author Emilio Cobos Álvarez <>
Mon, 18 Mar 2019 15:15:13 +0000
changeset 523637 94682e23ba118dcfab3843a3280618b2e1686ecb
parent 521758 a4d1dd58552d02854ce438e11dc4c97ec885f166
child 524823 f5dd833c3b60b3365d2c49d930748e33a22651b6
permissions -rw-r--r--
Bug 1472637 - Don't display alt text while loading, to match other UAs. r=tnikkel Differential Revision:

/* -*- 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 */

/* rendering object for replaced elements with image data */

#ifndef nsImageFrame_h___
#define nsImageFrame_h___

#include "nsAtomicContainerFrame.h"
#include "nsIIOService.h"
#include "nsIObserver.h"

#include "imgINotificationObserver.h"

#include "nsDisplayList.h"
#include "imgIContainer.h"
#include "mozilla/Attributes.h"
#include "mozilla/DebugOnly.h"
#include "mozilla/StaticPtr.h"
#include "nsIReflowCallback.h"
#include "nsTObserverArray.h"

class nsFontMetrics;
class nsImageMap;
class nsIURI;
class nsILoadGroup;
class nsDisplayImage;
class nsPresContext;
class nsImageFrame;
class nsTransform2D;
class nsImageLoadingContent;

namespace mozilla {
class PresShell;
namespace layers {
class ImageContainer;
class ImageLayer;
class LayerManager;
}  // namespace layers
}  // namespace mozilla

class nsImageListener final : public imgINotificationObserver {
  virtual ~nsImageListener();

  explicit nsImageListener(nsImageFrame* aFrame);


  void SetFrame(nsImageFrame* frame) { mFrame = frame; }

  nsImageFrame* mFrame;

class nsImageFrame : public nsAtomicContainerFrame, public nsIReflowCallback {
  template <typename T>
  using Maybe = mozilla::Maybe<T>;
  using Nothing = mozilla::Nothing;
  using Visibility = mozilla::Visibility;

  typedef mozilla::image::ImgDrawResult ImgDrawResult;
  typedef mozilla::layers::ImageContainer ImageContainer;
  typedef mozilla::layers::ImageLayer ImageLayer;
  typedef mozilla::layers::LayerManager LayerManager;


  virtual void DestroyFrom(nsIFrame* aDestructRoot,
                           PostDestroyData& aPostDestroyData) override;
  virtual void DidSetComputedStyle(ComputedStyle* aOldComputedStyle) override;

  virtual void Init(nsIContent* aContent, nsContainerFrame* aParent,
                    nsIFrame* aPrevInFlow) override;
  virtual void BuildDisplayList(nsDisplayListBuilder* aBuilder,
                                const nsDisplayListSet& aLists) override;
  virtual nscoord GetMinISize(gfxContext* aRenderingContext) override;
  virtual nscoord GetPrefISize(gfxContext* aRenderingContext) override;
  virtual mozilla::IntrinsicSize GetIntrinsicSize() override;
  virtual nsSize GetIntrinsicRatio() override;
  virtual void Reflow(nsPresContext* aPresContext, ReflowOutput& aDesiredSize,
                      const ReflowInput& aReflowInput,
                      nsReflowStatus& aStatus) override;

  virtual nsresult GetContentForEvent(mozilla::WidgetEvent* aEvent,
                                      nsIContent** aContent) override;
  virtual nsresult HandleEvent(nsPresContext* aPresContext,
                               mozilla::WidgetGUIEvent* aEvent,
                               nsEventStatus* aEventStatus) override;
  mozilla::Maybe<Cursor> GetCursor(const nsPoint&) override;
  virtual nsresult AttributeChanged(int32_t aNameSpaceID, nsAtom* aAttribute,
                                    int32_t aModType) override;

  void OnVisibilityChange(
      Visibility aNewVisibility,
      const Maybe<OnNonvisible>& aNonvisibleAction = Nothing()) override;

  void ResponsiveContentDensityChanged();
  void SetupForContentURLRequest();
  bool ShouldShowBrokenImageIcon() const;

  virtual mozilla::a11y::AccType AccessibleType() override;

  virtual bool IsFrameOfType(uint32_t aFlags) const override {
    return nsAtomicContainerFrame::IsFrameOfType(
        aFlags & ~(nsIFrame::eReplaced | nsIFrame::eReplacedSizing));

  virtual nsresult GetFrameName(nsAString& aResult) const override;
  void List(FILE* out = stderr, const char* aPrefix = "",
            uint32_t aFlags = 0) const override;

  virtual LogicalSides GetLogicalSkipSides(
      const ReflowInput* aReflowInput = nullptr) const override;

  nsresult GetIntrinsicImageSize(nsSize& aSize);

  static void ReleaseGlobals() {
    if (gIconLoad) {
      gIconLoad = nullptr;

  already_AddRefed<imgIRequest> GetCurrentRequest() const;
  nsresult Notify(imgIRequest* aRequest, int32_t aType, const nsIntRect* aData);

   * Function to test whether aContent, which has aComputedStyle as its style,
   * should get an image frame.  Note that this method is only used by the
   * frame constructor; it's only here because it uses gIconLoad for now.
  static bool ShouldCreateImageFrameFor(const mozilla::dom::Element& aElement,
                                        ComputedStyle& aStyle);

  ImgDrawResult DisplayAltFeedback(gfxContext& aRenderingContext,
                                   const nsRect& aDirtyRect, nsPoint aPt,
                                   uint32_t aFlags);

  ImgDrawResult DisplayAltFeedbackWithoutLayer(
      nsDisplayItem* aItem, mozilla::wr::DisplayListBuilder& aBuilder,
      mozilla::wr::IpcResourceUpdateQueue& aResources,
      const mozilla::layers::StackingContextHelper& aSc,
      mozilla::layers::RenderRootStateManager* aManager,
      nsDisplayListBuilder* aDisplayListBuilder, nsPoint aPt, uint32_t aFlags);

  nsRect GetInnerArea() const;

   * Return a map element associated with this image.
  mozilla::dom::Element* GetMapElement() const;

   * Return true if the image has associated image map.
  bool HasImageMap() const { return mImageMap || GetMapElement(); }

  nsImageMap* GetImageMap();
  nsImageMap* GetExistingImageMap() const { return mImageMap; }

  virtual void AddInlineMinISize(gfxContext* aRenderingContext,
                                 InlineMinISizeData* aData) override;

  void DisconnectMap();

  // nsIReflowCallback
  virtual bool ReflowFinished() override;
  virtual void ReflowCallbackCanceled() override;

  // The kind of image frame we are.
  enum class Kind : uint8_t {
    // For an nsImageLoadingContent.
    // For css 'content: url(..)' on non-generated content.
    // For a child of a ::before / ::after pseudo-element that had an url() item
    // for the content property.

  // Creates a suitable continuing frame for this frame.
  nsImageFrame* CreateContinuingFrame(nsIPresShell*, ComputedStyle*) const;

  friend nsIFrame* NS_NewImageFrame(nsIPresShell*, ComputedStyle*);
  friend nsIFrame* NS_NewImageFrameForContentProperty(nsIPresShell*,
  friend nsIFrame* NS_NewImageFrameForGeneratedContentIndex(nsIPresShell*,

  nsImageFrame(ComputedStyle* aStyle, nsPresContext* aPresContext, Kind aKind)
      : nsImageFrame(aStyle, aPresContext, kClassID, aKind) {}

  nsImageFrame(ComputedStyle*, nsPresContext* aPresContext, ClassID, Kind);

  nsImageFrame(ComputedStyle* aStyle, nsPresContext* aPresContext, ClassID aID)
      : nsImageFrame(aStyle, aPresContext, aID, Kind::ImageElement) {}

  virtual ~nsImageFrame();

  void EnsureIntrinsicSizeAndRatio();

  bool GotInitialReflow() const {
    return !HasAnyStateBits(NS_FRAME_FIRST_REFLOW);

  virtual mozilla::LogicalSize ComputeSize(
      gfxContext* aRenderingContext, mozilla::WritingMode aWritingMode,
      const mozilla::LogicalSize& aCBSize, nscoord aAvailableISize,
      const mozilla::LogicalSize& aMargin, const mozilla::LogicalSize& aBorder,
      const mozilla::LogicalSize& aPadding, ComputeSizeFlags aFlags) override;

  bool IsServerImageMap();

  void TranslateEventCoords(const nsPoint& aPoint, nsIntPoint& aResult);

  bool GetAnchorHREFTargetAndNode(nsIURI** aHref, nsString& aTarget,
                                  nsIContent** aNode);
   * Computes the width of the string that fits into the available space
   * @param in aLength total length of the string in PRUnichars
   * @param in aMaxWidth width not to be exceeded
   * @param out aMaxFit length of the string that fits within aMaxWidth
   *            in PRUnichars
   * @return width of the string that fits within aMaxWidth
  nscoord MeasureString(const char16_t* aString, int32_t aLength,
                        nscoord aMaxWidth, uint32_t& aMaxFit,
                        gfxContext& aContext, nsFontMetrics& aFontMetrics);

  void DisplayAltText(nsPresContext* aPresContext,
                      gfxContext& aRenderingContext, const nsString& aAltText,
                      const nsRect& aRect);

  ImgDrawResult PaintImage(gfxContext& aRenderingContext, nsPoint aPt,
                           const nsRect& aDirtyRect, imgIContainer* aImage,
                           uint32_t aFlags);

   * If we're ready to decode - that is, if our current request's image is
   * available and our decoding heuristics are satisfied - then trigger a decode
   * for our image at the size we predict it will be drawn next time it's
   * painted.
  void MaybeDecodeForPredictedSize();

  friend class nsImageListener;
  friend class nsImageLoadingContent;
  friend class mozilla::PresShell;

  nsresult OnSizeAvailable(imgIRequest* aRequest, imgIContainer* aImage);
  nsresult OnFrameUpdate(imgIRequest* aRequest, const nsIntRect* aRect);
  nsresult OnLoadComplete(imgIRequest* aRequest, nsresult aStatus);

   * Notification that aRequest will now be the current request.
  void NotifyNewCurrentRequest(imgIRequest* aRequest, nsresult aStatus);

  /// Always sync decode our image when painting if @aForce is true.
  void SetForceSyncDecoding(bool aForce) { mForceSyncDecoding = aForce; }

   * Computes the predicted dest rect that we'll draw into, in app units, based
   * upon the provided frame content box. (The content box is what
   * nsDisplayImage::GetBounds() returns.)
   * The result is not necessarily contained in the frame content box.
  nsRect PredictedDestRect(const nsRect& aFrameContentBox);

  // random helpers
  inline void SpecToURI(const nsAString& aSpec, nsIIOService* aIOService,
                        nsIURI** aURI);

  inline void GetLoadGroup(nsPresContext* aPresContext,
                           nsILoadGroup** aLoadGroup);
  nscoord GetContinuationOffset() const;
  void GetDocumentCharacterSet(nsACString& aCharset) const;
  bool ShouldDisplaySelection();

   * Recalculate mIntrinsicSize from the image.
   * @return whether aImage's size did _not_
   *         match our previous intrinsic size.
  bool UpdateIntrinsicSize(imgIContainer* aImage);

   * Recalculate mIntrinsicRatio from the image.
   * @return whether aImage's ratio did _not_
   *         match our previous intrinsic ratio.
  bool UpdateIntrinsicRatio(imgIContainer* aImage);

   * This function calculates the transform for converting between
   * source space & destination space. May fail if our image has a
   * percent-valued or zero-valued height or width.
   * @param aTransform The transform object to populate.
   * @return whether we succeeded in creating the transform.
  bool GetSourceToDestTransform(nsTransform2D& aTransform);

   * Helper function to check whether the request corresponds to a load we don't
   * care about.  Most of the decoder observer methods will bail early if this
   * returns true.
  bool IsPendingLoad(imgIRequest* aRequest) const;

   * Function to convert a dirty rect in the source image to a dirty
   * rect for the image frame.
  nsRect SourceRectToDest(const nsIntRect& aRect);

   * Triggers invalidation for both our image display item and, if appropriate,
   * our alt-feedback display item.
   * @param aLayerInvalidRect The area to invalidate in layer space. If null,
   * the entire layer will be invalidated.
   * @param aFrameInvalidRect The area to invalidate in frame space. If null,
   * the entire frame will be invalidated.
  void InvalidateSelf(const nsIntRect* aLayerInvalidRect,
                      const nsRect* aFrameInvalidRect);

  RefPtr<nsImageMap> mImageMap;

  RefPtr<nsImageListener> mListener;

  // An image request created for content: url(..).
  RefPtr<imgRequestProxy> mContentURLRequest;

  nsCOMPtr<imgIContainer> mImage;
  nsCOMPtr<imgIContainer> mPrevImage;
  nsSize mComputedSize;
  mozilla::IntrinsicSize mIntrinsicSize;
  nsSize mIntrinsicRatio;

  const Kind mKind;
  bool mContentURLRequestRegistered;
  bool mDisplayingIcon;
  bool mFirstFrameComplete;
  bool mReflowCallbackPosted;
  bool mForceSyncDecoding;

  static nsIIOService* sIOService;

  /* loading / broken image icon support */

  // XXXbz this should be handled by the prescontext, I think; that
  // way we would have a single iconload per mozilla session instead
  // of one per document...

  // LoadIcons: initiate the loading of the static icons used to show
  // loading / broken images
  nsresult LoadIcons(nsPresContext* aPresContext);
  nsresult LoadIcon(const nsAString& aSpec, nsPresContext* aPresContext,
                    imgRequestProxy** aRequest);

  class IconLoad final : public nsIObserver, public imgINotificationObserver {
    // private class that wraps the data and logic needed for
    // broken image and loading image icons

    void Shutdown();


    void AddIconObserver(nsImageFrame* frame) {
                 "Observer shouldn't aleady be in array");

    void RemoveIconObserver(nsImageFrame* frame) {
      mozilla::DebugOnly<bool> didRemove = mIconObservers.RemoveElement(frame);
      MOZ_ASSERT(didRemove, "Observer not in array");

    ~IconLoad() {}

    void GetPrefs();
    nsTObserverArray<nsImageFrame*> mIconObservers;

    RefPtr<imgRequestProxy> mLoadingImage;
    RefPtr<imgRequestProxy> mBrokenImage;
    bool mPrefForceInlineAltText;
    bool mPrefShowPlaceholders;
    bool mPrefShowLoadingPlaceholder;

  // singleton pattern: one LoadIcons instance is used
  static mozilla::StaticRefPtr<IconLoad> gIconLoad;

  friend class nsDisplayImage;

 * Note that nsDisplayImage does not receive events. However, an image element
 * is replaced content so its background will be z-adjacent to the
 * image itself, and hence receive events just as if the image itself
 * received events.
class nsDisplayImage final : public nsDisplayImageContainer {
  typedef mozilla::layers::LayerManager LayerManager;

  nsDisplayImage(nsDisplayListBuilder* aBuilder, nsImageFrame* aFrame,
                 imgIContainer* aImage, imgIContainer* aPrevImage)
      : nsDisplayImageContainer(aBuilder, aFrame),
        mPrevImage(aPrevImage) {
  virtual ~nsDisplayImage() { MOZ_COUNT_DTOR(nsDisplayImage); }

  virtual nsDisplayItemGeometry* AllocateGeometry(
      nsDisplayListBuilder* aBuilder) override;
  virtual void ComputeInvalidationRegion(
      nsDisplayListBuilder* aBuilder, const nsDisplayItemGeometry* aGeometry,
      nsRegion* aInvalidRegion) const override;
  virtual void Paint(nsDisplayListBuilder* aBuilder, gfxContext* aCtx) override;

  virtual already_AddRefed<imgIContainer> GetImage() override;

   * @return The dest rect we'll use when drawing this image, in app units.
   *         Not necessarily contained in this item's bounds.
  virtual nsRect GetDestRect() const override;

  virtual void UpdateDrawResult(
      mozilla::image::ImgDrawResult aResult) override {
    nsDisplayItemGenericImageGeometry::UpdateDrawResult(this, aResult);

  virtual LayerState GetLayerState(
      nsDisplayListBuilder* aBuilder, LayerManager* aManager,
      const ContainerLayerParameters& aParameters) override;
  nsRect GetBounds(bool* aSnap) const {
    *aSnap = true;

    nsImageFrame* imageFrame = static_cast<nsImageFrame*>(mFrame);
    return imageFrame->GetInnerArea() + ToReferenceFrame();

  virtual nsRect GetBounds(nsDisplayListBuilder* aBuilder,
                           bool* aSnap) const override {
    return GetBounds(aSnap);

  virtual nsRegion GetOpaqueRegion(nsDisplayListBuilder* aBuilder,
                                   bool* aSnap) const override;

  virtual already_AddRefed<Layer> BuildLayer(
      nsDisplayListBuilder* aBuilder, LayerManager* aManager,
      const ContainerLayerParameters& aContainerParameters) override;
  virtual bool CreateWebRenderCommands(
      mozilla::wr::DisplayListBuilder& aBuilder,
      mozilla::wr::IpcResourceUpdateQueue& aResources,
      const StackingContextHelper& aSc,
      mozilla::layers::RenderRootStateManager* aManager,
      nsDisplayListBuilder* aDisplayListBuilder) override;

  nsCOMPtr<imgIContainer> mImage;
  nsCOMPtr<imgIContainer> mPrevImage;

#endif /* nsImageFrame_h___ */