Common up SVG transform "change detection" (classification)

third_party/WebKit/Source/core/layout/svg/LayoutSVGTransformableContainer.cpp

 /*
  * Copyright (C) 2004, 2005 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2004, 2005, 2006 Rob Buis <buis@kde.org>
  * Copyright (C) 2009 Google, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 54 matching lines @@
     }
     return LayoutSVGContainer::isChildAllowed(child, style);
 }
 
 void LayoutSVGTransformableContainer::setNeedsTransformUpdate()
 {
     setMayNeedPaintInvalidationSubtree();
     m_needsTransformUpdate = true;
 }
 
-static std::pair<double, double> scaleReference(const AffineTransform& transform)
-{
-    return std::make_pair(transform.xScaleSquared(), transform.yScaleSquared());
-}
-
-LayoutSVGContainer::TransformChange LayoutSVGTransformableContainer::calculateLocalTransform()
+SVGTransformChange LayoutSVGTransformableContainer::calculateLocalTransform()
 {
     SVGGraphicsElement* element = toSVGGraphicsElement(this->element());
     ASSERT(element);
 
     // If we're either the layoutObject for a <use> element, or for any <g> element inside the shadow
     // tree, that was created during the use/symbol/svg expansion in SVGUseElement. These containers
     // need to respect the translations induced by their corresponding use elements x/y attributes.
     SVGUseElement* useElement = nullptr;
     if (isSVGUseElement(*element)) {
         useElement = toSVGUseElement(element);
@@ skipping 10 matching lines @@
             useElement->y()->currentValue()->value(lengthContext));
         // TODO(fs): Signal this on style update instead. (Since these are
         // suppose to be presentation attributes now, this does feel a bit
         // broken...)
         if (translation != m_additionalTranslation)
             setNeedsTransformUpdate();
         m_additionalTranslation = translation;
     }
 
     if (!m_needsTransformUpdate)
-        return TransformChange::None;
+        return SVGTransformChange::None;
 
-    std::pair<double, double> oldScale = scaleReference(m_localTransform);
+    SVGTransformChangeDetector changeDetector(m_localTransform);
     m_localTransform = element->calculateAnimatedLocalTransform();
     m_localTransform.translate(m_additionalTranslation.width(), m_additionalTranslation.height());
     m_needsTransformUpdate = false;
-    return scaleReference(m_localTransform) != oldScale
-        ? TransformChange::Full : TransformChange::ScaleInvariant;
+    return changeDetector.computeChange(m_localTransform);
 }
 
 } // namespace blink