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AudioBuffer

Macros

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef AudioBuffer_h_
#define AudioBuffer_h_

#include "nsWrapperCache.h"
#include "nsCycleCollectionParticipant.h"
#include "mozilla/Attributes.h"
#include "mozilla/StaticPtr.h"
#include "mozilla/StaticMutex.h"
#include "nsTArray.h"
#include "js/TypeDecls.h"
#include "mozilla/MemoryReporting.h"
#include "mozilla/dom/TypedArray.h"

namespace mozilla {

class ErrorResult;
class ThreadSharedFloatArrayBufferList;

namespace dom {

struct AudioBufferOptions;

/**
 * An AudioBuffer keeps its data either in the mJSChannels objects, which
 * are Float32Arrays, or in mSharedChannels if the mJSChannels objects' buffers
 * are detached.
 */
class AudioBuffer final : public nsWrapperCache
{
public:
  // If non-null, aInitialContents must have number of channels equal to
  // aNumberOfChannels and their lengths must be at least aLength.
  static already_AddRefed<AudioBuffer>
  Create(nsPIDOMWindowInner* aWindow, uint32_t aNumberOfChannels,
         uint32_t aLength, float aSampleRate,
         already_AddRefed<ThreadSharedFloatArrayBufferList> aInitialContents,
         ErrorResult& aRv);

  static already_AddRefed<AudioBuffer>
  Create(nsPIDOMWindowInner* aWindow, uint32_t aNumberOfChannels,
         uint32_t aLength, float aSampleRate,
         ErrorResult& aRv)
  {
    return Create(aWindow, aNumberOfChannels, aLength, aSampleRate,
                  nullptr, aRv);
  }

  size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;

  NS_INLINE_DECL_CYCLE_COLLECTING_NATIVE_REFCOUNTING(AudioBuffer)
  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_NATIVE_CLASS(AudioBuffer)

  static already_AddRefed<AudioBuffer>
  Constructor(const GlobalObject& aGlobal,
              const AudioBufferOptions& aOptions, ErrorResult& aRv);

  nsPIDOMWindowInner* GetParentObject() const
  {
    nsCOMPtr<nsPIDOMWindowInner> parentObject = do_QueryReferent(mOwnerWindow);
    return parentObject;
  }

  JSObject* WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto) override;

  float SampleRate() const
  {
    return mSampleRate;
  }

  uint32_t Length() const
  {
    return mLength;
  }

  double Duration() const
  {
    return mLength / static_cast<double> (mSampleRate);
  }

  uint32_t NumberOfChannels() const
  {
    return mJSChannels.Length();
  }

  /**
   * If mSharedChannels is non-null, copies its contents to
   * new Float32Arrays in mJSChannels. Returns a Float32Array.
   */
  void GetChannelData(JSContext* aJSContext, uint32_t aChannel,
                      JS::MutableHandle<JSObject*> aRetval,
                      ErrorResult& aRv);

  void CopyFromChannel(const Float32Array& aDestination, uint32_t aChannelNumber,
                       uint32_t aStartInChannel, ErrorResult& aRv);
  void CopyToChannel(JSContext* aJSContext, const Float32Array& aSource,
                     uint32_t aChannelNumber, uint32_t aStartInChannel,
                     ErrorResult& aRv);

  /**
   * Returns a ThreadSharedFloatArrayBufferList containing the sample data.
   * Can return null if there is no data.
   */
  ThreadSharedFloatArrayBufferList* GetThreadSharedChannelsForRate(JSContext* aContext);

protected:
  AudioBuffer(nsPIDOMWindowInner* aWindow, uint32_t aNumberOfChannels,
              uint32_t aLength, float aSampleRate,
              already_AddRefed<ThreadSharedFloatArrayBufferList>
                aInitialContents);
  ~AudioBuffer();

  bool RestoreJSChannelData(JSContext* aJSContext);

  already_AddRefed<ThreadSharedFloatArrayBufferList>
  StealJSArrayDataIntoSharedChannels(JSContext* aJSContext);

  void ClearJSChannels();

  nsWeakPtr mOwnerWindow;
  // Float32Arrays
  AutoTArray<JS::Heap<JSObject*>, 2> mJSChannels;

  // mSharedChannels aggregates the data from mJSChannels. This is non-null
  // if and only if the mJSChannels' buffers are detached.
  RefPtr<ThreadSharedFloatArrayBufferList> mSharedChannels;

  uint32_t mLength;
  float mSampleRate;
};

} // namespace dom
} // namespace mozilla

#endif