue(const AudioDevice* device) = 0;
// Sets the audio volume or gain value to prefs for a device.
virtual void SetVolumeGainValue(const AudioDevice& device, double value) = 0;
// Reads the audio mute value from prefs for a device.
virtual bool GetMuteValue(const AudioDevice& device) = 0;
// Sets the audio mute value to prefs for a device.
virtual void SetMuteValue(const AudioDevice& device, bool mute_on) = 0;
virtual AudioDeviceState GetDeviceState(const AudioDevice& device) = 0;
virtual void SetDeviceState(const AudioDevice& device,
AudioDeviceState state) = 0;
// Reads the audio output allowed value from prefs.
virtual bool GetAudioOutputAllowedValue() = 0;
// Adds an audio preference observer.
virtual void AddAudioPrefObserver(AudioPrefObserver* observer) = 0;
// Removes an audio preference observer.
virtual void RemoveAudioPrefObserver(AudioPrefObserver* observer) = 0;
virtual ~AudioDevicesPrefHandler() {}
friend class base::RefCountedThreadSafe<AudioDevicesPrefHandler>;
} // namespace chromeos