[svg] Make svgView override existing data selectively

Source/core/svg/SVGViewSpec.cpp

 /*
  * Copyright (C) 2007, 2010 Rob Buis <buis@kde.org>
  *
  * 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
@@ skipping 53 matching lines @@
         const LChar* end = ptr + spec.length();
         return parseViewSpecInternal(ptr, end);
     }
     const UChar* ptr = spec.characters16();
     const UChar* end = ptr + spec.length();
     return parseViewSpecInternal(ptr, end);
 }
 
 void SVGViewSpec::reset()
 {
-    resetZoomAndPan();
-    m_transform->baseValue()->clear();
-    updateViewBox(FloatRect());
-    ASSERT(preserveAspectRatio());
-    preserveAspectRatio()->baseValue()->setAlign(SVGPreserveAspectRatio::SVG_PRESERVEASPECTRATIO_XMIDYMID);
-    preserveAspectRatio()->baseValue()->setMeetOrSlice(SVGPreserveAspectRatio::SVG_MEETORSLICE_MEET);
+    if (m_contextElement) {

[fs, 2015/03/18 13:43:08]

This is pretty similar to inheritViewAttributes in SVGSVGElement. Do you think
it would work to something like:

<old reset(): just set defaults>
if (m_contextElement)
    inheritViewAttributesFromElement(m_contextElement);

where inheritViewAttributesFromElement was essentially this branch (but without
all the else-branches). inheritViewAttributes could then be implemented as:

view->...(this->bla());
...
view->inheritViewAttributesFromElement(viewElement);

It means some overwriting would take place though, but I suspect that nothing to
worry about. (Alternative would be to collect attribute in a defined order, and
then set.)

+        m_transform->baseValue()->clear();
+
+        if (m_contextElement->hasAttribute(SVGNames::viewBoxAttr))
+            updateViewBox(m_contextElement->viewBox()->currentValue()->value());
+        else
+            updateViewBox(FloatRect());
+
+        if (m_contextElement->hasAttribute(SVGNames::preserveAspectRatioAttr)) {
+            preserveAspectRatio()->baseValue()->setAlign(m_contextElement->preserveAspectRatio()->currentValue()->align());
+            preserveAspectRatio()->baseValue()->setMeetOrSlice(m_contextElement->preserveAspectRatio()->currentValue()->meetOrSlice());
+        } else {
+            preserveAspectRatio()->baseValue()->setAlign(SVGPreserveAspectRatio::SVG_PRESERVEASPECTRATIO_XMIDYMID);
+            preserveAspectRatio()->baseValue()->setMeetOrSlice(SVGPreserveAspectRatio::SVG_MEETORSLICE_MEET);
+        }
+
+        if (m_contextElement->hasAttribute(SVGNames::zoomAndPanAttr))
+            setZoomAndPan(m_contextElement->zoomAndPan());
+        else
+            resetZoomAndPan();
+    } else {
+        resetZoomAndPan();
+        m_transform->baseValue()->clear();
+        updateViewBox(FloatRect());
+        ASSERT(preserveAspectRatio());
+        preserveAspectRatio()->baseValue()->setAlign(SVGPreserveAspectRatio::SVG_PRESERVEASPECTRATIO_XMIDYMID);
+        preserveAspectRatio()->baseValue()->setMeetOrSlice(SVGPreserveAspectRatio::SVG_MEETORSLICE_MEET);
+    }
+
     m_viewTargetString = emptyString();
 }
 
 void SVGViewSpec::detachContextElement()
 {
     m_transform = nullptr;
     clearViewBox();
     clearPreserveAspectRatio();
     m_contextElement = nullptr;
 }
@@ skipping 122 matching lines @@
             ptr++;
     }
 
     if (ptr >= end || *ptr != ')')
         return false;
 
     return true;
 }
 
 }