Adding support of viewport units to SVG

third_party/WebKit/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/NodeComputedStyle.h"
+#include "core/frame/FrameView.h"
 #include "core/layout/LayoutObject.h"
 #include "core/style/ComputedStyle.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 180 matching lines @@
         break;
     case CSSPrimitiveValue::UnitType::Picas:
         userUnits = value * cssPixelsPerPica;
         break;
     case CSSPrimitiveValue::UnitType::Rems:
         userUnits = convertValueFromEMSToUserUnits(rootElementStyle(m_context), value);
         break;
     case CSSPrimitiveValue::UnitType::Chs:
         userUnits = convertValueFromCHSToUserUnits(value);
         break;
+    case CSSPrimitiveValue::UnitType::ViewportWidth:
+    case CSSPrimitiveValue::UnitType::ViewportHeight:
+    case CSSPrimitiveValue::UnitType::ViewportMin:
+    case CSSPrimitiveValue::UnitType::ViewportMax:
+        userUnits = convertValueFromViewportUnitsToUserUnits(fromUnit, 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 27 matching lines @@
     case CSSPrimitiveValue::UnitType::Centimeters:
         return value / cssPixelsPerCentimeter;
     case CSSPrimitiveValue::UnitType::Millimeters:
         return value / cssPixelsPerMillimeter;
     case CSSPrimitiveValue::UnitType::Inches:
         return value / cssPixelsPerInch;
     case CSSPrimitiveValue::UnitType::Points:
         return value / cssPixelsPerPoint;
     case CSSPrimitiveValue::UnitType::Picas:
         return value / cssPixelsPerPica;
+    case CSSPrimitiveValue::UnitType::ViewportWidth:
+    case CSSPrimitiveValue::UnitType::ViewportHeight:
+    case CSSPrimitiveValue::UnitType::ViewportMin:
+    case CSSPrimitiveValue::UnitType::ViewportMax:
+        return convertValueFromUserUnitsToViewportUnits(toUnit, value);
     default:
         break;
     }
 
     ASSERT_NOT_REACHED();
     return 0;
 }
 
 float SVGLengthContext::convertValueFromUserUnitsToCHS(float value) const
 {
@@ skipping 36 matching lines @@
 {
     const ComputedStyle* style = computedStyleForLengthResolving(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
     return value * ceilf(style->fontMetrics().xHeight() / style->effectiveZoom());
 }
 
+static inline float viewportLengthPercent(const float widthOrHeight)
+{
+    return widthOrHeight / 100;
+}
+
+static inline float viewportMinPercent(const FloatSize& viewportSize)
+{
+    return std::min(viewportSize.width(), viewportSize.height()) / 100;
+}
+
+static inline float viewportMaxPercent(const FloatSize& viewportSize)
+{
+    return std::max(viewportSize.width(), viewportSize.height()) / 100;
+}
+
+
+float SVGLengthContext::convertValueFromUserUnitsToViewportUnits(CSSPrimitiveValue::UnitType toUnit, float value) const
+{
+    if (!m_context)
+        return 0;
+
+    const ComputedStyle* style = computedStyleForLengthResolving(m_context);
+    if (!style)
+        return 0;
+
+    const Document& document = m_context->document();
+    FrameView* view = document.view();
+    if (!view)
+        return 0;
+
+    FloatSize viewportSize(view->width(), view->height());
+
+    switch (toUnit) {

[fs, 2016/01/04 19:40:05]

I think this would be slightly if it was using same approach as dimensionForMode
- i.e have a helper that returns either the viewport width/height/min/man and
then apply that to |value| as needed. Should get rid of the duplication between
the "From" and "To" cases.

[Shanmuga Pandi, 2016/01/05 10:04:49]

Done.

+    case CSSPrimitiveValue::UnitType::ViewportWidth:
+        return value / viewportLengthPercent(viewportSize.width()) / style->effectiveZoom();
+
+    case CSSPrimitiveValue::UnitType::ViewportHeight:
+        return value / viewportLengthPercent(viewportSize.height()) / style->effectiveZoom();
+
+    case CSSPrimitiveValue::UnitType::ViewportMin:
+        return value / viewportMinPercent(viewportSize) / style->effectiveZoom();
+
+    case CSSPrimitiveValue::UnitType::ViewportMax:
+        return value / viewportMaxPercent(viewportSize) / style->effectiveZoom();
+    default:
+        break;
+    }
+
+    ASSERT_NOT_REACHED();
+    return 0;
+}
+
+float SVGLengthContext::convertValueFromViewportUnitsToUserUnits(CSSPrimitiveValue::UnitType fromUnit, float value) const
+{
+    if (!m_context)
+        return 0;
+
+    const ComputedStyle* style = computedStyleForLengthResolving(m_context);
+    if (!style)
+        return 0;
+
+    const Document& document = m_context->document();
+    FrameView* view = document.view();
+    if (!view)
+        return 0;
+
+    FloatSize viewportSize(view->width(), view->height());
+
+    switch (fromUnit) {
+    case CSSPrimitiveValue::UnitType::ViewportWidth:
+        return value * viewportLengthPercent(viewportSize.width()) / style->effectiveZoom();
+
+    case CSSPrimitiveValue::UnitType::ViewportHeight:
+        return value * viewportLengthPercent(viewportSize.height()) / style->effectiveZoom();
+
+    case CSSPrimitiveValue::UnitType::ViewportMin:
+        return value * viewportMinPercent(viewportSize) / style->effectiveZoom();
+
+    case CSSPrimitiveValue::UnitType::ViewportMax:
+        return value * viewportMaxPercent(viewportSize) / style->effectiveZoom();
+    default:
+        break;
+    }
+
+    ASSERT_NOT_REACHED();
+    return 0;
+}
+
 bool SVGLengthContext::determineViewport(FloatSize& viewportSize) const
 {
     if (!m_context)
         return false;
 
     // Root <svg> element lengths are resolved against the top level viewport.
     if (m_context->isOutermostSVGSVGElement()) {
         viewportSize = toSVGSVGElement(m_context)->currentViewportSize();
         return true;
     }
 
     // Take size from nearest viewport element.
     SVGElement* viewportElement = m_context->viewportElement();
     if (!isSVGSVGElement(viewportElement))
         return false;
 
     const SVGSVGElement& svg = toSVGSVGElement(*viewportElement);
     viewportSize = svg.currentViewBoxRect().size();
     if (viewportSize.isEmpty())
         viewportSize = svg.currentViewportSize();
 
     return true;
 }
 
 }