Issue paint offset for SVGText, etc.

third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/paint/PaintPropertyTreeBuilder.h"
 
 #include "core/frame/FrameView.h"
 #include "core/frame/LocalFrame.h"
 #include "core/frame/Settings.h"
 #include "core/layout/LayoutInline.h"
@@ skipping 244 matching lines @@
       floatValueForLength(style.transformOriginY(), borderBoxSize.height()),
       style.transformOriginZ());
 }
 
 // SVG does not use the general transform update of |updateTransform|, instead
 // creating a transform node for SVG-specific transforms without 3D.
 void PaintPropertyTreeBuilder::updateTransformForNonRootSVG(
     const LayoutObject& object,
     PaintPropertyTreeBuilderContext& context) {
   DCHECK(object.isSVG() && !object.isSVGRoot());
-  // SVG (other than SVGForeignObject) does not use paint offset internally.
-  DCHECK(object.isSVGForeignObject() ||
+  // SVG does not use paint offset internally, except for those inheriting from
+  // LayoutBoxModelObject or LayoutText which will use HTML painters.
+  DCHECK(object.isBoxModelObject() || object.isText() ||
          context.current.paintOffset == LayoutPoint());
 
   if (object.needsPaintPropertyUpdate()) {
+    // SVGForeignObject issues paint offset using its location() which contains
+    // its viewport offset, so here we must use localSVGTransform() which does
+    // not contain the viewport offset, instead of localToSVGParentTransform().
     // TODO(pdr): Refactor this so all non-root SVG objects use the same
     // transform function.
     const AffineTransform& transform = object.isSVGForeignObject()
                                            ? object.localSVGTransform()
                                            : object.localToSVGParentTransform();
     // TODO(pdr): Check for the presence of a transform instead of the value.
     // Checking for an identity matrix will cause the property tree structure
     // to change during animations if the animation passes through the
     // identity matrix.
     if (!transform.isIdentity()) {
@@ skipping 568 matching lines @@
         overrideContaineringBlockContextFromRealContainingBlock(
             toLayoutBlock(*boxModelObject.container()), context.current);
       } else {
         context.current = context.fixedPosition;
       }
       break;
     default:
       ASSERT_NOT_REACHED();
   }
 
-  // SVGForeignObject needs paint offset because its viewport offset is baked
-  // into its location(), while its localSVGTransform() doesn't contain the
-  // offset.
-  if (boxModelObject.isBox() &&
-      (!boxModelObject.isSVG() || boxModelObject.isSVGRoot() ||
-       boxModelObject.isSVGForeignObject())) {
+  // The following condition also includes any SVG objects inheriting LayoutBox

[pdr., 2016/11/16 03:53:49]

Nit: ...inheriting [from] LayoutBox...

[Xianzhu, 2016/11/16 04:05:48]

Done.

+  // and using HTML painters which will offset the paint origin by the object's
+  // location().
+  if (boxModelObject.isBox()) {
     // TODO(pdr): Several calls in this function walk back up the tree to
     // calculate containers (e.g., topLeftLocation, offsetForInFlowPosition*).
     // The containing block and other containers can be stored on
     // PaintPropertyTreeBuilderContext instead of recomputing them.
     context.current.paintOffset.moveBy(
         toLayoutBox(boxModelObject).topLeftLocation());
     // This is a weird quirk that table cells paint as children of table rows,
     // but their location have the row's location baked-in.
     // Similar adjustment is done in LayoutTableCell::offsetFromContainer().
     if (boxModelObject.isTableCell()) {
@@ skipping 37 matching lines @@
 #endif
 
   updateOverflowClip(object, context);
   updatePerspective(object, context);
   updateSvgLocalToBorderBoxTransform(object, context);
   updateScrollAndScrollTranslation(object, context);
   updateOutOfFlowContext(object, context);
 }
 
 }  // namespace blink