Bug 1483882 - Teach IDTracker about Shadow DOM. r=smaug

Differential Revision: https://phabricator.services.mozilla.com/D3533

dom/base/DocumentOrShadowRoot.cpp

@@ -349,6 +349,18 @@ DocumentOrShadowRoot::RemoveIDTargetObserver(nsAtom* aID,
   entry->RemoveContentChangeCallback(aObserver, aData, aForImage);
 }
 
+
+Element*
+DocumentOrShadowRoot::LookupImageElement(const nsAString& aId)
+{
+  if (aId.IsEmpty()) {
+    return nullptr;
+  }
+
+  nsIdentifierMapEntry* entry = mIdentifierMap.GetEntry(aId);
+  return entry ? entry->GetImageIdElement() : nullptr;
+}
+
 void
 DocumentOrShadowRoot::ReportEmptyGetElementByIdArg()
 {

dom/base/DocumentOrShadowRoot.h

@@ -160,6 +160,15 @@ public:
   void RemoveIDTargetObserver(nsAtom* aID, IDTargetObserver aObserver,
                               void* aData, bool aForImage);
 
+  /**
+   * Lookup an image element using its associated ID, which is usually provided
+   * by |-moz-element()|. Similar to GetElementById, with the difference that
+   * elements set using mozSetImageElement have higher priority.
+   * @param aId the ID associated the element we want to lookup
+   * @return the element associated with |aId|
+   */
+  Element* LookupImageElement(const nsAString& aElementId);
+
   /**
    * Check that aId is not empty and log a message to the console
    * service if it is.

dom/base/FragmentOrElement.cpp

@@ -1464,10 +1464,6 @@ NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(FragmentOrElement)
     unbind the child nodes.
   } */
 
-  // Clear flag here because unlinking slots will clear the
-  // containing shadow root pointer.
-  tmp->UnsetFlags(NODE_IS_IN_SHADOW_TREE);
-
   if (ShadowRoot* shadowRoot = tmp->GetShadowRoot()) {
     for (nsIContent* child = shadowRoot->GetFirstChild();
          child;

dom/base/IDTracker.cpp

@@ -17,9 +17,28 @@
 namespace mozilla {
 namespace dom {
 
+static DocumentOrShadowRoot*
+DocOrShadowFromContent(nsIContent& aContent)
+{
+  ShadowRoot* shadow = aContent.GetContainingShadow();
+
+  // We never look in <svg:use> shadow trees, for backwards compat.
+  while (shadow && shadow->Host()->IsSVGElement(nsGkAtoms::use)) {
+    shadow = shadow->Host()->GetContainingShadow();
+  }
+
+  if (shadow) {
+    return shadow;
+  }
+
+  return aContent.OwnerDoc();
+}
+
 void
-IDTracker::Reset(nsIContent* aFromContent, nsIURI* aURI,
-                 bool aWatch, bool aReferenceImage)
+IDTracker::Reset(nsIContent* aFromContent,
+                 nsIURI* aURI,
+                 bool aWatch,
+                 bool aReferenceImage)
 {
   MOZ_ASSERT(aFromContent, "Reset() expects non-null content pointer");
 
@@ -34,13 +53,11 @@ IDTracker::Reset(nsIContent* aFromContent, nsIURI* aURI,
   // document charset, hopefully...
   NS_UnescapeURL(refPart);
 
-  // Get the current document
-  nsIDocument *doc = aFromContent->OwnerDoc();
-  if (!doc) {
-    return;
-  }
-
+  // Get the thing to observe changes to.
+  nsIDocument* doc = aFromContent->OwnerDoc();
+  DocumentOrShadowRoot* docOrShadow = DocOrShadowFromContent(*aFromContent);
   auto encoding = doc->GetDocumentCharacterSet();
+
   nsAutoString ref;
   nsresult rv = encoding->DecodeWithoutBOMHandling(refPart, ref);
   if (NS_FAILED(rv) || ref.IsEmpty()) {
@@ -49,7 +66,7 @@ IDTracker::Reset(nsIContent* aFromContent, nsIURI* aURI,
   rv = NS_OK;
 
   nsIContent* bindingParent = aFromContent->GetBindingParent();
-  if (bindingParent) {
+  if (bindingParent && !aFromContent->IsInShadowTree()) {
     nsXBLBinding* binding = bindingParent->GetXBLBinding();
     if (!binding) {
       // This happens, for example, if aFromContent is part of the content
@@ -100,6 +117,7 @@ IDTracker::Reset(nsIContent* aFromContent, nsIURI* aURI,
     RefPtr<nsIDocument::ExternalResourceLoad> load;
     doc = doc->RequestExternalResource(aURI, aFromContent,
                                        getter_AddRefs(load));
+    docOrShadow = doc;
     if (!doc) {
       if (!load || !aWatch) {
         // Nothing will ever happen here
@@ -109,9 +127,7 @@ IDTracker::Reset(nsIContent* aFromContent, nsIURI* aURI,
       DocumentLoadNotification* observer =
         new DocumentLoadNotification(this, ref);
       mPendingNotification = observer;
-      if (observer) {
-        load->AddObserver(observer);
-      }
+      load->AddObserver(observer);
       // Keep going so we set up our watching stuff a bit
     }
   }
@@ -124,51 +140,49 @@ IDTracker::Reset(nsIContent* aFromContent, nsIURI* aURI,
   }
 
   mReferencingImage = aReferenceImage;
-
-  HaveNewDocument(doc, aWatch, ref);
+  HaveNewDocumentOrShadowRoot(docOrShadow, aWatch, ref);
 }
 
 void
-IDTracker::ResetWithID(nsIContent* aFromContent, const nsString& aID,
+IDTracker::ResetWithID(nsIContent* aFromContent,
+                       nsAtom* aID,
                        bool aWatch)
 {
-  nsIDocument *doc = aFromContent->OwnerDoc();
-  if (!doc)
-    return;
-
-  // XXX Need to take care of XBL/XBL2
+  MOZ_ASSERT(aFromContent);
+  MOZ_ASSERT(aID);
 
   if (aWatch) {
-    RefPtr<nsAtom> atom = NS_Atomize(aID);
-    if (!atom)
-      return;
+    RefPtr<nsAtom> atom = aID;
     atom.swap(mWatchID);
   }
 
   mReferencingImage = false;
 
-  HaveNewDocument(doc, aWatch, aID);
+  DocumentOrShadowRoot* docOrShadow = DocOrShadowFromContent(*aFromContent);
+  HaveNewDocumentOrShadowRoot(docOrShadow, aWatch, nsDependentAtomString(aID));
 }
 
 void
-IDTracker::HaveNewDocument(nsIDocument* aDocument, bool aWatch,
-                           const nsString& aRef)
+IDTracker::HaveNewDocumentOrShadowRoot(
+  DocumentOrShadowRoot* aDocOrShadow,
+  bool aWatch,
+  const nsString& aRef)
 {
   if (aWatch) {
-    mWatchDocument = aDocument;
-    if (mWatchDocument) {
-      mElement = mWatchDocument->AddIDTargetObserver(mWatchID, Observe, this,
-                                                     mReferencingImage);
+    mWatchDocumentOrShadowRoot = nullptr;
+    if (aDocOrShadow) {
+      mWatchDocumentOrShadowRoot = &aDocOrShadow->AsNode();
+      mElement = aDocOrShadow->AddIDTargetObserver(mWatchID, Observe, this, mReferencingImage);
     }
     return;
   }
 
-  if (!aDocument) {
+  if (!aDocOrShadow) {
     return;
   }
 
-  Element *e = mReferencingImage ? aDocument->LookupImageElement(aRef) :
-                                   aDocument->GetElementById(aRef);
+  Element* e = mReferencingImage ? aDocOrShadow->LookupImageElement(aRef)
+                                 : aDocOrShadow->GetElementById(aRef);
   if (e) {
     mElement = e;
   }
@@ -177,32 +191,33 @@ IDTracker::HaveNewDocument(nsIDocument* aDocument, bool aWatch,
 void
 IDTracker::Traverse(nsCycleCollectionTraversalCallback* aCB)
 {
-  NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(*aCB, "mWatchDocument");
-  aCB->NoteXPCOMChild(mWatchDocument);
-  NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(*aCB, "mContent");
+  NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(*aCB, "mWatchDocumentOrShadowRoot");
+  aCB->NoteXPCOMChild(mWatchDocumentOrShadowRoot);
+  NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(*aCB, "mElement");
   aCB->NoteXPCOMChild(mElement);
 }
 
 void
 IDTracker::Unlink()
 {
-  if (mWatchDocument && mWatchID) {
-    mWatchDocument->RemoveIDTargetObserver(mWatchID, Observe, this,
-                                           mReferencingImage);
+  if (mWatchID) {
+    if (DocumentOrShadowRoot* docOrShadow = GetWatchDocOrShadowRoot()) {
+      docOrShadow->RemoveIDTargetObserver(
+        mWatchID, Observe, this, mReferencingImage);
+    }
   }
   if (mPendingNotification) {
     mPendingNotification->Clear();
     mPendingNotification = nullptr;
   }
-  mWatchDocument = nullptr;
+  mWatchDocumentOrShadowRoot = nullptr;
   mWatchID = nullptr;
   mElement = nullptr;
   mReferencingImage = false;
 }
 
 bool
-IDTracker::Observe(Element* aOldElement,
-                   Element* aNewElement, void* aData)
+IDTracker::Observe(Element* aOldElement, Element* aNewElement, void* aData)
 {
   IDTracker* p = static_cast<IDTracker*>(aData);
   if (p->mPendingNotification) {
@@ -216,17 +231,14 @@ IDTracker::Observe(Element* aOldElement,
   }
   bool keepTracking = p->IsPersistent();
   if (!keepTracking) {
-    p->mWatchDocument = nullptr;
+    p->mWatchDocumentOrShadowRoot = nullptr;
     p->mWatchID = nullptr;
   }
   return keepTracking;
 }
 
-NS_IMPL_ISUPPORTS_INHERITED0(IDTracker::ChangeNotification,
-                             mozilla::Runnable)
-
-NS_IMPL_ISUPPORTS(IDTracker::DocumentLoadNotification,
-                  nsIObserver)
+NS_IMPL_ISUPPORTS_INHERITED0(IDTracker::ChangeNotification, mozilla::Runnable)
+NS_IMPL_ISUPPORTS(IDTracker::DocumentLoadNotification, nsIObserver)
 
 NS_IMETHODIMP
 IDTracker::DocumentLoadNotification::Observe(nsISupports* aSubject,
@@ -241,7 +253,7 @@ IDTracker::DocumentLoadNotification::Observe(nsISupports* aSubject,
     NS_ASSERTION(!mTarget->mElement, "Why do we have content here?");
     // If we got here, that means we had Reset() called with aWatch ==
     // true.  So keep watching if IsPersistent().
-    mTarget->HaveNewDocument(doc, mTarget->IsPersistent(), mRef);
+    mTarget->HaveNewDocumentOrShadowRoot(doc, mTarget->IsPersistent(), mRef);
     mTarget->ElementChanged(nullptr, mTarget->mElement);
   }
   return NS_OK;

dom/base/IDTracker.h

@@ -9,6 +9,7 @@
 
 #include "mozilla/Attributes.h"
 #include "mozilla/dom/Element.h"
+#include "mozilla/dom/ShadowRoot.h"
 #include "nsAtom.h"
 #include "nsIDocument.h"
 #include "nsThreadUtils.h"
@@ -39,10 +40,10 @@ class IDTracker {
 public:
   typedef mozilla::dom::Element Element;
 
-  IDTracker()
-    : mReferencingImage(false)
-  {}
-  ~IDTracker() {
+  IDTracker() = default;
+
+  ~IDTracker()
+  {
     Unlink();
   }
 
@@ -63,7 +64,9 @@ public:
    * @param aReferenceImage whether the ID references image elements which are
    * subject to the document's mozSetImageElement overriding mechanism.
    */
-  void Reset(nsIContent* aFrom, nsIURI* aURI, bool aWatch = true,
+  void Reset(nsIContent* aFrom,
+             nsIURI* aURI,
+             bool aWatch = true,
              bool aReferenceImage = false);
 
   /**
@@ -75,8 +78,7 @@ public:
    * changes, so ElementChanged won't fire and get() will always return the same
    * value, the current element for the ID.
    */
-  void ResetWithID(nsIContent* aFrom, const nsString& aID,
-                   bool aWatch = true);
+  void ResetWithID(nsIContent* aFrom, nsAtom* aID, bool aWatch = true);
 
   /**
    * Clears the reference. ElementChanged is not triggered. get() will return
@@ -92,7 +94,8 @@ protected:
    * to call this superclass method to change mElement. This is called
    * at script-runnable time.
    */
-  virtual void ElementChanged(Element* aFrom, Element* aTo) {
+  virtual void ElementChanged(Element* aFrom, Element* aTo)
+  {
     mElement = aTo;
   }
 
@@ -106,8 +109,9 @@ protected:
    * Set ourselves up with our new document.  Note that aDocument might be
    * null.  Either aWatch must be false or aRef must be empty.
    */
-  void HaveNewDocument(nsIDocument* aDocument, bool aWatch,
-                       const nsString& aRef);
+  void HaveNewDocumentOrShadowRoot(DocumentOrShadowRoot*,
+                                   bool aWatch,
+                                   const nsString& aRef);
 
 private:
   static bool Observe(Element* aOldElement,
@@ -167,9 +171,8 @@ private:
                                    public nsIObserver
   {
   public:
-    DocumentLoadNotification(IDTracker* aTarget,
-                             const nsString& aRef) :
-      Notification(aTarget)
+    DocumentLoadNotification(IDTracker* aTarget, const nsString& aRef)
+      : Notification(aTarget)
     {
       if (!mTarget->IsPersistent()) {
         mRef = aRef;
@@ -187,11 +190,24 @@ private:
   };
   friend class DocumentLoadNotification;
 
-  RefPtr<nsAtom>      mWatchID;
-  nsCOMPtr<nsIDocument>  mWatchDocument;
+  DocumentOrShadowRoot* GetWatchDocOrShadowRoot() const
+  {
+    if (!mWatchDocumentOrShadowRoot) {
+      return nullptr;
+    }
+    MOZ_ASSERT(mWatchDocumentOrShadowRoot->IsDocument() ||
+               mWatchDocumentOrShadowRoot->IsShadowRoot());
+    if (ShadowRoot* shadow = ShadowRoot::FromNode(*mWatchDocumentOrShadowRoot)) {
+      return shadow;
+    }
+    return mWatchDocumentOrShadowRoot->AsDocument();
+  }
+
+  RefPtr<nsAtom> mWatchID;
+  nsCOMPtr<nsINode> mWatchDocumentOrShadowRoot; // Always a `DocumentOrShadowRoot`.
   RefPtr<Element> mElement;
   RefPtr<Notification> mPendingNotification;
-  bool                   mReferencingImage;
+  bool mReferencingImage = false;
 };
 
 inline void

dom/base/nsDocument.cpp

@@ -4953,16 +4953,6 @@ nsIDocument::MozSetImageElement(const nsAString& aImageElementId,
   }
 }
 
-Element*
-nsIDocument::LookupImageElement(const nsAString& aId)
-{
-  if (aId.IsEmpty())
-    return nullptr;
-
-  nsIdentifierMapEntry* entry = mIdentifierMap.GetEntry(aId);
-  return entry ? entry->GetImageIdElement() : nullptr;
-}
-
 void
 nsIDocument::DispatchContentLoadedEvents()
 {

dom/base/nsIDocument.h

@@ -2844,15 +2844,6 @@ public:
   using mozilla::dom::DocumentOrShadowRoot::GetElementsByTagNameNS;
   using mozilla::dom::DocumentOrShadowRoot::GetElementsByClassName;
 
-  /**
-   * Lookup an image element using its associated ID, which is usually provided
-   * by |-moz-element()|. Similar to GetElementById, with the difference that
-   * elements set using mozSetImageElement have higher priority.
-   * @param aId the ID associated the element we want to lookup
-   * @return the element associated with |aId|
-   */
-  Element* LookupImageElement(const nsAString& aElementId);
-
   mozilla::dom::DocumentTimeline* Timeline();
   mozilla::LinkedList<mozilla::dom::DocumentTimeline>& Timelines()
   {

dom/smil/nsSMILTimeValueSpec.cpp

@@ -105,8 +105,7 @@ nsSMILTimeValueSpec::ResolveReferences(nsIContent* aContextNode)
   RefPtr<Element> oldReferencedElement = mReferencedElement.get();
 
   if (mParams.mDependentElemID) {
-    mReferencedElement.ResetWithID(aContextNode,
-        nsDependentAtomString(mParams.mDependentElemID));
+    mReferencedElement.ResetWithID(aContextNode, mParams.mDependentElemID);
   } else if (mParams.mType == nsSMILTimeValueSpecParams::EVENT) {
     Element* target = mOwner->GetTargetElement();
     mReferencedElement.ResetWithElement(target);

layout/reftests/svg/fragid-shadow-1.html

@@ -0,0 +1,22 @@
+<!doctype html>
+<svg style="position: absolute; width: 0; height: 0">
+  <defs>
+    <pattern id="rect" width="100" height="100">
+      <rect fill="red" width="100" height="100" />
+    </pattern>
+  </defs>
+</svg>
+<div id="host"></div>
+<script>
+  // Should peek the pattern from the shadow root (green), not from the document (red).
+  host.attachShadow({ mode: "open" }).innerHTML = `
+    <svg width="100" height="100">
+      <defs>
+        <pattern id="rect" width="100" height="100">
+          <rect fill="lime" width="100" height="100" />
+        </pattern>
+      </defs>
+      <rect fill="url(#rect)" width="100" height="100" />
+    </svg>
+  `;
+</script>

layout/reftests/svg/fragid-shadow-2.html

@@ -0,0 +1,17 @@
+<!doctype html>
+<div id="host"></div>
+<script>
+  // Test dynamic id changes inside the shadow root.
+  host.attachShadow({ mode: "open" }).innerHTML = `
+    <svg width="100" height="100">
+      <defs>
+        <pattern id="rect1" width="100" height="100">
+          <rect fill="lime" width="100" height="100" />
+        </pattern>
+      </defs>
+      <rect fill="url(#rect)" width="100" height="100" />
+    </svg>
+  `;
+  document.body.offsetTop;
+  host.shadowRoot.getElementById("rect1").id = "rect";
+</script>

layout/reftests/svg/fragid-shadow-3.html

@@ -0,0 +1,14 @@
+<!doctype html>
+<div id="host"></div>
+<svg height="0">
+  <!-- use an empty g to force fragid-shadow-resource.svg to load before onload -->
+  <use href="fragid-shadow-resource.svg#empty">
+</svg>
+<script>
+  // Test that external resource URIs resolve properly inside shadow trees.
+  host.attachShadow({ mode: "open" }).innerHTML = `
+    <svg width="100" height="100">
+      <rect fill="url(fragid-shadow-resource.svg#rect)" width="100" height="100" />
+    </svg>
+  `;
+</script>

layout/reftests/svg/fragid-shadow-4.html

@@ -0,0 +1,13 @@
+<!doctype html>
+<div id="host"></div>
+<script>
+  // Test references in <svg:use> work properly.
+  host.attachShadow({ mode: "open" }).innerHTML = `
+    <svg width="100" height="100">
+      <defs>
+        <rect fill="lime" id="rect-4" width="100" height="100">
+      </defs>
+      <use href="#rect-4" />
+    </svg>
+  `;
+</script>

layout/reftests/svg/fragid-shadow-5.html

@@ -0,0 +1,13 @@
+<!doctype html>
+<div id="host"></div>
+<script>
+  // Test absolute URIs inside shadow trees, which behave the same way as just the fragment id.
+  host.attachShadow({ mode: "open" }).innerHTML = `
+    <svg width="100" height="100">
+      <defs>
+        <rect fill="lime" id="rect-5" width="100" height="100">
+      </defs>
+      <use href="${location.href}#rect-5" />
+    </svg>
+  `;
+</script>

layout/reftests/svg/fragid-shadow-6.html

@@ -0,0 +1,23 @@
+<!doctype html>
+<svg style="position: absolute; width: 0; height: 0">
+  <defs>
+    <pattern id="rect" width="100" height="100">
+      <rect fill="red" width="100" height="100" />
+    </pattern>
+  </defs>
+</svg>
+<div id="host"></div>
+<script>
+  // Should peek the pattern from the shadow root (green), not from the document (red),
+  // even though the uri is absolute.
+  host.attachShadow({ mode: "open" }).innerHTML = `
+    <svg width="100" height="100">
+      <defs>
+        <pattern id="rect" width="100" height="100">
+          <rect fill="lime" width="100" height="100" />
+        </pattern>
+      </defs>
+      <rect fill="url(${location.href}#rect)" width="100" height="100" />
+    </svg>
+  `;
+</script>

layout/reftests/svg/fragid-shadow-7.html

@@ -0,0 +1,28 @@
+<!doctype html>
+<svg style="position: absolute; width: 0; height: 0">
+  <defs>
+    <pattern id="rect" width="100" height="100">
+      <rect fill="red" width="100" height="100" />
+    </pattern>
+  </defs>
+</svg>
+<div id="host"></div>
+<script>
+  // Test references from a <svg:use> subtree.
+  host.attachShadow({ mode: "open" }).innerHTML = `
+    <svg width="100" height="100">
+      <defs>
+        <pattern id="rect" width="100" height="100">
+          <rect fill="lime" width="100" height="100" />
+        </pattern>
+        <symbol id="useme">
+          <pattern id="rect" width="100" height="100">
+            <rect fill="red" width="100" height="100" />
+          </pattern>
+          <rect fill="url(#rect)" width="100" height="100" />
+        </symbol>
+      </defs>
+      <use href="#useme" />
+    </svg>
+  `;
+</script>

layout/reftests/svg/fragid-shadow-8.html

@@ -0,0 +1,15 @@
+<!doctype html>
+<svg width="100" height="100">
+  <defs>
+    <pattern id="rect" width="100" height="100">
+      <rect fill="lime" width="100" height="100" />
+    </pattern>
+    <symbol id="useme">
+      <pattern id="rect" width="100" height="100">
+        <rect fill="red" width="100" height="100" />
+      </pattern>
+      <rect fill="url(#rect)" width="100" height="100" />
+    </symbol>
+  </defs>
+  <use href="#useme" />
+</svg>

layout/reftests/svg/fragid-shadow-ref.html

@@ -0,0 +1,4 @@
+<!doctype html>
+<svg width="100" height="100">
+  <rect fill="lime" width="100" height="100" />
+</svg>

layout/reftests/svg/fragid-shadow-resource.svg

@@ -0,0 +1,8 @@
+<svg xmlns="http://www.w3.org/2000/svg">
+  <defs>
+    <g id="empty" />
+    <pattern id="rect" width="100" height="100">
+      <rect fill="lime" width="100" height="100" />
+    </pattern>
+  </defs>
+</svg>

layout/reftests/svg/reftest.list

@@ -552,3 +552,13 @@ fuzzy-if(skiaContent,0-1,0-100) == tspan-xy-anchor-end-01.svg tspan-xy-anchor-en
 == currentColor-override-flood.svg pass.svg
 == currentColor-override-lighting.svg currentColor-override-lighting-ref.svg
 == currentColor-override-stop.svg pass.svg
+
+# Shadow DOM id tracking.
+pref(dom.webcomponents.shadowdom.enabled,true) == fragid-shadow-1.html fragid-shadow-ref.html
+pref(dom.webcomponents.shadowdom.enabled,true) == fragid-shadow-2.html fragid-shadow-ref.html
+pref(dom.webcomponents.shadowdom.enabled,true) == fragid-shadow-3.html fragid-shadow-ref.html
+pref(dom.webcomponents.shadowdom.enabled,true) == fragid-shadow-4.html fragid-shadow-ref.html
+pref(dom.webcomponents.shadowdom.enabled,true) == fragid-shadow-5.html fragid-shadow-ref.html
+pref(dom.webcomponents.shadowdom.enabled,true) == fragid-shadow-6.html fragid-shadow-ref.html
+pref(dom.webcomponents.shadowdom.enabled,true) == fragid-shadow-7.html fragid-shadow-ref.html
+pref(dom.webcomponents.shadowdom.enabled,true) == fragid-shadow-8.html fragid-shadow-ref.html