[svg] Make svgView override existing data selectively

Source/core/svg/SVGViewSpec.cpp

Index: Source/core/svg/SVGViewSpec.cpp
diff --git a/Source/core/svg/SVGViewSpec.cpp b/Source/core/svg/SVGViewSpec.cpp
index 071e969517c018f1d43211232641f648faee73ba..512dd2a8af1094b1d024d4feb1c789f6b3ffdee9 100644
--- a/Source/core/svg/SVGViewSpec.cpp
+++ b/Source/core/svg/SVGViewSpec.cpp
@@ -71,12 +71,35 @@ bool SVGViewSpec::parseViewSpec(const String& spec)
 
 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();
 }