Deprecate currentView, useCurrentView properties of SVGSVGElement and SVGViewSpec interface

third_party/WebKit/Source/core/svg/SVGSVGElement.cpp

Index: third_party/WebKit/Source/core/svg/SVGSVGElement.cpp
diff --git a/third_party/WebKit/Source/core/svg/SVGSVGElement.cpp b/third_party/WebKit/Source/core/svg/SVGSVGElement.cpp
index 10ded6d7cdffa2533f11d42e047733da4873ec98..b52700b10a500affe8075a2c68c3e8aebffd22ee 100644
--- a/third_party/WebKit/Source/core/svg/SVGSVGElement.cpp
+++ b/third_party/WebKit/Source/core/svg/SVGSVGElement.cpp
@@ -636,16 +636,7 @@ AffineTransform SVGSVGElement::viewBoxToViewTransform(float viewWidth, float vie
     if (!m_useCurrentView || !m_viewSpec)
         return SVGFitToViewBox::viewBoxToViewTransform(currentViewBoxRect(), preserveAspectRatio()->currentValue(), viewWidth, viewHeight);
 
-    AffineTransform ctm = SVGFitToViewBox::viewBoxToViewTransform(currentViewBoxRect(), m_viewSpec->preserveAspectRatio()->currentValue(), viewWidth, viewHeight);
-    SVGTransformList* transformList = m_viewSpec->transform();
-    if (transformList->isEmpty())
-        return ctm;
-
-    AffineTransform transform;
-    if (transformList->concatenate(transform))
-        ctm *= transform;
-
-    return ctm;
+    return SVGFitToViewBox::viewBoxToViewTransform(currentViewBoxRect(), m_viewSpec->preserveAspectRatio()->currentValue(), viewWidth, viewHeight);;
 }
 
 void SVGSVGElement::setupInitialView(const String& fragmentIdentifier, Element* anchorNode)
@@ -658,24 +649,6 @@ void SVGSVGElement::setupInitialView(const String& fragmentIdentifier, Element*
     bool hadUseCurrentView = m_useCurrentView;
     m_useCurrentView = false;
 
-    if (fragmentIdentifier.startsWith("svgView(")) {

[fs, 2016/07/21 13:08:27]

This is still in the spec AFAIK. the only thing that should be removed here is:

 * the SVGViewSpec interface
 * the SVGSVGElement.useCurrentView and SVGSVGElement.currentView

i.e the DOM exposed bits. Any cleanup that isn't obvious "JS only" (like
removing the ScriptWrappable and related bits; *FromJavascript methods;
obviously dead code) is best done as a follow-up (and the removal here would not
be subject to that.)

[foolip, 2016/07/22 04:44:39]

Hmm, so this gets at the same thing I'm wondering about on blink-dev. To remove
only the web-exposed bits of this but keeping all the internals, has any
meaningful simplification been achieved?

I looked around in cs.chromium.org but am not really familiar with any of the
history, so what would happen if SVGViewSpec and SVGViewElement were removed
entirely?

(I added davve@ and pdr@ in case they have thoughts on the matter.)

[fs, 2016/07/22 08:31:38]

Just of the top of my head, some simplifications we could do:

 * Simpler types. Since we no longer need to expose the "exact" semantics of
SVGTransformList et.c, we could use a more efficient (and thus simpler) internal
representation.

 * Slightly simpler lifetimes. Oilpan fixed this quite a bit already (and there
are bits that are dead already from that - like
SVGViewSpec::detachContextElement.)

 * Removing SVGViewElement probably means we can simplify the setup of the (now
internal-only) SVGViewSpec (less need for things like
inheritViewAttributesFromElement, although removing the SVGViewSpec interface is
likely the bigger help there.)

 * With both gone we'd only have a single user of SVGZoomAndPan, and it's
possible we do something with that. (I'd be a bit surprised if anyone actually
used the functionality that is exposes though...)

When you start pulling the strings, it's quite possible more things fall off as
well.

-        if (!view)
-            view = currentView(); // Create the SVGViewSpec.
-
-        view->inheritViewAttributesFromElement(this);
-
-        if (view->parseViewSpec(fragmentIdentifier)) {
-            UseCounter::count(document(), UseCounter::SVGSVGElementFragmentSVGView);
-            m_useCurrentView = true;
-        } else {
-            view->reset();
-        }
-
-        if (layoutObject && (hadUseCurrentView || m_useCurrentView))
-            markForLayoutAndParentResourceInvalidation(layoutObject);
-        return;
-    }
-
     // Spec: If the SVG fragment identifier addresses a 'view' element within an SVG document (e.g., MyDrawing.svg#MyView
     // or MyDrawing.svg#xpointer(id('MyView'))) then the closest ancestor 'svg' element is displayed in the viewport.
     // Any view specification attributes included on the given 'view' element override the corresponding view specification