Reduce how often LayoutSVGShape::updateShapeFromElement is called

Source/core/layout/svg/LayoutSVGRect.cpp

 /*
  * Copyright (C) 2011 University of Szeged
  * Copyright (C) 2011 Renata Hodovan <reni@webkit.org>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 25 matching lines @@
 LayoutSVGRect::LayoutSVGRect(SVGRectElement* node)
     : LayoutSVGShape(node)
     , m_usePathFallback(false)
 {
 }
 
 LayoutSVGRect::~LayoutSVGRect()
 {
 }
 
+void LayoutSVGRect::styleDidChange(StyleDifference diff, const ComputedStyle* oldStyle)
+{
+    if (diff.needsFullLayout() && oldStyle) {
+        const SVGComputedStyle& oldSvgStyle = oldStyle->svgStyle();
+        const SVGComputedStyle& svgStyle = style()->svgStyle();
+        if (oldSvgStyle.rx() != svgStyle.rx()
+            || oldSvgStyle.ry() != svgStyle.ry()
+            || oldSvgStyle.vectorEffect() != svgStyle.vectorEffect()
+            || definitelyHasSimpleStroke(oldSvgStyle) != definitelyHasSimpleStroke(svgStyle))
+            setNeedsShapeUpdate();
+    }
+
+    // Superclass will take care of calling clientStyleChanged.
+    LayoutSVGShape::styleDidChange(diff, oldStyle);
+}
+
 void LayoutSVGRect::updateShapeFromElement()
 {
-    // Before creating a new object we need to clear the cached bounding box
-    // to avoid using garbage.
-    m_fillBoundingBox = FloatRect();
-    m_strokeBoundingBox = FloatRect();
     m_usePathFallback = false;
-    SVGRectElement* rect = toSVGRectElement(element());
-    ASSERT(rect);
 
-    SVGLengthContext lengthContext(rect);
+    // Fallback to LayoutSVGShape and path-based hit detection if the rect
+    // has rounded corners or a non-scaling or non-simple stroke.
+    SVGLengthContext lengthContext(toSVGRectElement(element()));
+    if (lengthContext.valueForLength(styleRef().svgStyle().rx(), styleRef(), SVGLengthMode::Width) > 0
+        || lengthContext.valueForLength(styleRef().svgStyle().ry(), styleRef(), SVGLengthMode::Height) > 0
+        || hasNonScalingStroke()
+        || !definitelyHasSimpleStroke(style()->svgStyle())) {
+        LayoutSVGShape::updateShapeFromElement();
+        m_usePathFallback = true;
+        return;
+    }
+
+    clearPath();
+}
+
+void LayoutSVGRect::updateStrokeAndFillBoundingBoxes()
+{
+    SVGLengthContext lengthContext(toSVGRectElement(element()));
     FloatSize boundingBoxSize(
         lengthContext.valueForLength(styleRef().width(), styleRef(), SVGLengthMode::Width),
         lengthContext.valueForLength(styleRef().height(), styleRef(), SVGLengthMode::Height));
 
     // Spec: "A negative value is an error."
-    if (boundingBoxSize.width() < 0 || boundingBoxSize.height() < 0)
+    if (boundingBoxSize.width() < 0 || boundingBoxSize.height() < 0) {
+        m_fillBoundingBox = FloatRect();
+        m_strokeBoundingBox = FloatRect();
         return;
+    }
 
-    // Spec: "A value of zero disables rendering of the element."
-    if (!boundingBoxSize.isEmpty()) {
-        // Fallback to LayoutSVGShape and path-based hit detection if the rect
-        // has rounded corners or a non-scaling or non-simple stroke.
-        if (lengthContext.valueForLength(styleRef().svgStyle().rx(), styleRef(), SVGLengthMode::Width) > 0
-            || lengthContext.valueForLength(styleRef().svgStyle().ry(), styleRef(), SVGLengthMode::Height) > 0
-            || hasNonScalingStroke()
-            || !definitelyHasSimpleStroke()) {
-            LayoutSVGShape::updateShapeFromElement();
-            m_usePathFallback = true;
+    if (m_usePathFallback) {
+        // Spec: "A value of zero disables rendering of the element." so we can skip
+        // the path fallback and rely on the existing bounding box calculation.
+        if (!boundingBoxSize.isEmpty()) {
+            LayoutSVGShape::updateStrokeAndFillBoundingBoxes();
             return;
         }
+        m_usePathFallback = false;
+        clearPath();
     }
 
     m_fillBoundingBox = FloatRect(
         FloatPoint(
             lengthContext.valueForLength(styleRef().svgStyle().x(), styleRef(), SVGLengthMode::Width),
             lengthContext.valueForLength(styleRef().svgStyle().y(), styleRef(), SVGLengthMode::Height)),
         boundingBoxSize);
     m_strokeBoundingBox = m_fillBoundingBox;
     if (style()->svgStyle().hasStroke())
         m_strokeBoundingBox.inflate(strokeWidth() / 2);
 }
 
 bool LayoutSVGRect::shapeDependentStrokeContains(const FloatPoint& point)
 {
     // The optimized code below does not support non-simple strokes so we need
     // to fall back to LayoutSVGShape::shapeDependentStrokeContains in these cases.
-    if (m_usePathFallback || !definitelyHasSimpleStroke()) {
-        if (!hasPath())
+    if (m_usePathFallback || !definitelyHasSimpleStroke(style()->svgStyle())) {
+        if (!m_usePathFallback)
             LayoutSVGShape::updateShapeFromElement();
         return LayoutSVGShape::shapeDependentStrokeContains(point);
     }
 
     const float halfStrokeWidth = strokeWidth() / 2;
     const float halfWidth = m_fillBoundingBox.width() / 2;
     const float halfHeight = m_fillBoundingBox.height() / 2;
 
     const FloatPoint fillBoundingBoxCenter = FloatPoint(m_fillBoundingBox.x() + halfWidth, m_fillBoundingBox.y() + halfHeight);
     const float absDeltaX = std::abs(point.x() - fillBoundingBoxCenter.x());
     const float absDeltaY = std::abs(point.y() - fillBoundingBoxCenter.y());
 
     if (!(absDeltaX <= halfWidth + halfStrokeWidth && absDeltaY <= halfHeight + halfStrokeWidth))
         return false;
 
     return (halfWidth - halfStrokeWidth <= absDeltaX)
         || (halfHeight - halfStrokeWidth <= absDeltaY);
 }
 
 bool LayoutSVGRect::shapeDependentFillContains(const FloatPoint& point, const WindRule fillRule) const
 {
     if (m_usePathFallback)
         return LayoutSVGShape::shapeDependentFillContains(point, fillRule);
     return m_fillBoundingBox.contains(point.x(), point.y());
 }
 
 // Returns true if the stroke is continuous and definitely uses miter joins.
-bool LayoutSVGRect::definitelyHasSimpleStroke() const
+bool LayoutSVGRect::definitelyHasSimpleStroke(const SVGComputedStyle& svgStyle) const
 {
-    const SVGComputedStyle& svgStyle = style()->svgStyle();
-
     // The four angles of a rect are 90 degrees. Using the formula at:
     // http://www.w3.org/TR/SVG/painting.html#StrokeMiterlimitProperty
     // when the join style of the rect is "miter", the ratio of the miterLength
     // to the stroke-width is found to be
     // miterLength / stroke-width = 1 / sin(45 degrees)
     //                            = 1 / (1 / sqrt(2))
     //                            = sqrt(2)
     //                            = 1.414213562373095...
     // When sqrt(2) exceeds the miterlimit, then the join style switches to
     // "bevel". When the miterlimit is greater than or equal to sqrt(2) then
     // the join style remains "miter".
     //
     // An approximation of sqrt(2) is used here because at certain precise
     // miterlimits, the join style used might not be correct (e.g. a miterlimit
     // of 1.4142135 should result in bevel joins, but may be drawn using miter
     // joins).
     return svgStyle.strokeDashArray()->isEmpty()
         && svgStyle.joinStyle() == MiterJoin
         && svgStyle.strokeMiterLimit() >= 1.5;
 }
 
 }