Source/WebCore/rendering/svg/RenderSVGPath.cpp

/*
 * Copyright (C) 2004, 2005, 2007 Nikolas Zimmermann <zimmermann@kde.org>
 * Copyright (C) 2004, 2005, 2008 Rob Buis <buis@kde.org>
 * Copyright (C) 2005, 2007 Eric Seidel <eric@webkit.org>
 * Copyright (C) 2009 Google, Inc.
 * Copyright (C) 2009 Dirk Schulze <krit@webkit.org>
 * Copyright (C) Research In Motion Limited 2010. All rights reserved.
 * Copyright (C) 2009 Jeff Schiller <codedread@gmail.com>
 * Copyright (C) 2011 Renata Hodovan <reni@webkit.org>
 * Copyright (C) 2011 University of Szeged
 *
 * 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.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 */

#include "config.h"
#include "RenderSVGPath.h"

#include "Gradient.h"
#include "SVGPathElement.h"
#include "SVGSubpathData.h"
#include <wtf/IsoMallocInlines.h>

namespace WebCore {

WTF_MAKE_ISO_ALLOCATED_IMPL(RenderSVGPath);

RenderSVGPath::RenderSVGPath(SVGGraphicsElement& element, RenderStyle&& style)
    : LegacyRenderSVGShape(element, WTFMove(style))
{
}

RenderSVGPath::~RenderSVGPath() = default;

void RenderSVGPath::updateShapeFromElement()
{
    LegacyRenderSVGShape::updateShapeFromElement();
    updateZeroLengthSubpaths();

    m_strokeBoundingBox = calculateUpdatedStrokeBoundingBox();
}

FloatRect RenderSVGPath::calculateUpdatedStrokeBoundingBox() const
{
    FloatRect strokeBoundingBox = m_strokeBoundingBox;

    if (style().svgStyle().hasStroke()) {
        // FIXME: zero-length subpaths do not respect vector-effect = non-scaling-stroke.
        float strokeWidth = this->strokeWidth();
        for (size_t i = 0; i < m_zeroLengthLinecapLocations.size(); ++i)
            strokeBoundingBox.unite(zeroLengthSubpathRect(m_zeroLengthLinecapLocations[i], strokeWidth));
    }

    return strokeBoundingBox;
}

static void useStrokeStyleToFill(GraphicsContext& context)
{
    if (auto gradient = context.strokeGradient())
        context.setFillGradient(*gradient, context.state().strokeGradientSpaceTransform);
    else if (Pattern* pattern = context.strokePattern())
        context.setFillPattern(*pattern);
    else
        context.setFillColor(context.strokeColor());
}

void RenderSVGPath::strokeShape(GraphicsContext& context) const
{
    if (!style().hasVisibleStroke())
        return;

    LegacyRenderSVGShape::strokeShape(context);

    if (m_zeroLengthLinecapLocations.isEmpty())
        return;

    Path* usePath;
    AffineTransform nonScalingTransform;

    if (hasNonScalingStroke())
        nonScalingTransform = nonScalingStrokeTransform();

    GraphicsContextStateSaver stateSaver(context, true);
    useStrokeStyleToFill(context);
    for (size_t i = 0; i < m_zeroLengthLinecapLocations.size(); ++i) {
        usePath = zeroLengthLinecapPath(m_zeroLengthLinecapLocations[i]);
        if (hasNonScalingStroke())
            usePath = nonScalingStrokePath(usePath, nonScalingTransform);
        context.fillPath(*usePath);
    }
}

bool RenderSVGPath::shapeDependentStrokeContains(const FloatPoint& point, PointCoordinateSpace pointCoordinateSpace)
{
    if (LegacyRenderSVGShape::shapeDependentStrokeContains(point, pointCoordinateSpace))
        return true;

    for (size_t i = 0; i < m_zeroLengthLinecapLocations.size(); ++i) {
        ASSERT(style().svgStyle().hasStroke());
        float strokeWidth = this->strokeWidth();
        if (style().capStyle() == LineCap::Square) {
            if (zeroLengthSubpathRect(m_zeroLengthLinecapLocations[i], strokeWidth).contains(point))
                return true;
        } else {
            ASSERT(style().capStyle() == LineCap::Round);
            FloatPoint radiusVector(point.x() - m_zeroLengthLinecapLocations[i].x(), point.y() -  m_zeroLengthLinecapLocations[i].y());
            if (radiusVector.lengthSquared() < strokeWidth * strokeWidth * .25f)
                return true;
        }
    }
    return false;
}

bool RenderSVGPath::shouldStrokeZeroLengthSubpath() const
{
    // Spec(11.4): Any zero length subpath shall not be stroked if the "stroke-linecap" property has a value of butt
    // but shall be stroked if the "stroke-linecap" property has a value of round or square
    return style().svgStyle().hasStroke() && style().capStyle() != LineCap::Butt;
}

Path* RenderSVGPath::zeroLengthLinecapPath(const FloatPoint& linecapPosition) const
{
    static NeverDestroyed<Path> tempPath;

    tempPath.get().clear();
    if (style().capStyle() == LineCap::Square)
        tempPath.get().addRect(zeroLengthSubpathRect(linecapPosition, this->strokeWidth()));
    else
        tempPath.get().addEllipse(zeroLengthSubpathRect(linecapPosition, this->strokeWidth()));

    return &tempPath.get();
}

FloatRect RenderSVGPath::zeroLengthSubpathRect(const FloatPoint& linecapPosition, float strokeWidth) const
{
    return FloatRect(linecapPosition.x() - strokeWidth / 2, linecapPosition.y() - strokeWidth / 2, strokeWidth, strokeWidth);
}

void RenderSVGPath::updateZeroLengthSubpaths()
{
    m_zeroLengthLinecapLocations.clear();

    if (!strokeWidth() || !shouldStrokeZeroLengthSubpath())
        return;

    SVGSubpathData subpathData(m_zeroLengthLinecapLocations);
    path().apply([&subpathData](const PathElement& pathElement) {
        SVGSubpathData::updateFromPathElement(subpathData, pathElement);
    });
    subpathData.pathIsDone();
}

bool RenderSVGPath::isRenderingDisabled() const
{
    // For a polygon, polyline or path, rendering is disabled if there is no path data.
    // No path data is possible in the case of a missing or empty 'd' or 'points' attribute.
    return path().isEmpty();
}

}