Implement mapAncestorToLocal for LayoutSVG{ModelObject,Block}

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

 /*
  * Copyright (C) 2007, 2008 Rob Buis <buis@kde.org>
  * Copyright (C) 2007 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2007 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2009 Google, Inc.  All rights reserved.
  * Copyright (C) 2009 Dirk Schulze <krit@webkit.org>
  * Copyright (C) Research In Motion Limited 2009-2010. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 98 matching lines @@
         return rect;
     }
 
     LayoutRect rect;
     const LayoutSVGRoot& svgRoot = mapRectToSVGRootForPaintInvalidation(object,
         paintInvalidationRect, rect, strokeWidthForHairlinePadding);
     svgRoot.mapToVisibleRectInAncestorSpace(paintInvalidationContainer, rect, paintInvalidationState);
     return rect;
 }
 
+static const LayoutSVGRoot& computeTransformToSVGRoot(const LayoutObject& object, AffineTransform& rootBorderBoxTransform)
+{
+    ASSERT(object.isSVG() && !object.isSVGRoot());
+
+    const LayoutObject* parent;
+    for (parent = &object; !parent->isSVGRoot(); parent = parent->parent())
+        rootBorderBoxTransform.preMultiply(parent->localToParentTransform());
+
+    const LayoutSVGRoot& svgRoot = toLayoutSVGRoot(*parent);
+    rootBorderBoxTransform.preMultiply(svgRoot.localToBorderBoxTransform());
+    return svgRoot;
+}
+
 const LayoutSVGRoot& SVGLayoutSupport::mapRectToSVGRootForPaintInvalidation(const LayoutObject& object,
     const FloatRect& localPaintInvalidationRect, LayoutRect& rect, float strokeWidthForHairlinePadding)
 {
-    ASSERT(object.isSVG() && !object.isSVGRoot());
-
-    const LayoutObject* parent;
     AffineTransform rootBorderBoxTransform;
-    for (parent = &object; !parent->isSVGRoot(); parent = parent->parent())
-        rootBorderBoxTransform.preMultiply(parent->localToParentTransform());
-
-    const LayoutSVGRoot& svgRoot = toLayoutSVGRoot(*parent);
-    rootBorderBoxTransform.preMultiply(svgRoot.localToBorderBoxTransform());
+    const LayoutSVGRoot& svgRoot = computeTransformToSVGRoot(object, rootBorderBoxTransform);
 
     rect = adjustedEnclosingIntRect(rootBorderBoxTransform.mapRect(localPaintInvalidationRect),
         rootBorderBoxTransform, strokeWidthForHairlinePadding);
-
     return svgRoot;
 }
 
 void SVGLayoutSupport::mapLocalToAncestor(const LayoutObject* object, const LayoutBoxModelObject* ancestor, TransformState& transformState, bool* wasFixed, const PaintInvalidationState* paintInvalidationState)
 {
     transformState.applyTransform(object->localToParentTransform());
 
     if (paintInvalidationState && paintInvalidationState->canMapToContainer(ancestor)) {
         // |svgTransform| contains localToBorderBoxTransform mentioned below.
         transformState.applyTransform(paintInvalidationState->svgTransform());
         transformState.move(paintInvalidationState->paintOffset());
         return;
     }
 
     LayoutObject* parent = object->parent();
 
     // At the SVG/HTML boundary (aka LayoutSVGRoot), we apply the localToBorderBoxTransform
     // to map an element from SVG viewport coordinates to CSS box coordinates.
     // LayoutSVGRoot's mapLocalToAncestor method expects CSS box coordinates.
     if (parent->isSVGRoot())
         transformState.applyTransform(toLayoutSVGRoot(parent)->localToBorderBoxTransform());
 
     MapCoordinatesFlags mode = UseTransforms;
     parent->mapLocalToAncestor(ancestor, transformState, mode, wasFixed, paintInvalidationState);
 }
 
+void SVGLayoutSupport::mapAncestorToLocal(const LayoutObject& object, const LayoutBoxModelObject* ancestor, TransformState& transformState)
+{
+    // |object| is either a LayoutSVGModelObject or a LayoutSVGBlock here. In

[pdr., 2016/03/01 22:58:39]

Can you add an assert for this?

[fs, 2016/03/02 08:54:30]

It's a bit of a handful to express, but sure, added.

+    // the former case, |object| can never be an ancestor while in the latter
+    // the caller is responsible for doing the ancestor check. Because of this,
+    // computing the transform to the SVG root is always what we want to do here.
+    ASSERT(ancestor != &object);
+    AffineTransform localToSVGRoot;
+    const LayoutSVGRoot& svgRoot = computeTransformToSVGRoot(object, localToSVGRoot);
+
+    MapCoordinatesFlags mode = UseTransforms | ApplyContainerFlip;
+    svgRoot.mapAncestorToLocal(ancestor, transformState, mode);
+
+    transformState.applyTransform(localToSVGRoot);
+}
+
 const LayoutObject* SVGLayoutSupport::pushMappingToContainer(const LayoutObject* object, const LayoutBoxModelObject* ancestorToStopAt, LayoutGeometryMap& geometryMap)
 {
     ASSERT_UNUSED(ancestorToStopAt, ancestorToStopAt != object);
 
     LayoutObject* parent = object->parent();
 
     // At the SVG/HTML boundary (aka LayoutSVGRoot), we apply the localToBorderBoxTransform
     // to map an element from SVG viewport coordinates to CSS box coordinates.
     // LayoutSVGRoot's mapLocalToAncestor method expects CSS box coordinates.
     if (parent->isSVGRoot()) {
@@ skipping 395 matching lines @@
 
     return closestText;
 }
 
 LayoutObject* SVGLayoutSupport::findClosestLayoutSVGText(LayoutObject* layoutObject, const FloatPoint& point)
 {
     return searchTreeForFindClosestLayoutSVGText(layoutObject, point).candidateLayoutObject;
 }
 
 } // namespace blink