dom/html/HTMLImageElement.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #include "mozilla/dom/HTMLImageElement.h"
   8 #include "mozilla/PresShell.h"
   9 #include "mozilla/dom/BindContext.h"
  10 #include "mozilla/dom/BindingUtils.h"
  11 #include "mozilla/dom/HTMLImageElementBinding.h"
  12 #include "mozilla/dom/NameSpaceConstants.h"
  13 #include "nsGenericHTMLElement.h"
  14 #include "nsGkAtoms.h"
  15 #include "nsStyleConsts.h"
  16 #include "nsPresContext.h"
  17 #include "nsSize.h"
  18 #include "mozilla/dom/Document.h"
  19 #include "nsImageFrame.h"
  20 #include "nsIScriptContext.h"
  21 #include "nsContentUtils.h"
  22 #include "nsContainerFrame.h"
  23 #include "nsNodeInfoManager.h"
  24 #include "mozilla/MouseEvents.h"
  25 #include "nsContentPolicyUtils.h"
  26 #include "nsFocusManager.h"
  27 #include "mozilla/dom/DOMIntersectionObserver.h"
  28 #include "mozilla/dom/HTMLFormElement.h"
  29 #include "mozilla/dom/MutationEventBinding.h"
  30 #include "mozilla/dom/UserActivation.h"
  31 #include "nsAttrValueOrString.h"
  32 #include "imgLoader.h"
  33 #include "Image.h"
  34
  35 // Responsive images!
  36 #include "mozilla/dom/HTMLSourceElement.h"
  37 #include "mozilla/dom/ResponsiveImageSelector.h"
  38
  39 #include "imgINotificationObserver.h"
  40 #include "imgRequestProxy.h"
  41
  42 #include "mozilla/CycleCollectedJSContext.h"
  43
  44 #include "mozilla/EventDispatcher.h"
  45 #include "mozilla/MappedDeclarationsBuilder.h"
  46 #include "mozilla/Maybe.h"
  47 #include "mozilla/RestyleManager.h"
  48
  49 #include "nsLayoutUtils.h"
  50
  51 using namespace mozilla::net;
  52 using mozilla::Maybe;
  53
  54 NS_IMPL_NS_NEW_HTML_ELEMENT(Image)
  55
  56 #ifdef DEBUG
  57 // Is aSubject a previous sibling of aNode.
  58 static bool IsPreviousSibling(const nsINode* aSubject, const nsINode* aNode) {
  59   if (aSubject == aNode) {
  60     return false;
  61   }
  62
  63   nsINode* parent = aSubject->GetParentNode();
  64   if (parent && parent == aNode->GetParentNode()) {
  65     const Maybe<uint32_t> indexOfSubject = parent->ComputeIndexOf(aSubject);
  66     const Maybe<uint32_t> indexOfNode = parent->ComputeIndexOf(aNode);
  67     if (MOZ_LIKELY(indexOfSubject.isSome() && indexOfNode.isSome())) {
  68       return *indexOfSubject < *indexOfNode;
  69     }
  70     // XXX Keep the odd traditional behavior for now.
  71     return indexOfSubject.isNothing() && indexOfNode.isSome();
  72   }
  73
  74   return false;
  75 }
  76 #endif
  77
  78 namespace mozilla::dom {
  79
  80 // Calls LoadSelectedImage on host element unless it has been superseded or
  81 // canceled -- this is the synchronous section of "update the image data".
  82 // https://html.spec.whatwg.org/multipage/embedded-content.html#update-the-image-data
  83 class ImageLoadTask final : public MicroTaskRunnable {
  84  public:
  85   ImageLoadTask(HTMLImageElement* aElement, bool aAlwaysLoad,
  86                 bool aUseUrgentStartForChannel)
  87       : MicroTaskRunnable(),
  88         mElement(aElement),
  89         mAlwaysLoad(aAlwaysLoad),
  90         mUseUrgentStartForChannel(aUseUrgentStartForChannel) {
  91     mDocument = aElement->OwnerDoc();
  92     mDocument->BlockOnload();
  93   }
  94
  95   void Run(AutoSlowOperation& aAso) override {
  96     if (mElement->mPendingImageLoadTask == this) {
  97       mElement->mPendingImageLoadTask = nullptr;
  98       mElement->mUseUrgentStartForChannel = mUseUrgentStartForChannel;
  99       mElement->LoadSelectedImage(true, true, mAlwaysLoad);
 100     }
 101     mDocument->UnblockOnload(false);
 102   }
 103
 104   bool Suppressed() override {
 105     nsIGlobalObject* global = mElement->GetOwnerGlobal();
 106     return global && global->IsInSyncOperation();
 107   }
 108
 109   bool AlwaysLoad() const { return mAlwaysLoad; }
 110
 111  private:
 112   ~ImageLoadTask() = default;
 113   RefPtr<HTMLImageElement> mElement;
 114   nsCOMPtr<Document> mDocument;
 115   bool mAlwaysLoad;
 116
 117   // True if we want to set nsIClassOfService::UrgentStart to the channel to
 118   // get the response ASAP for better user responsiveness.
 119   bool mUseUrgentStartForChannel;
 120 };
 121
 122 HTMLImageElement::HTMLImageElement(
 123     already_AddRefed<mozilla::dom::NodeInfo>&& aNodeInfo)
 124     : nsGenericHTMLElement(std::move(aNodeInfo)) {
 125   // We start out broken
 126   AddStatesSilently(ElementState::BROKEN);
 127 }
 128
 129 HTMLImageElement::~HTMLImageElement() { nsImageLoadingContent::Destroy(); }
 130
 131 NS_IMPL_CYCLE_COLLECTION_INHERITED(HTMLImageElement, nsGenericHTMLElement,
 132                                    mResponsiveSelector)
 133
 134 NS_IMPL_ISUPPORTS_CYCLE_COLLECTION_INHERITED(HTMLImageElement,
 135                                              nsGenericHTMLElement,
 136                                              nsIImageLoadingContent,
 137                                              imgINotificationObserver)
 138
 139 NS_IMPL_ELEMENT_CLONE(HTMLImageElement)
 140
 141 bool HTMLImageElement::IsInteractiveHTMLContent() const {
 142   return HasAttr(nsGkAtoms::usemap) ||
 143          nsGenericHTMLElement::IsInteractiveHTMLContent();
 144 }
 145
 146 void HTMLImageElement::AsyncEventRunning(AsyncEventDispatcher* aEvent) {
 147   nsImageLoadingContent::AsyncEventRunning(aEvent);
 148 }
 149
 150 void HTMLImageElement::GetCurrentSrc(nsAString& aValue) {
 151   nsCOMPtr<nsIURI> currentURI;
 152   GetCurrentURI(getter_AddRefs(currentURI));
 153   if (currentURI) {
 154     nsAutoCString spec;
 155     currentURI->GetSpec(spec);
 156     CopyUTF8toUTF16(spec, aValue);
 157   } else {
 158     SetDOMStringToNull(aValue);
 159   }
 160 }
 161
 162 bool HTMLImageElement::Draggable() const {
 163   // images may be dragged unless the draggable attribute is false
 164   return !AttrValueIs(kNameSpaceID_None, nsGkAtoms::draggable,
 165                       nsGkAtoms::_false, eIgnoreCase);
 166 }
 167
 168 bool HTMLImageElement::Complete() {
 169   // It is still not clear what value should img.complete return in various
 170   // cases, see https://github.com/whatwg/html/issues/4884
 171
 172   if (!HasAttr(nsGkAtoms::srcset) && !HasNonEmptyAttr(nsGkAtoms::src)) {
 173     return true;
 174   }
 175
 176   if (!mCurrentRequest || mPendingRequest) {
 177     return false;
 178   }
 179
 180   uint32_t status;
 181   mCurrentRequest->GetImageStatus(&status);
 182   return (status &
 183           (imgIRequest::STATUS_LOAD_COMPLETE | imgIRequest::STATUS_ERROR)) != 0;
 184 }
 185
 186 CSSIntPoint HTMLImageElement::GetXY() {
 187   nsIFrame* frame = GetPrimaryFrame(FlushType::Layout);
 188   if (!frame) {
 189     return CSSIntPoint(0, 0);
 190   }
 191   return CSSIntPoint::FromAppUnitsRounded(
 192       frame->GetOffsetTo(frame->PresShell()->GetRootFrame()));
 193 }
 194
 195 int32_t HTMLImageElement::X() { return GetXY().x; }
 196
 197 int32_t HTMLImageElement::Y() { return GetXY().y; }
 198
 199 void HTMLImageElement::GetDecoding(nsAString& aValue) {
 200   GetEnumAttr(nsGkAtoms::decoding, kDecodingTableDefault->tag, aValue);
 201 }
 202
 203 // https://whatpr.org/html/3752/urls-and-fetching.html#lazy-loading-attributes
 204 static const nsAttrValue::EnumTable kLoadingTable[] = {
 205     {"eager", HTMLImageElement::Loading::Eager},
 206     {"lazy", HTMLImageElement::Loading::Lazy},
 207     {nullptr, 0}};
 208
 209 void HTMLImageElement::GetLoading(nsAString& aValue) const {
 210   GetEnumAttr(nsGkAtoms::loading, kLoadingTable[0].tag, aValue);
 211 }
 212
 213 HTMLImageElement::Loading HTMLImageElement::LoadingState() const {
 214   const nsAttrValue* val = mAttrs.GetAttr(nsGkAtoms::loading);
 215   if (!val) {
 216     return HTMLImageElement::Loading::Eager;
 217   }
 218   return static_cast<HTMLImageElement::Loading>(val->GetEnumValue());
 219 }
 220
 221 already_AddRefed<Promise> HTMLImageElement::Decode(ErrorResult& aRv) {
 222   return nsImageLoadingContent::QueueDecodeAsync(aRv);
 223 }
 224
 225 bool HTMLImageElement::ParseAttribute(int32_t aNamespaceID, nsAtom* aAttribute,
 226                                       const nsAString& aValue,
 227                                       nsIPrincipal* aMaybeScriptedPrincipal,
 228                                       nsAttrValue& aResult) {
 229   if (aNamespaceID == kNameSpaceID_None) {
 230     if (aAttribute == nsGkAtoms::align) {
 231       return ParseAlignValue(aValue, aResult);
 232     }
 233     if (aAttribute == nsGkAtoms::crossorigin) {
 234       ParseCORSValue(aValue, aResult);
 235       return true;
 236     }
 237     if (aAttribute == nsGkAtoms::decoding) {
 238       return aResult.ParseEnumValue(aValue, kDecodingTable,
 239                                     /* aCaseSensitive = */ false,
 240                                     kDecodingTableDefault);
 241     }
 242     if (aAttribute == nsGkAtoms::loading) {
 243       return aResult.ParseEnumValue(aValue, kLoadingTable,
 244                                     /* aCaseSensitive = */ false,
 245                                     kLoadingTable);
 246     }
 247     if (ParseImageAttribute(aAttribute, aValue, aResult)) {
 248       return true;
 249     }
 250   }
 251
 252   return nsGenericHTMLElement::ParseAttribute(aNamespaceID, aAttribute, aValue,
 253                                               aMaybeScriptedPrincipal, aResult);
 254 }
 255
 256 void HTMLImageElement::MapAttributesIntoRule(
 257     MappedDeclarationsBuilder& aBuilder) {
 258   MapImageAlignAttributeInto(aBuilder);
 259   MapImageBorderAttributeInto(aBuilder);
 260   MapImageMarginAttributeInto(aBuilder);
 261   MapImageSizeAttributesInto(aBuilder, MapAspectRatio::Yes);
 262   MapCommonAttributesInto(aBuilder);
 263 }
 264
 265 nsChangeHint HTMLImageElement::GetAttributeChangeHint(const nsAtom* aAttribute,
 266                                                       int32_t aModType) const {
 267   nsChangeHint retval =
 268       nsGenericHTMLElement::GetAttributeChangeHint(aAttribute, aModType);
 269   if (aAttribute == nsGkAtoms::usemap || aAttribute == nsGkAtoms::ismap) {
 270     retval |= nsChangeHint_ReconstructFrame;
 271   } else if (aAttribute == nsGkAtoms::alt) {
 272     if (aModType == MutationEvent_Binding::ADDITION ||
 273         aModType == MutationEvent_Binding::REMOVAL) {
 274       retval |= nsChangeHint_ReconstructFrame;
 275     }
 276   }
 277   return retval;
 278 }
 279
 280 NS_IMETHODIMP_(bool)
 281 HTMLImageElement::IsAttributeMapped(const nsAtom* aAttribute) const {
 282   static const MappedAttributeEntry* const map[] = {
 283       sCommonAttributeMap, sImageMarginSizeAttributeMap,
 284       sImageBorderAttributeMap, sImageAlignAttributeMap};
 285
 286   return FindAttributeDependence(aAttribute, map);
 287 }
 288
 289 nsMapRuleToAttributesFunc HTMLImageElement::GetAttributeMappingFunction()
 290     const {
 291   return &MapAttributesIntoRule;
 292 }
 293
 294 void HTMLImageElement::BeforeSetAttr(int32_t aNameSpaceID, nsAtom* aName,
 295                                      const nsAttrValue* aValue, bool aNotify) {
 296   if (aNameSpaceID == kNameSpaceID_None && mForm &&
 297       (aName == nsGkAtoms::name || aName == nsGkAtoms::id)) {
 298     // remove the image from the hashtable as needed
 299     if (const auto* old = GetParsedAttr(aName); old && !old->IsEmptyString()) {
 300       mForm->RemoveImageElementFromTable(
 301           this, nsDependentAtomString(old->GetAtomValue()));
 302     }
 303   }
 304
 305   return nsGenericHTMLElement::BeforeSetAttr(aNameSpaceID, aName, aValue,
 306                                              aNotify);
 307 }
 308
 309 void HTMLImageElement::AfterSetAttr(int32_t aNameSpaceID, nsAtom* aName,
 310                                     const nsAttrValue* aValue,
 311                                     const nsAttrValue* aOldValue,
 312                                     nsIPrincipal* aMaybeScriptedPrincipal,
 313                                     bool aNotify) {
 314   if (aNameSpaceID != kNameSpaceID_None) {
 315     return nsGenericHTMLElement::AfterSetAttr(aNameSpaceID, aName, aValue,
 316                                               aOldValue,
 317                                               aMaybeScriptedPrincipal, aNotify);
 318   }
 319
 320   nsAttrValueOrString attrVal(aValue);
 321   if (aName == nsGkAtoms::src) {
 322     mSrcURI = nullptr;
 323     if (aValue && !aValue->IsEmptyString()) {
 324       StringToURI(attrVal.String(), OwnerDoc(), getter_AddRefs(mSrcURI));
 325     }
 326   }
 327
 328   if (aValue) {
 329     AfterMaybeChangeAttr(aNameSpaceID, aName, attrVal, aOldValue,
 330                          aMaybeScriptedPrincipal, aNotify);
 331   }
 332
 333   if (mForm && (aName == nsGkAtoms::name || aName == nsGkAtoms::id) && aValue &&
 334       !aValue->IsEmptyString()) {
 335     // add the image to the hashtable as needed
 336     MOZ_ASSERT(aValue->Type() == nsAttrValue::eAtom,
 337                "Expected atom value for name/id");
 338     mForm->AddImageElementToTable(
 339         this, nsDependentAtomString(aValue->GetAtomValue()));
 340   }
 341
 342   bool forceReload = false;
 343
 344   if (aName == nsGkAtoms::loading && !mLoading) {
 345     if (aValue && Loading(aValue->GetEnumValue()) == Loading::Lazy) {
 346       SetLazyLoading();
 347     } else if (aOldValue &&
 348                Loading(aOldValue->GetEnumValue()) == Loading::Lazy) {
 349       StopLazyLoading(StartLoading::Yes);
 350     }
 351   } else if (aName == nsGkAtoms::src && !aValue) {
 352     // NOTE: regular src value changes are handled in AfterMaybeChangeAttr, so
 353     // this only needs to handle unsetting the src attribute.
 354     // Mark channel as urgent-start before load image if the image load is
 355     // initaiated by a user interaction.
 356     mUseUrgentStartForChannel = UserActivation::IsHandlingUserInput();
 357
 358     // AfterMaybeChangeAttr handles setting src since it needs to catch
 359     // img.src = img.src, so we only need to handle the unset case
 360     if (InResponsiveMode()) {
 361       if (mResponsiveSelector && mResponsiveSelector->Content() == this) {
 362         mResponsiveSelector->SetDefaultSource(VoidString());
 363       }
 364       UpdateSourceSyncAndQueueImageTask(true);
 365     } else {
 366       // Bug 1076583 - We still behave synchronously in the non-responsive case
 367       CancelImageRequests(aNotify);
 368     }
 369   } else if (aName == nsGkAtoms::srcset) {
 370     // Mark channel as urgent-start before load image if the image load is
 371     // initaiated by a user interaction.
 372     mUseUrgentStartForChannel = UserActivation::IsHandlingUserInput();
 373
 374     mSrcsetTriggeringPrincipal = aMaybeScriptedPrincipal;
 375
 376     PictureSourceSrcsetChanged(this, attrVal.String(), aNotify);
 377   } else if (aName == nsGkAtoms::sizes) {
 378     // Mark channel as urgent-start before load image if the image load is
 379     // initiated by a user interaction.
 380     mUseUrgentStartForChannel = UserActivation::IsHandlingUserInput();
 381
 382     PictureSourceSizesChanged(this, attrVal.String(), aNotify);
 383   } else if (aName == nsGkAtoms::decoding) {
 384     // Request sync or async image decoding.
 385     SetSyncDecodingHint(
 386         aValue && static_cast<ImageDecodingType>(aValue->GetEnumValue()) ==
 387                       ImageDecodingType::Sync);
 388   } else if (aName == nsGkAtoms::referrerpolicy) {
 389     ReferrerPolicy referrerPolicy = GetReferrerPolicyAsEnum();
 390     // FIXME(emilio): Why only  when not in responsive mode? Also see below for
 391     // aNotify.
 392     forceReload = aNotify && !InResponsiveMode() &&
 393                   referrerPolicy != ReferrerPolicy::_empty &&
 394                   referrerPolicy != ReferrerPolicyFromAttr(aOldValue);
 395   } else if (aName == nsGkAtoms::crossorigin) {
 396     // FIXME(emilio): The aNotify bit seems a bit suspicious, but it is useful
 397     // to avoid extra sync loads, specially in non-responsive mode. Ideally we
 398     // can unify the responsive and non-responsive code paths (bug 1076583), and
 399     // simplify this a bit.
 400     forceReload = aNotify && GetCORSMode() != AttrValueToCORSMode(aOldValue);
 401   }
 402
 403   if (forceReload) {
 404     // Because we load image synchronously in non-responsive-mode, we need to do
 405     // reload after the attribute has been set if the reload is triggered by
 406     // cross origin / referrer policy changing.
 407     //
 408     // Mark channel as urgent-start before load image if the image load is
 409     // initiated by a user interaction.
 410     mUseUrgentStartForChannel = UserActivation::IsHandlingUserInput();
 411     if (InResponsiveMode()) {
 412       // Per spec, full selection runs when this changes, even though
 413       // it doesn't directly affect the source selection
 414       UpdateSourceSyncAndQueueImageTask(true);
 415     } else if (ShouldLoadImage()) {
 416       // Bug 1076583 - We still use the older synchronous algorithm in
 417       // non-responsive mode. Force a new load of the image with the
 418       // new cross origin policy
 419       ForceReload(aNotify, IgnoreErrors());
 420     }
 421   }
 422
 423   return nsGenericHTMLElement::AfterSetAttr(
 424       aNameSpaceID, aName, aValue, aOldValue, aMaybeScriptedPrincipal, aNotify);
 425 }
 426
 427 void HTMLImageElement::OnAttrSetButNotChanged(int32_t aNamespaceID,
 428                                               nsAtom* aName,
 429                                               const nsAttrValueOrString& aValue,
 430                                               bool aNotify) {
 431   AfterMaybeChangeAttr(aNamespaceID, aName, aValue, nullptr, nullptr, aNotify);
 432   return nsGenericHTMLElement::OnAttrSetButNotChanged(aNamespaceID, aName,
 433                                                       aValue, aNotify);
 434 }
 435
 436 void HTMLImageElement::AfterMaybeChangeAttr(
 437     int32_t aNamespaceID, nsAtom* aName, const nsAttrValueOrString& aValue,
 438     const nsAttrValue* aOldValue, nsIPrincipal* aMaybeScriptedPrincipal,
 439     bool aNotify) {
 440   if (aNamespaceID != kNameSpaceID_None || aName != nsGkAtoms::src) {
 441     return;
 442   }
 443
 444   // We need to force our image to reload.  This must be done here, not in
 445   // AfterSetAttr or BeforeSetAttr, because we want to do it even if the attr is
 446   // being set to its existing value, which is normally optimized away as a
 447   // no-op.
 448   //
 449   // If we are in responsive mode, we drop the forced reload behavior,
 450   // but still trigger a image load task for img.src = img.src per
 451   // spec.
 452   //
 453   // Both cases handle unsetting src in AfterSetAttr
 454   // Mark channel as urgent-start before load image if the image load is
 455   // initaiated by a user interaction.
 456   mUseUrgentStartForChannel = UserActivation::IsHandlingUserInput();
 457
 458   mSrcTriggeringPrincipal = nsContentUtils::GetAttrTriggeringPrincipal(
 459       this, aValue.String(), aMaybeScriptedPrincipal);
 460
 461   if (InResponsiveMode()) {
 462     if (mResponsiveSelector && mResponsiveSelector->Content() == this) {
 463       mResponsiveSelector->SetDefaultSource(mSrcURI, mSrcTriggeringPrincipal);
 464     }
 465     UpdateSourceSyncAndQueueImageTask(true);
 466   } else if (aNotify && ShouldLoadImage()) {
 467     // If aNotify is false, we are coming from the parser or some such place;
 468     // we'll get bound after all the attributes have been set, so we'll do the
 469     // sync image load from BindToTree. Skip the LoadImage call in that case.
 470
 471     // Note that this sync behavior is partially removed from the spec, bug
 472     // 1076583
 473
 474     // A hack to get animations to reset. See bug 594771.
 475     mNewRequestsWillNeedAnimationReset = true;
 476
 477     // Force image loading here, so that we'll try to load the image from
 478     // network if it's set to be not cacheable.
 479     // Potentially, false could be passed here rather than aNotify since
 480     // UpdateState will be called by SetAttrAndNotify, but there are two
 481     // obstacles to this: 1) LoadImage will end up calling
 482     // UpdateState(aNotify), and we do not want it to call UpdateState(false)
 483     // when aNotify is true, and 2) When this function is called by
 484     // OnAttrSetButNotChanged, SetAttrAndNotify will not subsequently call
 485     // UpdateState.
 486     LoadSelectedImage(/* aForce = */ true, aNotify,
 487                       /* aAlwaysLoad = */ true);
 488
 489     mNewRequestsWillNeedAnimationReset = false;
 490   }
 491 }
 492
 493 void HTMLImageElement::GetEventTargetParent(EventChainPreVisitor& aVisitor) {
 494   // We handle image element with attribute ismap in its corresponding frame
 495   // element. Set mMultipleActionsPrevented here to prevent the click event
 496   // trigger the behaviors in Element::PostHandleEventForLinks
 497   WidgetMouseEvent* mouseEvent = aVisitor.mEvent->AsMouseEvent();
 498   if (mouseEvent && mouseEvent->IsLeftClickEvent() && IsMap()) {
 499     mouseEvent->mFlags.mMultipleActionsPrevented = true;
 500   }
 501   nsGenericHTMLElement::GetEventTargetParent(aVisitor);
 502 }
 503
 504 nsINode* HTMLImageElement::GetScopeChainParent() const {
 505   if (mForm) {
 506     return mForm;
 507   }
 508   return nsGenericHTMLElement::GetScopeChainParent();
 509 }
 510
 511 bool HTMLImageElement::IsHTMLFocusable(bool aWithMouse, bool* aIsFocusable,
 512                                        int32_t* aTabIndex) {
 513   int32_t tabIndex = TabIndex();
 514
 515   if (IsInComposedDoc() && FindImageMap()) {
 516     if (aTabIndex) {
 517       // Use tab index on individual map areas
 518       *aTabIndex = (sTabFocusModel & eTabFocus_linksMask) ? 0 : -1;
 519     }
 520     // Image map is not focusable itself, but flag as tabbable
 521     // so that image map areas get walked into.
 522     *aIsFocusable = false;
 523
 524     return false;
 525   }
 526
 527   if (aTabIndex) {
 528     // Can be in tab order if tabindex >=0 and form controls are tabbable.
 529     *aTabIndex = (sTabFocusModel & eTabFocus_formElementsMask) ? tabIndex : -1;
 530   }
 531
 532   *aIsFocusable = IsFormControlDefaultFocusable(aWithMouse) &&
 533                   (tabIndex >= 0 || GetTabIndexAttrValue().isSome());
 534
 535   return false;
 536 }
 537
 538 nsresult HTMLImageElement::BindToTree(BindContext& aContext, nsINode& aParent) {
 539   nsresult rv = nsGenericHTMLElement::BindToTree(aContext, aParent);
 540   NS_ENSURE_SUCCESS(rv, rv);
 541
 542   nsImageLoadingContent::BindToTree(aContext, aParent);
 543
 544   UpdateFormOwner();
 545
 546   if (HaveSrcsetOrInPicture()) {
 547     if (IsInComposedDoc() && !mInDocResponsiveContent) {
 548       aContext.OwnerDoc().AddResponsiveContent(this);
 549       mInDocResponsiveContent = true;
 550     }
 551
 552     // Mark channel as urgent-start before load image if the image load is
 553     // initaiated by a user interaction.
 554     mUseUrgentStartForChannel = UserActivation::IsHandlingUserInput();
 555
 556     // Run selection algorithm when an img element is inserted into a document
 557     // in order to react to changes in the environment. See note of
 558     // https://html.spec.whatwg.org/multipage/embedded-content.html#img-environment-changes
 559     //
 560     // We also do this in PictureSourceAdded() if it is in <picture>, so here
 561     // we only need to do if its parent is not <picture>, even if there is no
 562     // <source>.
 563     if (!IsInPicture()) {
 564       UpdateSourceSyncAndQueueImageTask(false);
 565     }
 566   } else if (!InResponsiveMode() && HasAttr(nsGkAtoms::src)) {
 567     // We skip loading when our attributes were set from parser land,
 568     // so trigger a aForce=false load now to check if things changed.
 569     // This isn't necessary for responsive mode, since creating the
 570     // image load task is asynchronous we don't need to take special
 571     // care to avoid doing so when being filled by the parser.
 572
 573     // Mark channel as urgent-start before load image if the image load is
 574     // initaiated by a user interaction.
 575     mUseUrgentStartForChannel = UserActivation::IsHandlingUserInput();
 576
 577     // We still act synchronously for the non-responsive case (Bug
 578     // 1076583), but still need to delay if it is unsafe to run
 579     // script.
 580
 581     // If loading is temporarily disabled, don't even launch MaybeLoadImage.
 582     // Otherwise MaybeLoadImage may run later when someone has reenabled
 583     // loading.
 584     if (LoadingEnabled() && ShouldLoadImage()) {
 585       nsContentUtils::AddScriptRunner(
 586           NewRunnableMethod<bool>("dom::HTMLImageElement::MaybeLoadImage", this,
 587                                   &HTMLImageElement::MaybeLoadImage, false));
 588     }
 589   }
 590
 591   return rv;
 592 }
 593
 594 void HTMLImageElement::UnbindFromTree(bool aNullParent) {
 595   if (mForm) {
 596     if (aNullParent || !FindAncestorForm(mForm)) {
 597       ClearForm(true);
 598     } else {
 599       UnsetFlags(MAYBE_ORPHAN_FORM_ELEMENT);
 600     }
 601   }
 602
 603   if (mInDocResponsiveContent) {
 604     OwnerDoc()->RemoveResponsiveContent(this);
 605     mInDocResponsiveContent = false;
 606   }
 607
 608   nsImageLoadingContent::UnbindFromTree(aNullParent);
 609   nsGenericHTMLElement::UnbindFromTree(aNullParent);
 610 }
 611
 612 void HTMLImageElement::UpdateFormOwner() {
 613   if (!mForm) {
 614     mForm = FindAncestorForm();
 615   }
 616
 617   if (mForm && !HasFlag(ADDED_TO_FORM)) {
 618     // Now we need to add ourselves to the form
 619     nsAutoString nameVal, idVal;
 620     GetAttr(nsGkAtoms::name, nameVal);
 621     GetAttr(nsGkAtoms::id, idVal);
 622
 623     SetFlags(ADDED_TO_FORM);
 624
 625     mForm->AddImageElement(this);
 626
 627     if (!nameVal.IsEmpty()) {
 628       mForm->AddImageElementToTable(this, nameVal);
 629     }
 630
 631     if (!idVal.IsEmpty()) {
 632       mForm->AddImageElementToTable(this, idVal);
 633     }
 634   }
 635 }
 636
 637 void HTMLImageElement::MaybeLoadImage(bool aAlwaysForceLoad) {
 638   // Our base URI may have changed, or we may have had responsive parameters
 639   // change while not bound to the tree. However, at this moment, we should have
 640   // updated the responsive source in other places, so we don't have to re-parse
 641   // src/srcset here. Just need to LoadImage.
 642
 643   // Note, check LoadingEnabled() after LoadImage call.
 644
 645   LoadSelectedImage(aAlwaysForceLoad, /* aNotify */ true, aAlwaysForceLoad);
 646
 647   if (!LoadingEnabled()) {
 648     CancelImageRequests(true);
 649   }
 650 }
 651
 652 void HTMLImageElement::NodeInfoChanged(Document* aOldDoc) {
 653   nsGenericHTMLElement::NodeInfoChanged(aOldDoc);
 654
 655   // Reparse the URI if needed. Note that we can't check whether we already have
 656   // a parsed URI, because it might be null even if we have a valid src
 657   // attribute, if we tried to parse with a different base.
 658   mSrcURI = nullptr;
 659   nsAutoString src;
 660   if (GetAttr(nsGkAtoms::src, src) && !src.IsEmpty()) {
 661     StringToURI(src, OwnerDoc(), getter_AddRefs(mSrcURI));
 662   }
 663
 664   // Unlike the LazyLoadImageObserver, the intersection observer
 665   // for the viewport could contain the element even if
 666   // it's not lazy-loading. For instance, the element has
 667   // started to load, but haven't reached to the viewport.
 668   // So here we always try to unobserve it.
 669   if (auto* observer = aOldDoc->GetLazyLoadImageObserverViewport()) {
 670     observer->Unobserve(*this);
 671   }
 672
 673   if (mLazyLoading) {
 674     aOldDoc->GetLazyLoadImageObserver()->Unobserve(*this);
 675     mLazyLoading = false;
 676     SetLazyLoading();
 677   }
 678
 679   // Run selection algorithm synchronously when an img element's adopting steps
 680   // are run, in order to react to changes in the environment, per spec,
 681   // https://html.spec.whatwg.org/multipage/images.html#reacting-to-dom-mutations,
 682   // and
 683   // https://html.spec.whatwg.org/multipage/images.html#reacting-to-environment-changes.
 684   if (InResponsiveMode()) {
 685     UpdateResponsiveSource();
 686   }
 687
 688   // Force reload image if adoption steps are run.
 689   // If loading is temporarily disabled, don't even launch script runner.
 690   // Otherwise script runner may run later when someone has reenabled loading.
 691   StartLoadingIfNeeded();
 692 }
 693
 694 // static
 695 already_AddRefed<HTMLImageElement> HTMLImageElement::Image(
 696     const GlobalObject& aGlobal, const Optional<uint32_t>& aWidth,
 697     const Optional<uint32_t>& aHeight, ErrorResult& aError) {
 698   nsCOMPtr<nsPIDOMWindowInner> win = do_QueryInterface(aGlobal.GetAsSupports());
 699   Document* doc;
 700   if (!win || !(doc = win->GetExtantDoc())) {
 701     aError.Throw(NS_ERROR_FAILURE);
 702     return nullptr;
 703   }
 704
 705   RefPtr<mozilla::dom::NodeInfo> nodeInfo = doc->NodeInfoManager()->GetNodeInfo(
 706       nsGkAtoms::img, nullptr, kNameSpaceID_XHTML, ELEMENT_NODE);
 707
 708   auto* nim = nodeInfo->NodeInfoManager();
 709   RefPtr<HTMLImageElement> img = new (nim) HTMLImageElement(nodeInfo.forget());
 710
 711   if (aWidth.WasPassed()) {
 712     img->SetWidth(aWidth.Value(), aError);
 713     if (aError.Failed()) {
 714       return nullptr;
 715     }
 716
 717     if (aHeight.WasPassed()) {
 718       img->SetHeight(aHeight.Value(), aError);
 719       if (aError.Failed()) {
 720         return nullptr;
 721       }
 722     }
 723   }
 724
 725   return img.forget();
 726 }
 727
 728 uint32_t HTMLImageElement::Height() { return GetWidthHeightForImage().height; }
 729
 730 uint32_t HTMLImageElement::Width() { return GetWidthHeightForImage().width; }
 731
 732 nsIntSize HTMLImageElement::NaturalSize() {
 733   if (!mCurrentRequest) {
 734     return {};
 735   }
 736
 737   nsCOMPtr<imgIContainer> image;
 738   mCurrentRequest->GetImage(getter_AddRefs(image));
 739   if (!image) {
 740     return {};
 741   }
 742
 743   nsIntSize size;
 744   Unused << image->GetHeight(&size.height);
 745   Unused << image->GetWidth(&size.width);
 746
 747   ImageResolution resolution = image->GetResolution();
 748   // NOTE(emilio): What we implement here matches the image-set() spec, but it's
 749   // unclear whether this is the right thing to do, see
 750   // https://github.com/whatwg/html/pull/5574#issuecomment-826335244.
 751   if (mResponsiveSelector) {
 752     float density = mResponsiveSelector->GetSelectedImageDensity();
 753     MOZ_ASSERT(density >= 0.0);
 754     resolution.ScaleBy(density);
 755   }
 756
 757   resolution.ApplyTo(size.width, size.height);
 758   return size;
 759 }
 760
 761 nsresult HTMLImageElement::CopyInnerTo(HTMLImageElement* aDest) {
 762   nsresult rv = nsGenericHTMLElement::CopyInnerTo(aDest);
 763   if (NS_FAILED(rv)) {
 764     return rv;
 765   }
 766
 767   // In SetAttr (called from nsGenericHTMLElement::CopyInnerTo), aDest skipped
 768   // doing the image load because we passed in false for aNotify.  But we
 769   // really do want it to do the load, so set it up to happen once the cloning
 770   // reaches a stable state.
 771   if (!aDest->InResponsiveMode() && aDest->HasAttr(nsGkAtoms::src) &&
 772       aDest->ShouldLoadImage()) {
 773     // Mark channel as urgent-start before load image if the image load is
 774     // initaiated by a user interaction.
 775     mUseUrgentStartForChannel = UserActivation::IsHandlingUserInput();
 776
 777     nsContentUtils::AddScriptRunner(
 778         NewRunnableMethod<bool>("dom::HTMLImageElement::MaybeLoadImage", aDest,
 779                                 &HTMLImageElement::MaybeLoadImage, false));
 780   }
 781
 782   return NS_OK;
 783 }
 784
 785 CORSMode HTMLImageElement::GetCORSMode() {
 786   return AttrValueToCORSMode(GetParsedAttr(nsGkAtoms::crossorigin));
 787 }
 788
 789 JSObject* HTMLImageElement::WrapNode(JSContext* aCx,
 790                                      JS::Handle<JSObject*> aGivenProto) {
 791   return HTMLImageElement_Binding::Wrap(aCx, this, aGivenProto);
 792 }
 793
 794 #ifdef DEBUG
 795 HTMLFormElement* HTMLImageElement::GetForm() const { return mForm; }
 796 #endif
 797
 798 void HTMLImageElement::SetForm(HTMLFormElement* aForm) {
 799   MOZ_ASSERT(aForm, "Don't pass null here");
 800   NS_ASSERTION(!mForm,
 801                "We don't support switching from one non-null form to another.");
 802
 803   mForm = aForm;
 804 }
 805
 806 void HTMLImageElement::ClearForm(bool aRemoveFromForm) {
 807   NS_ASSERTION((mForm != nullptr) == HasFlag(ADDED_TO_FORM),
 808                "Form control should have had flag set correctly");
 809
 810   if (!mForm) {
 811     return;
 812   }
 813
 814   if (aRemoveFromForm) {
 815     nsAutoString nameVal, idVal;
 816     GetAttr(nsGkAtoms::name, nameVal);
 817     GetAttr(nsGkAtoms::id, idVal);
 818
 819     mForm->RemoveImageElement(this);
 820
 821     if (!nameVal.IsEmpty()) {
 822       mForm->RemoveImageElementFromTable(this, nameVal);
 823     }
 824
 825     if (!idVal.IsEmpty()) {
 826       mForm->RemoveImageElementFromTable(this, idVal);
 827     }
 828   }
 829
 830   UnsetFlags(ADDED_TO_FORM);
 831   mForm = nullptr;
 832 }
 833
 834 void HTMLImageElement::UpdateSourceSyncAndQueueImageTask(
 835     bool aAlwaysLoad, const HTMLSourceElement* aSkippedSource) {
 836   // Per spec, when updating the image data or reacting to environment
 837   // changes, we always run the full selection (including selecting the source
 838   // element and the best fit image from srcset) even if it doesn't directly
 839   // affect the source selection.
 840   //
 841   // However, in the spec of updating the image data, the selection of image
 842   // source URL is in the asynchronous part (i.e. in a microtask), and so this
 843   // doesn't guarantee that the image style is correct after we flush the style
 844   // synchornously. So here we update the responsive source synchronously always
 845   // to make sure the image source is always up-to-date after each DOM mutation.
 846   // Spec issue: https://github.com/whatwg/html/issues/8207.
 847   const bool changed = UpdateResponsiveSource(aSkippedSource);
 848
 849   // If loading is temporarily disabled, we don't want to queue tasks
 850   // that may then run when loading is re-enabled.
 851   if (!LoadingEnabled() || !ShouldLoadImage()) {
 852     return;
 853   }
 854
 855   // Ensure that we don't overwrite a previous load request that requires
 856   // a complete load to occur.
 857   bool alwaysLoad = aAlwaysLoad;
 858   if (mPendingImageLoadTask) {
 859     alwaysLoad = alwaysLoad || mPendingImageLoadTask->AlwaysLoad();
 860   }
 861
 862   if (!changed && !alwaysLoad) {
 863     return;
 864   }
 865
 866   QueueImageLoadTask(alwaysLoad);
 867 }
 868
 869 bool HTMLImageElement::HaveSrcsetOrInPicture() {
 870   if (HasAttr(nsGkAtoms::srcset)) {
 871     return true;
 872   }
 873
 874   return IsInPicture();
 875 }
 876
 877 bool HTMLImageElement::InResponsiveMode() {
 878   // When we lose srcset or leave a <picture> element, the fallback to img.src
 879   // will happen from the microtask, and we should behave responsively in the
 880   // interim
 881   return mResponsiveSelector || mPendingImageLoadTask ||
 882          HaveSrcsetOrInPicture();
 883 }
 884
 885 bool HTMLImageElement::SelectedSourceMatchesLast(nsIURI* aSelectedSource) {
 886   // If there was no selected source previously, we don't want to short-circuit
 887   // the load. Similarly for if there is no newly selected source.
 888   if (!mLastSelectedSource || !aSelectedSource) {
 889     return false;
 890   }
 891   bool equal = false;
 892   return NS_SUCCEEDED(mLastSelectedSource->Equals(aSelectedSource, &equal)) &&
 893          equal;
 894 }
 895
 896 nsresult HTMLImageElement::LoadSelectedImage(bool aForce, bool aNotify,
 897                                              bool aAlwaysLoad) {
 898   // In responsive mode, we have to make sure we ran the full selection algrithm
 899   // before loading the selected image.
 900   // Use this assertion to catch any cases we missed.
 901   MOZ_ASSERT(!UpdateResponsiveSource(),
 902              "The image source should be the same because we update the "
 903              "responsive source synchronously");
 904
 905   // The density is default to 1.0 for the src attribute case.
 906   double currentDensity = mResponsiveSelector
 907                               ? mResponsiveSelector->GetSelectedImageDensity()
 908                               : 1.0;
 909
 910   nsCOMPtr<nsIURI> selectedSource;
 911   nsCOMPtr<nsIPrincipal> triggeringPrincipal;
 912   ImageLoadType type = eImageLoadType_Normal;
 913   bool hasSrc = false;
 914   if (mResponsiveSelector) {
 915     selectedSource = mResponsiveSelector->GetSelectedImageURL();
 916     triggeringPrincipal =
 917         mResponsiveSelector->GetSelectedImageTriggeringPrincipal();
 918     type = eImageLoadType_Imageset;
 919   } else if (mSrcURI || HasAttr(nsGkAtoms::src)) {
 920     hasSrc = true;
 921     if (mSrcURI) {
 922       selectedSource = mSrcURI;
 923       if (HaveSrcsetOrInPicture()) {
 924         // If we have a srcset attribute or are in a <picture> element, we
 925         // always use the Imageset load type, even if we parsed no valid
 926         // responsive sources from either, per spec.
 927         type = eImageLoadType_Imageset;
 928       }
 929       triggeringPrincipal = mSrcTriggeringPrincipal;
 930     }
 931   }
 932
 933   if (!aAlwaysLoad && SelectedSourceMatchesLast(selectedSource)) {
 934     // Update state when only density may have changed (i.e., the source to load
 935     // hasn't changed, and we don't do any request at all). We need (apart from
 936     // updating our internal state) to tell the image frame because its
 937     // intrinsic size may have changed.
 938     //
 939     // In the case we actually trigger a new load, that load will trigger a call
 940     // to nsImageFrame::NotifyNewCurrentRequest, which takes care of that for
 941     // us.
 942     SetDensity(currentDensity);
 943     return NS_OK;
 944   }
 945
 946   // Before we actually defer the lazy-loading
 947   if (mLazyLoading) {
 948     if (!selectedSource ||
 949         !nsContentUtils::IsImageAvailable(this, selectedSource,
 950                                           triggeringPrincipal, GetCORSMode())) {
 951       return NS_OK;
 952     }
 953     StopLazyLoading(StartLoading::No);
 954   }
 955
 956   nsresult rv = NS_ERROR_FAILURE;
 957
 958   // src triggers an error event on invalid URI, unlike other loads.
 959   if (selectedSource || hasSrc) {
 960     rv = LoadImage(selectedSource, aForce, aNotify, type, triggeringPrincipal);
 961   }
 962
 963   mLastSelectedSource = selectedSource;
 964   mCurrentDensity = currentDensity;
 965
 966   if (NS_FAILED(rv)) {
 967     CancelImageRequests(aNotify);
 968   }
 969   return rv;
 970 }
 971
 972 void HTMLImageElement::PictureSourceSrcsetChanged(nsIContent* aSourceNode,
 973                                                   const nsAString& aNewValue,
 974                                                   bool aNotify) {
 975   MOZ_ASSERT(aSourceNode == this || IsPreviousSibling(aSourceNode, this),
 976              "Should not be getting notifications for non-previous-siblings");
 977
 978   nsIContent* currentSrc =
 979       mResponsiveSelector ? mResponsiveSelector->Content() : nullptr;
 980
 981   if (aSourceNode == currentSrc) {
 982     // We're currently using this node as our responsive selector
 983     // source.
 984     nsCOMPtr<nsIPrincipal> principal;
 985     if (aSourceNode == this) {
 986       principal = mSrcsetTriggeringPrincipal;
 987     } else if (auto* source = HTMLSourceElement::FromNode(aSourceNode)) {
 988       principal = source->GetSrcsetTriggeringPrincipal();
 989     }
 990     mResponsiveSelector->SetCandidatesFromSourceSet(aNewValue, principal);
 991   }
 992
 993   if (!mInDocResponsiveContent && IsInComposedDoc()) {
 994     OwnerDoc()->AddResponsiveContent(this);
 995     mInDocResponsiveContent = true;
 996   }
 997
 998   // This always triggers the image update steps per the spec, even if
 999   // we are not using this source.
1000   UpdateSourceSyncAndQueueImageTask(true);
1001 }
1002
1003 void HTMLImageElement::PictureSourceSizesChanged(nsIContent* aSourceNode,
1004                                                  const nsAString& aNewValue,
1005                                                  bool aNotify) {
1006   MOZ_ASSERT(aSourceNode == this || IsPreviousSibling(aSourceNode, this),
1007              "Should not be getting notifications for non-previous-siblings");
1008
1009   nsIContent* currentSrc =
1010       mResponsiveSelector ? mResponsiveSelector->Content() : nullptr;
1011
1012   if (aSourceNode == currentSrc) {
1013     // We're currently using this node as our responsive selector
1014     // source.
1015     mResponsiveSelector->SetSizesFromDescriptor(aNewValue);
1016   }
1017
1018   // This always triggers the image update steps per the spec, even if
1019   // we are not using this source.
1020   UpdateSourceSyncAndQueueImageTask(true);
1021 }
1022
1023 void HTMLImageElement::PictureSourceMediaOrTypeChanged(nsIContent* aSourceNode,
1024                                                        bool aNotify) {
1025   MOZ_ASSERT(IsPreviousSibling(aSourceNode, this),
1026              "Should not be getting notifications for non-previous-siblings");
1027
1028   // This always triggers the image update steps per the spec, even if
1029   // we are not switching to/from this source
1030   UpdateSourceSyncAndQueueImageTask(true);
1031 }
1032
1033 void HTMLImageElement::PictureSourceDimensionChanged(
1034     HTMLSourceElement* aSourceNode, bool aNotify) {
1035   MOZ_ASSERT(IsPreviousSibling(aSourceNode, this),
1036              "Should not be getting notifications for non-previous-siblings");
1037
1038   // "width" and "height" affect the dimension of images, but they don't have
1039   // impact on the selection of <source> elements. In other words,
1040   // UpdateResponsiveSource doesn't change the source, so all we need to do is
1041   // just request restyle.
1042   if (mResponsiveSelector && mResponsiveSelector->Content() == aSourceNode) {
1043     InvalidateAttributeMapping();
1044   }
1045 }
1046
1047 void HTMLImageElement::PictureSourceAdded(HTMLSourceElement* aSourceNode) {
1048   MOZ_ASSERT(!aSourceNode || IsPreviousSibling(aSourceNode, this),
1049              "Should not be getting notifications for non-previous-siblings");
1050
1051   UpdateSourceSyncAndQueueImageTask(true);
1052 }
1053
1054 void HTMLImageElement::PictureSourceRemoved(HTMLSourceElement* aSourceNode) {
1055   MOZ_ASSERT(!aSourceNode || IsPreviousSibling(aSourceNode, this),
1056              "Should not be getting notifications for non-previous-siblings");
1057
1058   UpdateSourceSyncAndQueueImageTask(true, aSourceNode);
1059 }
1060
1061 bool HTMLImageElement::UpdateResponsiveSource(
1062     const HTMLSourceElement* aSkippedSource) {
1063   bool hadSelector = !!mResponsiveSelector;
1064
1065   nsIContent* currentSource =
1066       mResponsiveSelector ? mResponsiveSelector->Content() : nullptr;
1067
1068   // Walk source nodes previous to ourselves if IsInPicture().
1069   nsINode* candidateSource =
1070       IsInPicture() ? GetParentElement()->GetFirstChild() : this;
1071
1072   // Initialize this as nullptr so we don't have to nullify it when runing out
1073   // of siblings without finding ourself, e.g. XBL magic.
1074   RefPtr<ResponsiveImageSelector> newResponsiveSelector = nullptr;
1075
1076   for (; candidateSource; candidateSource = candidateSource->GetNextSibling()) {
1077     if (aSkippedSource == candidateSource) {
1078       continue;
1079     }
1080
1081     if (candidateSource == currentSource) {
1082       // found no better source before current, re-run selection on
1083       // that and keep it if it's still usable.
1084       bool changed = mResponsiveSelector->SelectImage(true);
1085       if (mResponsiveSelector->NumCandidates()) {
1086         bool isUsableCandidate = true;
1087
1088         // an otherwise-usable source element may still have a media query that
1089         // may not match any more.
1090         if (candidateSource->IsHTMLElement(nsGkAtoms::source) &&
1091             !SourceElementMatches(candidateSource->AsElement())) {
1092           isUsableCandidate = false;
1093         }
1094
1095         if (isUsableCandidate) {
1096           // We are still using the current source, but the selected image may
1097           // be changed, so always set the density from the selected image.
1098           SetDensity(mResponsiveSelector->GetSelectedImageDensity());
1099           return changed;
1100         }
1101       }
1102
1103       // no longer valid
1104       newResponsiveSelector = nullptr;
1105       if (candidateSource == this) {
1106         // No further possibilities
1107         break;
1108       }
1109     } else if (candidateSource == this) {
1110       // We are the last possible source
1111       newResponsiveSelector =
1112           TryCreateResponsiveSelector(candidateSource->AsElement());
1113       break;
1114     } else if (auto* source = HTMLSourceElement::FromNode(candidateSource)) {
1115       if (RefPtr<ResponsiveImageSelector> selector =
1116               TryCreateResponsiveSelector(source)) {
1117         newResponsiveSelector = selector.forget();
1118         // This led to a valid source, stop
1119         break;
1120       }
1121     }
1122   }
1123
1124   // If we reach this point, either:
1125   // - there was no selector originally, and there is not one now
1126   // - there was no selector originally, and there is one now
1127   // - there was a selector, and there is a different one now
1128   // - there was a selector, and there is not one now
1129   SetResponsiveSelector(std::move(newResponsiveSelector));
1130   return hadSelector || mResponsiveSelector;
1131 }
1132
1133 /*static */
1134 bool HTMLImageElement::SupportedPictureSourceType(const nsAString& aType) {
1135   nsAutoString type;
1136   nsAutoString params;
1137
1138   nsContentUtils::SplitMimeType(aType, type, params);
1139   if (type.IsEmpty()) {
1140     return true;
1141   }
1142
1143   return imgLoader::SupportImageWithMimeType(
1144       NS_ConvertUTF16toUTF8(type), AcceptedMimeTypes::IMAGES_AND_DOCUMENTS);
1145 }
1146
1147 bool HTMLImageElement::SourceElementMatches(Element* aSourceElement) {
1148   MOZ_ASSERT(aSourceElement->IsHTMLElement(nsGkAtoms::source));
1149
1150   MOZ_ASSERT(IsInPicture());
1151   MOZ_ASSERT(IsPreviousSibling(aSourceElement, this));
1152
1153   // Check media and type
1154   auto* src = static_cast<HTMLSourceElement*>(aSourceElement);
1155   if (!src->MatchesCurrentMedia()) {
1156     return false;
1157   }
1158
1159   nsAutoString type;
1160   return !src->GetAttr(nsGkAtoms::type, type) ||
1161          SupportedPictureSourceType(type);
1162 }
1163
1164 already_AddRefed<ResponsiveImageSelector>
1165 HTMLImageElement::TryCreateResponsiveSelector(Element* aSourceElement) {
1166   nsCOMPtr<nsIPrincipal> principal;
1167
1168   // Skip if this is not a <source> with matching media query
1169   bool isSourceTag = aSourceElement->IsHTMLElement(nsGkAtoms::source);
1170   if (isSourceTag) {
1171     if (!SourceElementMatches(aSourceElement)) {
1172       return nullptr;
1173     }
1174     auto* source = HTMLSourceElement::FromNode(aSourceElement);
1175     principal = source->GetSrcsetTriggeringPrincipal();
1176   } else if (aSourceElement->IsHTMLElement(nsGkAtoms::img)) {
1177     // Otherwise this is the <img> tag itself
1178     MOZ_ASSERT(aSourceElement == this);
1179     principal = mSrcsetTriggeringPrincipal;
1180   }
1181
1182   // Skip if has no srcset or an empty srcset
1183   nsString srcset;
1184   if (!aSourceElement->GetAttr(nsGkAtoms::srcset, srcset)) {
1185     return nullptr;
1186   }
1187
1188   if (srcset.IsEmpty()) {
1189     return nullptr;
1190   }
1191
1192   // Try to parse
1193   RefPtr<ResponsiveImageSelector> sel =
1194       new ResponsiveImageSelector(aSourceElement);
1195   if (!sel->SetCandidatesFromSourceSet(srcset, principal)) {
1196     // No possible candidates, don't need to bother parsing sizes
1197     return nullptr;
1198   }
1199
1200   nsAutoString sizes;
1201   aSourceElement->GetAttr(nsGkAtoms::sizes, sizes);
1202   sel->SetSizesFromDescriptor(sizes);
1203
1204   // If this is the <img> tag, also pull in src as the default source
1205   if (!isSourceTag) {
1206     MOZ_ASSERT(aSourceElement == this);
1207     if (mSrcURI) {
1208       sel->SetDefaultSource(mSrcURI, mSrcTriggeringPrincipal);
1209     }
1210   }
1211
1212   return sel.forget();
1213 }
1214
1215 /* static */
1216 bool HTMLImageElement::SelectSourceForTagWithAttrs(
1217     Document* aDocument, bool aIsSourceTag, const nsAString& aSrcAttr,
1218     const nsAString& aSrcsetAttr, const nsAString& aSizesAttr,
1219     const nsAString& aTypeAttr, const nsAString& aMediaAttr,
1220     nsAString& aResult) {
1221   MOZ_ASSERT(aIsSourceTag || (aTypeAttr.IsEmpty() && aMediaAttr.IsEmpty()),
1222              "Passing type or media attrs makes no sense without aIsSourceTag");
1223   MOZ_ASSERT(!aIsSourceTag || aSrcAttr.IsEmpty(),
1224              "Passing aSrcAttr makes no sense with aIsSourceTag set");
1225
1226   if (aSrcsetAttr.IsEmpty()) {
1227     if (!aIsSourceTag) {
1228       // For an <img> with no srcset, we would always select the src attr.
1229       aResult.Assign(aSrcAttr);
1230       return true;
1231     }
1232     // Otherwise, a <source> without srcset is never selected
1233     return false;
1234   }
1235
1236   // Would not consider source tags with unsupported media or type
1237   if (aIsSourceTag &&
1238       ((!aMediaAttr.IsVoid() && !HTMLSourceElement::WouldMatchMediaForDocument(
1239                                     aMediaAttr, aDocument)) ||
1240        (!aTypeAttr.IsVoid() && !SupportedPictureSourceType(aTypeAttr)))) {
1241     return false;
1242   }
1243
1244   // Using srcset or picture <source>, build a responsive selector for this tag.
1245   RefPtr<ResponsiveImageSelector> sel = new ResponsiveImageSelector(aDocument);
1246
1247   sel->SetCandidatesFromSourceSet(aSrcsetAttr);
1248   if (!aSizesAttr.IsEmpty()) {
1249     sel->SetSizesFromDescriptor(aSizesAttr);
1250   }
1251   if (!aIsSourceTag) {
1252     sel->SetDefaultSource(aSrcAttr);
1253   }
1254
1255   if (sel->GetSelectedImageURLSpec(aResult)) {
1256     return true;
1257   }
1258
1259   if (!aIsSourceTag) {
1260     // <img> tag with no match would definitively load nothing.
1261     aResult.Truncate();
1262     return true;
1263   }
1264
1265   // <source> tags with no match would leave source yet-undetermined.
1266   return false;
1267 }
1268
1269 void HTMLImageElement::DestroyContent() {
1270   // Clear mPendingImageLoadTask to avoid running LoadSelectedImage() after
1271   // getting destroyed.
1272   mPendingImageLoadTask = nullptr;
1273
1274   mResponsiveSelector = nullptr;
1275
1276   nsImageLoadingContent::Destroy();
1277   nsGenericHTMLElement::DestroyContent();
1278 }
1279
1280 void HTMLImageElement::MediaFeatureValuesChanged() {
1281   UpdateSourceSyncAndQueueImageTask(false);
1282 }
1283
1284 bool HTMLImageElement::ShouldLoadImage() const {
1285   return OwnerDoc()->ShouldLoadImages();
1286 }
1287
1288 void HTMLImageElement::SetLazyLoading() {
1289   if (mLazyLoading) {
1290     return;
1291   }
1292
1293   // If scripting is disabled don't do lazy load.
1294   // https://whatpr.org/html/3752/images.html#updating-the-image-data
1295   //
1296   // Same for printing.
1297   Document* doc = OwnerDoc();
1298   if (!doc->IsScriptEnabled() || doc->IsStaticDocument()) {
1299     return;
1300   }
1301
1302   doc->EnsureLazyLoadImageObserver().Observe(*this);
1303   mLazyLoading = true;
1304   UpdateImageState(true);
1305 }
1306
1307 void HTMLImageElement::StartLoadingIfNeeded() {
1308   if (!LoadingEnabled() || !ShouldLoadImage()) {
1309     return;
1310   }
1311
1312   // Use script runner for the case the adopt is from appendChild.
1313   // Bug 1076583 - We still behave synchronously in the non-responsive case
1314   nsContentUtils::AddScriptRunner(
1315       InResponsiveMode()
1316           ? NewRunnableMethod<bool>("dom::HTMLImageElement::QueueImageLoadTask",
1317                                     this, &HTMLImageElement::QueueImageLoadTask,
1318                                     true)
1319           : NewRunnableMethod<bool>("dom::HTMLImageElement::MaybeLoadImage",
1320                                     this, &HTMLImageElement::MaybeLoadImage,
1321                                     true));
1322 }
1323
1324 void HTMLImageElement::StopLazyLoading(StartLoading aStartLoading) {
1325   if (!mLazyLoading) {
1326     return;
1327   }
1328   mLazyLoading = false;
1329   Document* doc = OwnerDoc();
1330   if (auto* obs = doc->GetLazyLoadImageObserver()) {
1331     obs->Unobserve(*this);
1332   }
1333
1334   if (aStartLoading == StartLoading::Yes) {
1335     StartLoadingIfNeeded();
1336   }
1337 }
1338
1339 const StyleLockedDeclarationBlock*
1340 HTMLImageElement::GetMappedAttributesFromSource() const {
1341   if (!IsInPicture() || !mResponsiveSelector) {
1342     return nullptr;
1343   }
1344
1345   const auto* source =
1346       HTMLSourceElement::FromNodeOrNull(mResponsiveSelector->Content());
1347   if (!source) {
1348     return nullptr;
1349   }
1350
1351   MOZ_ASSERT(IsPreviousSibling(source, this),
1352              "Incorrect or out-of-date source");
1353   return source->GetAttributesMappedForImage();
1354 }
1355
1356 void HTMLImageElement::InvalidateAttributeMapping() {
1357   if (!IsInPicture()) {
1358     return;
1359   }
1360
1361   nsPresContext* presContext = nsContentUtils::GetContextForContent(this);
1362   if (!presContext) {
1363     return;
1364   }
1365
1366   // Note: Unfortunately, we have to use RESTYLE_SELF, instead of using
1367   // RESTYLE_STYLE_ATTRIBUTE or other ways, to avoid re-selector-match because
1368   // we are using Gecko_GetExtraContentStyleDeclarations() to retrieve the
1369   // extra declaration block from |this|'s width and height attributes, and
1370   // other restyle hints seems not enough.
1371   // FIXME: We may refine this together with the restyle for presentation
1372   // attributes in RestyleManger::AttributeChagned()
1373   presContext->RestyleManager()->PostRestyleEvent(
1374       this, RestyleHint::RESTYLE_SELF, nsChangeHint(0));
1375 }
1376
1377 void HTMLImageElement::SetResponsiveSelector(
1378     RefPtr<ResponsiveImageSelector>&& aSource) {
1379   if (mResponsiveSelector == aSource) {
1380     return;
1381   }
1382
1383   mResponsiveSelector = std::move(aSource);
1384
1385   // Invalidate the style if needed.
1386   InvalidateAttributeMapping();
1387
1388   // Update density.
1389   SetDensity(mResponsiveSelector
1390                  ? mResponsiveSelector->GetSelectedImageDensity()
1391                  : 1.0);
1392 }
1393
1394 void HTMLImageElement::SetDensity(double aDensity) {
1395   if (mCurrentDensity == aDensity) {
1396     return;
1397   }
1398
1399   mCurrentDensity = aDensity;
1400
1401   // Invalidate the reflow.
1402   if (nsImageFrame* f = do_QueryFrame(GetPrimaryFrame())) {
1403     f->ResponsiveContentDensityChanged();
1404   }
1405 }
1406
1407 void HTMLImageElement::QueueImageLoadTask(bool aAlwaysLoad) {
1408   RefPtr<ImageLoadTask> task =
1409       new ImageLoadTask(this, aAlwaysLoad, mUseUrgentStartForChannel);
1410   // The task checks this to determine if it was the last
1411   // queued event, and so earlier tasks are implicitly canceled.
1412   mPendingImageLoadTask = task;
1413   CycleCollectedJSContext::Get()->DispatchToMicroTask(task.forget());
1414 }
1415
1416 }  // namespace mozilla::dom