WebCore/svg/graphics/cairo/SVGPaintServerGradientCairo.cpp

/*
 * Copyright (C) 2007 Alp Toker <alp@atoker.com>
 *
 * 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 "SVGPaintServerGradient.h"
#include "SVGPaintServerLinearGradient.h"
#include "SVGPaintServerRadialGradient.h"

#include "GraphicsContext.h"
#include "RenderObject.h"
#include "RenderPath.h"
#include "RenderStyle.h"
#include "SVGGradientElement.h"

namespace WebCore {

bool SVGPaintServerGradient::setup(GraphicsContext*& context, const RenderObject* object, SVGPaintTargetType type, bool isPaintingText) const
{
    m_ownerElement->buildGradient();

    cairo_t* cr = context->platformContext();
    cairo_pattern_t* pattern;

    cairo_matrix_t matrix;
    cairo_matrix_init_identity (&matrix);
    const cairo_matrix_t gradient_matrix = gradientTransform();

    // TODO: revise this code, it is known not to work in many cases
    if (this->type() == LinearGradientPaintServer) {
        const SVGPaintServerLinearGradient* linear = static_cast<const SVGPaintServerLinearGradient*>(this);

        if (boundingBoxMode()) {
            // TODO: use RenderPathCairo's strokeBBox?
            double x1, y1, x2, y2;
            cairo_fill_extents(cr, &x1, &y1, &x2, &y2);
            cairo_matrix_translate(&matrix, x1, y1);
            cairo_matrix_scale(&matrix, x2 - x1, y2 - y1);
            cairo_matrix_multiply(&matrix, &matrix, &gradient_matrix);
            cairo_matrix_invert(&matrix);
        }

        double x0, x1, y0, y1;
        x0 = linear->gradientStart().x();
        y0 = linear->gradientStart().y();
        x1 = linear->gradientEnd().x();
        y1 = linear->gradientEnd().y();
        pattern = cairo_pattern_create_linear(x0, y0, x1, y1);

    } else if (this->type() == RadialGradientPaintServer) {
        // const SVGPaintServerRadialGradient* radial = static_cast<const SVGPaintServerRadialGradient*>(this);
        // TODO: pattern = cairo_pattern_create_radial();
        return false;
    } else {
        return false;
    }

    cairo_pattern_set_filter(pattern, CAIRO_FILTER_BILINEAR);

    switch (spreadMethod()) {
        case SPREADMETHOD_PAD:
            cairo_pattern_set_extend(pattern, CAIRO_EXTEND_PAD);
            break;
        case SPREADMETHOD_REFLECT:
            cairo_pattern_set_extend(pattern, CAIRO_EXTEND_REFLECT);
            break;
        case SPREADMETHOD_REPEAT:
            cairo_pattern_set_extend(pattern, CAIRO_EXTEND_REPEAT);
            break;
        default:
            cairo_pattern_set_extend(pattern, CAIRO_EXTEND_NONE);
            break;
    }

    cairo_pattern_set_matrix(pattern, &matrix);

    const Vector<SVGGradientStop>& stops = gradientStops();

    for (unsigned i = 0; i < stops.size(); ++i) {
        float offset = stops[i].first;
        Color color = stops[i].second;

        cairo_pattern_add_color_stop_rgba(pattern, offset, color.red(), color.green(), color.blue(), color.alpha());
    }

    cairo_set_source(cr, pattern);
    cairo_pattern_destroy(pattern);

    return true;
}

} // namespace WebCore

#endif