[WIP] CSS Motion Path: offset shorthand ready for position and anchor

third_party/WebKit/Source/core/css/StylePropertySerializer.cpp

Index: third_party/WebKit/Source/core/css/StylePropertySerializer.cpp
diff --git a/third_party/WebKit/Source/core/css/StylePropertySerializer.cpp b/third_party/WebKit/Source/core/css/StylePropertySerializer.cpp
index c067f76c1c233ecc83699205fe30ab7b41faca5f..f31bc6e63e4088702356dea8df9bacfcfab8a5a1 100644
--- a/third_party/WebKit/Source/core/css/StylePropertySerializer.cpp
+++ b/third_party/WebKit/Source/core/css/StylePropertySerializer.cpp
@@ -27,6 +27,7 @@
 #include "core/css/CSSCustomPropertyDeclaration.h"
 #include "core/css/CSSPendingSubstitutionValue.h"
 #include "core/css/CSSPropertyMetadata.h"
+#include "core/css/CSSValuePair.h"
 #include "core/css/CSSValuePool.h"
 #include "wtf/StdLibExtras.h"
 #include "wtf/text/StringBuilder.h"
@@ -457,7 +458,7 @@ String StylePropertySerializer::getPropertyValue(CSSPropertyID propertyID) const
     case CSSPropertyMotion:
         return getShorthandValue(motionShorthand());
     case CSSPropertyOffset:
-        return getShorthandValue(offsetShorthand());
+        return offsetValue();
     case CSSPropertyWebkitMarginCollapse:
         return getShorthandValue(webkitMarginCollapseShorthand());
     case CSSPropertyOverflow:
@@ -546,6 +547,44 @@ void StylePropertySerializer::appendFontLonghandValueIfNotNormal(CSSPropertyID p
     result.append(value);
 }
 
+String StylePropertySerializer::offsetValue() const
+{
+    const CSSValue* offsetPathValue = m_propertySet.getPropertyCSSValue(CSSPropertyOffsetPath);
+    const CSSValue* offsetDistanceValue = m_propertySet.getPropertyCSSValue(CSSPropertyOffsetDistance);
+    const CSSValue* offsetRotationValue = m_propertySet.getPropertyCSSValue(CSSPropertyOffsetRotation);
+
+    const CSSValue* offsetPositionValue = nullptr;
+    const CSSValue* offsetAnchorValue = nullptr;
+    if (RuntimeEnabledFeatures::cssOffsetPositionAnchorEnabled()) {
+        offsetPositionValue = m_propertySet.getPropertyCSSValue(CSSPropertyOffsetPosition);
+        offsetAnchorValue = m_propertySet.getPropertyCSSValue(CSSPropertyOffsetAnchor);
+    }
+
+    StringBuilder result;
+    if (offsetPositionValue && offsetPositionValue->isValuePair()) {
+        result.append(offsetPositionValue->cssText());
+        result.append(' ');
+    }
+    result.append(offsetPathValue->cssText());
+    result.append(' ');
+    result.append(offsetDistanceValue->cssText());
+    result.append(' ');
+    result.append(offsetRotationValue->cssText());
+
+    bool anchorIsCentre = !offsetAnchorValue;
+    if (offsetAnchorValue && offsetAnchorValue->isValuePair()) {
+        const CSSValuePair* pair = toCSSValuePair(offsetAnchorValue);
+        const CSSPrimitiveValue& first = toCSSPrimitiveValue(pair->first());
+        const CSSPrimitiveValue& second = toCSSPrimitiveValue(pair->second());
+        anchorIsCentre = first.isPercentage() && first.getDoubleValue() == 50 && second.isPercentage() && second.getDoubleValue() == 50;
+    }
+    if (!anchorIsCentre) {
+        result.append('/');
+        result.append(offsetAnchorValue->cssText());
+    }
+    return result.toString();
+}
+
 String StylePropertySerializer::fontValue() const
 {
     int fontSizePropertyIndex = m_propertySet.findPropertyIndex(CSSPropertyFontSize);