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

/*
 * Copyright (C) 2012, 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
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 * DAMAGE.
 */

#ifndef OfflineAudioContext_h
#define OfflineAudioContext_h

#include "modules/ModulesExport.h"
#include "modules/webaudio/BaseAudioContext.h"
#include "wtf/HashMap.h"

namespace blink {

class ExceptionState;
class OfflineAudioDestinationHandler;

class MODULES_EXPORT OfflineAudioContext final : public BaseAudioContext {
  DEFINE_WRAPPERTYPEINFO();

 public:
  static OfflineAudioContext* create(ExecutionContext*,
                                     unsigned numberOfChannels,
                                     unsigned numberOfFrames,
                                     float sampleRate,
                                     ExceptionState&);

  ~OfflineAudioContext() override;

  DECLARE_VIRTUAL_TRACE();

  unsigned length() const { return m_totalRenderFrames; }

  ScriptPromise startOfflineRendering(ScriptState*);

  ScriptPromise suspendContext(ScriptState*, double);
  ScriptPromise resumeContext(ScriptState*) final;

  // This is to implement the pure virtual method from BaseAudioContext.
  // CANNOT be called from an OfflineAudioContext.
  ScriptPromise suspendContext(ScriptState*) final;

  void rejectPendingResolvers() override;

  bool hasRealtimeConstraint() final { return false; }

  DEFINE_ATTRIBUTE_EVENT_LISTENER(complete);

  // Fire completion event when the rendering is finished.
  void fireCompletionEvent();

  // This is same with the online version in BaseAudioContext class except
  // for returning a boolean value after checking the scheduled suspends.
  bool handlePreOfflineRenderTasks();

  void handlePostOfflineRenderTasks();

  // Resolve a suspend scheduled at the specified frame. With this specified
  // frame as a unique key, the associated promise resolver can be retrieved
  // from the map (m_scheduledSuspends) and resolved.
  void resolveSuspendOnMainThread(size_t);

  // The HashMap with 'zero' key is needed because |currentSampleFrame| can be
  // zero.
  using SuspendMap = HeapHashMap<size_t,
                                 Member<ScriptPromiseResolver>,
                                 DefaultHash<size_t>::Hash,
                                 WTF::UnsignedWithZeroKeyHashTraits<size_t>>;

  using OfflineGraphAutoLocker = DeferredTaskHandler::OfflineGraphAutoLocker;

 private:
  OfflineAudioContext(Document*,
                      unsigned numberOfChannels,
                      size_t numberOfFrames,
                      float sampleRate,
                      ExceptionState&);

  // Fetch directly the destination handler.
  OfflineAudioDestinationHandler& destinationHandler();

  AudioBuffer* renderTarget() const { return m_renderTarget.get(); }

  // Check if the rendering needs to be suspended.
  bool shouldSuspend();

  Member<AudioBuffer> m_renderTarget;

  // This map is to store the timing of scheduled suspends (frame) and the
  // associated promise resolver. This storage can only be modified by the
  // main thread and accessed by the audio thread with the graph lock.
  //
  // The map consists of key-value pairs of:
  // { size_t quantizedFrame: ScriptPromiseResolver resolver }
  //
  // Note that |quantizedFrame| is a unique key, since you can have only one
  // suspend scheduled for a certain frame. Accessing to this must be
  // protected by the offline context lock.
  SuspendMap m_scheduledSuspends;

  Member<ScriptPromiseResolver> m_completeResolver;

  // This flag is necessary to indicate the rendering has actually started.
  // Note that initial state of context is 'Suspended', which is the same
  // state when the context is suspended.
  bool m_isRenderingStarted;

  // Total render sample length.
  size_t m_totalRenderFrames;
};

}  // namespace blink

#endif  // OfflineAudioContext_h