Don't paint repeating header if only the border spacing exceeds page height

third_party/WebKit/Source/core/paint/TableSectionPainter.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/TableSectionPainter.h"
 
 #include "core/layout/LayoutTableCell.h"
 #include "core/layout/LayoutTableCol.h"
 #include "core/layout/LayoutTableRow.h"
 #include "core/paint/BoxClipper.h"
@@ skipping 34 matching lines @@
     const LayoutPoint& paintOffset,
     const CollapsedBorderValue& currentBorderValue,
     ItemToPaint itemToPaint) {
   if (!m_layoutTableSection.isRepeatingHeaderGroup())
     return;
 
   LayoutTable* table = m_layoutTableSection.table();
   LayoutPoint paginationOffset = paintOffset;
   LayoutUnit pageHeight = table->pageLogicalHeightForOffset(LayoutUnit());
 
-  // Move paginationOffset to the top of the next page.
+  LayoutUnit headerGroupOffset = table->blockOffsetToFirstRepeatableHeader();
   // The header may have a pagination strut before it so we need to account for
   // that when establishing its position.
-  LayoutUnit headerGroupOffset = table->blockOffsetToFirstRepeatableHeader();
   if (LayoutTableRow* row = m_layoutTableSection.firstRow())
     headerGroupOffset += row->paginationStrut();
   LayoutUnit offsetToNextPage =
       pageHeight - intMod(headerGroupOffset, pageHeight);
+  // Move paginationOffset to the top of the next page.
   paginationOffset.move(LayoutUnit(), offsetToNextPage);
   // Now move paginationOffset to the top of the page the cull rect starts on.
   if (paintInfo.cullRect().m_rect.y() > paginationOffset.y()) {
     paginationOffset.move(LayoutUnit(), pageHeight *
                                             ((paintInfo.cullRect().m_rect.y() -
                                               paginationOffset.y()) /
                                              pageHeight)
                                                 .toInt());
   }
+
+  // We only want to consider pages where we going to paint a row, so exclude
+  // captions and border spacing from the table.
+  LayoutRect sectionsRect(LayoutPoint(), table->size());
+  table->subtractCaptionRect(sectionsRect);
+  LayoutUnit totalHeightOfRows =
+      sectionsRect.height() - table->vBorderSpacing();

[mstensho (USE GERRIT), 2016/11/02 20:14:26]

This is wrong in vertical writing modes, but I guess it's always been so...

   LayoutUnit bottomBound =
       std::min(LayoutUnit(paintInfo.cullRect().m_rect.maxY()),
-               paintOffset.y() + table->logicalHeight());
-  paginationOffset.move(LayoutUnit(), -m_layoutTableSection.logicalTop());
+               paintOffset.y() + totalHeightOfRows);
+
   while (paginationOffset.y() < bottomBound) {
     LayoutPoint nestedOffset =
         paginationOffset +
         LayoutPoint(LayoutUnit(),
                     m_layoutTableSection.offsetForRepeatingHeader());
     if (itemToPaint == PaintCollapsedBorders)
       paintCollapsedSectionBorders(paintInfo, nestedOffset, currentBorderValue);
     else
       paintSection(paintInfo, nestedOffset);
     paginationOffset.move(0, pageHeight.toInt());
@@ skipping 307 matching lines @@
   LayoutRect bounds = BoxPainter(m_layoutTableSection)
                           .boundsForDrawingRecorder(paintInfo, paintOffset);
   LayoutObjectDrawingRecorder recorder(paintInfo.context, m_layoutTableSection,
                                        type, bounds);
   BoxPainter::paintBoxShadow(
       paintInfo, LayoutRect(paintOffset, m_layoutTableSection.size()),
       m_layoutTableSection.styleRef(), shadowStyle);
 }
 
 }  // namespace blink