Paint collapsed borders of a table as one display item

third_party/WebKit/Source/core/paint/TablePainter.cpp

 // Copyright 2014 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/paint/TablePainter.h"
 
 #include "core/layout/LayoutTable.h"
 #include "core/layout/LayoutTableSection.h"
 #include "core/style/CollapsedBorderValue.h"
 #include "core/paint/BoxClipper.h"
@@ skipping 26 matching lines @@
     for (LayoutObject* child = m_layoutTable.firstChild(); child;
          child = child->nextSibling()) {
       if (child->isBox() && !toLayoutBox(child)->hasSelfPaintingLayer() &&
           (child->isTableSection() || child->isTableCaption())) {
         LayoutPoint childPoint = m_layoutTable.flipForWritingModeForChild(
             toLayoutBox(child), paintOffset);
         child->paint(paintInfoForDescendants, childPoint);
       }
     }
 
-    if (m_layoutTable.collapseBorders() &&
-        shouldPaintDescendantBlockBackgrounds(paintPhase) &&
-        m_layoutTable.style()->visibility() == EVisibility::Visible) {
-      // Using our cached sorted styles, we then do individual passes,
-      // painting each style of border from lowest precedence to highest
-      // precedence.
-      LayoutTable::CollapsedBorderValues collapsedBorders =
-          m_layoutTable.collapsedBorders();
-      size_t count = collapsedBorders.size();
-      for (size_t i = 0; i < count; ++i) {
-        for (LayoutTableSection* section = m_layoutTable.bottomSection();
-             section; section = m_layoutTable.sectionAbove(section)) {
-          LayoutPoint childPoint =
-              m_layoutTable.flipForWritingModeForChild(section, paintOffset);
-          TableSectionPainter(*section).paintCollapsedBorders(
-              paintInfoForDescendants, childPoint, collapsedBorders[i]);
-        }
-      }
-    }
+    if (shouldPaintDescendantBlockBackgrounds(paintPhase))
+      paintCollapsedBorders(paintInfoForDescendants, paintOffset);
   }
 
   if (shouldPaintSelfOutline(paintPhase))
     ObjectPainter(m_layoutTable).paintOutline(paintInfo, paintOffset);
 }
 
+void TablePainter::paintCollapsedBorders(const PaintInfo& paintInfo,
+                                         const LayoutPoint& paintOffset) {
+  if (!m_layoutTable.hasCollapsedBorders() ||
+      m_layoutTable.style()->visibility() != EVisibility::Visible)
+    return;
+
+  LayoutTable::CollapsedBordersInfo& collapsedBorders =
+      m_layoutTable.getCollapsedBordersInfo();
+  if (paintInfo.context.getPaintController().clientCacheIsValid(

[wkorman, 2016/11/03 05:26:13]

This looks like the first call of clientCacheIsValid() outside of
PaintController itself, may be worth a comment noting that this is unusual since
painting collapsed borders is itself unusual and so we manage its cache
invalidation specially. Or maybe we expect there may be more calls to
clientCacheIsValid() for similar cases later. Figured worth mentioning since it
caught my eye.

[Xianzhu, 2016/11/03 16:06:13]

Done.

+          m_layoutTable) &&
+      collapsedBorders.lastPaintResult != FullyPainted &&
+      collapsedBorders.lastPaintRect != paintInfo.cullRect())
+    m_layoutTable.setDisplayItemsUncached();
+
+  if (!DrawingRecorder::useCachedDrawingIfPossible(
+          paintInfo.context, m_layoutTable,
+          DisplayItem::kTableCollapsedBorders)) {
+    DrawingRecorder recorder(
+        paintInfo.context, m_layoutTable, DisplayItem::kTableCollapsedBorders,
+        FloatRect(LayoutRect(paintOffset, m_layoutTable.size())));
+
+    // Using our cached sorted styles, we then do individual passes, painting
+    // each style of border from lowest precedence to highest precedence.
+    PaintResult paintResult = FullyPainted;
+    for (const auto& borderValue : collapsedBorders.values) {
+      for (LayoutTableSection* section = m_layoutTable.bottomSection(); section;
+           section = m_layoutTable.sectionAbove(section)) {
+        LayoutPoint childPoint =
+            m_layoutTable.flipForWritingModeForChild(section, paintOffset);
+        if (TableSectionPainter(*section).paintCollapsedBorders(
+                paintInfo, childPoint, borderValue) ==
+            MayBeClippedByPaintDirtyRect)
+          paintResult = MayBeClippedByPaintDirtyRect;
+      }
+    }
+    collapsedBorders.lastPaintResult = paintResult;
+    collapsedBorders.lastPaintRect = paintInfo.cullRect();
+  }
+}
+
 void TablePainter::paintBoxDecorationBackground(
     const PaintInfo& paintInfo,
     const LayoutPoint& paintOffset) {
   if (!m_layoutTable.hasBoxDecorationBackground() ||
       m_layoutTable.style()->visibility() != EVisibility::Visible)
     return;
 
   LayoutRect rect(paintOffset, m_layoutTable.size());
   m_layoutTable.subtractCaptionRect(rect);
   BoxPainter(m_layoutTable)
@@ skipping 12 matching lines @@
 
   LayoutRect rect(paintOffset, m_layoutTable.size());
   m_layoutTable.subtractCaptionRect(rect);
 
   LayoutObjectDrawingRecorder recorder(paintInfo.context, m_layoutTable,
                                        paintInfo.phase, rect);
   BoxPainter(m_layoutTable).paintMaskImages(paintInfo, rect);
 }
 
 }  // namespace blink