src/cobalt/speech/microphone_manager.h

// Copyright 2016 The Cobalt Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#ifndef COBALT_SPEECH_MICROPHONE_MANAGER_H_
#define COBALT_SPEECH_MICROPHONE_MANAGER_H_

#include <memory>
#include <string>

#include "cobalt/speech/speech_configuration.h"

#include "base/callback.h"
#include "base/optional.h"
#include "base/threading/thread.h"
#include "base/timer/timer.h"
#include "cobalt/dom/event.h"
#include "cobalt/media/base/audio_bus.h"
#include "cobalt/speech/microphone.h"

namespace cobalt {
namespace speech {

// This class is used for microphone creation, control and destruction. It has
// a self-managed poller to fetch audio data from microphone.
class MicrophoneManager {
 public:
  enum class MicrophoneError {
    kAudioCapture,
    kAborted,
  };
  typedef media::AudioBus AudioBus;
  typedef base::Callback<void(std::unique_ptr<AudioBus>)> DataReceivedCallback;
  typedef base::Closure CompletionCallback;
  typedef base::Closure SuccessfulOpenCallback;
  typedef base::Callback<void(MicrophoneError, std::string)> ErrorCallback;
  typedef base::Callback<std::unique_ptr<Microphone>(int)> MicrophoneCreator;

  MicrophoneManager(const DataReceivedCallback& data_received,
                    const SuccessfulOpenCallback& successful_open,
                    const CompletionCallback& completion,
                    const ErrorCallback& error,
                    const MicrophoneCreator& microphone_creator);

  ~MicrophoneManager();

  // Open microphone to receive voice and start a timer to fetch audio data from
  // microphone.
  void Open();
  // Close microphone and stop the timer from receiving audio data.
  void Close();

 private:
  enum State { kStarted, kStopped, kError };

  // Returns true if the creation succeeded or the microphone is already a valid
  // one.
  bool CreateIfNecessary();
  void OpenInternal();
  void CloseInternal();
  void DestroyInternal();

  // Timer callback for fetching audio data.
  void Read();

  const DataReceivedCallback data_received_callback_;
  const CompletionCallback completion_callback_;
  const ErrorCallback error_callback_;
  const SuccessfulOpenCallback successful_open_callback_;
  const MicrophoneCreator microphone_creator_;

  std::unique_ptr<Microphone> microphone_;

  // Microphone state.
  State state_;
  // Repeat timer to poll mic events.
  base::Optional<base::RepeatingTimer> poll_mic_events_timer_;
  // Microphone thread.
  base::Thread thread_;
};

}  // namespace speech
}  // namespace cobalt

#endif  //  COBALT_SPEECH_MICROPHONE_MANAGER_H_