Add StyleDifference::needsVisualRectUpdate

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 543 matching lines @@
       diff.setNeedsFullLayout();
     else
       diff.setNeedsPositionedMovementLayout();
   }
 
   if (diffNeedsPaintInvalidationSubtree(other))
     diff.setNeedsPaintInvalidationSubtree();
   else if (diffNeedsPaintInvalidationObject(other))
     diff.setNeedsPaintInvalidationObject();
 
+  if (diffNeedsVisualRectUpdate(other))
+    diff.setNeedsVisualRectUpdate();
+
   updatePropertySpecificDifferences(other, diff);
 
   // The following condition needs to be at last, because it may depend on
   // conditions in diff computed above.
   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.
@@ skipping 423 matching lines @@
     for (const AtomicString& property :
          *value->customInvalidationProperties()) {
       if (!dataEquivalent(getVariable(property), other.getVariable(property)))
         return true;
     }
   }
 
   return false;
 }
 
+// This doesn't include conditions needing layout or overflow recomputation
+// which implies visual rect update.
+bool ComputedStyle::diffNeedsVisualRectUpdate(
+    const ComputedStyle& other) const {
+  // Visual rect is empty if visibility is hidden.
+  if (visibility() != other.visibility())

[pdr., 2017/03/20 21:23:04]

Where was this logic before this patch? Can we remove the old code that was
detecting visibility changes?

[Xianzhu, 2017/03/20 22:26:35]

This is to make https://codereview.chromium.org/2732573003/ work. Previously
visibility change only caused needsPaintInvalidationObject which just caused
shouldDoFullPaintInvalidationWithoutGeometryChange().

Visibility affects visual rects through the visibility conditions in
localVisualRect() methods.

In the new patch I removed visibility change condition from
diffNeedsPaintInvalidationObject because visibility changes cause either empty
or non-empty visual rects, and diffNeedsVisualRectUpdate() is good.

+    return true;
+
+  // Need to update visual rect of the resizer.
+  if (resize() != other.resize())

[pdr., 2017/03/20 21:23:04]

The old code seemed to check against RESIZE_NONE whereas this checks against
changes. Is that the optimization you're referring to in the change description?

[Xianzhu, 2017/03/20 22:26:35]

The old code always invalidates the whole box container resizer when the box is
resized. With this change we'll just incrementally invalidate the box if needed
and invalidate the resizer if needed.

paint/invalidation/textarea-appearance-none-resize-handle-expected.txt shows the
effect of the optimization.

Here I don't check RESIZE_NONE for safety of future changes about visual size of
resizer according to different resizer styles.

+    return true;
+
+  return false;
+}
+
 void ComputedStyle::updatePropertySpecificDifferences(
     const ComputedStyle& other,
     StyleDifference& diff) const {
   if (m_box->zIndex() != other.m_box->zIndex() ||
       isStackingContext() != other.isStackingContext())
     diff.setZIndexChanged();
 
   if (m_rareNonInheritedData.get() != other.m_rareNonInheritedData.get()) {
     if (!transformDataEquivalent(other) ||
         m_rareNonInheritedData->m_perspective !=
@@ skipping 1462 matching lines @@
     if (value < 0)
       fvalue -= 0.5f;
     else
       fvalue += 0.5f;
   }
 
   return roundForImpreciseConversion<int>(fvalue / zoomFactor);
 }
 
 }  // namespace blink