Optimize collapsed border calculation (step 1)

third_party/WebKit/Source/core/layout/LayoutTable.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, 2010, 2013 Apple Inc.
  *               All rights reserved.
  * Copyright (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  *
@@ skipping 40 matching lines @@
 namespace blink {
 
 using namespace HTMLNames;
 
 LayoutTable::LayoutTable(Element* element)
     : LayoutBlock(element),
       head_(nullptr),
       foot_(nullptr),
       first_body_(nullptr),
       collapsed_borders_valid_(false),
+      needs_invalidate_collapsed_borders_for_all_cells_(false),
       has_col_elements_(false),
       needs_section_recalc_(false),
       column_logical_width_changed_(false),
       column_layout_objects_valid_(false),
       no_cell_colspan_at_least_(0),
       h_spacing_(0),
       v_spacing_(0),
       border_start_(0),
       border_end_(0) {
   DCHECK(!ChildrenInline());
@@ skipping 702 matching lines @@
   // to update the value as its used by flexbox layout. crbug.com/367324
   SetIntrinsicContentLogicalHeight(ContentLogicalHeight());
 
   column_logical_width_changed_ = false;
   ClearNeedsLayout();
 }
 
 void LayoutTable::InvalidateCollapsedBorders() {
   collapsed_borders_.clear();
   collapsed_borders_valid_ = false;
+  needs_invalidate_collapsed_borders_for_all_cells_ = true;
   SetMayNeedPaintInvalidation();
 }
 
+void LayoutTable::InvalidateCollapsedBordersForAllCellsIfNeeded() {
+  DCHECK(CollapseBorders());

[wkorman, 2017/04/27 20:11:15]

I was briefly confused with this vs. CollapsedBorders(). We should revise one or
the other method name to make clearer the difference (former checks whether
style is set, latter returns the collapsed border values instance, and differ by
only one char amidst name).

[Xianzhu, 2017/04/28 20:31:44]

Created https://codereview.chromium.org/2850633003/ to rename it.

+
+  if (!needs_invalidate_collapsed_borders_for_all_cells_)
+    return;
+  needs_invalidate_collapsed_borders_for_all_cells_ = false;
+
+  for (LayoutObject* section = FirstChild(); section;
+       section = section->NextSibling()) {
+    if (!section->IsTableSection())
+      continue;
+    for (LayoutTableRow* row = ToLayoutTableSection(section)->FirstRow(); row;
+         row = row->NextRow()) {
+      for (LayoutTableCell* cell = row->FirstCell(); cell;
+           cell = cell->NextCell()) {
+        DCHECK_EQ(cell->Table(), this);
+        cell->InvalidateCollapsedBorderValues();
+      }
+    }
+  }
+}
+
 // Collect all the unique border values that we want to paint in a sorted list.
 // During the collection, each cell saves its recalculated borders into the
 // cache of its containing section, and invalidates itself if any border
 // changes. This method doesn't affect layout.
 void LayoutTable::RecalcCollapsedBordersIfNeeded() {
   if (collapsed_borders_valid_ || !CollapseBorders())
     return;
   collapsed_borders_valid_ = true;
   collapsed_borders_.clear();
   for (LayoutObject* section = FirstChild(); section;
@@ skipping 942 matching lines @@
 }
 
 LayoutUnit LayoutTable::PaddingRight() const {
   if (CollapseBorders())
     return LayoutUnit();
 
   return LayoutBlock::PaddingRight();
 }
 
 }  // namespace blink