text: // 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 CONTENT_RENDERER_MEDIA_WEBAUDIOSOURCEPROVIDER_IMPL_H_
  #define CONTENT_RENDERER_MEDIA_WEBAUDIOSOURCEPROVIDER_IMPL_H_
  
  #include "base/callback.h"
  #include "base/memory/weak_ptr.h"
  #include "base/synchronization/lock.h"
  #include "content/common/content_export.h"
  #include "media/base/audio_renderer_sink.h"
  #include "third_party/WebKit/public/platform/WebAudioSourceProvider.h"
  #include "third_party/WebKit/public/platform/WebVector.h"
  
  namespace blink {
  class WebAudioSourceProviderClient;
  }
  
  namespace content {
  
  // WebAudioSourceProviderImpl provides a bridge between classes:
  //     blink::WebAudioSourceProvider <---> media::AudioRendererSink
  //
  // WebAudioSourceProviderImpl wraps an existing audio sink that is used unless
  // WebKit has set a client via setClient(). While a client is set WebKit will
  // periodically call provideInput() to render a certain number of audio
  // sample-frames using the sink's RenderCallback to get the data.
  //
  // All calls are protected by a lock.
  class CONTENT_EXPORT WebAudioSourceProviderImpl
      : NON_EXPORTED_BASE(public blink::WebAudioSourceProvider),
        NON_EXPORTED_BASE(public media::AudioRendererSink) {
   public:
    explicit WebAudioSourceProviderImpl(
        const scoped_refptr<media::AudioRendererSink>& sink);
  
    // blink::WebAudioSourceProvider implementation.
    virtual void setClient(blink::WebAudioSourceProviderClient* client);
    virtual void provideInput(const blink::WebVector<float*>& audio_data,
                              size_t number_of_frames);
  
    // media::AudioRendererSink implementation.
    virtual void Start() OVERRIDE;
    virtual void Stop() OVERRIDE;
    virtual void Play() OVERRIDE;
    virtual void Pause() OVERRIDE;
    virtual bool SetVolume(double volume) OVERRIDE;
    virtual void Initialize(const media::AudioParameters& params,
                            RenderCallback* renderer) OVERRIDE;
  
   protected:
    virtual ~WebAudioSourceProviderImpl();
  
   private:
    // Calls setFormat() on |client_| from the Blink renderer thread.
    void OnSetFormat();
  
    base::WeakPtrFactory<WebAudioSourceProviderImpl> weak_this_;
  
    // Closure that posts a task to call OnSetFormat() on the renderer thread.
    base::Closure set_format_cb_;
  
    // Set to true when Initialize() is called.
    int channels_;
    int sample_rate_;
    double volume_;
  
    // Tracks the current playback state.
    enum PlaybackState { kStopped, kStarted, kPlaying };
    PlaybackState state_;
  
    // Where audio comes from.
    media::AudioRendererSink::RenderCallback* renderer_;
  
    // 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_;
    scoped_refptr<media::AudioRendererSink> sink_;
    scoped_ptr<media::AudioBus> bus_wrapper_;
  
    DISALLOW_IMPLICIT_CONSTRUCTORS(WebAudioSourceProviderImpl);
  };
  
  }  // namespace content
  
  #endif  // CONTENT_RENDERER_MEDIA_WEBAUDIOSOURCEPROVIDER_IMPL_H_
  