Style changes to visual overflow do not require a layout

Source/core/rendering/style/RenderStyle.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 451 matching lines @@
             return true;
 
         if (rareNonInheritedData->m_deprecatedFlexibleBox.get() != other.rareNonInheritedData->m_deprecatedFlexibleBox.get()
             && *rareNonInheritedData->m_deprecatedFlexibleBox.get() != *other.rareNonInheritedData->m_deprecatedFlexibleBox.get())
             return true;
 
         if (rareNonInheritedData->m_flexibleBox.get() != other.rareNonInheritedData->m_flexibleBox.get()
             && *rareNonInheritedData->m_flexibleBox.get() != *other.rareNonInheritedData->m_flexibleBox.get())
             return true;
 
-        // FIXME: We should add an optimized form of layout that just recomputes visual overflow.
-        if (!rareNonInheritedData->shadowDataEquivalent(*other.rareNonInheritedData.get()))
-            return true;
-
         if (!rareNonInheritedData->reflectionDataEquivalent(*other.rareNonInheritedData.get()))
             return true;
 
         if (rareNonInheritedData->m_multiCol.get() != other.rareNonInheritedData->m_multiCol.get()
             && *rareNonInheritedData->m_multiCol.get() != *other.rareNonInheritedData->m_multiCol.get())
             return true;
 
         // If the counter directives change, trigger a relayout to re-calculate counter values and rebuild the counter node tree.
         const CounterDirectiveMap* mapA = rareNonInheritedData->m_counterDirectives.get();
         const CounterDirectiveMap* mapB = other.rareNonInheritedData->m_counterDirectives.get();
@@ skipping 95 matching lines @@
             return true;
     } else if (noninherited_flags.effectiveDisplay == LIST_ITEM) {
         if (inherited_flags._list_style_type != other.inherited_flags._list_style_type
             || inherited_flags._list_style_position != other.inherited_flags._list_style_position)
             return true;
     }
 
     if ((visibility() == COLLAPSE) != (other.visibility() == COLLAPSE))
         return true;
 
-    if (!m_background->outline().visuallyEqual(other.m_background->outline())) {
-        // FIXME: We only really need to recompute the overflow but we don't have an optimized layout for it.
-        return true;
-    }
-
     // Movement of non-static-positioned object is special cased in RenderStyle::visualInvalidationDiff().
 
     return false;
 }
 
 bool RenderStyle::diffNeedsFullLayout(const RenderStyle& other) const
 {
     if (m_box.get() != other.m_box.get()) {
         if (m_box->width() != other.m_box->width()
             || m_box->minWidth() != other.m_box->minWidth()
@@ skipping 43 matching lines @@
         if (rareNonInheritedData->m_mask != other.rareNonInheritedData->m_mask
             || rareNonInheritedData->m_maskBoxImage != other.rareNonInheritedData->m_maskBoxImage)
             return true;
     }
 
     return false;
 }
 
 bool RenderStyle::diffNeedsPaintInvalidationObject(const RenderStyle& other) const
 {
+    if (!m_background->outline().visuallyEqual(other.m_background->outline()))
+        return true;
+
     if (inherited_flags._visibility != other.inherited_flags._visibility
         || inherited_flags.m_printColorAdjust != other.inherited_flags.m_printColorAdjust
         || inherited_flags._insideLink != other.inherited_flags._insideLink
         || !surround->border.visuallyEqual(other.surround->border)
         || !m_background->visuallyEqual(*other.m_background))
         return true;
 
     if (rareInheritedData.get() != other.rareInheritedData.get()) {
         if (rareInheritedData->userModify != other.rareInheritedData->userModify
             || rareInheritedData->userSelect != other.rareInheritedData->userSelect
             || rareInheritedData->m_imageRendering != other.rareInheritedData->m_imageRendering)
             return true;
     }
 
     if (rareNonInheritedData.get() != other.rareNonInheritedData.get()) {
         if (rareNonInheritedData->userDrag != other.rareNonInheritedData->userDrag
             || rareNonInheritedData->m_objectFit != other.rareNonInheritedData->m_objectFit
             || rareNonInheritedData->m_objectPosition != other.rareNonInheritedData->m_objectPosition
+            || !rareNonInheritedData->shadowDataEquivalent(*other.rareNonInheritedData.get())
             || !dataEquivalent(rareNonInheritedData->m_shapeOutside, other.rareNonInheritedData->m_shapeOutside)
             || !dataEquivalent(rareNonInheritedData->m_clipPath, other.rareNonInheritedData->m_clipPath))
             return true;
     }
 
     return false;
 }
 
 void RenderStyle::updatePropertySpecificDifferences(const RenderStyle& other, StyleDifference& diff) const
 {
     // StyleAdjuster has ensured that zIndex is non-auto only if it's applicable.
     if (m_box->zIndex() != other.m_box->zIndex() || m_box->hasAutoZIndex() != other.m_box->hasAutoZIndex())
         diff.setZIndexChanged();
 
     if (rareNonInheritedData.get() != other.rareNonInheritedData.get()) {
         if (!transformDataEquivalent(other))
             diff.setTransformChanged();
 
         if (rareNonInheritedData->opacity != other.rareNonInheritedData->opacity)
             diff.setOpacityChanged();
 
         if (rareNonInheritedData->m_filter != other.rareNonInheritedData->m_filter)
             diff.setFilterChanged();
+
+        if (!rareNonInheritedData->shadowDataEquivalent(*other.rareNonInheritedData.get()))
+            diff.setVisualOverflowChanged();
     }
 
+    if (!m_background->outline().visuallyEqual(other.m_background->outline()) || !surround->border.visualOverflowEqual(other.surround->border))
+        diff.setVisualOverflowChanged();
+
     if (!diff.needsPaintInvalidation()) {
         if (inherited->color != other.inherited->color
             || inherited_flags.m_textUnderline != other.inherited_flags.m_textUnderline
             || visual->textDecoration != other.visual->textDecoration) {
             diff.setTextOrColorChanged();
         } else if (rareNonInheritedData.get() != other.rareNonInheritedData.get()) {
             if (rareNonInheritedData->m_textDecorationStyle != other.rareNonInheritedData->m_textDecorationStyle
                 || rareNonInheritedData->m_textDecorationColor != other.rareNonInheritedData->m_textDecorationColor)
                 diff.setTextOrColorChanged();
         } else if (rareInheritedData.get() != other.rareInheritedData.get()) {
@@ skipping 1042 matching lines @@
         horizontal || includeLogicalRightEdge);
 
     edges[BSLeft] = BorderEdge(borderLeftWidth(),
         visitedDependentColor(CSSPropertyBorderLeftColor),
         borderLeftStyle(),
         borderLeftIsTransparent(),
         !horizontal || includeLogicalLeftEdge);
 }
 
 } // namespace blink