[SVG] Refactor getIntersectionList() and getEnclosureList()

Source/core/svg/SVGGraphicsElement.cpp

Index: Source/core/svg/SVGGraphicsElement.cpp
diff --git a/Source/core/svg/SVGGraphicsElement.cpp b/Source/core/svg/SVGGraphicsElement.cpp
index 93f7c6332419c75ebefd8b97b3d6b68df545a327..7a9868dfbfe91f81eeb226aeed8309ca87154900 100644
--- a/Source/core/svg/SVGGraphicsElement.cpp
+++ b/Source/core/svg/SVGGraphicsElement.cpp
@@ -66,24 +66,43 @@ PassRefPtr<SVGMatrixTearOff> SVGGraphicsElement::getTransformToElement(SVGElemen
     return SVGMatrixTearOff::create(ctm);
 }
 
-static AffineTransform computeCTM(SVGGraphicsElement* element, SVGElement::CTMScope mode, SVGGraphicsElement::StyleUpdateStrategy styleUpdateStrategy)
+static bool isViewportElement(const Element* element)
 {
-    ASSERT(element);
-    if (styleUpdateStrategy == SVGGraphicsElement::AllowStyleUpdate)
-        element->document().updateLayoutIgnorePendingStylesheets();
+    return (element->hasTagName(SVGNames::svgTag)
+        || element->hasTagName(SVGNames::symbolTag)
+        || element->hasTagName(SVGNames::foreignObjectTag)
+        || element->hasTagName(SVGNames::imageTag));
+}
+
+AffineTransform SVGGraphicsElement::computeCTM(SVGElement::CTMScope mode,
+    SVGGraphicsElement::StyleUpdateStrategy styleUpdateStrategy, const SVGGraphicsElement* ancestor) const
+{
+    if (styleUpdateStrategy == AllowStyleUpdate)
+        document().updateLayoutIgnorePendingStylesheets();
 
     AffineTransform ctm;
+    bool done = false;
 
-    SVGElement* stopAtElement = mode == SVGGraphicsElement::NearestViewportScope ? element->nearestViewportElement() : 0;
-    for (Element* currentElement = element; currentElement; currentElement = currentElement->parentOrShadowHostElement()) {
+    for (const Element* currentElement = this; currentElement && !done;
+        currentElement = currentElement->parentOrShadowHostElement()) {
         if (!currentElement->isSVGElement())
             break;
 
         ctm = toSVGElement(currentElement)->localCoordinateSpaceTransform(mode).multiply(ctm);
 
-        // For getCTM() computation, stop at the nearest viewport element
-        if (currentElement == stopAtElement)
+        switch (mode) {
+        case NearestViewportScope:
+            // Stop at the nearest viewport ancestor.
+            done = currentElement != this && isViewportElement(currentElement);
+            break;
+        case AncestorScope:
+            // Stop at the designated ancestor.
+            done = currentElement == ancestor;
+            break;
+        default:
+            ASSERT(mode == ScreenScope);
             break;
+        }
     }
 
     return ctm;
@@ -91,12 +110,12 @@ static AffineTransform computeCTM(SVGGraphicsElement* element, SVGElement::CTMSc
 
 AffineTransform SVGGraphicsElement::getCTM(StyleUpdateStrategy styleUpdateStrategy)
 {
-    return computeCTM(this, NearestViewportScope, styleUpdateStrategy);
+    return computeCTM(NearestViewportScope, styleUpdateStrategy);
 }
 
 AffineTransform SVGGraphicsElement::getScreenCTM(StyleUpdateStrategy styleUpdateStrategy)
 {
-    return computeCTM(this, ScreenScope, styleUpdateStrategy);
+    return computeCTM(ScreenScope, styleUpdateStrategy);
 }
 
 PassRefPtr<SVGMatrixTearOff> SVGGraphicsElement::getCTMFromJavascript()
@@ -204,14 +223,6 @@ void SVGGraphicsElement::svgAttributeChanged(const QualifiedName& attrName)
     ASSERT_NOT_REACHED();
 }
 
-static bool isViewportElement(Node* node)
-{
-    return (node->hasTagName(SVGNames::svgTag)
-        || node->hasTagName(SVGNames::symbolTag)
-        || node->hasTagName(SVGNames::foreignObjectTag)
-        || node->hasTagName(SVGNames::imageTag));
-}
-
 SVGElement* SVGGraphicsElement::nearestViewportElement() const
 {
     for (Element* current = parentOrShadowHostElement(); current; current = current->parentOrShadowHostElement()) {