Update documentation and cleanup impls for localToSVGParentTransform()

third_party/WebKit/Source/core/layout/LayoutObject.h

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  *           (C) 2000 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  *           (C) 2004 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2012 Apple Inc.
  *               All rights reserved.
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 650 matching lines @@
   // This is used for all computation of objectBoundingBox relative units and by
   // SVGLocatable::getBBox().
   // NOTE: Markers are not specifically ignored here by SVG 1.1 spec, but we
   // ignore them since stroke-width is ignored (and marker size can depend on
   // stroke-width). objectBoundingBox is returned local coordinates.
   // The name objectBoundingBox is taken from the SVG 1.1 spec.
   virtual FloatRect objectBoundingBox() const;
   virtual FloatRect strokeBoundingBox() const;
 
   // Returns the smallest rectangle enclosing all of the painted content
-  // respecting clipping, masking, filters, opacity, stroke-width and markers
+  // respecting clipping, masking, filters, opacity, stroke-width and markers.
+  // For most SVG objects, the local SVG coordinate space is the space where
+  // localSVGTransform applies. For SVG objects defining viewports (e.g.
+  // LayoutSVGForeignObject, LayoutSVGViewportContainer,
+  // LayoutSVGResourceMarker), the local SVG coordinate space is the viewport
+  // space.
   virtual FloatRect visualRectInLocalSVGCoordinates() const;
 
-  // This only returns the transform="" value from the SVG element.
+  // This returns the transform applying to the local SVG coordinate space,
+  // which combines the transform attribute value or CSS transform properties,
+  // and animation motion transform.
+  // See SVGGraphicsElement::calculateAnimatedLocalTransform().
   // Most callsites want localToParentTransform() instead.
   virtual AffineTransform localSVGTransform() const;

[pdr., 2016/11/18 20:35:10]

Are there any remaining callsites of this after
https://crrev.com/74454dfeaa27a9f696824e0a2a1548175d2e26ab? I think it can be
removed entirely.

[Xianzhu, 2016/11/18 22:19:12]

One callsite is in SVGLayoutTreeAsText which does need it.

The existence of localSVGTransform() also makes it easier to explain
localToSVGParentTransform().

 
-  // Returns the full transform mapping from local coordinates to local coords
-  // for the parent SVG layoutObject
-  // This includes any viewport transforms and x/y offsets as well as the
-  // transform="" value off the element.
-  virtual const AffineTransform& localToSVGParentTransform() const;
+  // Returns the full transform mapping from local coordinates to parent's local
+  // coordinates. For most SVG objects, this is the same as localSVGTransform.
+  // For SVG objects defining viewports (see visualRectInLocalSVGCoordinates),
+  // this includes any viewport transforms and x/y offsets as well as
+  // localSVGTransform.
+  virtual AffineTransform localToSVGParentTransform() const {
+    return localSVGTransform();
+  }
 
   // SVG uses FloatPoint precise hit testing, and passes the point in parent
   // coordinates instead of in paint invalidation container coordinates.
   // Eventually the rest of the layout tree will move to a similar model.
   virtual bool nodeAtFloatPoint(HitTestResult&,
                                 const FloatPoint& pointInParent,
                                 HitTestAction);
 
   // End of SVG-specific methods.
 
@@ skipping 1934 matching lines @@
 CORE_EXPORT void showLineTree(const blink::LayoutObject*);
 CORE_EXPORT void showLayoutTree(const blink::LayoutObject* object1);
 // We don't make object2 an optional parameter so that showLayoutTree
 // can be called from gdb easily.
 CORE_EXPORT void showLayoutTree(const blink::LayoutObject* object1,
                                 const blink::LayoutObject* object2);
 
 #endif
 
 #endif  // LayoutObject_h