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

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

 /*
  * Copyright (C) 1997 Martin Jones (mjones@kde.org)
  *           (C) 1997 Torben Weis (weis@kde.org)
  *           (C) 1998 Waldo Bastian (bastian@kde.org)
  *           (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2008, 2009, 2010, 2013 Apple Inc.
  *               All rights reserved.
  * Copyright (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  *
@@ skipping 1262 matching lines @@
   m_overflow.reset();
   m_overflowingCells.clear();
   m_forceSlowPaintPathWithOverflowingCell = false;
 #if DCHECK_IS_ON()
   bool hasOverflowingCell = false;
 #endif
   // Now that our height has been determined, add in overflow from cells.
   for (unsigned r = 0; r < totalRows; r++) {
     unsigned nCols = numCols(r);
     for (unsigned c = 0; c < nCols; c++) {
-      CellStruct& cs = cellAt(r, c);
-      LayoutTableCell* cell = cs.primaryCell();
-      if (!cell || cs.inColSpan)
-        continue;
-      if (r < totalRows - 1 && cell == primaryCellAt(r + 1, c))
+      const auto* cell = originatingCellAt(r, c);

[chrishtr, 2017/03/31 22:59:06]

Why the changes here?

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

I added originatingCellAt() in a previous CL. The old code is just to find
originatingCellAt().

+      if (!cell)
         continue;
       addOverflowFromChild(cell);
 #if DCHECK_IS_ON()
       hasOverflowingCell |= cell->hasVisualOverflow();
 #endif
       if (cell->hasVisualOverflow() &&
           !m_forceSlowPaintPathWithOverflowingCell) {
         m_overflowingCells.insert(cell);
         if (m_overflowingCells.size() > maxAllowedOverflowingCellsCount) {
           // We need to set m_forcesSlowPaintPath only if there is a least one
@@ skipping 225 matching lines @@
   // section's (see bug 96691).
   if (!style()->isLeftToRightDirection())
     tableAlignedRect.setX(columnPos[columnPos.size() - 1] -
                           tableAlignedRect.maxX());
 
   return tableAlignedRect;
 }
 
 CellSpan LayoutTableSection::dirtiedRows(const LayoutRect& damageRect) const {
   if (m_forceSlowPaintPathWithOverflowingCell)
-    return fullTableRowSpan();
+    return fullSectionRowSpan();
 
   if (!m_grid.size())
     return CellSpan(0, 0);
 
   CellSpan coveredRows = spannedRows(damageRect);
 
   // To issue paint invalidations for the border we might need to paint
   // invalidate the first or last row even if they are not spanned themselves.
   CHECK_LT(coveredRows.start(), m_rowPos.size());
   if (coveredRows.start() == m_rowPos.size() - 1 &&
@@ skipping 587 matching lines @@
   if (table()->header() == this && isRepeatingHeaderGroup()) {
     transformState.flatten();
     FloatRect rect = transformState.lastPlanarQuad().boundingBox();
     rect.setHeight(table()->logicalHeight());
     transformState.setQuad(FloatQuad(rect));
   }
   return LayoutTableBoxComponent::mapToVisualRectInAncestorSpaceInternal(
       ancestor, transformState, flags);
 }
 
+bool LayoutTableSection::paintedOutputOfObjectHasNoEffectRegardlessOfSize()
+    const {
+  // LayoutTableSection paints background from columns.
+  if (table()->hasColElements())

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

Sometimes I expect table might have col elements but no need to paint anything
due to style, is that worth considering now or in future?

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

paintedOutputOfObjectHasNoEffectRegardlessOfSize() should be super fast
otherwise the purpose would be defeated. Table cols are rare, and I think in
many cases cols are defined to add col backgrounds, so I prefer not checking col
backgrounds.

+    return false;
+  return LayoutTableBoxComponent::
+      paintedOutputOfObjectHasNoEffectRegardlessOfSize();
+}
+
 }  // namespace blink