Source code

Revision control

Copy as Markdown

Other Tools

/* -*- 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 */
#ifndef mozilla_dom_HTMLImageElement_h
#define mozilla_dom_HTMLImageElement_h
#include "mozilla/Attributes.h"
#include "nsGenericHTMLElement.h"
#include "nsImageLoadingContent.h"
#include "Units.h"
#include "nsCycleCollectionParticipant.h"
namespace mozilla {
class EventChainPreVisitor;
namespace dom {
class ImageLoadTask;
class ResponsiveImageSelector;
class HTMLImageElement final : public nsGenericHTMLElement,
public nsImageLoadingContent {
friend class HTMLSourceElement;
friend class HTMLPictureElement;
friend class ImageLoadTask;
explicit HTMLImageElement(
already_AddRefed<mozilla::dom::NodeInfo>&& aNodeInfo);
static already_AddRefed<HTMLImageElement> Image(
const GlobalObject& aGlobal, const Optional<uint32_t>& aWidth,
const Optional<uint32_t>& aHeight, ErrorResult& aError);
// nsISupports
bool Draggable() const override;
ResponsiveImageSelector* GetResponsiveImageSelector() {
return mResponsiveSelector.get();
// Element
bool IsInteractiveHTMLContent() const override;
// EventTarget
void AsyncEventRunning(AsyncEventDispatcher* aEvent) override;
// override from nsImageLoadingContent
CORSMode GetCORSMode() override;
// nsIContent
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;
NS_IMETHOD_(bool) IsAttributeMapped(const nsAtom* aAttribute) const override;
nsMapRuleToAttributesFunc GetAttributeMappingFunction() const override;
void GetEventTargetParent(EventChainPreVisitor& aVisitor) override;
nsINode* GetScopeChainParent() const override;
bool IsHTMLFocusable(bool aWithMouse, bool* aIsFocusable,
int32_t* aTabIndex) override;
nsresult BindToTree(BindContext&, nsINode& aParent) override;
void UnbindFromTree(UnbindContext&) override;
nsresult Clone(dom::NodeInfo*, nsINode** aResult) const override;
void NodeInfoChanged(Document* aOldDoc) override;
nsresult CopyInnerTo(HTMLImageElement* aDest);
void MaybeLoadImage(bool aAlwaysForceLoad);
bool IsMap() { return GetBoolAttr(nsGkAtoms::ismap); }
void SetIsMap(bool aIsMap, ErrorResult& aError) {
SetHTMLBoolAttr(nsGkAtoms::ismap, aIsMap, aError);
MOZ_CAN_RUN_SCRIPT uint32_t Width();
void SetWidth(uint32_t aWidth, ErrorResult& aError) {
SetUnsignedIntAttr(nsGkAtoms::width, aWidth, 0, aError);
MOZ_CAN_RUN_SCRIPT uint32_t Height();
void SetHeight(uint32_t aHeight, ErrorResult& aError) {
SetUnsignedIntAttr(nsGkAtoms::height, aHeight, 0, aError);
nsIntSize NaturalSize();
uint32_t NaturalHeight() { return NaturalSize().height; }
uint32_t NaturalWidth() { return NaturalSize().width; }
bool Complete();
uint32_t Hspace() {
return GetDimensionAttrAsUnsignedInt(nsGkAtoms::hspace, 0);
void SetHspace(uint32_t aHspace, ErrorResult& aError) {
SetUnsignedIntAttr(nsGkAtoms::hspace, aHspace, 0, aError);
uint32_t Vspace() {
return GetDimensionAttrAsUnsignedInt(nsGkAtoms::vspace, 0);
void SetVspace(uint32_t aVspace, ErrorResult& aError) {
SetUnsignedIntAttr(nsGkAtoms::vspace, aVspace, 0, aError);
void GetAlt(nsAString& aAlt) { GetHTMLAttr(nsGkAtoms::alt, aAlt); }
void SetAlt(const nsAString& aAlt, ErrorResult& aError) {
SetHTMLAttr(nsGkAtoms::alt, aAlt, aError);
void GetSrc(nsAString& aSrc) { GetURIAttr(nsGkAtoms::src, nullptr, aSrc); }
void SetSrc(const nsAString& aSrc, ErrorResult& aError) {
SetHTMLAttr(nsGkAtoms::src, aSrc, aError);
void SetSrc(const nsAString& aSrc, nsIPrincipal* aTriggeringPrincipal,
ErrorResult& aError) {
SetHTMLAttr(nsGkAtoms::src, aSrc, aTriggeringPrincipal, aError);
void GetSrcset(nsAString& aSrcset) {
GetHTMLAttr(nsGkAtoms::srcset, aSrcset);
void SetSrcset(const nsAString& aSrcset, nsIPrincipal* aTriggeringPrincipal,
ErrorResult& aError) {
SetHTMLAttr(nsGkAtoms::srcset, aSrcset, aTriggeringPrincipal, aError);
void GetCrossOrigin(nsAString& aResult) {
// Null for both missing and invalid defaults is ok, since we
// always parse to an enum value, so we don't need an invalid
// default, and we _want_ the missing default to be null.
GetEnumAttr(nsGkAtoms::crossorigin, nullptr, aResult);
void SetCrossOrigin(const nsAString& aCrossOrigin, ErrorResult& aError) {
SetOrRemoveNullableStringAttr(nsGkAtoms::crossorigin, aCrossOrigin, aError);
void GetUseMap(nsAString& aUseMap) {
GetHTMLAttr(nsGkAtoms::usemap, aUseMap);
void SetUseMap(const nsAString& aUseMap, ErrorResult& aError) {
SetHTMLAttr(nsGkAtoms::usemap, aUseMap, aError);
void GetName(nsAString& aName) { GetHTMLAttr(nsGkAtoms::name, aName); }
void SetName(const nsAString& aName, ErrorResult& aError) {
SetHTMLAttr(nsGkAtoms::name, aName, aError);
void GetAlign(nsAString& aAlign) { GetHTMLAttr(nsGkAtoms::align, aAlign); }
void SetAlign(const nsAString& aAlign, ErrorResult& aError) {
SetHTMLAttr(nsGkAtoms::align, aAlign, aError);
void GetLongDesc(nsAString& aLongDesc) {
GetURIAttr(nsGkAtoms::longdesc, nullptr, aLongDesc);
void SetLongDesc(const nsAString& aLongDesc, ErrorResult& aError) {
SetHTMLAttr(nsGkAtoms::longdesc, aLongDesc, aError);
void GetSizes(nsAString& aSizes) { GetHTMLAttr(nsGkAtoms::sizes, aSizes); }
void SetSizes(const nsAString& aSizes, ErrorResult& aError) {
SetHTMLAttr(nsGkAtoms::sizes, aSizes, aError);
void GetCurrentSrc(nsAString& aValue);
void GetBorder(nsAString& aBorder) {
GetHTMLAttr(nsGkAtoms::border, aBorder);
void SetBorder(const nsAString& aBorder, ErrorResult& aError) {
SetHTMLAttr(nsGkAtoms::border, aBorder, aError);
void SetReferrerPolicy(const nsAString& aReferrer, ErrorResult& aError) {
SetHTMLAttr(nsGkAtoms::referrerpolicy, aReferrer, aError);
void GetReferrerPolicy(nsAString& aReferrer) {
GetEnumAttr(nsGkAtoms::referrerpolicy, "", aReferrer);
void SetDecoding(const nsAString& aDecoding, ErrorResult& aError) {
SetHTMLAttr(nsGkAtoms::decoding, aDecoding, aError);
void GetDecoding(nsAString& aValue);
void SetLoading(const nsAString& aLoading, ErrorResult& aError) {
SetHTMLAttr(nsGkAtoms::loading, aLoading, aError);
bool IsAwaitingLoadOrLazyLoading() const {
return mLazyLoading || mPendingImageLoadTask;
bool IsLazyLoading() const { return mLazyLoading; }
already_AddRefed<Promise> Decode(ErrorResult& aRv);
void GetLowsrc(nsAString& aLowsrc) {
GetURIAttr(nsGkAtoms::lowsrc, nullptr, aLowsrc);
void SetLowsrc(const nsAString& aLowsrc, ErrorResult& aError) {
SetHTMLAttr(nsGkAtoms::lowsrc, aLowsrc, aError);
#ifdef DEBUG
HTMLFormElement* GetForm() const;
void SetForm(HTMLFormElement* aForm);
void ClearForm(bool aRemoveFromForm);
void DestroyContent() override;
void MediaFeatureValuesChanged();
* Given a hypothetical <img> or <source> tag with the given parameters,
* return what URI we would attempt to use, if any. Used by the preloader to
* resolve sources prior to DOM creation.
* @param aDocument The document this image would be for, for referencing
* viewport width and DPI/zoom
* @param aIsSourceTag If these parameters are for a <source> tag (as in a
* <picture>) rather than an <img> tag. Note that some attrs are unused
* when this is true an vice versa
* @param aSrcAttr [ignored if aIsSourceTag] The src attr for this image.
* @param aSrcsetAttr The srcset attr for this image/source
* @param aSizesAttr The sizes attr for this image/source
* @param aTypeAttr [ignored if !aIsSourceTag] The type attr for this source.
* Should be a void string to differentiate no type attribute
* from an empty one.
* @param aMediaAttr [ignored if !aIsSourceTag] The media attr for this
* source. Should be a void string to differentiate no
* media attribute from an empty one.
* @param aResult A reference to store the resulting URL spec in if we
* selected a source. This value is not guaranteed to parse to
* a valid URL, merely the URL that the tag would attempt to
* resolve and load (which may be the empty string). This
* parameter is not modified if return value is false.
* @return True if we were able to select a final source, false if further
* sources would be considered. It follows that this always returns
* true if !aIsSourceTag.
* Note that the return value may be true with an empty string as the result,
* which implies that the parameters provided describe a tag that would select
* no source. This is distinct from a return of false which implies that
* further <source> or <img> tags would be considered.
static bool SelectSourceForTagWithAttrs(
Document* aDocument, bool aIsSourceTag, const nsAString& aSrcAttr,
const nsAString& aSrcsetAttr, const nsAString& aSizesAttr,
const nsAString& aTypeAttr, const nsAString& aMediaAttr,
nsAString& aResult);
enum class FromIntersectionObserver : bool { No, Yes };
enum class StartLoading : bool { No, Yes };
void StopLazyLoading(StartLoading);
// This is used when restyling, for retrieving the extra style from the source
// element.
const StyleLockedDeclarationBlock* GetMappedAttributesFromSource() const;
FetchPriority GetFetchPriorityForImage() const override;
virtual ~HTMLImageElement();
// Update the responsive source synchronously and queues a task to run
// LoadSelectedImage pending stable state.
// Pending Bug 1076583 this is only used by the responsive image
// algorithm (InResponsiveMode()) -- synchronous actions when just
// using img.src will bypass this, and update source and kick off
// image load synchronously.
void UpdateSourceSyncAndQueueImageTask(
bool aAlwaysLoad, const HTMLSourceElement* aSkippedSource = nullptr);
// True if we have a srcset attribute or a <picture> parent, regardless of if
// any valid responsive sources were parsed from either.
bool HaveSrcsetOrInPicture();
// True if we are using the newer image loading algorithm. This will be the
// only mode after Bug 1076583
bool InResponsiveMode();
// True if the given URL equals the last URL that was loaded by this element.
bool SelectedSourceMatchesLast(nsIURI* aSelectedSource);
// Load the current mResponsiveSelector (responsive mode) or src attr image.
// Note: This doesn't run the full selection for the responsive selector.
nsresult LoadSelectedImage(bool aForce, bool aNotify, bool aAlwaysLoad);
// True if this string represents a type we would support on <source type>
static bool SupportedPictureSourceType(const nsAString& aType);
// Update/create/destroy mResponsiveSelector
void PictureSourceSrcsetChanged(nsIContent* aSourceNode,
const nsAString& aNewValue, bool aNotify);
void PictureSourceSizesChanged(nsIContent* aSourceNode,
const nsAString& aNewValue, bool aNotify);
// As we re-run the source selection on these mutations regardless,
// we don't actually care which changed or to what
void PictureSourceMediaOrTypeChanged(nsIContent* aSourceNode, bool aNotify);
// This is called when we update "width" or "height" attribute of source
// element.
void PictureSourceDimensionChanged(HTMLSourceElement* aSourceNode,
bool aNotify);
void PictureSourceAdded(HTMLSourceElement* aSourceNode = nullptr);
// This should be called prior to the unbind, such that nextsibling works
void PictureSourceRemoved(HTMLSourceElement* aSourceNode = nullptr);
// Re-evaluates all source nodes (picture <source>,<img>) and finds
// the best source set for mResponsiveSelector. If a better source
// is found, creates a new selector and feeds the source to it. If
// the current ResponsiveSelector is not changed, runs
// SelectImage(true) to re-evaluate its candidates.
// Because keeping the existing selector is the common case (and we
// often do no-op reselections), this does not re-parse values for
// the existing mResponsiveSelector, meaning you need to update its
// parameters as appropriate before calling (or null it out to force
// recreation)
// if |aSkippedSource| is non-null, we will skip it when running the
// algorithm. This is used when we need to update the source when we are
// removing the source element.
// Returns true if the source has changed, and false otherwise.
bool UpdateResponsiveSource(
const HTMLSourceElement* aSkippedSource = nullptr);
// Given a <source> node that is a previous sibling *or* ourselves, try to
// create a ResponsiveSelector.
// If the node's srcset/sizes make for an invalid selector, returns
// nullptr. This does not guarantee the resulting selector matches an image,
// only that it is valid.
already_AddRefed<ResponsiveImageSelector> TryCreateResponsiveSelector(
Element* aSourceElement);
JSObject* WrapNode(JSContext*, JS::Handle<JSObject*> aGivenProto) override;
void UpdateFormOwner();
void BeforeSetAttr(int32_t aNameSpaceID, nsAtom* aName,
const nsAttrValue* aValue, bool aNotify) override;
void AfterSetAttr(int32_t aNameSpaceID, nsAtom* aName,
const nsAttrValue* aValue, const nsAttrValue* aOldValue,
nsIPrincipal* aMaybeScriptedPrincipal,
bool aNotify) override;
void OnAttrSetButNotChanged(int32_t aNamespaceID, nsAtom* aName,
const nsAttrValueOrString& aValue,
bool aNotify) override;
// Override for nsImageLoadingContent.
nsIContent* AsContent() override { return this; }
// Created when we're tracking responsive image state
RefPtr<ResponsiveImageSelector> mResponsiveSelector;
// This is a weak reference that this element and the HTMLFormElement
// cooperate in maintaining.
HTMLFormElement* mForm = nullptr;
bool SourceElementMatches(Element* aSourceElement);
static void MapAttributesIntoRule(MappedDeclarationsBuilder&);
* This function is called by AfterSetAttr and OnAttrSetButNotChanged.
* It will not be called if the value is being unset.
* @param aNamespaceID the namespace of the attr being set
* @param aName the localname of the attribute being set
* @param aValue the value it's being set to represented as either a string or
* a parsed nsAttrValue.
* @param aOldValue the value previously set. Will be null if no value was
* previously set. This value should only be used when
* aValueMaybeChanged is true; when aValueMaybeChanged is false,
* aOldValue should be considered unreliable.
* @param aNotify Whether we plan to notify document observers.
void AfterMaybeChangeAttr(int32_t aNamespaceID, nsAtom* aName,
const nsAttrValueOrString& aValue,
const nsAttrValue* aOldValue,
nsIPrincipal* aMaybeScriptedPrincipal,
bool aNotify);
bool ShouldLoadImage() const;
// Set this image as a lazy load image due to loading="lazy".
void SetLazyLoading();
void StartLoadingIfNeeded();
bool IsInPicture() const {
return GetParentElement() &&
void InvalidateAttributeMapping();
void SetResponsiveSelector(RefPtr<ResponsiveImageSelector>&& aSource);
void SetDensity(double aDensity);
// Queue an image load task (via microtask).
void QueueImageLoadTask(bool aAlwaysLoad);
RefPtr<ImageLoadTask> mPendingImageLoadTask;
nsCOMPtr<nsIURI> mSrcURI;
nsCOMPtr<nsIPrincipal> mSrcTriggeringPrincipal;
nsCOMPtr<nsIPrincipal> mSrcsetTriggeringPrincipal;
// Last URL that was attempted to load by this element.
nsCOMPtr<nsIURI> mLastSelectedSource;
// Last pixel density that was selected.
double mCurrentDensity = 1.0;
bool mInDocResponsiveContent = false;
} // namespace dom
} // namespace mozilla
#endif /* mozilla_dom_HTMLImageElement_h */