Add grid/flex layout support for <fieldset>

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

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 865 matching lines @@
     LayoutUnit sumFlexBaseSize;
     double totalFlexGrow;
     double totalFlexShrink;
     double totalWeightedFlexShrink;
     LayoutUnit sumHypotheticalMainSize;
 
     PaintLayerScrollableArea::PreventRelayoutScope preventRelayoutScope(layoutScope);
 
     m_orderIterator.first();
     LayoutUnit crossAxisOffset = flowAwareBorderBefore() + flowAwarePaddingBefore();
-    while (computeNextFlexLine(orderedChildren, sumFlexBaseSize, totalFlexGrow, totalFlexShrink, totalWeightedFlexShrink, sumHypotheticalMainSize, relayoutChildren)) {
+    while (computeNextFlexLine(orderedChildren, sumFlexBaseSize, totalFlexGrow, totalFlexShrink, totalWeightedFlexShrink, sumHypotheticalMainSize, relayoutChildren, layoutScope)) {
         LayoutUnit containerMainInnerSize = mainAxisContentExtent(sumHypotheticalMainSize);
         // availableFreeSpace is the initial amount of free space in this flexbox.
         // remainingFreeSpace starts out at the same value but as we place and lay out
         // flex items we subtract from it. Note that both values can be negative.
         LayoutUnit remainingFreeSpace = containerMainInnerSize - sumFlexBaseSize;
         FlexSign flexSign = (sumHypotheticalMainSize < containerMainInnerSize) ? PositiveFlexibility : NegativeFlexibility;
         freezeInflexibleItems(flexSign, orderedChildren, remainingFreeSpace, totalFlexGrow, totalFlexShrink, totalWeightedFlexShrink);
         // The initial free space gets calculated after freezing inflexible items. https://drafts.csswg.org/css-flexbox/#resolve-flexible-lengths step 3
         const LayoutUnit initialFreeSpace = remainingFreeSpace;
         while (!resolveFlexibleLengths(flexSign, orderedChildren, initialFreeSpace, remainingFreeSpace, totalFlexGrow, totalFlexShrink, totalWeightedFlexShrink)) {
@@ skipping 296 matching lines @@
     }
 
     if (crossAxisLengthIsDefinite(child, crossMin)) {
         LayoutUnit minValue = computeMainSizeFromAspectRatioUsing(child, crossMin);
         childSize = std::max(minValue, childSize);
     }
 
     return childSize;
 }
 
-bool LayoutFlexibleBox::computeNextFlexLine(OrderedFlexItemList& orderedChildren, LayoutUnit& sumFlexBaseSize, double& totalFlexGrow, double& totalFlexShrink, double& totalWeightedFlexShrink, LayoutUnit& sumHypotheticalMainSize, bool relayoutChildren)
+bool LayoutFlexibleBox::computeNextFlexLine(OrderedFlexItemList& orderedChildren, LayoutUnit& sumFlexBaseSize, double& totalFlexGrow, double& totalFlexShrink, double& totalWeightedFlexShrink, LayoutUnit& sumHypotheticalMainSize, bool relayoutChildren, SubtreeLayoutScope& layoutScope)
 {
     orderedChildren.clear();
     sumFlexBaseSize = LayoutUnit();
     totalFlexGrow = totalFlexShrink = totalWeightedFlexShrink = 0;
     sumHypotheticalMainSize = LayoutUnit();
 
     if (!m_orderIterator.currentChild())
         return false;
 
     LayoutUnit lineBreakLength = mainAxisContentExtent(LayoutUnit::max());
 
     bool lineHasInFlowItem = false;
 
+    // Fieldsets need to find their legend and position it inside the border of the object.
+    // The legend then gets skipped during normal layout.
+    // It doesn't get included in the normal layout process but is instead skipped.
+    LayoutObject* childToExclude = layoutSpecialExcludedChild(relayoutChildren, layoutScope);

[cbiesinger, 2016/07/20 01:42:31]

Thanks for doing this! I'll take a closer look tomorrow but briefly, I don't
think calling this inside this function works because we call it (potentially)
multiple times during layout of a single flexbox, whereas we probably only want
to layout the special excluded child once. I would call it from layoutFlexItems
and then just pass in the LayoutObject to this function so we can then skip it.

[Gleb Lanbin, 2016/07/21 18:25:31]

Done.

+
     for (LayoutBox* child = m_orderIterator.currentChild(); child; child = m_orderIterator.next()) {
+
+        if (childToExclude == child)
+            continue; // Skip this child, since it will be positioned by the specialized subclass (fieldsets runs).
+
         if (child->isOutOfFlowPositioned()) {
             orderedChildren.append(FlexItem(child));
             continue;
         }
 
         ChildLayoutType layoutType = relayoutChildren ? ForceLayout : LayoutIfNeeded;
 
         // If this condition is true, then computeMainAxisExtentForChild will call child.intrinsicContentLogicalHeight()
         // and child.scrollbarLogicalHeight(), so if the child has intrinsic min/max/preferred size,
         // run layout on it now to make sure its logical height and scroll bars are up to date.
@@ skipping 678 matching lines @@
             ASSERT(child);
             LayoutUnit lineCrossAxisExtent = lineContexts[lineNumber].crossAxisExtent;
             LayoutUnit originalOffset = lineContexts[lineNumber].crossAxisOffset - crossAxisStartEdge;
             LayoutUnit newOffset = contentExtent - originalOffset - lineCrossAxisExtent;
             adjustAlignmentForChild(*child, newOffset - originalOffset);
         }
     }
 }
 
 } // namespace blink