Repaint SVG subtree on viewport changes (resize)

third_party/WebKit/Source/core/layout/svg/LayoutSVGRoot.cpp

 /*
  * Copyright (C) 2004, 2005, 2007 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2004, 2005, 2007, 2008, 2009 Rob Buis <buis@kde.org>
  * Copyright (C) 2007 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2009 Google, Inc.
  * 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
@@ skipping 135 matching lines @@
   updateLogicalHeight();
 
   buildLocalToBorderBoxTransform();
   // TODO(fs): Temporarily, needing a layout implies that the local transform
   // has changed. This should be updated to be more precise and factor in the
   // actual (relevant) changes to the computed user-space transform.
   m_didScreenScaleFactorChange = selfNeedsLayout();
 
   SVGLayoutSupport::layoutResourcesIfNeeded(this);
 
+  // selfNeedsLayout() will cover changes to one (or more) of viewBox,
+  // current{Scale,Translate} and decorations.
+  const bool viewportMayHaveChanged = selfNeedsLayout() || oldSize != size();
+
+  // The scale of one or more of the SVG elements may have changed, or new
+  // content may have been exposed, so mark the entire subtree as needing paint
+  // invalidation checking. (It is only somewhat by coincidence that this
+  // condition happens to be the same as the one for viewport changes.)
+  if (viewportMayHaveChanged)
+    setMayNeedPaintInvalidationSubtree();
+
   SVGSVGElement* svg = toSVGSVGElement(node());
   ASSERT(svg);
   // When hasRelativeLengths() is false, no descendants have relative lengths
   // (hence no one is interested in viewport size changes).
-  m_isLayoutSizeChanged =
-      svg->hasRelativeLengths() && (selfNeedsLayout() || oldSize != size());
-
-  // The scale of one or more of the SVG elements may have changed, so mark
-  // the entire subtree as needing paint invalidation checking.
-  if (m_isLayoutSizeChanged)
-    setMayNeedPaintInvalidationSubtree();
+  m_isLayoutSizeChanged = viewportMayHaveChanged && svg->hasRelativeLengths();
 
   SVGLayoutSupport::layoutChildren(
       firstChild(), false, m_didScreenScaleFactorChange, m_isLayoutSizeChanged);
 
   if (m_needsBoundariesOrTransformUpdate) {
     updateCachedBoundaries();
     m_needsBoundariesOrTransformUpdate = false;
   }
 
   m_overflow.reset();
@@ skipping 290 matching lines @@
       if (result.addNodeToListBasedTestResult(node(), locationInContainer,
                                               boundsRect) == StopHitTesting)
         return true;
     }
   }
 
   return false;
 }
 
 }  // namespace blink