author Nathan Froyd <>
Fri, 21 Sep 2018 16:45:49 -0400
changeset 496222 a14c288aec85e9e772dbb5e118a16c16cb95cc83
parent 488329 36a50c3f679a741a2a3a1ca89b192e8656262d0d
child 497362 3039bfc0e2707fa57523756d29de73703baccd59
permissions -rw-r--r--
Bug 1492894 - part 1 - make the node hierarchy consistently constructed with NodeInfo&&; r=mccr8 Various places in dom/ use the pattern: already_AddRefed<NodeInfo> ni = ...; which is supposed to be disallowed by our static analysis code, but isn't, for whatever reason. To fix our static analysis code, we need to eliminate instances of the above pattern. Unfortunately, eliminating this pattern requires restructuring how Nodes are created. Most Node subclasses take `already_AddRefed<NodeInfo>&` in their constructors, and a few accept `already_AddRefed<NodeInfo>&&`. We need to enforce the latter pattern consistently, which requires changing dozens of source files.

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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 */
#if !defined(mozilla_dom_HTMLCanvasElement_h)
#define mozilla_dom_HTMLCanvasElement_h

#include "mozilla/Attributes.h"
#include "mozilla/WeakPtr.h"
#include "nsIDOMEventListener.h"
#include "nsIObserver.h"
#include "nsGenericHTMLElement.h"
#include "nsGkAtoms.h"
#include "nsSize.h"
#include "nsError.h"

#include "mozilla/dom/BindingDeclarations.h"
#include "mozilla/dom/CanvasRenderingContextHelper.h"
#include "mozilla/gfx/Rect.h"
#include "mozilla/layers/LayersTypes.h"

class nsICanvasRenderingContextInternal;
class nsITimerCallback;

namespace mozilla {

class WebGLContext;

namespace layers {
class AsyncCanvasRenderer;
class CanvasRenderer;
class CanvasLayer;
class Image;
class Layer;
class LayerManager;
class SharedSurfaceTextureClient;
class WebRenderCanvasData;
} // namespace layers
namespace gfx {
class SourceSurface;
class VRLayerChild;
} // namespace gfx

namespace dom {
class BlobCallback;
class CanvasCaptureMediaStream;
class File;
class HTMLCanvasPrintState;
class OffscreenCanvas;
class PrintCallback;
class RequestedFrameRefreshObserver;

// Listen visibilitychange and memory-pressure event and inform
// context when event is fired.
class HTMLCanvasElementObserver final : public nsIObserver
                                      , public nsIDOMEventListener

  explicit HTMLCanvasElementObserver(HTMLCanvasElement* aElement);
  void Destroy();

  void RegisterVisibilityChangeEvent();
  void UnregisterVisibilityChangeEvent();

  void RegisterMemoryPressureEvent();
  void UnregisterMemoryPressureEvent();


  HTMLCanvasElement* mElement;

 * FrameCaptureListener is used by captureStream() as a way of getting video
 * frames from the canvas. On a refresh driver tick after something has been
 * drawn to the canvas since the last such tick, all registered
 * FrameCaptureListeners whose `mFrameCaptureRequested` equals `true`,
 * will be given a copy of the just-painted canvas.
 * All FrameCaptureListeners get the same copy.
class FrameCaptureListener : public SupportsWeakPtr<FrameCaptureListener>

    : mFrameCaptureRequested(false) {}

   * Called when a frame capture is desired on next paint.
  void RequestFrameCapture() { mFrameCaptureRequested = true; }

   * Indicates to the canvas whether or not this listener has requested a frame.
  bool FrameCaptureRequested() const { return mFrameCaptureRequested; }

   * Interface through which new video frames will be provided while
   * `mFrameCaptureRequested` is `true`.
  virtual void NewFrame(already_AddRefed<layers::Image> aImage,
                        const TimeStamp& aTime) = 0;

  virtual ~FrameCaptureListener() {}

  bool mFrameCaptureRequested;

class HTMLCanvasElement final : public nsGenericHTMLElement,
                                public CanvasRenderingContextHelper
  enum {

  typedef layers::AsyncCanvasRenderer AsyncCanvasRenderer;
  typedef layers::CanvasRenderer CanvasRenderer;
  typedef layers::CanvasLayer CanvasLayer;
  typedef layers::Layer Layer;
  typedef layers::LayerManager LayerManager;
  typedef layers::WebRenderCanvasData WebRenderCanvasData;

  explicit HTMLCanvasElement(already_AddRefed<mozilla::dom::NodeInfo>&& aNodeInfo);


  // nsISupports

  // CC

  // WebIDL
  uint32_t Height()
    return GetUnsignedIntAttr(nsGkAtoms::height, DEFAULT_CANVAS_HEIGHT);
  void SetHeight(uint32_t aHeight, ErrorResult& aRv)
    if (mOffscreenCanvas) {

    SetUnsignedIntAttr(nsGkAtoms::height, aHeight, DEFAULT_CANVAS_HEIGHT, aRv);
  uint32_t Width()
    return GetUnsignedIntAttr(nsGkAtoms::width, DEFAULT_CANVAS_WIDTH);
  void SetWidth(uint32_t aWidth, ErrorResult& aRv)
    if (mOffscreenCanvas) {

    SetUnsignedIntAttr(nsGkAtoms::width, aWidth, DEFAULT_CANVAS_WIDTH, aRv);

  virtual already_AddRefed<nsISupports>
  GetContext(JSContext* aCx, const nsAString& aContextId,
             JS::Handle<JS::Value> aContextOptions,
             ErrorResult& aRv) override;

  void ToDataURL(JSContext* aCx, const nsAString& aType,
                 JS::Handle<JS::Value> aParams,
                 nsAString& aDataURL,
                 nsIPrincipal& aSubjectPrincipal,
                 ErrorResult& aRv);

  void ToBlob(JSContext* aCx,
              BlobCallback& aCallback,
              const nsAString& aType,
              JS::Handle<JS::Value> aParams,
              nsIPrincipal& aSubjectPrincipal,
              ErrorResult& aRv);

  OffscreenCanvas* TransferControlToOffscreen(ErrorResult& aRv);

  bool MozOpaque() const
    return GetBoolAttr(nsGkAtoms::moz_opaque);
  void SetMozOpaque(bool aValue, ErrorResult& aRv)
    if (mOffscreenCanvas) {

    SetHTMLBoolAttr(nsGkAtoms::moz_opaque, aValue, aRv);
  already_AddRefed<File> MozGetAsFile(const nsAString& aName,
                                      const nsAString& aType,
                                      nsIPrincipal& aSubjectPrincipal,
                                      ErrorResult& aRv);
  already_AddRefed<nsISupports> MozGetIPCContext(const nsAString& aContextId,
                                                 ErrorResult& aRv);
  PrintCallback* GetMozPrintCallback() const;
  void SetMozPrintCallback(PrintCallback* aCallback);

  CaptureStream(const Optional<double>& aFrameRate, nsIPrincipal& aSubjectPrincipal, ErrorResult& aRv);

   * Get the size in pixels of this canvas element
  nsIntSize GetSize();

   * Determine whether the canvas is write-only.
  bool IsWriteOnly();

   * Force the canvas to be write-only.
  void SetWriteOnly();

   * Notify that some canvas content has changed and the window may
   * need to be updated. aDamageRect is in canvas coordinates.
  void InvalidateCanvasContent(const mozilla::gfx::Rect* aDamageRect);
   * Notify that we need to repaint the entire canvas, including updating of
   * the layer tree.
  void InvalidateCanvas();

   * Get the number of contexts in this canvas, and request a context at
   * an index.
  int32_t CountContexts ();
  nsICanvasRenderingContextInternal *GetContextAtIndex (int32_t index);

   * Returns true if the canvas context content is guaranteed to be opaque
   * across its entire area.
  bool GetIsOpaque();
  virtual bool GetOpaqueAttr() override;

  virtual already_AddRefed<gfx::SourceSurface>
  GetSurfaceSnapshot(gfxAlphaType* aOutAlphaType = nullptr);

   * Register a FrameCaptureListener with this canvas.
   * The canvas hooks into the RefreshDriver while there are
   * FrameCaptureListeners registered.
   * The registered FrameCaptureListeners are stored as WeakPtrs, thus it's the
   * caller's responsibility to keep them alive. Once a registered
   * FrameCaptureListener is destroyed it will be automatically deregistered.
  nsresult RegisterFrameCaptureListener(FrameCaptureListener* aListener,
                                        bool aReturnPlaceholderData);

   * Returns true when there is at least one registered FrameCaptureListener
   * that has requested a frame capture.
  bool IsFrameCaptureRequested() const;

   * Processes destroyed FrameCaptureListeners and removes them if necessary.
   * Should there be none left, the FrameRefreshObserver will be unregistered.
  void ProcessDestroyedFrameListeners();

   * Called by the RefreshDriver hook when a frame has been captured.
   * Makes a copy of the provided surface and hands it to all
   * FrameCaptureListeners having requested frame capture.
  void SetFrameCapture(already_AddRefed<gfx::SourceSurface> aSurface,
                       const TimeStamp& aTime);

  virtual bool ParseAttribute(int32_t aNamespaceID,
                                nsAtom* aAttribute,
                                const nsAString& aValue,
                                nsIPrincipal* aMaybeScriptedPrincipal,
                                nsAttrValue& aResult) override;
  nsChangeHint GetAttributeChangeHint(const nsAtom* aAttribute, int32_t aModType) const override;

  virtual nsresult Clone(dom::NodeInfo*, nsINode** aResult) const override;
  nsresult CopyInnerTo(HTMLCanvasElement* aDest);

  void GetEventTargetParent(EventChainPreVisitor& aVisitor) override;

   * Helpers called by various users of Canvas

  already_AddRefed<Layer> GetCanvasLayer(nsDisplayListBuilder* aBuilder,
                                         Layer *aOldLayer,
                                         LayerManager *aManager);
  bool UpdateWebRenderCanvasData(nsDisplayListBuilder* aBuilder,
                                 WebRenderCanvasData* aCanvasData);
  bool InitializeCanvasRenderer(nsDisplayListBuilder* aBuilder,
                                CanvasRenderer* aRenderer);
  // Should return true if the canvas layer should always be marked inactive.
  // We should return true here if we can't do accelerated compositing with
  // a non-BasicCanvasLayer.
  bool ShouldForceInactiveLayer(LayerManager *aManager);

  // Call this whenever we need future changes to the canvas
  // to trigger fresh invalidation requests. This needs to be called
  // whenever we render the canvas contents to the screen, or whenever we
  // take a snapshot of the canvas that needs to be "live" (e.g. -moz-element).
  void MarkContextClean();

  // Call this after capturing a frame, so we can avoid unnecessary surface
  // copies for future frames when no drawing has occurred.
  void MarkContextCleanForFrameCapture();

  // Starts returning false when something is drawn.
  bool IsContextCleanForFrameCapture();

  nsresult GetContext(const nsAString& aContextId, nsISupports** aContext);

  layers::LayersBackend GetCompositorBackendType() const;

  void OnVisibilityChange();

  void OnMemoryPressure();

  static void SetAttrFromAsyncCanvasRenderer(AsyncCanvasRenderer *aRenderer);
  static void InvalidateFromAsyncCanvasRenderer(AsyncCanvasRenderer *aRenderer);

  already_AddRefed<layers::SharedSurfaceTextureClient> GetVRFrame();

  virtual ~HTMLCanvasElement();

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

  virtual nsIntSize GetWidthHeight() override;

  virtual already_AddRefed<nsICanvasRenderingContextInternal>
  CreateContext(CanvasContextType aContextType) override;

  nsresult ExtractData(JSContext* aCx,
                       nsIPrincipal& aSubjectPrincipal,
                       nsAString& aType,
                       const nsAString& aOptions,
                       nsIInputStream** aStream);
  nsresult ToDataURLImpl(JSContext* aCx,
                         nsIPrincipal& aSubjectPrincipal,
                         const nsAString& aMimeType,
                         const JS::Value& aEncoderOptions,
                         nsAString& aDataURL);
  nsresult MozGetAsFileImpl(const nsAString& aName,
                            const nsAString& aType,
                            nsIPrincipal& aSubjectPrincipal,
                            File** aResult);
  void CallPrintCallback();

  virtual nsresult AfterSetAttr(int32_t aNamespaceID, nsAtom* aName,
                                const nsAttrValue* aValue,
                                const nsAttrValue* aOldValue,
                                nsIPrincipal* aSubjectPrincipal,
                                bool aNotify) override;
  virtual nsresult OnAttrSetButNotChanged(int32_t aNamespaceID, nsAtom* aName,
                                          const nsAttrValueOrString& aValue,
                                          bool aNotify) override;

  AsyncCanvasRenderer* GetAsyncCanvasRenderer();

  bool mResetLayer;
  RefPtr<HTMLCanvasElement> mOriginalCanvas;
  RefPtr<PrintCallback> mPrintCallback;
  RefPtr<HTMLCanvasPrintState> mPrintState;
  nsTArray<WeakPtr<FrameCaptureListener>> mRequestedFrameListeners;
  RefPtr<RequestedFrameRefreshObserver> mRequestedFrameRefreshObserver;
  RefPtr<AsyncCanvasRenderer> mAsyncCanvasRenderer;
  RefPtr<OffscreenCanvas> mOffscreenCanvas;
  RefPtr<HTMLCanvasElementObserver> mContextObserver;

  // Record whether this canvas should be write-only or not.
  // We set this when script paints an image from a different origin.
  // We also transitively set it when script paints a canvas which
  // is itself write-only.
  bool                     mWriteOnly;

  bool IsPrintCallbackDone();

  void HandlePrintCallback(nsPresContext::nsPresContextType aType);

  nsresult DispatchPrintCallback(nsITimerCallback* aCallback);

  void ResetPrintCallback();

  HTMLCanvasElement* GetOriginalCanvas();

  CanvasContextType GetCurrentContextType() {
    return mCurrentContextType;

   * This function is called by AfterSetAttr and OnAttrSetButNotChanged.
   * This function will be called by AfterSetAttr whether the attribute is being
   * set or unset.
   * @param aNamespaceID the namespace of the attr being set
   * @param aName the localname of the attribute being set
   * @param aNotify Whether we plan to notify document observers.
  void AfterMaybeChangeAttr(int32_t aNamespaceID, nsAtom* aName, bool aNotify);

class HTMLCanvasPrintState final : public nsWrapperCache
  HTMLCanvasPrintState(HTMLCanvasElement* aCanvas,
                       nsICanvasRenderingContextInternal* aContext,
                       nsITimerCallback* aCallback);

  nsISupports* Context() const;

  void Done();

  void NotifyDone();

  bool mIsDone;


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

  HTMLCanvasElement* GetParentObject()
    return mCanvas;

  bool mPendingNotify;

  RefPtr<HTMLCanvasElement> mCanvas;
  nsCOMPtr<nsICanvasRenderingContextInternal> mContext;
  nsCOMPtr<nsITimerCallback> mCallback;

} // namespace dom
} // namespace mozilla

#endif /* mozilla_dom_HTMLCanvasElement_h */