Move viewport unit resolution to style recalc time

Source/core/css/resolver/FontBuilder.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Google Inc. 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
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 44 matching lines @@
     }
 
 private:
     FontBuilder* m_fontBuilder;
     FontDescription m_fontDescription;
 };
 
 FontBuilder::FontBuilder()
     : m_document(0)
     , m_useSVGZoomRules(false)
+    , m_fontSizehasViewportUnits(false)
     , m_fontDirty(false)
 {
 }
 
 void FontBuilder::initForStyleResolve(const Document& document, RenderStyle* style, bool useSVGZoomRules)
 {
     // All documents need to be in a frame (and thus have access to Settings)
     // for style-resolution to make sense.
     // Unfortunately SVG Animations currently violate this: crbug.com/260966
     // ASSERT(m_document->frame());
@@ skipping 242 matching lines @@
         case CSSValueSmaller:
             size = smallerFontSize(parentSize);
             break;
         default:
             return;
         }
 
         scope.fontDescription().setIsAbsoluteSize(parentIsAbsoluteSize && (valueID == CSSValueLarger || valueID == CSSValueSmaller));
     } else {
         scope.fontDescription().setIsAbsoluteSize(parentIsAbsoluteSize || !(primitiveValue->isPercentage() || primitiveValue->isFontRelativeLength()));
-        if (primitiveValue->isLength())
-            size = primitiveValue->computeLength<float>(CSSToLengthConversionData(parentStyle, rootElementStyle, 1.0, true));
-        else if (primitiveValue->isPercentage())
+        if (primitiveValue->isPercentage()) {
             size = (primitiveValue->getFloatValue() * parentSize) / 100.0f;
-        else if (primitiveValue->isCalculatedPercentageWithLength())
-            size = primitiveValue->cssCalcValue()->toCalcValue(CSSToLengthConversionData(parentStyle, rootElementStyle, 1.0f))->evaluate(parentSize);
-        else if (primitiveValue->isViewportPercentageLength())
-            size = valueForLength(primitiveValue->viewportPercentageLength(), 0, m_document->renderView());
-        else
-            return;
+        } else {
+            // If we have viewport units the conversion will mark the parent style as having viewport units.
+            bool parentHasViewportUnits = parentStyle->hasViewportUnits();
+            parentStyle->setHasViewportUnits(false);

[esprehn, 2013/12/04 06:02:28]

Why do you need to disable the viewport units flag here and then re-enable it
later?

[Timothy Loh, 2013/12/04 07:17:39]

This is one of the few places where we resolve viewport units where ems don't
refer to the current style. The conversion will set the bit on the parent style
and this works around it.

+            CSSToLengthConversionData conversionData(parentStyle, rootElementStyle, m_document->renderView(), 1.0f, true);
+            if (primitiveValue->isLength())
+                size = primitiveValue->computeLength<float>(conversionData);
+            else if (primitiveValue->isCalculatedPercentageWithLength())
+                size = primitiveValue->cssCalcValue()->toCalcValue(conversionData)->evaluate(parentSize);
+            else
+                ASSERT_NOT_REACHED();
+            m_fontSizehasViewportUnits = parentStyle->hasViewportUnits();
+            parentStyle->setHasViewportUnits(parentHasViewportUnits);
+        }
     }
 
     if (size < 0)
         return;
 
     // Overly large font sizes will cause crashes on some platforms (such as Windows).
     // Cap font size here to make sure that doesn't happen.
     size = std::min(maximumAllowedFontSize, size);
 
     setSize(scope.fontDescription(), effectiveZoom, size);
@@ skipping 313 matching lines @@
     FontOrientation fontOrientation;
     NonCJKGlyphOrientation glyphOrientation;
     getFontAndGlyphOrientation(documentStyle, fontOrientation, glyphOrientation);
     fontDescription.setOrientation(fontOrientation);
     fontDescription.setNonCJKGlyphOrientation(glyphOrientation);
     documentStyle->setFontDescription(fontDescription);
     documentStyle->font().update(fontSelector);
 }
 
 }