third_party/WebKit/Source/modules/webaudio/OfflineAudioDestinationNode.h

/*
 * Copyright (C) 2011, Google Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1.  Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2.  Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
 * DAMAGE.
 */

#ifndef OfflineAudioDestinationNode_h
#define OfflineAudioDestinationNode_h

#include "modules/webaudio/AudioBuffer.h"
#include "modules/webaudio/AudioDestinationNode.h"
#include "modules/webaudio/OfflineAudioContext.h"
#include "public/platform/WebThread.h"
#include "wtf/PassRefPtr.h"
#include "wtf/RefPtr.h"
#include <memory>

namespace blink {

class BaseAudioContext;
class AudioBus;
class OfflineAudioContext;

class OfflineAudioDestinationHandler final : public AudioDestinationHandler {
 public:
  static PassRefPtr<OfflineAudioDestinationHandler> create(
      AudioNode&,
      AudioBuffer* renderTarget);
  ~OfflineAudioDestinationHandler() override;

  // AudioHandler
  void dispose() override;
  void initialize() override;
  void uninitialize() override;

  OfflineAudioContext* context() const final;

  // AudioDestinationHandler
  void startRendering() override;
  void stopRendering() override;
  unsigned long maxChannelCount() const override;

  float sampleRate() const override { return m_renderTarget->sampleRate(); }

  size_t renderQuantumFrames() const { return renderQuantumSize; }

  WebThread* offlineRenderThread();

 private:
  OfflineAudioDestinationHandler(AudioNode&, AudioBuffer* renderTarget);

  static const size_t renderQuantumSize;

  // Set up the rendering and start. After setting the context up, it will
  // eventually call |doOfflineRendering|.
  void startOfflineRendering();

  // Suspend the rendering loop and notify the main thread to resolve the
  // associated promise.
  void suspendOfflineRendering();

  // Start the rendering loop.
  void doOfflineRendering();

  // Finish the rendering loop and notify the main thread to resolve the
  // promise with the rendered buffer.
  void finishOfflineRendering();

  // Suspend/completion callbacks for the main thread.
  void notifySuspend(size_t);
  void notifyComplete();

  // The offline version of render() method. If the rendering needs to be
  // suspended after checking, this stops the rendering and returns true.
  // Otherwise, it returns false after rendering one quantum.
  bool renderIfNotSuspended(AudioBus* sourceBus,
                            AudioBus* destinationBus,
                            size_t numberOfFrames);

  // This AudioHandler renders into this AudioBuffer.
  // This Persistent doesn't make a reference cycle including the owner
  // OfflineAudioDestinationNode.
  Persistent<AudioBuffer> m_renderTarget;
  // Temporary AudioBus for each render quantum.
  RefPtr<AudioBus> m_renderBus;

  // Rendering thread.
  std::unique_ptr<WebThread> m_renderThread;

  // These variables are for counting the number of frames for the current
  // progress and the remaining frames to be processed.
  size_t m_framesProcessed;
  size_t m_framesToProcess;

  // This flag is necessary to distinguish the state of the context between
  // 'created' and 'suspended'. If this flag is false and the current state
  // is 'suspended', it means the context is created and have not started yet.
  bool m_isRenderingStarted;

  // This flag indicates whether the rendering should be suspended or not.
  bool m_shouldSuspend;
};

class OfflineAudioDestinationNode final : public AudioDestinationNode {
 public:
  static OfflineAudioDestinationNode* create(BaseAudioContext*,
                                             AudioBuffer* renderTarget);

 private:
  OfflineAudioDestinationNode(BaseAudioContext&, AudioBuffer* renderTarget);
};

}  // namespace blink

#endif  // OfflineAudioDestinationNode_h