[web-animations] keyframes should be recomputed when "bolder" or "lig…

…hter" is used on a "font-weight" property

https://bugs.webkit.org/show_bug.cgi?id=251493

Reviewed by Antti Koivisto.

Keyframes can set the "font-weight" property to "bolder" or "lighter". When such values are used, we
recompute keyframes if the inherited "font-weight" value changes while an animation is active.

* LayoutTests/imported/w3c/web-platform-tests/web-animations/responsive/fontWeight-expected.txt:
* Source/WebCore/animation/KeyframeEffect.cpp:
(WebCore::KeyframeEffect::updateBlendingKeyframes):
(WebCore::KeyframeEffect::computeCSSAnimationBlendingKeyframes):
* Source/WebCore/animation/KeyframeEffect.h:
(WebCore::KeyframeEffect::hasRelativeFontWeight const):
* Source/WebCore/animation/KeyframeEffectStack.cpp:
(WebCore::KeyframeEffectStack::applyKeyframeEffects):
* Source/WebCore/style/StyleResolver.cpp:
(WebCore::Style::Resolver::keyframeStylesForAnimation):
* Source/WebCore/style/StyleResolver.h:

Canonical link: https://commits.webkit.org/259740@main

LayoutTests/imported/w3c/web-platform-tests/web-animations/responsive/fontWeight-expected.txt

@@ -1,4 +1,4 @@
 
-FAIL Relative font weight bolder responsive to style changes assert_not_equals: got disallowed value "400"
-FAIL Relative font weight lighter responsive to style changes assert_not_equals: got disallowed value "700"
+PASS Relative font weight bolder responsive to style changes
+PASS Relative font weight lighter responsive to style changes
 

Source/WebCore/animation/KeyframeEffect.cpp

@@ -896,6 +896,7 @@ void KeyframeEffect::updateBlendingKeyframes(RenderStyle& elementStyle, const St
     m_inheritedProperties.clear();
     m_currentColorProperties.clear();
     m_containsCSSVariableReferences = false;
+    m_hasRelativeFontWeight = false;
 
     for (auto& keyframe : m_parsedKeyframes) {
         KeyframeValue keyframeValue(keyframe.computedOffset, nullptr);
@@ -927,6 +928,8 @@ void KeyframeEffect::updateBlendingKeyframes(RenderStyle& elementStyle, const St
                         m_inheritedProperties.add(property.id());
                     else if (valueId == CSSValueCurrentcolor)
                         m_currentColorProperties.add(property.id());
+                    else if (property.id() == CSSPropertyFontWeight && (valueId == CSSValueBolder || valueId == CSSValueLighter))
+                        m_hasRelativeFontWeight = true;
                 }
             }
         }
@@ -1072,7 +1075,7 @@ void KeyframeEffect::computeCSSAnimationBlendingKeyframes(const RenderStyle& una
 
     KeyframeList keyframeList(AtomString { backingAnimation.name().string });
     if (auto* styleScope = Style::Scope::forOrdinal(*m_target, backingAnimation.nameStyleScopeOrdinal()))
-        styleScope->resolver().keyframeStylesForAnimation(*m_target, unanimatedStyle, resolutionContext, keyframeList, m_containsCSSVariableReferences, m_inheritedProperties, m_currentColorProperties);
+        styleScope->resolver().keyframeStylesForAnimation(*m_target, unanimatedStyle, resolutionContext, keyframeList, m_containsCSSVariableReferences, m_hasRelativeFontWeight, m_inheritedProperties, m_currentColorProperties);
 
     // Ensure resource loads for all the frames.
     for (auto& keyframe : keyframeList) {

Source/WebCore/animation/KeyframeEffect.h

@@ -183,6 +183,7 @@ class KeyframeEffect : public AnimationEffect, public CSSPropertyBlendingClient
     bool hasExplicitlyInheritedKeyframeProperty() const { return m_hasExplicitlyInheritedKeyframeProperty; }
     bool hasPropertySetToCurrentColor() const;
     bool hasColorSetToCurrentColor() const;
+    bool hasRelativeFontWeight() const { return m_hasRelativeFontWeight; }
 
 private:
     KeyframeEffect(Element*, PseudoId);
@@ -268,6 +269,7 @@ class KeyframeEffect : public AnimationEffect, public CSSPropertyBlendingClient
     bool m_hasKeyframeComposingAcceleratedProperty { false };
     bool m_containsCSSVariableReferences { false };
     bool m_hasExplicitlyInheritedKeyframeProperty { false };
+    bool m_hasRelativeFontWeight { false };
 };
 
 } // namespace WebCore

Source/WebCore/animation/KeyframeEffectStack.cpp

@@ -197,8 +197,13 @@ OptionSet<AnimationImpact> KeyframeEffectStack::applyKeyframeEffects(RenderStyle
                 && previousLastStyleChangeEventStyle->color() != targetStyle.color();
         };
 
+        auto fontWeightChanged = [&]() {
+            return effect->hasRelativeFontWeight() && previousLastStyleChangeEventStyle
+                && previousLastStyleChangeEventStyle->fontWeight() != targetStyle.fontWeight();
+        };
+
         auto logicalPropertyDidChange = propertyAffectingLogicalPropertiesChanged && effect->animatesDirectionAwareProperty();
-        if (logicalPropertyDidChange || fontSizeChanged || inheritedPropertyChanged() || cssVariableChanged() || currentColorPropertyChanged())
+        if (logicalPropertyDidChange || fontSizeChanged || inheritedPropertyChanged() || cssVariableChanged() || currentColorPropertyChanged() || fontWeightChanged())
             effect->propertyAffectingKeyframeResolutionDidChange(unanimatedStyle, resolutionContext);
 
         animation->resolve(targetStyle, resolutionContext);

Source/WebCore/style/StyleResolver.cpp

@@ -430,7 +430,7 @@ Vector<Ref<StyleRuleKeyframe>> Resolver::keyframeRulesForName(const AtomString&
     return deduplicatedKeyframes;
 }
 
-void Resolver::keyframeStylesForAnimation(const Element& element, const RenderStyle& elementStyle, const ResolutionContext& context, KeyframeList& list, bool& containsCSSVariableReferences, HashSet<CSSPropertyID>& inheritedProperties, HashSet<CSSPropertyID>& currentColorProperties)
+void Resolver::keyframeStylesForAnimation(const Element& element, const RenderStyle& elementStyle, const ResolutionContext& context, KeyframeList& list, bool& containsCSSVariableReferences, bool& hasRelativeFontWeight, HashSet<CSSPropertyID>& inheritedProperties, HashSet<CSSPropertyID>& currentColorProperties)
 {
     inheritedProperties.clear();
     currentColorProperties.clear();
@@ -442,6 +442,7 @@ void Resolver::keyframeStylesForAnimation(const Element& element, const RenderSt
         return;
 
     containsCSSVariableReferences = false;
+    hasRelativeFontWeight = false;
     // Construct and populate the style for each keyframe.
     for (auto& keyframeRule : keyframeRules) {
         // Add this keyframe style to all the indicated key times
@@ -465,6 +466,8 @@ void Resolver::keyframeStylesForAnimation(const Element& element, const RenderSt
                             inheritedProperties.add(property.id());
                         else if (valueId == CSSValueCurrentcolor)
                             currentColorProperties.add(property.id());
+                        else if (property.id() == CSSPropertyFontWeight && (valueId == CSSValueBolder || valueId == CSSValueLighter))
+                            hasRelativeFontWeight = true;
                     }
                 }
             }

Source/WebCore/style/StyleResolver.h

@@ -95,7 +95,7 @@ class Resolver : public RefCounted<Resolver> {
 
     ResolvedStyle styleForElement(const Element&, const ResolutionContext&, RuleMatchingBehavior = RuleMatchingBehavior::MatchAllRules);
 
-    void keyframeStylesForAnimation(const Element&, const RenderStyle& elementStyle, const ResolutionContext&, KeyframeList&, bool& containsCSSVariableReferences, HashSet<CSSPropertyID>& inheritedProperties, HashSet<CSSPropertyID>& currentColorProperties);
+    void keyframeStylesForAnimation(const Element&, const RenderStyle& elementStyle, const ResolutionContext&, KeyframeList&, bool& containsCSSVariableReferences, bool& hasRelativeFontWeight, HashSet<CSSPropertyID>& inheritedProperties, HashSet<CSSPropertyID>& currentColorProperties);
 
     WEBCORE_EXPORT std::optional<ResolvedStyle> styleForPseudoElement(const Element&, const PseudoElementRequest&, const ResolutionContext&);