Avoid multiple recursions through the tree when calculating percent height

third_party/WebKit/Source/core/layout/LayoutBox.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 574 matching lines @@
     if (!styleToUse.logicalMaxHeight().isMaxSizeNone()) {
         LayoutUnit maxH = computeLogicalHeightUsing(MaxSize, styleToUse.logicalMaxHeight(), intrinsicContentHeight);
         if (maxH != -1)
             logicalHeight = std::min(logicalHeight, maxH);
     }
     return std::max(logicalHeight, computeLogicalHeightUsing(MinSize, styleToUse.logicalMinHeight(), intrinsicContentHeight));
 }
 
 LayoutUnit LayoutBox::constrainContentBoxLogicalHeightByMinMax(LayoutUnit logicalHeight, LayoutUnit intrinsicContentHeight) const
 {
+    // If the min/max height and logical height are both percentages we take advantage of already knowing the current resolved percentage height
+    // to avoid recursing up through our containing blocks again to determine it.
     const ComputedStyle& styleToUse = styleRef();
     if (!styleToUse.logicalMaxHeight().isMaxSizeNone()) {
-        LayoutUnit maxH = computeContentLogicalHeight(MaxSize, styleToUse.logicalMaxHeight(), intrinsicContentHeight);
-        if (maxH != -1)
-            logicalHeight = std::min(logicalHeight, maxH);
+        if (styleToUse.logicalMaxHeight().hasPercent() && styleToUse.logicalHeight().hasPercent()) {
+            LayoutUnit availableLogicalHeight = logicalHeight / styleToUse.logicalHeight().value() * 100;
+            logicalHeight = std::min(logicalHeight, valueForLength(styleToUse.logicalMaxHeight(), availableLogicalHeight));
+        } else {
+            LayoutUnit maxHeight = computeContentLogicalHeight(MaxSize, styleToUse.logicalMaxHeight(), -1);
+            if (maxHeight != -1)
+                logicalHeight = std::min(logicalHeight, maxHeight);
+        }
     }
-    return std::max(logicalHeight, computeContentLogicalHeight(MinSize, styleToUse.logicalMinHeight(), intrinsicContentHeight));
+
+    if (styleToUse.logicalMinHeight().hasPercent() && styleToUse.logicalHeight().hasPercent()) {
+        LayoutUnit availableLogicalHeight = logicalHeight / styleToUse.logicalHeight().value() * 100;
+        logicalHeight = std::max(logicalHeight, valueForLength(styleToUse.logicalMinHeight(), availableLogicalHeight));
+    } else {
+        logicalHeight = std::max(logicalHeight, computeContentLogicalHeight(MinSize, styleToUse.logicalMinHeight(), intrinsicContentHeight));
+    }
+
+    return logicalHeight;
 }
 
 void LayoutBox::setLocationAndUpdateOverflowControlsIfNeeded(const LayoutPoint& location)
 {
     if (hasOverflowClip()) {
         IntSize oldPixelSnappedBorderRectSize = pixelSnappedBorderBoxRect().size();
         setLocation(location);
         if (pixelSnappedBorderBoxRect().size() != oldPixelSnappedBorderRectSize)
             scrollableArea()->updateAfterLayout();
         return;
@@ skipping 4228 matching lines @@
     StyleImage* borderImage = style()->borderImage().image();
     return borderImage && borderImage->canRender(*this, style()->effectiveZoom()) && borderImage->isLoaded();
 }
 
 ShapeOutsideInfo* LayoutBox::shapeOutsideInfo() const
 {
     return ShapeOutsideInfo::isEnabledFor(*this) ? ShapeOutsideInfo::info(*this) : nullptr;
 }
 
 } // namespace blink