SVG doesn't recognize rem units

Source/core/svg/SVGLengthContext.cpp

 /*
  * Copyright (C) 2004, 2005, 2006 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007 Rob Buis <buis@kde.org>
  * Copyright (C) 2007 Apple Inc. All rights reserved.
  * Copyright (C) Research In Motion Limited 2011. 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.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  */
 
 #include "config.h"
 #include "core/svg/SVGLengthContext.h"
 
 #include "core/css/CSSHelper.h"
 #include "core/css/CSSPrimitiveValue.h"
+#include "core/dom/NodeLayoutStyle.h"
 #include "core/layout/LayoutObject.h"
 #include "core/layout/style/LayoutStyle.h"
 #include "core/svg/SVGSVGElement.h"
 #include "platform/LengthFunctions.h"
 #include "platform/fonts/FontMetrics.h"
 
 namespace blink {
 
 static inline float dimensionForLengthMode(SVGLengthMode mode, const FloatSize& viewportSize)
 {
@@ skipping 123 matching lines @@
         break;
     case LengthTypeIN:
         userUnits = value * cssPixelsPerInch;
         break;
     case LengthTypePT:
         userUnits = value * cssPixelsPerPoint;
         break;
     case LengthTypePC:
         userUnits = value * cssPixelsPerPica;
         break;
+    case LengthTypeREMS:
+        userUnits = convertValueFromREMSToUserUnits(value);
+        break;
     default:
         ASSERT_NOT_REACHED();
         break;
     }
 
     // Since we mix css <length> values with svg's length values we need to
     // clamp values to the narrowest range, otherwise it can result in
     // rendering issues.
     return CSSPrimitiveValue::clampToCSSLengthRange(userUnits);
 }
@@ skipping 10 matching lines @@
         if (!determineViewport(viewportSize))
             return 0;
         // LengthTypePercentage is represented with 100% = 100.0.
         // Good for accuracy but could eventually be changed.
         return value * 100 / dimensionForLengthMode(mode, viewportSize);
     }
     case LengthTypeEMS:
         return convertValueFromUserUnitsToEMS(value);
     case LengthTypeEXS:
         return convertValueFromUserUnitsToEXS(value);
+    case LengthTypeREMS:
+        return convertValueFromUserUnitsToREMS(value);
     case LengthTypePX:
         return value;
     case LengthTypeCM:
         return value / cssPixelsPerCentimeter;
     case LengthTypeMM:
         return value / cssPixelsPerMillimeter;
     case LengthTypeIN:
         return value / cssPixelsPerInch;
     case LengthTypePT:
         return value / cssPixelsPerPoint;
@@ skipping 36 matching lines @@
 }
 
 float SVGLengthContext::convertValueFromEMSToUserUnits(float value) const
 {
     const LayoutStyle* style = layoutStyleForLengthResolving(m_context);
     if (!style)
         return 0;
     return value * style->specifiedFontSize();
 }
 
+float SVGLengthContext::convertValueFromUserUnitsToREMS(float value) const
+{
+    if (!m_context)
+        return 0;
+
+    const LayoutStyle* style = 0;
+    const ContainerNode* currentContext = m_context;
+
+    do {
+        if (currentContext->layoutObject()) {

[Erik Dahlström (inactive), 2015/04/02 07:58:41]

Do we really need this loop? Why not just fetch the document directly from
m_context->document()?

The same applies to the method below as well.

[Shanmuga Pandi, 2015/04/02 13:06:51]

Done.

+            const Document& document = currentContext->layoutObject()->document();
+            Node* documentElement = document.documentElement();
+            const LayoutStyle* documentStyle = document.layoutStyle();
+            style = documentElement && !currentContext->layoutObject()->isDocumentElement() ? documentElement->layoutStyle() : documentStyle;
+            if (!style)
+                style = documentStyle;
+            break;
+        }
+        currentContext = currentContext->parentNode();
+    } while (currentContext);
+
+    if (!style)
+        return 0;
+
+    float fontSize = style->specifiedFontSize();
+    if (!fontSize)
+        return 0;
+
+    return value / fontSize;
+}
+
+float SVGLengthContext::convertValueFromREMSToUserUnits(float value) const
+{
+    if (!m_context)
+        return 0;
+
+    const LayoutStyle* style = 0;
+    const ContainerNode* currentContext = m_context;
+
+    do {
+        if (currentContext->layoutObject()) {
+            const Document& document = currentContext->layoutObject()->document();
+            Node* documentElement = document.documentElement();
+            const LayoutStyle* documentStyle = document.layoutStyle();
+            style = documentElement && !currentContext->layoutObject()->isDocumentElement() ? documentElement->layoutStyle() : documentStyle;
+            if (!style)
+                style = documentStyle;
+            break;
+        }
+        currentContext = currentContext->parentNode();
+    } while (currentContext);
+
+    if (!style)
+        return 0;
+    return value * style->specifiedFontSize();
+}
+
 float SVGLengthContext::convertValueFromUserUnitsToEXS(float value) const
 {
     const LayoutStyle* style = layoutStyleForLengthResolving(m_context);
     if (!style)
         return 0;
 
     // Use of ceil allows a pixel match to the W3Cs expected output of coords-units-03-b.svg
     // if this causes problems in real world cases maybe it would be best to remove this
     float xHeight = ceilf(style->fontMetrics().xHeight());
     if (!xHeight)
@@ skipping 31 matching lines @@
 
     const SVGSVGElement& svg = toSVGSVGElement(*viewportElement);
     viewportSize = svg.currentViewBoxRect().size();
     if (viewportSize.isEmpty())
         viewportSize = svg.currentViewportSize();
 
     return true;
 }
 
 }