Add support for multiple text decorations with same line positioning

Source/core/style/ComputedStyle.cpp

Index: Source/core/style/ComputedStyle.cpp
diff --git a/Source/core/style/ComputedStyle.cpp b/Source/core/style/ComputedStyle.cpp
index 739ff8076e479bc25c6e072a6b41be9b39e1e3b5..351d60bedc37db26887455d409567824a205fff2 100644
--- a/Source/core/style/ComputedStyle.cpp
+++ b/Source/core/style/ComputedStyle.cpp
@@ -742,7 +742,7 @@ void ComputedStyle::updatePropertySpecificDifferences(const ComputedStyle& other
     if (!diff.needsPaintInvalidation()) {
         if (inherited->color != other.inherited->color
             || inherited->visitedLinkColor != other.inherited->visitedLinkColor
-            || inherited_flags.m_textUnderline != other.inherited_flags.m_textUnderline
+            || inherited_flags.m_hasSimpleUnderline != other.inherited_flags.m_hasSimpleUnderline
             || visual->textDecoration != other.visual->textDecoration) {
             diff.setTextOrColorChanged();
         } else if (rareNonInheritedData.get() != other.rareNonInheritedData.get()
@@ -1245,24 +1245,31 @@ FontStretch ComputedStyle::fontStretch() const { return fontDescription().stretc
 
 TextDecoration ComputedStyle::textDecorationsInEffect() const
 {
+    if (!inherited_flags.m_hasSimpleUnderline && !rareInheritedData->appliedTextDecorations)
+        return TextDecorationNone;
+    if (inherited_flags.m_hasSimpleUnderline)
+        return TextDecorationUnderline;
+
     int decorations = 0;
 
     const Vector<AppliedTextDecoration>& applied = appliedTextDecorations();
 
     for (size_t i = 0; i < applied.size(); ++i)
-        decorations |= applied[i].line();
+        decorations |= applied[i].lines();
 
     return static_cast<TextDecoration>(decorations);
 }
 
 const Vector<AppliedTextDecoration>& ComputedStyle::appliedTextDecorations() const
 {
-    if (!inherited_flags.m_textUnderline && !rareInheritedData->appliedTextDecorations) {
+    if (!inherited_flags.m_hasSimpleUnderline && !rareInheritedData->appliedTextDecorations) {
         DEFINE_STATIC_LOCAL(Vector<AppliedTextDecoration>, empty, ());
         return empty;
     }
-    if (inherited_flags.m_textUnderline) {
-        DEFINE_STATIC_LOCAL(Vector<AppliedTextDecoration>, underline, (1, AppliedTextDecoration(TextDecorationUnderline)));
+    if (inherited_flags.m_hasSimpleUnderline) {
+        DEFINE_STATIC_LOCAL(Vector<AppliedTextDecoration>, underline, (1, AppliedTextDecoration(TextDecorationUnderline, TextDecorationStyleSolid, Color::transparent, true)));
+        // Since we only have one of these in memory, just update the color before returning.
+        underline.at(0).applyPropagatedColor(visitedDependentSimpleUnderlineColor());
         return underline;
     }
 
@@ -1370,43 +1377,64 @@ void ComputedStyle::addAppliedTextDecoration(const AppliedTextDecoration& decora
     else if (!list->hasOneRef())
         list = list->copy();
 
-    if (inherited_flags.m_textUnderline) {
-        inherited_flags.m_textUnderline = false;
-        list->append(AppliedTextDecoration(TextDecorationUnderline));
-    }
-
     list->append(decoration);
 }
 
-void ComputedStyle::applyTextDecorations()
+void ComputedStyle::updateAppliedTextDecoration(size_t index, Color newColor)
 {
-    if (textDecoration() == TextDecorationNone)
+    RefPtr<AppliedTextDecorationList>& list = rareInheritedData.access()->appliedTextDecorations;
+
+    if (!list)
+        list = AppliedTextDecorationList::create();
+    else if (!list->hasOneRef())
+        list = list->copy();
+
+    list->at(index).applyPropagatedColor(newColor);
+}
+
+void ComputedStyle::applyTextDecorations(bool overrideExistingColors)
+{
+    if (textDecoration() == TextDecorationNone && !inherited_flags.m_hasSimpleUnderline && !rareInheritedData->appliedTextDecorations)
         return;
 
-    TextDecorationStyle style = textDecorationStyle();
-    StyleColor styleColor = decorationColorIncludingFallback(insideLink() == InsideVisitedLink);
+    // If we have a propagated color, update any other affected decorations.
+    if (overrideExistingColors && inherited_flags.m_hasSimpleUnderline) {
+        setSimpleUnderlineColor(colorIncludingFallback(CSSPropertyTextDecorationColor, false));
+        setSimpleUnderlineVisitedColor(colorIncludingFallback(CSSPropertyTextDecorationColor, true));
+    } else if (overrideExistingColors && rareInheritedData->appliedTextDecorations) {
+        for (size_t i = 0; i < rareInheritedData->appliedTextDecorations->size(); ++i) {
+            AppliedTextDecoration& decoration = rareInheritedData->appliedTextDecorations->at(i);
+            if (decoration.isAffectedByPropagatedColors())
+                updateAppliedTextDecoration(i, visitedDependentColor(CSSPropertyTextDecorationColor));
+        }
+    }
 
-    int decorations = textDecoration();
+    TextDecoration decorationLines = textDecoration();
+    TextDecorationStyle decorationStyle = textDecorationStyle();
+    StyleColor decorationColor = decorationColorIncludingFallback(insideLink() == InsideVisitedLink);
 
-    if (decorations & TextDecorationUnderline) {
-        // To save memory, we don't use AppliedTextDecoration objects in the
-        // common case of a single simple underline.
-        AppliedTextDecoration underline(TextDecorationUnderline, style, styleColor);
+    // To save memory, we don't use AppliedTextDecoration objects in the common case of a single simple underline.
+    if (!rareInheritedData->appliedTextDecorations && !inherited_flags.m_hasSimpleUnderline
+        && decorationLines == TextDecorationUnderline && decorationStyle == TextDecorationStyleSolid && decorationColor.isCurrentColor()) {
+        inherited_flags.m_hasSimpleUnderline = true;
+        setSimpleUnderlineColor(colorIncludingFallback(CSSPropertyTextDecorationColor, false));
+        setSimpleUnderlineVisitedColor(colorIncludingFallback(CSSPropertyTextDecorationColor, true));
+        return;
+    }
 
-        if (!rareInheritedData->appliedTextDecorations && underline.isSimpleUnderline())
-            inherited_flags.m_textUnderline = true;
-        else
-            addAppliedTextDecoration(underline);
+    // Clear the existing optimization if we have it.
+    if (inherited_flags.m_hasSimpleUnderline) {
+        inherited_flags.m_hasSimpleUnderline = false;
+        addAppliedTextDecoration(AppliedTextDecoration(TextDecorationUnderline, TextDecorationStyleSolid, visitedDependentSimpleUnderlineColor(), true));
     }
-    if (decorations & TextDecorationOverline)
-        addAppliedTextDecoration(AppliedTextDecoration(TextDecorationOverline, style, styleColor));
-    if (decorations & TextDecorationLineThrough)
-        addAppliedTextDecoration(AppliedTextDecoration(TextDecorationLineThrough, style, styleColor));
+
+    Color currentTextDecorationColor = visitedDependentColor(CSSPropertyTextDecorationColor);
+    addAppliedTextDecoration(AppliedTextDecoration(decorationLines, decorationStyle, decorationColor.resolve(currentTextDecorationColor), decorationColor.isCurrentColor()));
 }
 
 void ComputedStyle::clearAppliedTextDecorations()
 {
-    inherited_flags.m_textUnderline = false;
+    inherited_flags.m_hasSimpleUnderline = false;
 
     if (rareInheritedData->appliedTextDecorations)
         rareInheritedData.access()->appliedTextDecorations = nullptr;