OffscreenCanvas.h - mozsearch

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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 MOZILLA_DOM_OFFSCREENCANVAS_H_

#define MOZILLA_DOM_OFFSCREENCANVAS_H_

#include "gfxTypes.h"

#include "mozilla/dom/CanvasRenderingContextHelper.h"

#include "mozilla/dom/ImageEncoder.h"

#include "mozilla/dom/OffscreenCanvasDisplayHelper.h"

#include "mozilla/DOMEventTargetHelper.h"

#include "mozilla/layers/LayersTypes.h"

#include "mozilla/Maybe.h"

#include "mozilla/RefPtr.h"

#include "mozilla/UniquePtr.h"

#include "nsCycleCollectionParticipant.h"

struct JSContext;

namespace mozilla {

class CancelableRunnable;

class ErrorResult;

enum class RFPTarget : uint64_t;

namespace gfx {

class SourceSurface;

namespace dom {

enum class OffscreenRenderingContextId : uint8_t;

class Blob;

class EncodeCompleteCallback;

class OffscreenCanvasDisplayHelper;

class ImageBitmap;

struct ImageEncodeOptions;

using OwningOffscreenRenderingContext = class

    OwningOffscreenCanvasRenderingContext2DOrImageBitmapRenderingContextOrWebGLRenderingContextOrWebGL2RenderingContextOrGPUCanvasContext;

// This is helper class for transferring OffscreenCanvas to worker thread.

// Because OffscreenCanvas is not thread-safe. So we cannot pass Offscreen-

// Canvas to worker thread directly. Thus, we create this helper class and

// store necessary data in it then pass it to worker thread.

struct OffscreenCanvasCloneData final {

  OffscreenCanvasCloneData(OffscreenCanvasDisplayHelper* aDisplay,

                           uint32_t aWidth, uint32_t aHeight,

                           layers::LayersBackend aCompositorBackend,

                           layers::TextureType aTextureType, bool aNeutered,

                           bool aIsWriteOnly, nsIPrincipal* aExpandedReader);

  ~OffscreenCanvasCloneData();

  RefPtr<OffscreenCanvasDisplayHelper> mDisplay;

  uint32_t mWidth;

  uint32_t mHeight;

  layers::LayersBackend mCompositorBackendType;

  layers::TextureType mTextureType;

  bool mNeutered;

  bool mIsWriteOnly;

  RefPtr<nsIPrincipal> mExpandedReader;

};

class OffscreenCanvas final : public DOMEventTargetHelper,

                              public CanvasRenderingContextHelper {

 public:

  NS_DECL_ISUPPORTS_INHERITED

  NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(OffscreenCanvas,

                                           DOMEventTargetHelper)

  IMPL_EVENT_HANDLER(contextlost);

  IMPL_EVENT_HANDLER(contextrestored);

  OffscreenCanvas(nsIGlobalObject* aGlobal, uint32_t aWidth, uint32_t aHeight);

  OffscreenCanvas(nsIGlobalObject* aGlobal, uint32_t aWidth, uint32_t aHeight,

                  layers::LayersBackend aCompositorBackend,

                  layers::TextureType aTextureType,

                  already_AddRefed<OffscreenCanvasDisplayHelper> aDisplay);

  void Destroy();

  nsIGlobalObject* GetParentObject() const { return GetOwnerGlobal(); }

  virtual JSObject* WrapObject(JSContext* aCx,

                               JS::Handle<JSObject*> aGivenProto) override;

  static already_AddRefed<OffscreenCanvas> Constructor(

      const GlobalObject& aGlobal, uint32_t aWidth, uint32_t aHeight,

      ErrorResult& aRv);

  void ClearResources();

  uint32_t Width() const { return mWidth; }

  uint32_t Height() const { return mHeight; }

  void SetWidth(uint32_t aWidth, ErrorResult& aRv);

  void SetHeight(uint32_t aHeight, ErrorResult& aRv);

  void GetContext(JSContext* aCx, const OffscreenRenderingContextId& aContextId,

                  JS::Handle<JS::Value> aContextOptions,

                  Nullable<OwningOffscreenRenderingContext>& aResult,

                  ErrorResult& aRv);

  already_AddRefed<ImageBitmap> TransferToImageBitmap(ErrorResult& aRv);

  already_AddRefed<Promise> ConvertToBlob(const ImageEncodeOptions& aOptions,

                                          ErrorResult& aRv);

  already_AddRefed<Promise> ToBlob(JSContext* aCx, const nsAString& aType,

                                   JS::Handle<JS::Value> aParams,

                                   ErrorResult& aRv);

  Maybe<uint64_t> GetWindowID();

  nsICanvasRenderingContextInternal* GetContext() const {

    return mCurrentContext;

  CanvasContextType GetContextType() const { return mCurrentContextType; }

  already_AddRefed<gfx::SourceSurface> GetSurfaceSnapshot(

      gfxAlphaType* aOutAlphaType = nullptr);

  static already_AddRefed<OffscreenCanvas> CreateFromCloneData(

      nsIGlobalObject* aGlobal, OffscreenCanvasCloneData* aData);

  // Return true on main-thread, and return gfx.offscreencanvas.enabled

  // on worker thread.

  static bool PrefEnabledOnWorkerThread(JSContext* aCx, JSObject* aObj);

  UniquePtr<OffscreenCanvasCloneData> ToCloneData(JSContext* aCx);

  void UpdateDisplayData(const OffscreenCanvasDisplayData& aData);

  void CommitFrameToCompositor();

  void DequeueCommitToCompositor();

  void QueueCommitToCompositor();

  virtual bool GetOpaqueAttr() override { return false; }

  virtual nsIntSize GetWidthHeight() override {

    return nsIntSize(mWidth, mHeight);

  virtual already_AddRefed<nsICanvasRenderingContextInternal> CreateContext(

      CanvasContextType aContextType) override;

  void SetNeutered() {

    mWidth = 0;

    mHeight = 0;

    mNeutered = true;

  bool MayNeuter() const { return !mNeutered && !mCurrentContext; }

  void SetSize(const nsIntSize& aSize, ErrorResult& aRv);

  nsIPrincipal* GetExpandedReader() const { return mExpandedReader; }

  void SetWriteOnly(RefPtr<nsIPrincipal>&& aExpandedReader);

  void SetWriteOnly(nsIPrincipal* aExpandedReader = nullptr) {

    RefPtr<nsIPrincipal> expandedReader(aExpandedReader);

    SetWriteOnly(std::move(expandedReader));

  bool IsWriteOnly() const { return mIsWriteOnly; }

  // Determines if the caller should be able to read the content.

  bool CallerCanRead(nsIPrincipal& aPrincipal) const;

  layers::LayersBackend GetCompositorBackendType() const {

    return mCompositorBackendType;

  bool ShouldResistFingerprinting(mozilla::RFPTarget aTarget) const;

  bool IsTransferredFromElement() const { return !!mDisplay; }

 private:

  ~OffscreenCanvas();

  already_AddRefed<EncodeCompleteCallback> CreateEncodeCompleteCallback(

      Promise* aPromise);

  void CanvasAttrChanged() {

    ErrorResult dummy;

    UpdateContext(nullptr, JS::NullHandleValue, dummy);

  bool mNeutered = false;

  bool mIsWriteOnly = false;

  uint32_t mWidth = 0;

  uint32_t mHeight = 0;

  layers::LayersBackend mCompositorBackendType =

      layers::LayersBackend::LAYERS_NONE;

  layers::TextureType mTextureType = layers::TextureType::Unknown;

  RefPtr<OffscreenCanvasDisplayHelper> mDisplay;

  RefPtr<CancelableRunnable> mPendingCommit;

  RefPtr<nsIPrincipal> mExpandedReader;

  Maybe<OffscreenCanvasDisplayData> mPendingUpdate;

};

}  // namespace dom

}  // namespace mozilla

#endif  // MOZILLA_DOM_OFFSCREENCANVAS_H_