1 // Copyright (c) 2010 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_AUDIO_MIXER_H_ 6 #define CHROME_BROWSER_CHROMEOS_AUDIO_MIXER_H_ 7 #pragma once 8 9 #include "base/basictypes.h" 10 #include "base/callback.h" 11 12 namespace chromeos { 13 14 class AudioMixer { 15 public: 16 // Approximation of pure silence expressed in decibels. 17 static const double kSilenceDb = -200.0; 18 19 enum State { 20 UNINITIALIZED = 0, 21 INITIALIZING, 22 READY, 23 SHUTTING_DOWN, 24 IN_ERROR, 25 }; 26 AudioMixer()27 AudioMixer() {} ~AudioMixer()28 virtual ~AudioMixer() {} 29 30 // Non-Blocking call. Connect to Mixer, find a default device, then call the 31 // callback when complete with success code. 32 typedef Callback1<bool>::Type InitDoneCallback; 33 virtual void Init(InitDoneCallback* callback) = 0; 34 35 // Call may block. Mixer will be connected before returning, unless error. 36 virtual bool InitSync() = 0; 37 38 // Call may block. Returns a default of kSilenceDb on error. 39 virtual double GetVolumeDb() const = 0; 40 41 // Non-Blocking call. Returns the actual volume limits possible according 42 // to the mixer. Limits are left unchanged on error 43 virtual bool GetVolumeLimits(double* vol_min, double* vol_max) = 0; 44 45 // Non-blocking call. 46 virtual void SetVolumeDb(double vol_db) = 0; 47 48 // Call may block. Gets the mute state of the default device (true == mute). 49 // Returns a default of false on error. 50 virtual bool IsMute() const = 0; 51 52 // Non-Blocking call. 53 virtual void SetMute(bool mute) = 0; 54 55 // Returns READY if we have a valid working connection to the Mixer. 56 // This can return IN_ERROR if we lose the connection, even after an original 57 // successful init. Non-blocking call. 58 virtual State GetState() const = 0; 59 60 private: 61 DISALLOW_COPY_AND_ASSIGN(AudioMixer); 62 }; 63 64 } // namespace chromeos 65 66 #endif // CHROME_BROWSER_CHROMEOS_AUDIO_MIXER_H_ 67 68