Proper support for multiple text decorations.

Source/core/rendering/style/RenderStyle.cpp

Index: Source/core/rendering/style/RenderStyle.cpp
diff --git a/Source/core/rendering/style/RenderStyle.cpp b/Source/core/rendering/style/RenderStyle.cpp
index dfeb3bed61f5b2ce8ec111e0e8193140b5c768cd..553405cf723f756786f2d533c4ac4344d3e17363 100644
--- a/Source/core/rendering/style/RenderStyle.cpp
+++ b/Source/core/rendering/style/RenderStyle.cpp
@@ -28,6 +28,7 @@
 #include "core/css/resolver/StyleResolver.h"
 #include "core/rendering/RenderTheme.h"
 #include "core/rendering/TextAutosizer.h"
+#include "core/rendering/style/AppliedTextDecoration.h"
 #include "core/rendering/style/ContentData.h"
 #include "core/rendering/style/CursorList.h"
 #include "core/rendering/style/QuotesData.h"
@@ -688,7 +689,7 @@ unsigned RenderStyle::computeChangedContextSensitiveProperties(const RenderStyle
 
     if (!diff.needsRepaint()) {
         if (inherited->color != other.inherited->color
-            || inherited_flags._text_decorations != other.inherited_flags._text_decorations
+            || inherited_flags.m_textUnderline != other.inherited_flags.m_textUnderline
             || visual->textDecoration != other.visual->textDecoration) {
             changedContextSensitiveProperties |= ContextSensitivePropertyTextOrColor;
         } else if (rareNonInheritedData.get() != other.rareNonInheritedData.get()) {
@@ -699,7 +700,8 @@ unsigned RenderStyle::computeChangedContextSensitiveProperties(const RenderStyle
             if (rareInheritedData->textFillColor() != other.rareInheritedData->textFillColor()
                 || rareInheritedData->textStrokeColor() != other.rareInheritedData->textStrokeColor()
                 || rareInheritedData->textEmphasisColor() != other.rareInheritedData->textEmphasisColor()
-                || rareInheritedData->textEmphasisFill != other.rareInheritedData->textEmphasisFill)
+                || rareInheritedData->textEmphasisFill != other.rareInheritedData->textEmphasisFill
+                || rareInheritedData->appliedTextDecorations != other.rareInheritedData->appliedTextDecorations)
                 changedContextSensitiveProperties |= ContextSensitivePropertyTextOrColor;
         }
     }
@@ -1204,6 +1206,32 @@ float RenderStyle::computedFontSize() const { return fontDescription().computedS
 int RenderStyle::fontSize() const { return fontDescription().computedPixelSize(); }
 FontWeight RenderStyle::fontWeight() const { return fontDescription().weight(); }
 
+TextDecoration RenderStyle::textDecorationsInEffect() const
+{
+    int decorations = 0;
+
+    const Vector<AppliedTextDecoration>& applied = appliedTextDecorations();
+
+    for (size_t i = 0; i < applied.size(); ++i)
+        decorations |= applied[i].line();
+
+    return static_cast<TextDecoration>(decorations);
+}
+
+const Vector<AppliedTextDecoration>& RenderStyle::appliedTextDecorations() const
+{
+    if (!inherited_flags.m_textUnderline && !rareInheritedData->appliedTextDecorations) {
+        DEFINE_STATIC_LOCAL(Vector<AppliedTextDecoration>, empty, ());
+        return empty;
+    }
+    if (inherited_flags.m_textUnderline) {
+        DEFINE_STATIC_LOCAL(Vector<AppliedTextDecoration>, underline, (1, AppliedTextDecoration(TextDecorationUnderline)));
+        return underline;
+    }
+
+    return rareInheritedData->appliedTextDecorations->vector();
+}
+
 float RenderStyle::wordSpacing() const { return fontDescription().wordSpacing(); }
 float RenderStyle::letterSpacing() const { return fontDescription().letterSpacing(); }
 
@@ -1299,6 +1327,60 @@ void RenderStyle::setFontWeight(FontWeight weight)
     font().update(currentFontSelector);
 }
 
+void RenderStyle::addAppliedTextDecoration(const AppliedTextDecoration& decoration)
+{
+    bool isSimpleUnderline = decoration.isSimple() && decoration.line() == TextDecorationUnderline;
+
+    if (!rareInheritedData->appliedTextDecorations && isSimpleUnderline) {
+        // To save memory, we don't use AppliedTextDecoration objects in the
+        // common case of a single solid underline with the current color. Instead,
+        // we set a bit to indicate that a solid underline must be drawn with the
+        // current color.
+        inherited_flags.m_textUnderline = true;
+        return;
+    }
+
+    RefPtr<AppliedTextDecorationList>& list = rareInheritedData.access()->appliedTextDecorations;
+
+    if (!list)
+        list = AppliedTextDecorationList::create();
+    else if (!list->hasOneRef())
+        list = list->copy();
+
+    if (inherited_flags.m_textUnderline) {
+        inherited_flags.m_textUnderline = false;
+        list->append(AppliedTextDecoration(TextDecorationUnderline, TextDecorationStyleSolid, StyleColor::currentColor()));
+    }
+
+    list->append(decoration);
+}
+
+void RenderStyle::applyTextDecorations()
+{
+    if (textDecoration() == TextDecorationNone)
+        return;
+
+    TextDecorationStyle style = textDecorationStyle();
+    StyleColor styleColor = visitedDependentDecorationStyleColor();
+
+    int decorations = textDecoration();
+
+    if (decorations & TextDecorationUnderline)
+        addAppliedTextDecoration(AppliedTextDecoration(TextDecorationUnderline, style, styleColor));
+    if (decorations & TextDecorationOverline)
+        addAppliedTextDecoration(AppliedTextDecoration(TextDecorationOverline, style, styleColor));
+    if (decorations & TextDecorationLineThrough)
+        addAppliedTextDecoration(AppliedTextDecoration(TextDecorationLineThrough, style, styleColor));
+}
+
+void RenderStyle::clearAppliedTextDecorations()
+{
+    inherited_flags.m_textUnderline = false;
+
+    if (rareInheritedData->appliedTextDecorations)
+        rareInheritedData.access()->appliedTextDecorations = nullptr;
+}
+
 void RenderStyle::getShadowExtent(const ShadowList* shadowList, LayoutUnit &top, LayoutUnit &right, LayoutUnit &bottom, LayoutUnit &left) const
 {
     top = 0;
@@ -1376,10 +1458,29 @@ void RenderStyle::getShadowVerticalExtent(const ShadowList* shadowList, LayoutUn
     }
 }
 
-StyleColor RenderStyle::visitedDependentDecorationColor() const
+StyleColor RenderStyle::visitedDependentDecorationStyleColor() const
+{
+    bool visitedLink = insideLink() == InsideVisitedLink;
+
+    StyleColor styleColor = visitedLink ? visitedLinkTextDecorationColor() : textDecorationColor();
+
+    if (!styleColor.isCurrentColor())
+        return styleColor;
+
+    if (textStrokeWidth()) {
+        // Prefer stroke color if possible but not if it's fully transparent.
+        StyleColor textStrokeStyleColor = visitedLink ? visitedLinkTextStrokeColor() : textStrokeColor();
+        if (!textStrokeStyleColor.isCurrentColor() && textStrokeStyleColor.color().alpha())
+            return textStrokeStyleColor;
+    }
+
+    return visitedLink ? visitedLinkTextFillColor() : textFillColor();
+}
+
+Color RenderStyle::visitedDependentDecorationColor() const
 {
-    // Text decoration color fallback is handled in RenderObject::decorationColor.
-    return insideLink() == InsideVisitedLink ? visitedLinkTextDecorationColor() : textDecorationColor();
+    bool visitedLink = insideLink() == InsideVisitedLink;
+    return visitedDependentDecorationStyleColor().resolve(visitedLink ? visitedLinkColor() : color());
 }
 
 Color RenderStyle::colorIncludingFallback(int colorProperty, bool visitedLink) const