Paint backgrounds of a table section/row in one display item

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

 // Copyright 2016 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/layout/LayoutTableBoxComponent.h"
 
 #include "core/layout/LayoutTable.h"
 #include "core/style/ComputedStyle.h"
 
 namespace blink {
 
 bool LayoutTableBoxComponent::doCellsHaveDirtyWidth(
     const LayoutObject& tablePart,
     const LayoutTable& table,
     const StyleDifference& diff,
     const ComputedStyle& oldStyle) {
   // ComputedStyle::diffNeedsFullLayoutAndPaintInvalidation sets needsFullLayout
   // when border sizes change: checking diff.needsFullLayout() is an
   // optimization, not required for correctness.
   // TODO(dgrogan): Remove tablePart.needsLayout()? Perhaps it was an old
   // optimization but now it seems that diff.needsFullLayout() implies
   // tablePart.needsLayout().
   return diff.needsFullLayout() && tablePart.needsLayout() &&
          table.collapseBorders() &&
          !oldStyle.border().sizeEquals(tablePart.style()->border());
 }
 
+void LayoutTableBoxComponent::MutableForPainting::updatePaintResult(
+    PaintResult paintResult,
+    const CullRect& paintRect) {
+  // A table row or section may paint large background display item which
+  // contains paint operations of the background in each contained cell.
+  // The display item can be clipped by the paint rect to avoid painting
+  // on areas not interested. If we didn't fully paint and paint rect changes,
+  // we need to invalidate the display item.
+  auto& box = static_cast<LayoutTableBoxComponent&>(m_layoutObject);
+  if (box.m_lastPaintResult != FullyPainted && box.m_lastPaintRect != paintRect)
+    box.setDisplayItemsUncached();

[wkorman, 2017/03/31 22:15:41]

Why this vs invalidateDisplayItemClient?

[Xianzhu, 2017/03/31 23:26:30]

It should be invalidateDisplayItemClient. Done.

+
+  box.m_lastPaintResult = paintResult;
+  box.m_lastPaintRect = paintRect;
+}
+
 }  // namespace blink