Refine the criteria for ScrollAnchor-disabling properties

third_party/WebKit/Source/core/style/ComputedStyle.cpp

 /*
  * Copyright (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights
  * reserved.
  * Copyright (C) 2011 Adobe Systems Incorporated. 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
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 580 matching lines @@
       diff.setNeedsPositionedMovementLayout();
   }
 
   if (diffNeedsPaintInvalidationSubtree(other))
     diff.setNeedsPaintInvalidationSubtree();
   else if (diffNeedsPaintInvalidationObject(other))
     diff.setNeedsPaintInvalidationObject();
 
   updatePropertySpecificDifferences(other, diff);
 
-  // TODO(skobes): Refine the criteria for ScrollAnchor-disabling properties.
-  // Some things set needsLayout but shouldn't disable scroll anchoring.
-  if (diff.needsLayout() || diff.transformChanged())
+  if (scrollAnchorDisablingPropertyChanged(other, diff))
     diff.setScrollAnchorDisablingPropertyChanged();
 
   // Cursors are not checked, since they will be set appropriately in response
   // to mouse events, so they don't need to cause any paint invalidation or
   // layout.
 
   // Animations don't need to be checked either. We always set the new style on
   // the layoutObject, so we will get a chance to fire off the resulting
   // transition properly.
 
   return diff;
 }
 
+bool ComputedStyle::scrollAnchorDisablingPropertyChanged(
+    const ComputedStyle& other,
+    StyleDifference& diff) const {
+  if (m_nonInheritedData.m_position != other.m_nonInheritedData.m_position)
+    return true;
+
+  if (m_box.get() != other.m_box.get()) {
+    if (m_box->width() != other.m_box->width() ||
+        m_box->minWidth() != other.m_box->minWidth() ||
+        m_box->maxWidth() != other.m_box->maxWidth() ||
+        m_box->height() != other.m_box->height() ||
+        m_box->minHeight() != other.m_box->minHeight() ||
+        m_box->maxHeight() != other.m_box->maxHeight())
+      return true;
+  }
+
+  if (m_surround.get() != other.m_surround.get()) {
+    if (m_surround->margin != other.m_surround->margin ||
+        m_surround->offset != other.m_surround->offset ||
+        m_surround->padding != other.m_surround->padding)
+      return true;
+  }
+
+  if (diff.transformChanged())
+    return true;
+
+  return false;
+}
+
 bool ComputedStyle::diffNeedsFullLayoutAndPaintInvalidation(
     const ComputedStyle& other) const {
   // FIXME: Not all cases in this method need both full layout and paint
   // invalidation.
   // Should move cases into diffNeedsFullLayout() if
   // - don't need paint invalidation at all;
   // - or the layoutObject knows how to exactly invalidate paints caused by the
   //   layout change instead of forced full paint invalidation.
 
   if (m_surround.get() != other.m_surround.get()) {
@@ skipping 1746 matching lines @@
     if (value < 0)
       fvalue -= 0.5f;
     else
       fvalue += 0.5f;
   }
 
   return roundForImpreciseConversion<int>(fvalue / zoomFactor);
 }
 
 }  // namespace blink