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  77 // Calls LoadSelectedImage on host element unless it has been superseded or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