Optimize collapsed border calculation (step 2)

third_party/WebKit/Source/core/layout/LayoutTableCell.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, 2007, 2008, 2009 Apple Inc.
  *               All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 90 matching lines @@
   LayoutBlockFlow::WillBeRemovedFromTree();
 
   Section()->SetNeedsCellRecalc();
 
   // When borders collapse, removing a cell can affect the the width of
   // neighboring cells.
   LayoutTable* enclosing_table = Table();
   DCHECK(enclosing_table);
   if (!enclosing_table->CollapseBorders())
     return;
+  // TODO(wangxianzhu,dgrogan): The following seems incorrect if the cell has
+  // adjacent cells other than PreviousCell() and NextCell(). Could reuse some
+  // code in LayoutTableCell::InvalidateCollapsedBordersOfAffectedCells().
   if (PreviousCell()) {
     // TODO(dgrogan): Should this be setChildNeedsLayout or setNeedsLayout?
     // remove-cell-with-border-box.html only passes with setNeedsLayout but
     // other places use setChildNeedsLayout.
     PreviousCell()->SetNeedsLayout(LayoutInvalidationReason::kTableChanged);
     PreviousCell()->SetPreferredLogicalWidthsDirty();
   }
   if (NextCell()) {
     // TODO(dgrogan): Same as above re: setChildNeedsLayout vs setNeedsLayout.
     NextCell()->SetNeedsLayout(LayoutInvalidationReason::kTableChanged);
@@ skipping 369 matching lines @@
   // it from scratch.
   if (Style()->VerticalAlign() != old_style->VerticalAlign())
     ClearIntrinsicPadding();
 
   if (!Parent())
     return;
   LayoutTable* table = Table();
   if (!table)
     return;
 
-  LayoutTableBoxComponent::InvalidateCollapsedBordersOnStyleChange(
-      *this, *table, diff, *old_style);
+  if (LayoutTableBoxComponent::NeedsInvalidateCollapsedBordersOnStyleChange(
+          *this, *table, diff, *old_style))
+    InvalidateCollapsedBordersOfAffectedCells();
 
   if (LayoutTableBoxComponent::DoCellsHaveDirtyWidth(*this, *table, diff,
                                                      *old_style)) {
+    // TODO(wangxianzhu,dgrogan): The following seems incorrect if the cell has

[dgrogan, 2017/04/27 20:43:25]

Could you expound on this a little? When can a cell have adjacent cells other
than PreviousCell and NextCell? Do you mean above and below? Or something with
spans? Or something else entirely?

[Xianzhu, 2017/04/27 21:18:31]

Actually I'm not very sure if the TODO is valid. I will remove it if it's
invalid, otherwise will make it clearer.

For example:
<tr>
  <td rowspan="2">A</td><td>B</td>
</tr>
<tr>
  <td>C</td>
</tr>

It seems that A's border width may affect preferred width of both B and C.

(However, I'm not sure if C's border width should affect A. A's right border
actually has two segments which may differ in width. Currently LayoutTableCell
supports only one CollapsedBorderValue in each side so for layout it seems that
we just consider the first segment for now. @robhogan's
https://codereview.chromium.org/2791433003/ will support multiple segments
though.)

+    // adjacent cells other than PreviousCell() and NextCell(). Could reuse some
+    // code in LayoutTableCell::InvalidateCollapsedBordersOfAffectedCells().
     if (PreviousCell()) {
       // TODO(dgrogan) Add a layout test showing that setChildNeedsLayout is
       // needed instead of setNeedsLayout.
       PreviousCell()->SetChildNeedsLayout();
       PreviousCell()->SetPreferredLogicalWidthsDirty(kMarkOnlyThis);
     }
     if (NextCell()) {
       // TODO(dgrogan) Add a layout test showing that setChildNeedsLayout is
       // needed instead of setNeedsLayout.
       NextCell()->SetChildNeedsLayout();
@@ skipping 739 matching lines @@
         2);
   }
   return LayoutUnit();
 }
 
 void LayoutTableCell::Paint(const PaintInfo& paint_info,
                             const LayoutPoint& paint_offset) const {
   TableCellPainter(*this).Paint(paint_info, paint_offset);
 }
 
+void LayoutTableCell::InvalidateCollapsedBordersOfAffectedCells() {
+  auto* table = this->Table();
+  DCHECK(table && table->CollapseBorders());
+  if (table->NeedsInvalidateCollapsedBordersForAllCells())
+    return;
+
+  table->RecalcSectionsIfNeeded();
+  table->InvalidateCollapsedBorders();
+
+  InvalidateCollapsedBorderValues();
+
+  auto col_span = this->ColSpan();
+  auto row_span = this->RowSpan();
+  auto row = RowIndex();
+  auto effective_column =
+      table->AbsoluteColumnToEffectiveColumn(AbsoluteColumnIndex());
+  auto end_effective_column =
+      table->AbsoluteColumnToEffectiveColumn(AbsoluteColumnIndex() + col_span);
+  auto* section = this->Section();
+
+  // Invalidate cells above and below this cell.
+  for (auto c = effective_column; c < end_effective_column; ++c) {
+    if (auto* cell = section->PrimaryCellAboveInTable(row, c))
+      cell->InvalidateCollapsedBorderValues();
+    if (auto* cell = section->PrimaryCellBelowInTable(row, c))
+      cell->InvalidateCollapsedBorderValues();
+  }
+  // Invalidate cells before and after this cell.
+  for (unsigned i = 0; i < row_span; ++i) {
+    if (effective_column > 0) {
+      if (auto* cell = section->PrimaryCellAt(row + i, effective_column - 1))
+        cell->InvalidateCollapsedBorderValues();
+    }
+    if (auto* cell = section->PrimaryCellAt(row + i, end_effective_column))
+      cell->InvalidateCollapsedBorderValues();
+  }
+}
+
 void LayoutTableCell::RecalcCollapsedBorderValuesIfNeeded() const {
   Table()->InvalidateCollapsedBordersForAllCellsIfNeeded();
   if (collapsed_border_values_valid_)
     return;
 
   collapsed_border_values_valid_ = true;
 
   if (!Table()->CollapseBorders()) {
     if (collapsed_border_values_) {
       collapsed_borders_visually_changed_ = true;
@@ skipping 198 matching lines @@
 }
 
 bool LayoutTableCell::HasLineIfEmpty() const {
   if (GetNode() && HasEditableStyle(*GetNode()))
     return true;
 
   return LayoutBlock::HasLineIfEmpty();
 }
 
 }  // namespace blink