src/cobalt/media/blink/webaudiosourceprovider_impl.h

// Copyright 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.

#ifndef COBALT_MEDIA_BLINK_WEBAUDIOSOURCEPROVIDER_IMPL_H_
#define COBALT_MEDIA_BLINK_WEBAUDIOSOURCEPROVIDER_IMPL_H_

#include <string>

#include "base/basictypes.h"
#include "base/callback.h"
#include "base/memory/weak_ptr.h"
#include "base/synchronization/lock.h"
#include "cobalt/media/base/audio_renderer_sink.h"
#include "cobalt/media/blink/media_blink_export.h"
#include "starboard/types.h"
#include "third_party/WebKit/public/platform/WebAudioSourceProvider.h"
#include "third_party/WebKit/public/platform/WebVector.h"

namespace blink {
class WebAudioSourceProviderClient;
}

namespace cobalt {
namespace media {

// WebAudioSourceProviderImpl is either one of two things (but not both):
// - a connection between a RestartableAudioRendererSink (the |sink_|) passed in
//   constructor and an AudioRendererSink::RenderCallback passed on Initialize()
//   by means of an internal AudioRendererSink::RenderCallback.
// - a connection between the said AudioRendererSink::RenderCallback and a
//   blink::WebAudioSourceProviderClient passed via setClient() (the |client_|),
//   again using the internal AudioRendererSink::RenderCallback. Blink calls
//   provideInput() periodically to fetch the appropriate data.
//
// In either case, the internal RenderCallback allows for delivering a copy of
// the data if a listener is configured. WASPImpl is also a
// RestartableAudioRendererSink itself in order to be controlled (Play(),
// Pause() etc).
//
// All calls are protected by a lock.
class MEDIA_BLINK_EXPORT WebAudioSourceProviderImpl
    : NON_EXPORTED_BASE(public blink::WebAudioSourceProvider),
      NON_EXPORTED_BASE(public SwitchableAudioRendererSink) {
 public:
  using CopyAudioCB = base::Callback<void(
      std::unique_ptr<AudioBus>, uint32_t frames_delayed, int sample_rate)>;

  explicit WebAudioSourceProviderImpl(
      const scoped_refptr<SwitchableAudioRendererSink>& sink);

  // blink::WebAudioSourceProvider implementation.
  void setClient(blink::WebAudioSourceProviderClient* client) OVERRIDE;
  void provideInput(const blink::WebVector<float*>& audio_data,
                    size_t number_of_frames) OVERRIDE;

  // RestartableAudioRendererSink implementation.
  void Initialize(const AudioParameters& params,
                  RenderCallback* renderer) OVERRIDE;
  void Start() OVERRIDE;
  void Stop() OVERRIDE;
  void Play() OVERRIDE;
  void Pause() OVERRIDE;
  bool SetVolume(double volume) OVERRIDE;
  OutputDeviceInfo GetOutputDeviceInfo() OVERRIDE;
  bool CurrentThreadIsRenderingThread() OVERRIDE;
  void SwitchOutputDevice(const std::string& device_id,
                          const url::Origin& security_origin,
                          const OutputDeviceStatusCB& callback) OVERRIDE;

  // These methods allow a client to get a copy of the rendered audio.
  void SetCopyAudioCallback(const CopyAudioCB& callback);
  void ClearCopyAudioCallback();

  int RenderForTesting(AudioBus* audio_bus);

 private:
  friend class WebAudioSourceProviderImplTest;
  ~WebAudioSourceProviderImpl() OVERRIDE;

  // Calls setFormat() on |client_| from the Blink renderer thread.
  void OnSetFormat();

  // Used to keep the volume across reconfigurations.
  double volume_;

  // Tracks the current playback state.
  enum PlaybackState { kStopped, kStarted, kPlaying };
  PlaybackState state_;

  // Closure that calls OnSetFormat() on |client_| on the renderer thread.
  base::Closure set_format_cb_;
  // When set via setClient() it overrides |sink_| for consuming audio.
  blink::WebAudioSourceProviderClient* client_;

  // Where audio ends up unless overridden by |client_|.
  base::Lock sink_lock_;
  const scoped_refptr<SwitchableAudioRendererSink> sink_;
  std::unique_ptr<AudioBus> bus_wrapper_;

  // An inner class acting as a T filter where actual data can be tapped.
  class TeeFilter;
  const std::unique_ptr<TeeFilter> tee_filter_;

  // NOTE: Weak pointers must be invalidated before all other member variables.
  base::WeakPtrFactory<WebAudioSourceProviderImpl> weak_factory_;

  DISALLOW_IMPLICIT_CONSTRUCTORS(WebAudioSourceProviderImpl);
};

}  // namespace media
}  // namespace cobalt

#endif  // COBALT_MEDIA_BLINK_WEBAUDIOSOURCEPROVIDER_IMPL_H_