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fune/dom/html/HTMLImageElement.cpp
Sean Feng 71ce0cfc2a Bug 1687358 - Implement telemetry probes to determine the best possible threshold for <lazyload> r=emilio 
This patch implements five telemetry probes to help us learn how
lazyload thresholds perform in the wild.

Differential Revision: https://phabricator.services.mozilla.com/D102845
2021-01-29 17:03:25 +00:00

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/* -*- 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 http://mozilla.org/MPL/2.0/. */
#include "mozilla/dom/HTMLImageElement.h"
#include "mozilla/dom/BindingUtils.h"
#include "mozilla/dom/HTMLImageElementBinding.h"
#include "mozilla/dom/BindContext.h"
#include "mozilla/dom/NameSpaceConstants.h"
#include "nsGenericHTMLElement.h"
#include "nsGkAtoms.h"
#include "nsStyleConsts.h"
#include "nsPresContext.h"
#include "nsMappedAttributes.h"
#include "nsSize.h"
#include "mozilla/dom/Document.h"
#include "nsImageFrame.h"
#include "nsIScriptContext.h"
#include "nsContentUtils.h"
#include "nsContainerFrame.h"
#include "nsNodeInfoManager.h"
#include "mozilla/MouseEvents.h"
#include "nsContentPolicyUtils.h"
#include "nsFocusManager.h"
#include "mozilla/dom/DOMIntersectionObserver.h"
#include "mozilla/dom/HTMLFormElement.h"
#include "mozilla/dom/MutationEventBinding.h"
#include "mozilla/dom/UserActivation.h"
#include "nsAttrValueOrString.h"
#include "imgLoader.h"
#include "Image.h"
// Responsive images!
#include "mozilla/dom/HTMLSourceElement.h"
#include "mozilla/dom/ResponsiveImageSelector.h"
#include "imgINotificationObserver.h"
#include "imgRequestProxy.h"
#include "mozilla/CycleCollectedJSContext.h"
#include "mozilla/EventDispatcher.h"
#include "mozilla/EventStates.h"
#include "mozilla/MappedDeclarations.h"
#include "nsLayoutUtils.h"
using namespace mozilla::net;
NS_IMPL_NS_NEW_HTML_ELEMENT(Image)
#ifdef DEBUG
// Is aSubject a previous sibling of aNode.
static bool IsPreviousSibling(nsINode* aSubject, nsINode* aNode) {
if (aSubject == aNode) {
return false;
}
nsINode* parent = aSubject->GetParentNode();
if (parent && parent == aNode->GetParentNode()) {
return parent->ComputeIndexOf(aSubject) < parent->ComputeIndexOf(aNode);
}
return false;
}
#endif
namespace mozilla::dom {
// Calls LoadSelectedImage on host element unless it has been superseded or
// canceled -- this is the synchronous section of "update the image data".
// https://html.spec.whatwg.org/multipage/embedded-content.html#update-the-image-data
class ImageLoadTask final : public MicroTaskRunnable {
public:
ImageLoadTask(HTMLImageElement* aElement, bool aAlwaysLoad,
bool aUseUrgentStartForChannel)
: MicroTaskRunnable(),
mElement(aElement),
mAlwaysLoad(aAlwaysLoad),
mUseUrgentStartForChannel(aUseUrgentStartForChannel) {
mDocument = aElement->OwnerDoc();
mDocument->BlockOnload();
}
void Run(AutoSlowOperation& aAso) override {
if (mElement->mPendingImageLoadTask == this) {
mElement->mPendingImageLoadTask = nullptr;
mElement->mUseUrgentStartForChannel = mUseUrgentStartForChannel;
// Defer loading this image if loading="lazy" was set after this microtask
// was queued.
// NOTE: Using ShouldLoadImage() will violate the HTML standard spec
// because ShouldLoadImage() checks the document active state which should
// have done just once before this queue is created as per the spec, so
// we just check the lazy loading state here.
if (!mElement->IsLazyLoading()) {
mElement->LoadSelectedImage(true, true, mAlwaysLoad);
}
}
mDocument->UnblockOnload(false);
}
bool Suppressed() override {
nsIGlobalObject* global = mElement->GetOwnerGlobal();
return global && global->IsInSyncOperation();
}
bool AlwaysLoad() { return mAlwaysLoad; }
private:
~ImageLoadTask() = default;
RefPtr<HTMLImageElement> mElement;
nsCOMPtr<Document> mDocument;
bool mAlwaysLoad;
// True if we want to set nsIClassOfService::UrgentStart to the channel to
// get the response ASAP for better user responsiveness.
bool mUseUrgentStartForChannel;
};
HTMLImageElement::HTMLImageElement(
already_AddRefed<mozilla::dom::NodeInfo>&& aNodeInfo)
: nsGenericHTMLElement(std::move(aNodeInfo)),
mForm(nullptr),
mInDocResponsiveContent(false),
mCurrentDensity(1.0) {
// We start out broken
AddStatesSilently(NS_EVENT_STATE_BROKEN);
}
HTMLImageElement::~HTMLImageElement() { nsImageLoadingContent::Destroy(); }
NS_IMPL_CYCLE_COLLECTION_INHERITED(HTMLImageElement, nsGenericHTMLElement,
mResponsiveSelector)
NS_IMPL_ISUPPORTS_CYCLE_COLLECTION_INHERITED(HTMLImageElement,
nsGenericHTMLElement,
nsIImageLoadingContent,
imgINotificationObserver)
NS_IMPL_ELEMENT_CLONE(HTMLImageElement)
bool HTMLImageElement::IsInteractiveHTMLContent() const {
return HasAttr(kNameSpaceID_None, nsGkAtoms::usemap) ||
nsGenericHTMLElement::IsInteractiveHTMLContent();
}
void HTMLImageElement::AsyncEventRunning(AsyncEventDispatcher* aEvent) {
nsImageLoadingContent::AsyncEventRunning(aEvent);
}
void HTMLImageElement::GetCurrentSrc(nsAString& aValue) {
nsCOMPtr<nsIURI> currentURI;
GetCurrentURI(getter_AddRefs(currentURI));
if (currentURI) {
nsAutoCString spec;
currentURI->GetSpec(spec);
CopyUTF8toUTF16(spec, aValue);
} else {
SetDOMStringToNull(aValue);
}
}
bool HTMLImageElement::Draggable() const {
// images may be dragged unless the draggable attribute is false
return !AttrValueIs(kNameSpaceID_None, nsGkAtoms::draggable,
nsGkAtoms::_false, eIgnoreCase);
}
bool HTMLImageElement::Complete() {
// It is still not clear what value should img.complete return in various
// cases, see https://github.com/whatwg/html/issues/4884
if (!HasAttr(nsGkAtoms::srcset) && !HasNonEmptyAttr(nsGkAtoms::src)) {
return true;
}
if (!mCurrentRequest || mPendingRequest) {
return false;
}
uint32_t status;
mCurrentRequest->GetImageStatus(&status);
return (status &
(imgIRequest::STATUS_LOAD_COMPLETE | imgIRequest::STATUS_ERROR)) != 0;
}
CSSIntPoint HTMLImageElement::GetXY() {
nsIFrame* frame = GetPrimaryFrame(FlushType::Layout);
if (!frame) {
return CSSIntPoint(0, 0);
}
nsIFrame* layer = nsLayoutUtils::GetClosestLayer(frame->GetParent());
return CSSIntPoint::FromAppUnitsRounded(frame->GetOffsetTo(layer));
}
int32_t HTMLImageElement::X() { return GetXY().x; }
int32_t HTMLImageElement::Y() { return GetXY().y; }
void HTMLImageElement::GetDecoding(nsAString& aValue) {
GetEnumAttr(nsGkAtoms::decoding, kDecodingTableDefault->tag, aValue);
}
// https://whatpr.org/html/3752/urls-and-fetching.html#lazy-loading-attributes
static const nsAttrValue::EnumTable kLoadingTable[] = {
{"eager", HTMLImageElement::Loading::Eager},
{"lazy", HTMLImageElement::Loading::Lazy},
{nullptr, 0}};
void HTMLImageElement::GetLoading(nsAString& aValue) const {
GetEnumAttr(nsGkAtoms::loading, kLoadingTable[0].tag, aValue);
}
HTMLImageElement::Loading HTMLImageElement::LoadingState() const {
const nsAttrValue* val = mAttrs.GetAttr(nsGkAtoms::loading);
if (!val) {
return HTMLImageElement::Loading::Eager;
}
return static_cast<HTMLImageElement::Loading>(val->GetEnumValue());
}
already_AddRefed<Promise> HTMLImageElement::Decode(ErrorResult& aRv) {
return nsImageLoadingContent::QueueDecodeAsync(aRv);
}
bool HTMLImageElement::ParseAttribute(int32_t aNamespaceID, nsAtom* aAttribute,
const nsAString& aValue,
nsIPrincipal* aMaybeScriptedPrincipal,
nsAttrValue& aResult) {
if (aNamespaceID == kNameSpaceID_None) {
if (aAttribute == nsGkAtoms::align) {
return ParseAlignValue(aValue, aResult);
}
if (aAttribute == nsGkAtoms::crossorigin) {
ParseCORSValue(aValue, aResult);
return true;
}
if (aAttribute == nsGkAtoms::decoding) {
return aResult.ParseEnumValue(aValue, kDecodingTable,
/* aCaseSensitive = */ false,
kDecodingTableDefault);
}
if (aAttribute == nsGkAtoms::loading) {
return aResult.ParseEnumValue(aValue, kLoadingTable,
/* aCaseSensitive = */ false,
kLoadingTable);
}
if (ParseImageAttribute(aAttribute, aValue, aResult)) {
return true;
}
}
return nsGenericHTMLElement::ParseAttribute(aNamespaceID, aAttribute, aValue,
aMaybeScriptedPrincipal, aResult);
}
void HTMLImageElement::MapAttributesIntoRule(
const nsMappedAttributes* aAttributes, MappedDeclarations& aDecls) {
MapImageAlignAttributeInto(aAttributes, aDecls);
MapImageBorderAttributeInto(aAttributes, aDecls);
MapImageMarginAttributeInto(aAttributes, aDecls);
MapImageSizeAttributesInto(aAttributes, aDecls, MapAspectRatio::Yes);
MapCommonAttributesInto(aAttributes, aDecls);
}
nsChangeHint HTMLImageElement::GetAttributeChangeHint(const nsAtom* aAttribute,
int32_t aModType) const {
nsChangeHint retval =
nsGenericHTMLElement::GetAttributeChangeHint(aAttribute, aModType);
if (aAttribute == nsGkAtoms::usemap || aAttribute == nsGkAtoms::ismap) {
retval |= nsChangeHint_ReconstructFrame;
} else if (aAttribute == nsGkAtoms::alt) {
if (aModType == MutationEvent_Binding::ADDITION ||
aModType == MutationEvent_Binding::REMOVAL) {
retval |= nsChangeHint_ReconstructFrame;
}
}
return retval;
}
NS_IMETHODIMP_(bool)
HTMLImageElement::IsAttributeMapped(const nsAtom* aAttribute) const {
static const MappedAttributeEntry* const map[] = {
sCommonAttributeMap, sImageMarginSizeAttributeMap,
sImageBorderAttributeMap, sImageAlignAttributeMap};
return FindAttributeDependence(aAttribute, map);
}
nsMapRuleToAttributesFunc HTMLImageElement::GetAttributeMappingFunction()
const {
return &MapAttributesIntoRule;
}
nsresult HTMLImageElement::BeforeSetAttr(int32_t aNameSpaceID, nsAtom* aName,
const nsAttrValueOrString* aValue,
bool aNotify) {
if (aNameSpaceID == kNameSpaceID_None && mForm &&
(aName == nsGkAtoms::name || aName == nsGkAtoms::id)) {
// remove the image from the hashtable as needed
nsAutoString tmp;
GetAttr(kNameSpaceID_None, aName, tmp);
if (!tmp.IsEmpty()) {
mForm->RemoveImageElementFromTable(this, tmp);
}
}
return nsGenericHTMLElement::BeforeSetAttr(aNameSpaceID, aName, aValue,
aNotify);
}
nsresult HTMLImageElement::AfterSetAttr(int32_t aNameSpaceID, nsAtom* aName,
const nsAttrValue* aValue,
const nsAttrValue* aOldValue,
nsIPrincipal* aMaybeScriptedPrincipal,
bool aNotify) {
if (aNameSpaceID != kNameSpaceID_None) {
return nsGenericHTMLElement::AfterSetAttr(aNameSpaceID, aName, aValue,
aOldValue,
aMaybeScriptedPrincipal, aNotify);
}
nsAttrValueOrString attrVal(aValue);
if (aValue) {
AfterMaybeChangeAttr(aNameSpaceID, aName, attrVal, aOldValue,
aMaybeScriptedPrincipal, aNotify);
}
if (mForm && (aName == nsGkAtoms::name || aName == nsGkAtoms::id) && aValue &&
!aValue->IsEmptyString()) {
// add the image to the hashtable as needed
MOZ_ASSERT(aValue->Type() == nsAttrValue::eAtom,
"Expected atom value for name/id");
mForm->AddImageElementToTable(
this, nsDependentAtomString(aValue->GetAtomValue()));
}
bool forceReload = false;
if (aName == nsGkAtoms::loading) {
if (aValue &&
static_cast<HTMLImageElement::Loading>(aValue->GetEnumValue()) ==
Loading::Lazy &&
!ImageState().HasState(NS_EVENT_STATE_LOADING)) {
SetLazyLoading();
} else if (aOldValue &&
static_cast<HTMLImageElement::Loading>(
aOldValue->GetEnumValue()) == Loading::Lazy &&
!ImageState().HasState(NS_EVENT_STATE_LOADING)) {
StopLazyLoadingAndStartLoadIfNeeded(false);
}
} else if (aName == nsGkAtoms::src && !aValue) {
// NOTE: regular src value changes are handled in AfterMaybeChangeAttr, so
// this only needs to handle unsetting the src attribute.
// Mark channel as urgent-start before load image if the image load is
// initaiated by a user interaction.
mUseUrgentStartForChannel = UserActivation::IsHandlingUserInput();
// AfterMaybeChangeAttr handles setting src since it needs to catch
// img.src = img.src, so we only need to handle the unset case
if (InResponsiveMode()) {
if (mResponsiveSelector && mResponsiveSelector->Content() == this) {
mResponsiveSelector->SetDefaultSource(VoidString());
}
QueueImageLoadTask(true);
} else {
// Bug 1076583 - We still behave synchronously in the non-responsive case
CancelImageRequests(aNotify);
}
} else if (aName == nsGkAtoms::srcset) {
// Mark channel as urgent-start before load image if the image load is
// initaiated by a user interaction.
mUseUrgentStartForChannel = UserActivation::IsHandlingUserInput();
mSrcsetTriggeringPrincipal = aMaybeScriptedPrincipal;
PictureSourceSrcsetChanged(this, attrVal.String(), aNotify);
} else if (aName == nsGkAtoms::sizes) {
// Mark channel as urgent-start before load image if the image load is
// initiated by a user interaction.
mUseUrgentStartForChannel = UserActivation::IsHandlingUserInput();
PictureSourceSizesChanged(this, attrVal.String(), aNotify);
} else if (aName == nsGkAtoms::decoding) {
// Request sync or async image decoding.
SetSyncDecodingHint(
aValue && static_cast<ImageDecodingType>(aValue->GetEnumValue()) ==
ImageDecodingType::Sync);
} else if (aName == nsGkAtoms::referrerpolicy) {
ReferrerPolicy referrerPolicy = GetReferrerPolicyAsEnum();
// FIXME(emilio): Why only when not in responsive mode? Also see below for
// aNotify.
forceReload = aNotify && !InResponsiveMode() &&
referrerPolicy != ReferrerPolicy::_empty &&
referrerPolicy != ReferrerPolicyFromAttr(aOldValue);
} else if (aName == nsGkAtoms::crossorigin) {
// FIXME(emilio): The aNotify bit seems a bit suspicious, but it is useful
// to avoid extra sync loads, specially in non-responsive mode. Ideally we
// can unify the responsive and non-responsive code paths (bug 1076583), and
// simplify this a bit.
forceReload = aNotify && GetCORSMode() != AttrValueToCORSMode(aOldValue);
}
if (forceReload) {
// Because we load image synchronously in non-responsive-mode, we need to do
// reload after the attribute has been set if the reload is triggered by
// cross origin / referrer policy changing.
//
// Mark channel as urgent-start before load image if the image load is
// initiated by a user interaction.
mUseUrgentStartForChannel = UserActivation::IsHandlingUserInput();
if (InResponsiveMode()) {
// Per spec, full selection runs when this changes, even though
// it doesn't directly affect the source selection
QueueImageLoadTask(true);
} else if (ShouldLoadImage()) {
// Bug 1076583 - We still use the older synchronous algorithm in
// non-responsive mode. Force a new load of the image with the
// new cross origin policy
ForceReload(aNotify, IgnoreErrors());
}
}
return nsGenericHTMLElement::AfterSetAttr(
aNameSpaceID, aName, aValue, aOldValue, aMaybeScriptedPrincipal, aNotify);
}
nsresult HTMLImageElement::OnAttrSetButNotChanged(
int32_t aNamespaceID, nsAtom* aName, const nsAttrValueOrString& aValue,
bool aNotify) {
AfterMaybeChangeAttr(aNamespaceID, aName, aValue, nullptr, nullptr, aNotify);
return nsGenericHTMLElement::OnAttrSetButNotChanged(aNamespaceID, aName,
aValue, aNotify);
}
void HTMLImageElement::AfterMaybeChangeAttr(
int32_t aNamespaceID, nsAtom* aName, const nsAttrValueOrString& aValue,
const nsAttrValue* aOldValue, nsIPrincipal* aMaybeScriptedPrincipal,
bool aNotify) {
if (aNamespaceID != kNameSpaceID_None || aName != nsGkAtoms::src) {
return;
}
// We need to force our image to reload. This must be done here, not in
// AfterSetAttr or BeforeSetAttr, because we want to do it even if the attr is
// being set to its existing value, which is normally optimized away as a
// no-op.
//
// If we are in responsive mode, we drop the forced reload behavior,
// but still trigger a image load task for img.src = img.src per
// spec.
//
// Both cases handle unsetting src in AfterSetAttr
// Mark channel as urgent-start before load image if the image load is
// initaiated by a user interaction.
mUseUrgentStartForChannel = UserActivation::IsHandlingUserInput();
mSrcTriggeringPrincipal = nsContentUtils::GetAttrTriggeringPrincipal(
this, aValue.String(), aMaybeScriptedPrincipal);
if (InResponsiveMode()) {
if (mResponsiveSelector && mResponsiveSelector->Content() == this) {
mResponsiveSelector->SetDefaultSource(aValue.String(),
mSrcTriggeringPrincipal);
}
QueueImageLoadTask(true);
} else if (aNotify && ShouldLoadImage()) {
// If aNotify is false, we are coming from the parser or some such place;
// we'll get bound after all the attributes have been set, so we'll do the
// sync image load from BindToTree. Skip the LoadImage call in that case.
// Note that this sync behavior is partially removed from the spec, bug
// 1076583
// A hack to get animations to reset. See bug 594771.
mNewRequestsWillNeedAnimationReset = true;
// Force image loading here, so that we'll try to load the image from
// network if it's set to be not cacheable.
// Potentially, false could be passed here rather than aNotify since
// UpdateState will be called by SetAttrAndNotify, but there are two
// obstacles to this: 1) LoadImage will end up calling
// UpdateState(aNotify), and we do not want it to call UpdateState(false)
// when aNotify is true, and 2) When this function is called by
// OnAttrSetButNotChanged, SetAttrAndNotify will not subsequently call
// UpdateState.
LoadImage(aValue.String(), true, aNotify, eImageLoadType_Normal,
mSrcTriggeringPrincipal);
mNewRequestsWillNeedAnimationReset = false;
}
}
void HTMLImageElement::GetEventTargetParent(EventChainPreVisitor& aVisitor) {
// We handle image element with attribute ismap in its corresponding frame
// element. Set mMultipleActionsPrevented here to prevent the click event
// trigger the behaviors in Element::PostHandleEventForLinks
WidgetMouseEvent* mouseEvent = aVisitor.mEvent->AsMouseEvent();
if (mouseEvent && mouseEvent->IsLeftClickEvent() && IsMap()) {
mouseEvent->mFlags.mMultipleActionsPrevented = true;
}
nsGenericHTMLElement::GetEventTargetParent(aVisitor);
}
bool HTMLImageElement::IsHTMLFocusable(bool aWithMouse, bool* aIsFocusable,
int32_t* aTabIndex) {
int32_t tabIndex = TabIndex();
if (IsInComposedDoc() && FindImageMap()) {
if (aTabIndex) {
// Use tab index on individual map areas
*aTabIndex = (sTabFocusModel & eTabFocus_linksMask) ? 0 : -1;
}
// Image map is not focusable itself, but flag as tabbable
// so that image map areas get walked into.
*aIsFocusable = false;
return false;
}
if (aTabIndex) {
// Can be in tab order if tabindex >=0 and form controls are tabbable.
*aTabIndex = (sTabFocusModel & eTabFocus_formElementsMask) ? tabIndex : -1;
}
*aIsFocusable =
#ifdef XP_MACOSX
(!aWithMouse || nsFocusManager::sMouseFocusesFormControl) &&
#endif
(tabIndex >= 0 || GetTabIndexAttrValue().isSome());
return false;
}
nsresult HTMLImageElement::BindToTree(BindContext& aContext, nsINode& aParent) {
nsresult rv = nsGenericHTMLElement::BindToTree(aContext, aParent);
NS_ENSURE_SUCCESS(rv, rv);
nsImageLoadingContent::BindToTree(aContext, aParent);
UpdateFormOwner();
if (HaveSrcsetOrInPicture()) {
if (IsInComposedDoc() && !mInDocResponsiveContent) {
aContext.OwnerDoc().AddResponsiveContent(this);
mInDocResponsiveContent = true;
}
// Mark channel as urgent-start before load image if the image load is
// initaiated by a user interaction.
mUseUrgentStartForChannel = UserActivation::IsHandlingUserInput();
// Run selection algorithm when an img element is inserted into a document
// in order to react to changes in the environment. See note of
// https://html.spec.whatwg.org/multipage/embedded-content.html#img-environment-changes
QueueImageLoadTask(false);
} else if (!InResponsiveMode() &&
HasAttr(kNameSpaceID_None, nsGkAtoms::src)) {
// We skip loading when our attributes were set from parser land,
// so trigger a aForce=false load now to check if things changed.
// This isn't necessary for responsive mode, since creating the
// image load task is asynchronous we don't need to take special
// care to avoid doing so when being filled by the parser.
// Mark channel as urgent-start before load image if the image load is
// initaiated by a user interaction.
mUseUrgentStartForChannel = UserActivation::IsHandlingUserInput();
// We still act synchronously for the non-responsive case (Bug
// 1076583), but still need to delay if it is unsafe to run
// script.
// If loading is temporarily disabled, don't even launch MaybeLoadImage.
// Otherwise MaybeLoadImage may run later when someone has reenabled
// loading.
if (LoadingEnabled() && ShouldLoadImage()) {
nsContentUtils::AddScriptRunner(
NewRunnableMethod<bool>("dom::HTMLImageElement::MaybeLoadImage", this,
&HTMLImageElement::MaybeLoadImage, false));
}
}
return rv;
}
void HTMLImageElement::UnbindFromTree(bool aNullParent) {
if (mForm) {
if (aNullParent || !FindAncestorForm(mForm)) {
ClearForm(true);
} else {
UnsetFlags(MAYBE_ORPHAN_FORM_ELEMENT);
}
}
if (mInDocResponsiveContent) {
OwnerDoc()->RemoveResponsiveContent(this);
mInDocResponsiveContent = false;
}
nsImageLoadingContent::UnbindFromTree(aNullParent);
nsGenericHTMLElement::UnbindFromTree(aNullParent);
}
void HTMLImageElement::UpdateFormOwner() {
if (!mForm) {
mForm = FindAncestorForm();
}
if (mForm && !HasFlag(ADDED_TO_FORM)) {
// Now we need to add ourselves to the form
nsAutoString nameVal, idVal;
GetAttr(kNameSpaceID_None, nsGkAtoms::name, nameVal);
GetAttr(kNameSpaceID_None, nsGkAtoms::id, idVal);
SetFlags(ADDED_TO_FORM);
mForm->AddImageElement(this);
if (!nameVal.IsEmpty()) {
mForm->AddImageElementToTable(this, nameVal);
}
if (!idVal.IsEmpty()) {
mForm->AddImageElementToTable(this, idVal);
}
}
}
void HTMLImageElement::MaybeLoadImage(bool aAlwaysForceLoad) {
// Our base URI may have changed, or we may have had responsive parameters
// change while not bound to the tree. Re-parse src/srcset and call LoadImage,
// which is a no-op if it resolves to the same effective URI without aForce.
// Note, check LoadingEnabled() after LoadImage call.
LoadSelectedImage(aAlwaysForceLoad, /* aNotify */ true, aAlwaysForceLoad);
if (!LoadingEnabled()) {
CancelImageRequests(true);
}
}
EventStates HTMLImageElement::IntrinsicState() const {
return nsGenericHTMLElement::IntrinsicState() |
nsImageLoadingContent::ImageState();
}
void HTMLImageElement::NodeInfoChanged(Document* aOldDoc) {
nsGenericHTMLElement::NodeInfoChanged(aOldDoc);
// Unlike the LazyLoadImageObserver, the intersection observer
// for the viewport could contain the element even if
// it's not lazy-loading. For instance, the element has
// started to load, but haven't reached to the viewport.
// So here we always try to unobserve it.
if (auto* observer = aOldDoc->GetLazyLoadImageObserverViewport()) {
observer->Unobserve(*this);
}
if (mLazyLoading) {
aOldDoc->GetLazyLoadImageObserver()->Unobserve(*this);
aOldDoc->DecLazyLoadImageCount();
mLazyLoading = false;
SetLazyLoading();
}
// Force reload image if adoption steps are run.
// If loading is temporarily disabled, don't even launch script runner.
// Otherwise script runner may run later when someone has reenabled loading.
StartLoadingIfNeeded();
}
// static
already_AddRefed<HTMLImageElement> HTMLImageElement::Image(
const GlobalObject& aGlobal, const Optional<uint32_t>& aWidth,
const Optional<uint32_t>& aHeight, ErrorResult& aError) {
nsCOMPtr<nsPIDOMWindowInner> win = do_QueryInterface(aGlobal.GetAsSupports());
Document* doc;
if (!win || !(doc = win->GetExtantDoc())) {
aError.Throw(NS_ERROR_FAILURE);
return nullptr;
}
RefPtr<mozilla::dom::NodeInfo> nodeInfo = doc->NodeInfoManager()->GetNodeInfo(
nsGkAtoms::img, nullptr, kNameSpaceID_XHTML, ELEMENT_NODE);
auto* nim = nodeInfo->NodeInfoManager();
RefPtr<HTMLImageElement> img = new (nim) HTMLImageElement(nodeInfo.forget());
if (aWidth.WasPassed()) {
img->SetWidth(aWidth.Value(), aError);
if (aError.Failed()) {
return nullptr;
}
if (aHeight.WasPassed()) {
img->SetHeight(aHeight.Value(), aError);
if (aError.Failed()) {
return nullptr;
}
}
}
return img.forget();
}
uint32_t HTMLImageElement::Height() { return GetWidthHeightForImage().height; }
uint32_t HTMLImageElement::Width() { return GetWidthHeightForImage().width; }
uint32_t HTMLImageElement::NaturalHeight() {
uint32_t height = nsImageLoadingContent::NaturalHeight();
if (mResponsiveSelector) {
double density = mResponsiveSelector->GetSelectedImageDensity();
MOZ_ASSERT(density >= 0.0);
height = NSToIntRound(double(height) / density);
}
return height;
}
uint32_t HTMLImageElement::NaturalWidth() {
uint32_t width = nsImageLoadingContent::NaturalWidth();
if (mResponsiveSelector) {
double density = mResponsiveSelector->GetSelectedImageDensity();
MOZ_ASSERT(density >= 0.0);
width = NSToIntRound(double(width) / density);
}
return width;
}
nsresult HTMLImageElement::CopyInnerTo(HTMLImageElement* aDest) {
nsresult rv = nsGenericHTMLElement::CopyInnerTo(aDest);
if (NS_FAILED(rv)) {
return rv;
}
// In SetAttr (called from nsGenericHTMLElement::CopyInnerTo), aDest skipped
// doing the image load because we passed in false for aNotify. But we
// really do want it to do the load, so set it up to happen once the cloning
// reaches a stable state.
if (!aDest->InResponsiveMode() &&
aDest->HasAttr(kNameSpaceID_None, nsGkAtoms::src) &&
aDest->ShouldLoadImage()) {
// Mark channel as urgent-start before load image if the image load is
// initaiated by a user interaction.
mUseUrgentStartForChannel = UserActivation::IsHandlingUserInput();
nsContentUtils::AddScriptRunner(
NewRunnableMethod<bool>("dom::HTMLImageElement::MaybeLoadImage", aDest,
&HTMLImageElement::MaybeLoadImage, false));
}
return NS_OK;
}
CORSMode HTMLImageElement::GetCORSMode() {
return AttrValueToCORSMode(GetParsedAttr(nsGkAtoms::crossorigin));
}
JSObject* HTMLImageElement::WrapNode(JSContext* aCx,
JS::Handle<JSObject*> aGivenProto) {
return HTMLImageElement_Binding::Wrap(aCx, this, aGivenProto);
}
#ifdef DEBUG
HTMLFormElement* HTMLImageElement::GetForm() const { return mForm; }
#endif
void HTMLImageElement::SetForm(HTMLFormElement* aForm) {
MOZ_ASSERT(aForm, "Don't pass null here");
NS_ASSERTION(!mForm,
"We don't support switching from one non-null form to another.");
mForm = aForm;
}
void HTMLImageElement::ClearForm(bool aRemoveFromForm) {
NS_ASSERTION((mForm != nullptr) == HasFlag(ADDED_TO_FORM),
"Form control should have had flag set correctly");
if (!mForm) {
return;
}
if (aRemoveFromForm) {
nsAutoString nameVal, idVal;
GetAttr(kNameSpaceID_None, nsGkAtoms::name, nameVal);
GetAttr(kNameSpaceID_None, nsGkAtoms::id, idVal);
mForm->RemoveImageElement(this);
if (!nameVal.IsEmpty()) {
mForm->RemoveImageElementFromTable(this, nameVal);
}
if (!idVal.IsEmpty()) {
mForm->RemoveImageElementFromTable(this, idVal);
}
}
UnsetFlags(ADDED_TO_FORM);
mForm = nullptr;
}
void HTMLImageElement::QueueImageLoadTask(bool aAlwaysLoad) {
// If loading is temporarily disabled, we don't want to queue tasks
// that may then run when loading is re-enabled.
if (!LoadingEnabled() || !ShouldLoadImage()) {
return;
}
// Ensure that we don't overwrite a previous load request that requires
// a complete load to occur.
bool alwaysLoad = aAlwaysLoad;
if (mPendingImageLoadTask) {
alwaysLoad = alwaysLoad || mPendingImageLoadTask->AlwaysLoad();
}
RefPtr<ImageLoadTask> task =
new ImageLoadTask(this, alwaysLoad, mUseUrgentStartForChannel);
// The task checks this to determine if it was the last
// queued event, and so earlier tasks are implicitly canceled.
mPendingImageLoadTask = task;
CycleCollectedJSContext::Get()->DispatchToMicroTask(task.forget());
}
bool HTMLImageElement::HaveSrcsetOrInPicture() {
if (HasAttr(kNameSpaceID_None, nsGkAtoms::srcset)) {
return true;
}
Element* parent = nsINode::GetParentElement();
return (parent && parent->IsHTMLElement(nsGkAtoms::picture));
}
bool HTMLImageElement::InResponsiveMode() {
// When we lose srcset or leave a <picture> element, the fallback to img.src
// will happen from the microtask, and we should behave responsively in the
// interim
return mResponsiveSelector || mPendingImageLoadTask ||
HaveSrcsetOrInPicture();
}
bool HTMLImageElement::SelectedSourceMatchesLast(nsIURI* aSelectedSource) {
// If there was no selected source previously, we don't want to short-circuit
// the load. Similarly for if there is no newly selected source.
if (!mLastSelectedSource || !aSelectedSource) {
return false;
}
bool equal = false;
return NS_SUCCEEDED(mLastSelectedSource->Equals(aSelectedSource, &equal)) &&
equal;
}
nsresult HTMLImageElement::LoadSelectedImage(bool aForce, bool aNotify,
bool aAlwaysLoad) {
double currentDensity = 1.0; // default to 1.0 for the src attribute case
// Helper to update state when only density may have changed (i.e., the source
// to load hasn't changed, and we don't do any request at all). We need (apart
// from updating our internal state) to tell the image frame because its
// intrinsic size may have changed.
//
// In the case we actually trigger a new load, that load will trigger a call
// to nsImageFrame::NotifyNewCurrentRequest, which takes care of that for us.
auto UpdateDensityOnly = [&]() -> void {
if (mCurrentDensity == currentDensity) {
return;
}
mCurrentDensity = currentDensity;
if (nsImageFrame* f = do_QueryFrame(GetPrimaryFrame())) {
f->ResponsiveContentDensityChanged();
}
};
if (aForce) {
// In responsive mode we generally want to re-run the full selection
// algorithm whenever starting a new load, per spec.
//
// This also causes us to re-resolve the URI as appropriate.
const bool sourceChanged = UpdateResponsiveSource();
if (mResponsiveSelector) {
currentDensity = mResponsiveSelector->GetSelectedImageDensity();
}
if (!sourceChanged && !aAlwaysLoad) {
UpdateDensityOnly();
return NS_OK;
}
} else if (mResponsiveSelector) {
currentDensity = mResponsiveSelector->GetSelectedImageDensity();
}
nsresult rv = NS_ERROR_FAILURE;
nsCOMPtr<nsIURI> selectedSource;
if (mResponsiveSelector) {
nsCOMPtr<nsIURI> url = mResponsiveSelector->GetSelectedImageURL();
nsCOMPtr<nsIPrincipal> triggeringPrincipal =
mResponsiveSelector->GetSelectedImageTriggeringPrincipal();
selectedSource = url;
if (!aAlwaysLoad && SelectedSourceMatchesLast(selectedSource)) {
UpdateDensityOnly();
return NS_OK;
}
if (url) {
rv = LoadImage(url, aForce, aNotify, eImageLoadType_Imageset,
triggeringPrincipal);
}
} else {
nsAutoString src;
if (!GetAttr(kNameSpaceID_None, nsGkAtoms::src, src)) {
CancelImageRequests(aNotify);
rv = NS_OK;
} else {
Document* doc = OwnerDoc();
StringToURI(src, doc, getter_AddRefs(selectedSource));
if (!aAlwaysLoad && SelectedSourceMatchesLast(selectedSource)) {
UpdateDensityOnly();
return NS_OK;
}
// If we have a srcset attribute or are in a <picture> element,
// we always use the Imageset load type, even if we parsed no
// valid responsive sources from either, per spec.
rv = LoadImage(src, aForce, aNotify,
HaveSrcsetOrInPicture() ? eImageLoadType_Imageset
: eImageLoadType_Normal,
mSrcTriggeringPrincipal);
}
}
mLastSelectedSource = selectedSource;
mCurrentDensity = currentDensity;
if (NS_FAILED(rv)) {
CancelImageRequests(aNotify);
}
return rv;
}
void HTMLImageElement::PictureSourceSrcsetChanged(nsIContent* aSourceNode,
const nsAString& aNewValue,
bool aNotify) {
MOZ_ASSERT(aSourceNode == this || IsPreviousSibling(aSourceNode, this),
"Should not be getting notifications for non-previous-siblings");
nsIContent* currentSrc =
mResponsiveSelector ? mResponsiveSelector->Content() : nullptr;
if (aSourceNode == currentSrc) {
// We're currently using this node as our responsive selector
// source.
nsCOMPtr<nsIPrincipal> principal;
if (aSourceNode == this) {
principal = mSrcsetTriggeringPrincipal;
} else if (auto* source = HTMLSourceElement::FromNode(aSourceNode)) {
principal = source->GetSrcsetTriggeringPrincipal();
}
mResponsiveSelector->SetCandidatesFromSourceSet(aNewValue, principal);
}
if (!mInDocResponsiveContent && IsInComposedDoc()) {
OwnerDoc()->AddResponsiveContent(this);
mInDocResponsiveContent = true;
}
// This always triggers the image update steps per the spec, even if
// we are not using this source.
QueueImageLoadTask(true);
}
void HTMLImageElement::PictureSourceSizesChanged(nsIContent* aSourceNode,
const nsAString& aNewValue,
bool aNotify) {
MOZ_ASSERT(aSourceNode == this || IsPreviousSibling(aSourceNode, this),
"Should not be getting notifications for non-previous-siblings");
nsIContent* currentSrc =
mResponsiveSelector ? mResponsiveSelector->Content() : nullptr;
if (aSourceNode == currentSrc) {
// We're currently using this node as our responsive selector
// source.
mResponsiveSelector->SetSizesFromDescriptor(aNewValue);
}
// This always triggers the image update steps per the spec, even if
// we are not using this source.
QueueImageLoadTask(true);
}
void HTMLImageElement::PictureSourceMediaOrTypeChanged(nsIContent* aSourceNode,
bool aNotify) {
MOZ_ASSERT(IsPreviousSibling(aSourceNode, this),
"Should not be getting notifications for non-previous-siblings");
// This always triggers the image update steps per the spec, even if
// we are not switching to/from this source
QueueImageLoadTask(true);
}
void HTMLImageElement::PictureSourceAdded(nsIContent* aSourceNode) {
MOZ_ASSERT(aSourceNode == this || IsPreviousSibling(aSourceNode, this),
"Should not be getting notifications for non-previous-siblings");
QueueImageLoadTask(true);
}
void HTMLImageElement::PictureSourceRemoved(nsIContent* aSourceNode) {
MOZ_ASSERT(aSourceNode == this || IsPreviousSibling(aSourceNode, this),
"Should not be getting notifications for non-previous-siblings");
QueueImageLoadTask(true);
}
bool HTMLImageElement::UpdateResponsiveSource() {
bool hadSelector = !!mResponsiveSelector;
nsIContent* currentSource =
mResponsiveSelector ? mResponsiveSelector->Content() : nullptr;
Element* parent = nsINode::GetParentElement();
nsINode* candidateSource = nullptr;
if (parent && parent->IsHTMLElement(nsGkAtoms::picture)) {
// Walk source nodes previous to ourselves
candidateSource = parent->GetFirstChild();
} else {
candidateSource = this;
}
while (candidateSource) {
if (candidateSource == currentSource) {
// found no better source before current, re-run selection on
// that and keep it if it's still usable.
bool changed = mResponsiveSelector->SelectImage(true);
if (mResponsiveSelector->NumCandidates()) {
bool isUsableCandidate = true;
// an otherwise-usable source element may still have a media query that
// may not match any more.
if (candidateSource->IsHTMLElement(nsGkAtoms::source) &&
!SourceElementMatches(candidateSource->AsElement())) {
isUsableCandidate = false;
}
if (isUsableCandidate) {
return changed;
}
}
// no longer valid
mResponsiveSelector = nullptr;
if (candidateSource == this) {
// No further possibilities
break;
}
} else if (candidateSource == this) {
// We are the last possible source
if (!TryCreateResponsiveSelector(candidateSource->AsElement())) {
// Failed to find any source
mResponsiveSelector = nullptr;
}
break;
} else if (candidateSource->IsHTMLElement(nsGkAtoms::source) &&
TryCreateResponsiveSelector(candidateSource->AsElement())) {
// This led to a valid source, stop
break;
}
candidateSource = candidateSource->GetNextSibling();
}
if (!candidateSource) {
// Ran out of siblings without finding ourself, e.g. XBL magic.
mResponsiveSelector = nullptr;
}
// If we reach this point, either:
// - there was no selector originally, and there is not one now
// - there was no selector originally, and there is one now
// - there was a selector, and there is a different one now
// - there was a selector, and there is not one now
return hadSelector || mResponsiveSelector;
}
/*static */
bool HTMLImageElement::SupportedPictureSourceType(const nsAString& aType) {
nsAutoString type;
nsAutoString params;
nsContentUtils::SplitMimeType(aType, type, params);
if (type.IsEmpty()) {
return true;
}
return imgLoader::SupportImageWithMimeType(
NS_ConvertUTF16toUTF8(type).get(),
AcceptedMimeTypes::IMAGES_AND_DOCUMENTS);
}
bool HTMLImageElement::SourceElementMatches(Element* aSourceElement) {
MOZ_ASSERT(aSourceElement->IsHTMLElement(nsGkAtoms::source));
DebugOnly<Element*> parent(nsINode::GetParentElement());
MOZ_ASSERT(parent && parent->IsHTMLElement(nsGkAtoms::picture));
MOZ_ASSERT(IsPreviousSibling(aSourceElement, this));
// Check media and type
auto* src = static_cast<HTMLSourceElement*>(aSourceElement);
if (!src->MatchesCurrentMedia()) {
return false;
}
nsAutoString type;
if (src->GetAttr(kNameSpaceID_None, nsGkAtoms::type, type) &&
!SupportedPictureSourceType(type)) {
return false;
}
return true;
}
bool HTMLImageElement::TryCreateResponsiveSelector(Element* aSourceElement) {
nsCOMPtr<nsIPrincipal> principal;
// Skip if this is not a <source> with matching media query
bool isSourceTag = aSourceElement->IsHTMLElement(nsGkAtoms::source);
if (isSourceTag) {
if (!SourceElementMatches(aSourceElement)) {
return false;
}
auto* source = HTMLSourceElement::FromNode(aSourceElement);
principal = source->GetSrcsetTriggeringPrincipal();
} else if (aSourceElement->IsHTMLElement(nsGkAtoms::img)) {
// Otherwise this is the <img> tag itself
MOZ_ASSERT(aSourceElement == this);
principal = mSrcsetTriggeringPrincipal;
}
// Skip if has no srcset or an empty srcset
nsString srcset;
if (!aSourceElement->GetAttr(kNameSpaceID_None, nsGkAtoms::srcset, srcset)) {
return false;
}
if (srcset.IsEmpty()) {
return false;
}
// Try to parse
RefPtr<ResponsiveImageSelector> sel =
new ResponsiveImageSelector(aSourceElement);
if (!sel->SetCandidatesFromSourceSet(srcset, principal)) {
// No possible candidates, don't need to bother parsing sizes
return false;
}
nsAutoString sizes;
aSourceElement->GetAttr(kNameSpaceID_None, nsGkAtoms::sizes, sizes);
sel->SetSizesFromDescriptor(sizes);
// If this is the <img> tag, also pull in src as the default source
if (!isSourceTag) {
MOZ_ASSERT(aSourceElement == this);
nsAutoString src;
if (GetAttr(kNameSpaceID_None, nsGkAtoms::src, src) && !src.IsEmpty()) {
sel->SetDefaultSource(src, mSrcTriggeringPrincipal);
}
}
mResponsiveSelector = sel;
return true;
}
/* static */
bool HTMLImageElement::SelectSourceForTagWithAttrs(
Document* aDocument, bool aIsSourceTag, const nsAString& aSrcAttr,
const nsAString& aSrcsetAttr, const nsAString& aSizesAttr,
const nsAString& aTypeAttr, const nsAString& aMediaAttr,
nsAString& aResult) {
MOZ_ASSERT(aIsSourceTag || (aTypeAttr.IsEmpty() && aMediaAttr.IsEmpty()),
"Passing type or media attrs makes no sense without aIsSourceTag");
MOZ_ASSERT(!aIsSourceTag || aSrcAttr.IsEmpty(),
"Passing aSrcAttr makes no sense with aIsSourceTag set");
if (aSrcsetAttr.IsEmpty()) {
if (!aIsSourceTag) {
// For an <img> with no srcset, we would always select the src attr.
aResult.Assign(aSrcAttr);
return true;
}
// Otherwise, a <source> without srcset is never selected
return false;
}
// Would not consider source tags with unsupported media or type
if (aIsSourceTag &&
((!aMediaAttr.IsVoid() && !HTMLSourceElement::WouldMatchMediaForDocument(
aMediaAttr, aDocument)) ||
(!aTypeAttr.IsVoid() && !SupportedPictureSourceType(aTypeAttr)))) {
return false;
}
// Using srcset or picture <source>, build a responsive selector for this tag.
RefPtr<ResponsiveImageSelector> sel = new ResponsiveImageSelector(aDocument);
sel->SetCandidatesFromSourceSet(aSrcsetAttr);
if (!aSizesAttr.IsEmpty()) {
sel->SetSizesFromDescriptor(aSizesAttr);
}
if (!aIsSourceTag) {
sel->SetDefaultSource(aSrcAttr);
}
if (sel->GetSelectedImageURLSpec(aResult)) {
return true;
}
if (!aIsSourceTag) {
// <img> tag with no match would definitively load nothing.
aResult.Truncate();
return true;
}
// <source> tags with no match would leave source yet-undetermined.
return false;
}
void HTMLImageElement::DestroyContent() {
mResponsiveSelector = nullptr;
nsImageLoadingContent::Destroy();
nsGenericHTMLElement::DestroyContent();
}
void HTMLImageElement::MediaFeatureValuesChanged() {
QueueImageLoadTask(false);
}
bool HTMLImageElement::ShouldLoadImage() const {
return OwnerDoc()->ShouldLoadImages() && !mLazyLoading;
}
void HTMLImageElement::SetLazyLoading() {
if (mLazyLoading) {
return;
}
if (!StaticPrefs::dom_image_lazy_loading_enabled()) {
return;
}
// If scripting is disabled don't do lazy load.
// https://whatpr.org/html/3752/images.html#updating-the-image-data
//
// Same for printing.
Document* doc = OwnerDoc();
if (!doc->IsScriptEnabled() || doc->IsStaticDocument()) {
return;
}
doc->EnsureLazyLoadImageObserver().Observe(*this);
doc->EnsureLazyLoadImageObserverViewport().Observe(*this);
doc->IncLazyLoadImageCount();
mLazyLoading = true;
UpdateImageState(true);
}
void HTMLImageElement::StartLoadingIfNeeded() {
if (LoadingEnabled() && ShouldLoadImage()) {
// Use script runner for the case the adopt is from appendChild.
// Bug 1076583 - We still behave synchronously in the non-responsive case
nsContentUtils::AddScriptRunner(
(InResponsiveMode())
? NewRunnableMethod<bool>(
"dom::HTMLImageElement::QueueImageLoadTask", this,
&HTMLImageElement::QueueImageLoadTask, true)
: NewRunnableMethod<bool>("dom::HTMLImageElement::MaybeLoadImage",
this, &HTMLImageElement::MaybeLoadImage,
true));
}
}
void HTMLImageElement::StopLazyLoadingAndStartLoadIfNeeded(
bool aFromIntersectionObserver) {
if (!mLazyLoading) {
return;
}
mLazyLoading = false;
Document* doc = OwnerDoc();
doc->GetLazyLoadImageObserver()->Unobserve(*this);
StartLoadingIfNeeded();
if (aFromIntersectionObserver) {
doc->IncLazyLoadImageStarted();
} else {
doc->DecLazyLoadImageCount();
doc->GetLazyLoadImageObserverViewport()->Unobserve(*this);
}
}
void HTMLImageElement::LazyLoadImageReachedViewport() {
Document* doc = OwnerDoc();
doc->GetLazyLoadImageObserverViewport()->Unobserve(*this);
doc->IncLazyLoadImageReachViewport(!Complete());
}
} // namespace mozilla::dom
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