SVG <marker> painting TLC

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

 /*
  * Copyright (C) 2004, 2005, 2007, 2008 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Rob Buis <buis@kde.org>
  * Copyright (C) Research In Motion Limited 2009-2010. 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.
  *
@@ skipping 47 matching lines @@
 void LayoutSVGResourceMarker::removeClientFromCache(LayoutObject* client, bool markForInvalidation)
 {
     ASSERT(client);
     markClientForInvalidation(client, markForInvalidation ? BoundariesInvalidation : ParentOnlyInvalidation);
 }
 
 FloatRect LayoutSVGResourceMarker::markerBoundaries(const AffineTransform& markerTransformation) const
 {
     FloatRect coordinates = LayoutSVGContainer::paintInvalidationRectInLocalSVGCoordinates();
 
-    // Map paint invalidation rect into parent coordinate space, in which the marker boundaries have to be evaluated
+    // Map paint invalidation rect into parent coordinate space, in which the
+    // marker boundaries have to be evaluated.
     coordinates = localToSVGParentTransform().mapRect(coordinates);
 
     return markerTransformation.mapRect(coordinates);
 }
 
 const AffineTransform& LayoutSVGResourceMarker::localToSVGParentTransform() const
 {
     m_localToParentTransform = AffineTransform::translation(m_viewport.x(), m_viewport.y()) * viewportTransform();
     return m_localToParentTransform;
     // If this class were ever given a localTransform(), then the above would read:
@@ skipping 19 matching lines @@
     return toSVGMarkerElement(element())->markerUnits()->currentValue()->enumValue();
 }
 
 SVGMarkerOrientType LayoutSVGResourceMarker::orientType() const
 {
     return toSVGMarkerElement(element())->orientType()->currentValue()->enumValue();
 }
 
 AffineTransform LayoutSVGResourceMarker::markerTransformation(const FloatPoint& origin, float autoAngle, float strokeWidth) const
 {
-    bool useStrokeWidth = markerUnits() == SVGMarkerUnitsStrokeWidth;
+    // Apply scaling according to markerUnits ('strokeWidth' or 'userSpaceOnUse'.)
+    float markerScale = markerUnits() == SVGMarkerUnitsStrokeWidth ? strokeWidth : 1;
 
     AffineTransform transform;
     transform.translate(origin.x(), origin.y());
     transform.rotate(orientType() == SVGMarkerOrientAngle ? angle() : autoAngle);
-    transform = markerContentTransformation(transform, referencePoint(), useStrokeWidth ? strokeWidth : -1);
-    return transform;
+    return markerContentTransformation(transform, referencePoint(), markerScale);

[f(malita), 2016/04/27 14:15:17]

nit: markerContentTransformation concats scale(markerScale) to transform - can
we do that here instead and lose the param?

(actually there isn't much left in markerContentTransformation and this method
is its only client - maybe just merge the two?)

[fs, 2016/04/27 14:27:01]

Yeah, folding it makes sense. Done.

 }
 
-AffineTransform LayoutSVGResourceMarker::markerContentTransformation(const AffineTransform& contentTransformation, const FloatPoint& origin, float strokeWidth) const
+bool LayoutSVGResourceMarker::shouldPaint() const
 {
-    // The 'origin' coordinate maps to SVGs refX/refY, given in coordinates relative to the viewport established by the marker
+    // An empty viewBox disables rendering.
+    SVGMarkerElement* marker = toSVGMarkerElement(element());
+    ASSERT(marker);
+    return !marker->viewBox()->isSpecified()
+        || !marker->viewBox()->currentValue()->isValid()
+        || !marker->viewBox()->currentValue()->value().isEmpty();
+}
+
+AffineTransform LayoutSVGResourceMarker::markerContentTransformation(
+    const AffineTransform& contentTransformation, const FloatPoint& origin, float markerScale) const
+{
+    // The 'origin' coordinate maps to SVGs refX/refY, given in coordinates
+    // relative to the viewport established by the marker.
     FloatPoint mappedOrigin = viewportTransform().mapPoint(origin);
 
     AffineTransform transformation = contentTransformation;
-    if (strokeWidth != -1)
-        transformation.scaleNonUniform(strokeWidth, strokeWidth);
-
+    transformation.scale(markerScale);
     transformation.translate(-mappedOrigin.x(), -mappedOrigin.y());
     return transformation;
 }
 
 AffineTransform LayoutSVGResourceMarker::viewportTransform() const
 {
     SVGMarkerElement* marker = toSVGMarkerElement(element());
     ASSERT(marker);
 
     return marker->viewBoxToViewTransform(m_viewport.width(), m_viewport.height());
@@ skipping 15 matching lines @@
 
 bool LayoutSVGResourceMarker::calculateLocalTransform()
 {
     // 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.
     return selfNeedsLayout();
 }
 
 } // namespace blink