GeometryMapper: Support computing visual rects in spaces that are not direct ancestors.

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 144 matching lines @@
     RefPtr<ClipPaintPropertyNode> clipNode = ClipPaintPropertyNode::create(
         context.currentTransform,
         FloatRoundedRect(FloatRect(clipRect)),
         context.currentClip);
     context.currentClip = clipNode.get();
     object.getMutableForPainting().ensureObjectPaintProperties().setCssClip(clipNode.release());
 }
 
 void PaintPropertyTreeBuilder::updateLocalBorderBoxContext(const LayoutObject& object, const PaintPropertyTreeBuilderContext& context)
 {
-    // Note: Currently only layer painter makes use of the pre-computed context.
-    // This condition may be loosened with no adverse effects beside memory use.
-    if (!object.hasLayer())
-        return;
-
     std::unique_ptr<ObjectPaintProperties::LocalBorderBoxProperties> borderBoxContext =
         wrapUnique(new ObjectPaintProperties::LocalBorderBoxProperties);
     borderBoxContext->paintOffset = context.paintOffset;
-    borderBoxContext->transform = context.currentTransform;
-    borderBoxContext->clip = context.currentClip;
-    borderBoxContext->effect = context.currentEffect;
+    borderBoxContext->propertyTreeState = PropertyTreeState(context.currentTransform, context.currentClip, context.currentEffect);
     object.getMutableForPainting().ensureObjectPaintProperties().setLocalBorderBoxProperties(std::move(borderBoxContext));
 }
 
 // TODO(trchen): Remove this once we bake the paint offset into frameRect.
 void PaintPropertyTreeBuilder::updateScrollbarPaintOffset(const LayoutObject& object, const PaintPropertyTreeBuilderContext& context)
 {
     IntPoint roundedPaintOffset = roundedIntPoint(context.paintOffset);
     if (roundedPaintOffset == IntPoint())
         return;
 
@@ skipping 191 matching lines @@
         if (boxModelObject.isTableCell()) {
             LayoutObject* parentRow = boxModelObject.parent();
             ASSERT(parentRow && parentRow->isTableRow());
             context.paintOffset.moveBy(-toLayoutBox(parentRow)->topLeftLocation());
         }
     }
 }
 
 void PaintPropertyTreeBuilder::buildTreeNodes(const LayoutObject& object, PaintPropertyTreeBuilderContext& context)
 {
+    object.getMutableForPainting().clearObjectPaintProperties();

[chrishtr, 2016/06/30 16:49:55]

Now allocating an ObjectPaintProperties object for all boxes, to support
representation of property tree states for all
of them in O(1) time. This is needed for paint invalidation.

[pdr., 2016/06/30 21:21:50]

To enforce this and ensure we don't create too many of these, can you add:
if (!object.isBox())
    return;

[chrishtr, 2016/07/01 17:52:24]

Done (in updateLocalBorderBoxContext)

+
     if (!object.isBoxModelObject() && !object.isSVG())
         return;
 
-    object.getMutableForPainting().clearObjectPaintProperties();
-
     deriveBorderBoxFromContainerContext(object, context);
 
     updatePaintOffsetTranslation(object, context);
     updateTransform(object, context);
     updateEffect(object, context);
     updateCssClip(object, context);
     updateLocalBorderBoxContext(object, context);
     updateScrollbarPaintOffset(object, context);
     updateOverflowClip(object, context);
     // TODO(trchen): Insert flattening transform here, as specified by
     // http://www.w3.org/TR/css3-transforms/#transform-style-property
     updatePerspective(object, context);
     updateSvgLocalToBorderBoxTransform(object, context);
     updateScrollTranslation(object, context);
     updateOutOfFlowContext(object, context);
 }
 
 } // namespace blink