Attempt to clean up requiresLayoutToDetermineWidth to be more clear

Source/core/rendering/RenderBox.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2005 Allan Sandfeld Jensen (kde@carewolf.com)
  *           (C) 2005, 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Adobe Systems Incorporated. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 390 matching lines @@
 int RenderBox::pixelSnappedOffsetWidth() const
 {
     return snapSizeToPixel(offsetWidth(), x() + clientLeft());
 }
 
 int RenderBox::pixelSnappedOffsetHeight() const
 {
     return snapSizeToPixel(offsetHeight(), y() + clientTop());
 }
 
-bool RenderBox::requiresLayoutToDetermineWidth() const
+bool RenderBox::canDetermineWidthWithoutLayout() const
 {
+    // FIXME: There are likely many subclasses of RenderBlockFlow which

[Julien - ping for review, 2013/09/30 16:28:06]

Maybe also classes outside RenderBlockFlow?

+    // cannot determine their layout just from style!
+    // Perhaps we should create a "PlainRenderBlockFlow"
+    // and move this optimization there?
+    if (!isRenderBlockFlow()
+        // Flexbox items can be expanded beyond their width.
+        || isFlexItemIncludingDeprecated()
+        // Table Layout controls cell size, width is ignored.

[Julien - ping for review, 2013/09/30 16:28:06]

width is not ignored when doing a table layout. On the contrary, it is used to
determine the cell's width. What is important is that the table layout algorithm
can override the computed width, which is why we have to run layout.

+        || isTableCell())
+        return false;
+
     RenderStyle* style = this->style();
-    return !style->width().isFixed()
-        || !style->minWidth().isFixed()
-        || (!style->maxWidth().isUndefined() && !style->maxWidth().isFixed())
-        || !style->paddingLeft().isFixed()
-        || !style->paddingRight().isFixed()
-        || style->resize() != RESIZE_NONE
-        || style->boxSizing() == BORDER_BOX
-        || !isRenderBlock()
-        || !isRenderBlockFlow()
-        || isFlexItemIncludingDeprecated()
-        // TableCells can expand beyond a specified width.
-        || isTableCell();
+    return style->width().isFixed()
+        && style->minWidth().isFixed()
+        && (style->maxWidth().isUndefined() || style->maxWidth().isFixed())
+        && style->paddingLeft().isFixed()
+        && style->paddingRight().isFixed()
+        && style->boxSizing() == CONTENT_BOX;
 }
 
 LayoutUnit RenderBox::fixedOffsetWidth() const
 {
-    ASSERT(!requiresLayoutToDetermineWidth());
+    ASSERT(canDetermineWidthWithoutLayout());
 
     RenderStyle* style = this->style();
 
     LayoutUnit width = std::max(LayoutUnit(style->minWidth().value()), LayoutUnit(style->width().value()));
     if (style->maxWidth().isFixed())
         width = std::min(LayoutUnit(style->maxWidth().value()), width);
 
     LayoutUnit borderLeft = style->borderLeft().nonZero() ? style->borderLeft().width() : 0;
     LayoutUnit borderRight = style->borderRight().nonZero() ? style->borderRight().width() : 0;
 
@@ skipping 1640 matching lines @@
     float maxWidth = 0;
     for (RenderObject* child = renderer->firstChild(); child; child = child->nextSibling()) {
         if (!child->isListItem())
             continue;
 
         RenderBox* listItem = toRenderBox(child);
         for (RenderObject* itemChild = listItem->firstChild(); itemChild; itemChild = itemChild->nextSibling()) {
             if (!itemChild->isListMarker())
                 continue;
             RenderBox* itemMarker = toRenderBox(itemChild);
-            if (itemMarker->requiresLayoutToDetermineWidth() && itemMarker->needsLayout()) {
+            // FIXME: canDetermineWidthWithoutLayout expects us to use fixedOffsetWidth, which this code
+            // does not do! This check is likely wrong.
+            if (!itemMarker->canDetermineWidthWithoutLayout() && itemMarker->needsLayout()) {
                 // Make sure to compute the autosized width.
                 itemMarker->layout();

[Julien - ping for review, 2013/09/30 16:28:06]

layoutIfNeeded()?

             }
             maxWidth = max<float>(maxWidth, toRenderListMarker(itemMarker)->logicalWidth().toFloat());
             break;
         }
     }
     return maxWidth;
 }
 
 void RenderBox::computeLogicalWidthInRegion(LogicalExtentComputedValues& computedValues, RenderRegion* region) const
 {
@@ skipping 2663 matching lines @@
         return 0;
 
     if (!layoutState && !flowThreadContainingBlock())
         return 0;
 
     RenderBlock* containerBlock = containingBlock();
     return containerBlock->offsetFromLogicalTopOfFirstPage() + logicalTop();
 }
 
 } // namespace WebCore