Implement incremental paint property tree rebuilding

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

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  *           (C) 2004 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2011 Apple Inc.
  *               All rights reserved.
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved.
  *               (http://www.torchmobile.com/)
@@ skipping 1459 matching lines @@
     // Text nodes share style with their parents but the checked styles don't
     // apply to them, hence the !isText() check.
     if (!isText() && (diff.transformChanged() || diff.opacityChanged() ||
                       diff.zIndexChanged() || diff.filterChanged() ||
                       diff.backdropFilterChanged())) {
       // We don't need to invalidate paint of objects on SPv2 when only paint
       // property or paint order change. Mark the painting layer needing repaint
       // for changed paint property or paint order. Raster invalidation will be
       // issued if needed during paint.
       ObjectPaintInvalidator(*this).slowSetPaintingLayerNeedsRepaint();
+
+      // When transform, opacity, etc. change, paint properties will also change
+      // so we need to mark this object as needing an update.
+      // TODO(pdr): Also update in the non-spv2 codepath?

[pdr., 2016/11/11 23:50:27]

Xianzhu, do we need to do this (also setNeedsPaintPropertyUpdate in the other
half of this conditional) for spinvalidation?

[Xianzhu, 2016/11/12 00:30:48]

We still need to go through the traditional path for spinvalidation because
visual rects are relative to paint invalidation containers.

+      getMutableForPainting().setNeedsPaintPropertyUpdate();
     }
   } else {
     // If transform changed, and the layer does not paint into its own separate
     // backing, then we need to invalidate paints.
     if (diff.transformChanged()) {
       // Text nodes share style with their parents but transforms don't apply to
       // them, hence the !isText() check.
       if (!isText() && (!hasLayer() ||
                         !toLayoutBoxModelObject(this)
                              ->layer()
@@ skipping 2057 matching lines @@
     const blink::LayoutObject* root = object1;
     while (root->parent())
       root = root->parent();
     root->showLayoutTreeAndMark(object1, "*", object2, "-", 0);
   } else {
     WTFLogAlways("%s", "Cannot showLayoutTree. Root is (nil)");
   }
 }
 
 #endif