[view-transitions] Implement matching for view transition classes

LayoutTests/TestExpectations

@@ -7596,16 +7596,6 @@ imported/w3c/web-platform-tests/css/css-view-transitions/web-animations-api-pars
 # Test doesn't seem to pass on Chrome Canary.
 imported/w3c/web-platform-tests/css/css-view-transitions/view-transition-types-mutable-no-document-element-crashtest.html [ Skip ]
 
-# View transitions Level 2 - classes.
-imported/w3c/web-platform-tests/css/css-view-transitions/pseudo-with-classes-entry.html [ ImageOnlyFailure ]
-imported/w3c/web-platform-tests/css/css-view-transitions/pseudo-with-classes-exit.html [ ImageOnlyFailure ]
-imported/w3c/web-platform-tests/css/css-view-transitions/pseudo-with-classes-mismatch-ident.html [ ImageOnlyFailure ]
-imported/w3c/web-platform-tests/css/css-view-transitions/pseudo-with-classes-mismatch-partial.html [ ImageOnlyFailure ]
-imported/w3c/web-platform-tests/css/css-view-transitions/pseudo-with-classes-mismatch-wildcard.html [ ImageOnlyFailure ]
-imported/w3c/web-platform-tests/css/css-view-transitions/pseudo-with-classes-old-with-class-new-without.html [ ImageOnlyFailure ]
-imported/w3c/web-platform-tests/css/css-view-transitions/shadow-part-with-class-inside-shadow-important.html [ ImageOnlyFailure ]
-imported/w3c/web-platform-tests/css/css-view-transitions/shadow-part-with-class-inside-shadow.html [ ImageOnlyFailure ]
-
 # View transitions Level 2 - cross document transitions.
 imported/w3c/web-platform-tests/css/css-view-transitions/navigation/chromium-paint-holding-timeout.html [ ImageOnlyFailure ]
 imported/w3c/web-platform-tests/css/css-view-transitions/navigation/no-view-transition-with-cross-origin-redirect.sub.html [ ImageOnlyFailure ]

Source/WTF/Scripts/Preferences/UnifiedWebPreferences.yaml

@@ -7555,16 +7555,16 @@ ViewGestureDebuggingEnabled:
 ViewTransitionClassesEnabled:
   type: bool
   category: animation
-  status: testable
+  status: stable
   humanReadableName: "View Transition Classes"
   humanReadableDescription: "Support specifying classes for view transitions"
   defaultValue:
     WebKitLegacy:
-      default: false
+      default: true
     WebKit:
-      default: false
+      default: true
     WebCore:
-      default: false
+      default: true
 
 ViewTransitionTypesEnabled:
   type: bool

Source/WebCore/css/CSSSelector.cpp

@@ -385,6 +385,13 @@ static void appendPossiblyQuotedIdentifier(StringBuilder& builder, const Possibl
         serializeString(identifier.identifier, builder);
 }
 
+WTF::TextStream& operator<<(WTF::TextStream& ts, PossiblyQuotedIdentifier identifier)
+{
+    StringBuilder builder;
+    appendPossiblyQuotedIdentifier(builder, identifier);
+    return ts << builder.toString();
+}
+
 static void appendCommaSeparatedPossiblyQuotedIdentifierList(StringBuilder& builder, const FixedVector<PossiblyQuotedIdentifier>& list)
 {
     builder.append(interleave(list, appendPossiblyQuotedIdentifier, ", "_s));

Source/WebCore/css/CSSSelector.h

@@ -39,6 +39,8 @@ struct PossiblyQuotedIdentifier {
     bool isNull() const { return identifier.isNull(); }
 };
 
+WTF::TextStream& operator<<(WTF::TextStream&, PossiblyQuotedIdentifier);
+
 enum class SelectorSpecificityIncrement {
     ClassA = 0x10000,
     ClassB = 0x100,

Source/WebCore/css/SelectorChecker.cpp

@@ -1271,9 +1271,19 @@ bool SelectorChecker::checkOne(CheckingContext& checkingContext, LocalContext& c
             if (checkingContext.pseudoId != CSSSelector::pseudoId(selector.pseudoElement()) || !selector.argumentList())
                 return false;
 
-            // Wildcard always matches.
-            auto& argument = selector.argumentList()->first();
-            return argument == starAtom() || argument == checkingContext.pseudoElementNameArgument;
+            auto& list = *selector.argumentList();
+            auto& name = list.first();
+            if (name != starAtom() && name != checkingContext.pseudoElementNameArgument)
+                return false;
+
+            if (list.size() == 1)
+                return true;
+
+            return std::ranges::all_of(list.begin() + 1, list.end(),
+                [&](const PossiblyQuotedIdentifier& classSelector) {
+                    return checkingContext.classList.contains(classSelector.identifier);
+                }
+            );
         }
 
         default:

Source/WebCore/css/SelectorChecker.h

@@ -86,6 +86,7 @@ class SelectorChecker {
         PseudoId pseudoId { PseudoId::None };
         AtomString pseudoElementNameArgument;
         std::optional<StyleScrollbarState> scrollbarState;
+        Vector<AtomString> classList;
         RefPtr<const ContainerNode> scope;
         const Element* hasScope { nullptr };
         bool matchesAllHasScopes { false };

Source/WebCore/dom/ViewTransition.cpp

@@ -331,6 +331,21 @@ static ExceptionOr<void> checkDuplicateViewTransitionName(const AtomString& name
     return { };
 }
 
+static Vector<AtomString> effectiveViewTransitionClassList(RenderLayerModelObject& renderer, Element& originatingElement, Style::Scope& documentScope)
+{
+    auto classList = renderer.style().viewTransitionClasses();
+    if (classList.isEmpty())
+        return { };
+
+    auto scope = Style::Scope::forOrdinal(originatingElement, classList.first().scopeOrdinal);
+    if (!scope || scope != &documentScope)
+        return { };
+
+    return WTF::map(classList, [&](auto& item) {
+        return item.name;
+    });
+}
+
 static LayoutRect captureOverflowRect(RenderLayerModelObject& renderer)
 {
     if (!renderer.hasLayer())
@@ -465,6 +480,10 @@ ExceptionOr<void> ViewTransition::captureOldState()
             capture.oldImage = snapshotElementVisualOverflowClippedToViewport(*frame, renderer.get(), capture.oldOverflowRect);
         capture.oldLayerToLayoutOffset = layerToLayoutOffset(renderer.get());
 
+        auto styleable = Styleable::fromRenderer(renderer);
+        ASSERT(styleable);
+        capture.classList = effectiveViewTransitionClassList(renderer, styleable->element, document()->styleScope());
+
         auto transitionName = renderer->style().viewTransitionName();
         m_namedElements.add(transitionName->name, capture);
     }
@@ -495,7 +514,9 @@ ExceptionOr<void> ViewTransition::captureNewState()
                     CapturedElement capturedElement;
                     m_namedElements.add(name, capturedElement);
                 }
-                m_namedElements.find(name)->newElement = *styleable;
+                auto namedElement = m_namedElements.find(name);
+                namedElement->classList = effectiveViewTransitionClassList(renderer, styleable->element, document()->styleScope());
+                namedElement->newElement = *styleable;
             }
             return { };
         }, *view->layer());

Source/WebCore/dom/ViewTransition.h

@@ -66,6 +66,7 @@ struct CapturedElement {
     LayoutSize oldSize;
     RefPtr<MutableStyleProperties> oldProperties;
     WeakStyleable newElement;
+    Vector<AtomString> classList;
 
     RefPtr<MutableStyleProperties> groupStyleProperties;
 };

Source/WebCore/rendering/updating/RenderTreeUpdater.cpp

@@ -372,15 +372,15 @@ void RenderTreeUpdater::updateAfterDescendants(Element& element, const Style::El
 
 static bool pseudoStyleCacheIsInvalid(RenderElement* renderer, RenderStyle* newStyle)
 {
-    const RenderStyle& currentStyle = renderer->style();
+    const auto& currentStyle = renderer->style();
 
-    const PseudoStyleCache* pseudoStyleCache = currentStyle.cachedPseudoStyles();
+    const auto* pseudoStyleCache = currentStyle.cachedPseudoStyles();
     if (!pseudoStyleCache)
         return false;
 
     for (auto& cache : pseudoStyleCache->styles) {
-        PseudoId pseudoId = cache->pseudoElementType();
-        std::unique_ptr<RenderStyle> newPseudoStyle = renderer->getUncachedPseudoStyle({ pseudoId }, newStyle, newStyle);
+        Style::PseudoElementIdentifier pseudoElementIdentifier { cache->pseudoElementType(), cache->pseudoElementNameArgument() };
+        auto newPseudoStyle = renderer->getUncachedPseudoStyle(pseudoElementIdentifier, newStyle, newStyle);
         if (!newPseudoStyle)
             return true;
         if (*newPseudoStyle != *cache) {

Source/WebCore/style/ElementRuleCollector.cpp

@@ -453,6 +453,21 @@ void ElementRuleCollector::matchUARules(const RuleSet& rules)
     sortAndTransferMatchedRules(DeclarationOrigin::UserAgent);
 }
 
+static Vector<AtomString> classListForNamedViewTransitionPseudoElement(const Document& document, const AtomString& name)
+{
+    auto* activeViewTransition = document.activeViewTransition();
+    if (!activeViewTransition)
+        return { };
+
+    ASSERT(!name.isNull());
+
+    auto* capturedElement = activeViewTransition->namedElements().find(name);
+    if (!capturedElement)
+        return { };
+
+    return capturedElement->classList;
+}
+
 inline bool ElementRuleCollector::ruleMatches(const RuleData& ruleData, unsigned& specificity, ScopeOrdinal styleScopeOrdinal, const ContainerNode* scopingRoot)
 {
     // We know a sufficiently simple single part selector matches simply because we found it from the rule hash when filtering the RuleSet.
@@ -508,6 +523,8 @@ inline bool ElementRuleCollector::ruleMatches(const RuleData& ruleData, unsigned
         context.pseudoId = m_pseudoElementRequest->pseudoId();
         context.pseudoElementNameArgument = m_pseudoElementRequest->nameArgument();
         context.scrollbarState = m_pseudoElementRequest->scrollbarState();
+        if (isNamedViewTransitionPseudoElement(m_pseudoElementRequest->identifier()))
+            context.classList = classListForNamedViewTransitionPseudoElement(element().document(), context.pseudoElementNameArgument);
     }
     context.styleScopeOrdinal = styleScopeOrdinal;
     context.selectorMatchingState = m_selectorMatchingState;