device/bluetooth/bluetooth_audio_sink.h

   1 // Copyright 2014 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 DEVICE_BLUETOOTH_BLUETOOTH_AUDIO_SINK_H_
   6 #define DEVICE_BLUETOOTH_BLUETOOTH_AUDIO_SINK_H_
   7
   8 #include <stdint.h>
   9 #include <string>
  10 #include <vector>
  11
  12 #include "base/callback.h"
  13 #include "base/memory/ref_counted.h"
  14 #include "base/memory/scoped_ptr.h"
  15 #include "device/bluetooth/bluetooth_export.h"
  16
  17 namespace device {
  18
  19 // TODO(mcchou): Define a BluetoothAudioSink specific IOBuffer abstraction.
  20
  21 // BluetoothAudioSink represents a local A2DP audio sink where a remote device
  22 // can stream audio data. Once a BluetoothAudioSink is successfully registered,
  23 // user applications can obtain a pointer to a BluetoothAudioSink object via
  24 // the interface provided by BluetoothAdapter. The validity of a
  25 // BluetoothAudioSink depends on whether BluetoothAdapter is present and whether
  26 // it is powered.
  27 class DEVICE_BLUETOOTH_EXPORT BluetoothAudioSink
  28     : public base::RefCounted<BluetoothAudioSink> {
  29  public:
  30   // Possible values indicating the connection states between the
  31   // BluetoothAudioSink and the remote device.
  32   enum State {
  33     STATE_INVALID,  // BluetoothAdapter not presented or not powered.
  34     STATE_DISCONNECTED,  // Not connected.
  35     STATE_IDLE,  // Connected but not streaming.
  36     STATE_PENDING,  // Connected, streaming but not acquired.
  37     STATE_ACTIVE,  // Connected, streaming and acquired.
  38   };
  39
  40   // Possible types of error raised by Audio Sink object.
  41   enum ErrorCode {
  42     ERROR_UNSUPPORTED_PLATFORM,  // A2DP sink not supported on current platform.
  43     ERROR_INVALID_ADAPTER,  // BluetoothAdapter not present/powered.
  44     ERROR_NOT_REGISTERED,  // BluetoothAudioSink not registered.
  45     ERROR_NOT_UNREGISTERED,  // BluetoothAudioSink not unregistered.
  46   };
  47
  48   // Options to configure an A2DP audio sink.
  49   struct Options {
  50     Options();
  51     ~Options();
  52
  53     uint8_t codec;
  54     std::vector<uint8_t> capabilities;
  55   };
  56
  57   // Interface for observing changes from a BluetoothAudioSink.
  58   class Observer {
  59    public:
  60     virtual ~Observer() {}
  61
  62     // Called when the state of the BluetoothAudioSink object is changed.
  63     // |audio_sink| indicates the object being changed, and |state| indicates
  64     // the new state of that object.
  65     virtual void BluetoothAudioSinkStateChanged(
  66         BluetoothAudioSink* audio_sink,
  67         BluetoothAudioSink::State state) = 0;
  68
  69     // Called when the volume of the BluetoothAudioSink object is changed.
  70     // |audio_sink| indicates the object being changed, and |volume| indicates
  71     // the new volume level of that object.
  72     virtual void BluetoothAudioSinkVolumeChanged(
  73         BluetoothAudioSink* audio_sink,
  74         uint16_t volume) = 0;
  75
  76     // TODO(mcchou): Add method to monitor the availability of audio data during
  77     // the streaming. This method should associate with BluetoothAudioSink
  78     // specific IOBuffer wrapping fd, read_mtu and write_mtu.
  79   };
  80
  81   // The ErrorCallback is used for the methods that can fail in which case it
  82   // is called.
  83   typedef base::Callback<void(ErrorCode)> ErrorCallback;
  84
  85   // Possible volumes for media transport are 0-127, and 128 is used to
  86   // represent invalid volume.
  87   static const uint16_t kInvalidVolume;
  88
  89   // Unregisters the audio sink. An audio sink will unregister itself
  90   // automatically in its destructor, but calling Unregister is recommended,
  91   // since user applications can be notified of an error returned by the call.
  92   virtual void Unregister(const base::Closure& callback,
  93                           const ErrorCallback& error_callback) = 0;
  94
  95   // Adds and removes an observer for events on the BluetoothAudioSink object.
  96   // If monitoring multiple audio sinks, check the |audio_sink| parameter of
  97   // observer methods to determine which audio sink is issuing the event.
  98   virtual void AddObserver(Observer* observer) = 0;
  99   virtual void RemoveObserver(Observer* observer) = 0;
 100
 101   // Getters for state and volume.
 102   virtual State GetState() const = 0;
 103
 104   // Returns the current volume level of the audio sink. The valid volumes are
 105   // 0-127, and |kInvalidVolume| is returned instead if the volume is unknown.
 106   virtual uint16_t GetVolume() const = 0;
 107
 108  protected:
 109   friend class base::RefCounted<BluetoothAudioSink>;
 110   BluetoothAudioSink();
 111
 112   // The destructor invokes Unregister() to ensure the audio sink will be
 113   // unregistered even if the user applications fail to do so.
 114   virtual ~BluetoothAudioSink();
 115
 116  private:
 117   DISALLOW_COPY_AND_ASSIGN(BluetoothAudioSink);
 118 };
 119
 120 }  // namespace device
 121
 122 #endif  // DEVICE_BLUETOOTH_BLUETOOTH_AUDIO_SINK_H_