WebCore/svg/SVGLinearGradientElement.cpp

/*
    Copyright (C) 2004, 2005, 2006, 2008 Nikolas Zimmermann <zimmermann@kde.org>
                  2004, 2005, 2006, 2007 Rob Buis <buis@kde.org>
                  2008 Eric Seidel <eric@webkit.org>
                  2008 Dirk Schulze <krit@webkit.org>

    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"

#if ENABLE(SVG)
#include "SVGLinearGradientElement.h"

#include "Document.h"
#include "FloatPoint.h"
#include "LinearGradientAttributes.h"
#include "MappedAttribute.h"
#include "SVGLength.h"
#include "SVGNames.h"
#include "SVGPaintServerLinearGradient.h"
#include "SVGTransform.h"
#include "SVGTransformList.h"
#include "SVGUnitTypes.h"

namespace WebCore {

SVGLinearGradientElement::SVGLinearGradientElement(const QualifiedName& tagName, Document* doc)
    : SVGGradientElement(tagName, doc)
    , m_x1(this, SVGNames::x1Attr, LengthModeWidth)
    , m_y1(this, SVGNames::y1Attr, LengthModeHeight)
    , m_x2(this, SVGNames::x2Attr, LengthModeWidth, "100%")
    , m_y2(this, SVGNames::y2Attr, LengthModeHeight)
{
    // Spec: If the x2 attribute is not specified, the effect is as if a value of "100%" were specified.
}

SVGLinearGradientElement::~SVGLinearGradientElement()
{
}

void SVGLinearGradientElement::parseMappedAttribute(MappedAttribute* attr)
{
    if (attr->name() == SVGNames::x1Attr)
        setX1BaseValue(SVGLength(LengthModeWidth, attr->value()));
    else if (attr->name() == SVGNames::y1Attr)
        setY1BaseValue(SVGLength(LengthModeHeight, attr->value()));
    else if (attr->name() == SVGNames::x2Attr)
        setX2BaseValue(SVGLength(LengthModeWidth, attr->value()));
    else if (attr->name() == SVGNames::y2Attr)
        setY2BaseValue(SVGLength(LengthModeHeight, attr->value()));
    else
        SVGGradientElement::parseMappedAttribute(attr);
}

void SVGLinearGradientElement::svgAttributeChanged(const QualifiedName& attrName)
{
    SVGGradientElement::svgAttributeChanged(attrName);

    if (!m_resource)
        return;

    if (attrName == SVGNames::x1Attr || attrName == SVGNames::y1Attr ||
        attrName == SVGNames::x2Attr || attrName == SVGNames::y2Attr)
        m_resource->invalidate();
}

void SVGLinearGradientElement::buildGradient() const
{
    LinearGradientAttributes attributes = collectGradientProperties();

    RefPtr<SVGPaintServerLinearGradient> linearGradient = WTF::static_pointer_cast<SVGPaintServerLinearGradient>(m_resource);

    FloatPoint startPoint = FloatPoint::narrowPrecision(attributes.x1(), attributes.y1());
    FloatPoint endPoint = FloatPoint::narrowPrecision(attributes.x2(), attributes.y2());

    RefPtr<Gradient> gradient = Gradient::create(startPoint, endPoint);
    gradient->setSpreadMethod(attributes.spreadMethod());

    Vector<SVGGradientStop> m_stops = attributes.stops();
    float previousOffset = 0.0f;
    for (unsigned i = 0; i < m_stops.size(); ++i) {
        float offset = std::min(std::max(previousOffset, m_stops[i].first), 1.0f);
        previousOffset = offset;
        gradient->addColorStop(offset, m_stops[i].second);
    }

    linearGradient->setGradient(gradient);

    if (attributes.stops().isEmpty())
        return;

    // This code should go away.  PaintServers should go away too.
    // Only this code should care about bounding boxes
    linearGradient->setBoundingBoxMode(attributes.boundingBoxMode());
    linearGradient->setGradientStops(attributes.stops());

    // These should possibly be supported on Gradient
    linearGradient->setGradientTransform(attributes.gradientTransform());
    linearGradient->setGradientStart(startPoint);
    linearGradient->setGradientEnd(endPoint);
}

LinearGradientAttributes SVGLinearGradientElement::collectGradientProperties() const
{
    LinearGradientAttributes attributes;
    HashSet<const SVGGradientElement*> processedGradients;

    bool isLinear = true;
    const SVGGradientElement* current = this;

    while (current) {
        if (!attributes.hasSpreadMethod() && current->hasAttribute(SVGNames::spreadMethodAttr))
            attributes.setSpreadMethod((GradientSpreadMethod) current->spreadMethod());

        if (!attributes.hasBoundingBoxMode() && current->hasAttribute(SVGNames::gradientUnitsAttr))
            attributes.setBoundingBoxMode(current->gradientUnits() == SVGUnitTypes::SVG_UNIT_TYPE_OBJECTBOUNDINGBOX);

        if (!attributes.hasGradientTransform() && current->hasAttribute(SVGNames::gradientTransformAttr))
            attributes.setGradientTransform(current->gradientTransform()->consolidate().matrix());

        if (!attributes.hasStops()) {
            const Vector<SVGGradientStop>& stops(current->buildStops());
            if (!stops.isEmpty())
                attributes.setStops(stops);
        }

        if (isLinear) {
            const SVGLinearGradientElement* linear = static_cast<const SVGLinearGradientElement*>(current);

            if (!attributes.hasX1() && current->hasAttribute(SVGNames::x1Attr))
                attributes.setX1(linear->x1().valueAsPercentage());

            if (!attributes.hasY1() && current->hasAttribute(SVGNames::y1Attr))
                attributes.setY1(linear->y1().valueAsPercentage());

            if (!attributes.hasX2() && current->hasAttribute(SVGNames::x2Attr))
                attributes.setX2(linear->x2().valueAsPercentage());

            if (!attributes.hasY2() && current->hasAttribute(SVGNames::y2Attr))
                attributes.setY2(linear->y2().valueAsPercentage());
        }

        processedGradients.add(current);

        // Respect xlink:href, take attributes from referenced element
        Node* refNode = ownerDocument()->getElementById(SVGURIReference::getTarget(current->href()));
        if (refNode && (refNode->hasTagName(SVGNames::linearGradientTag) || refNode->hasTagName(SVGNames::radialGradientTag))) {
            current = static_cast<const SVGGradientElement*>(const_cast<const Node*>(refNode));

            // Cycle detection
            if (processedGradients.contains(current))
                return LinearGradientAttributes();

            isLinear = current->gradientType() == LinearGradientPaintServer;
        } else
            current = 0;
    }

    return attributes;
}

}

#endif // ENABLE(SVG)