WebCore/svg/graphics/cg/CgSupport.cpp

/*
 * Copyright (C) 2005 Apple Computer, Inc.  All rights reserved.
 *               2006 Rob Buis <buis@kde.org>
 *               2008 Nikolas Zimmermann <zimmermann@kde.org>
 *
 * 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.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
 */


#include "config.h"

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

#include <ApplicationServices/ApplicationServices.h>
#include "FloatConversion.h"
#include "GraphicsContext.h"
#include "RenderStyle.h"
#include "SVGPaintServer.h"
#include "SVGRenderStyle.h"
#include <wtf/Assertions.h>

namespace WebCore {

CGAffineTransform CGAffineTransformMakeMapBetweenRects(CGRect source, CGRect dest)
{
    CGAffineTransform transform = CGAffineTransformMakeTranslation(dest.origin.x - source.origin.x, dest.origin.y - source.origin.y);
    transform = CGAffineTransformScale(transform, dest.size.width/source.size.width, dest.size.height/source.size.height);
    return transform;
}

void applyStrokeStyleToContext(GraphicsContext* context, RenderStyle* style, const RenderObject* object)
{
    context->setStrokeThickness(SVGRenderStyle::cssPrimitiveToLength(object, style->svgStyle()->strokeWidth(), 1.0f));
    context->setLineCap(style->svgStyle()->capStyle());
    context->setLineJoin(style->svgStyle()->joinStyle());
    context->setMiterLimit(style->svgStyle()->strokeMiterLimit());

    const DashArray& dashes = dashArrayFromRenderingStyle(style);
    double dashOffset = SVGRenderStyle::cssPrimitiveToLength(object, style->svgStyle()->strokeDashOffset(), 0.0f);

    CGContextSetLineDash(context->platformContext(), narrowPrecisionToCGFloat(dashOffset), dashes.data(), dashes.size());
}

CGContextRef scratchContext()
{
    static CGContextRef scratch = 0;
    if (!scratch) {
        CFMutableDataRef empty = CFDataCreateMutable(NULL, 0);
        CGDataConsumerRef consumer = CGDataConsumerCreateWithCFData(empty);
        scratch = CGPDFContextCreate(consumer, NULL, NULL);
        CGDataConsumerRelease(consumer);
        CFRelease(empty);

        CGFloat black[4] = {0, 0, 0, 1};
        CGContextSetFillColor(scratch, black);
        CGContextSetStrokeColor(scratch, black);
     }
    return scratch;
}

FloatRect strokeBoundingBox(const Path& path, RenderStyle* style, const RenderObject* object)
 {
    // the bbox might grow if the path is stroked.
    // and CGPathGetBoundingBox doesn't support that, so we'll have
    // to make an alternative call...
 
    // FIXME: since this is mainly used to decide what to repaint,
    // perhaps it would be sufficien to just outset the fill bbox by
    // the stroke width - that should be way cheaper and simpler than
    // what we do here.
 
    CGPathRef cgPath = path.platformPath();

    CGContextRef context = scratchContext();
    CGContextSaveGState(context);

    CGContextBeginPath(context);
    CGContextAddPath(context, cgPath);

    GraphicsContext gc(context);
    applyStrokeStyleToContext(&gc, style, object);

    CGContextReplacePathWithStrokedPath(context);
    if (CGContextIsPathEmpty(context)) {
        // CGContextReplacePathWithStrokedPath seems to fail to create a path sometimes, this is not well understood.
        // returning here prevents CG from logging to the console from CGContextGetPathBoundingBox
        CGContextRestoreGState(context);
        return FloatRect();
    }

    CGRect box = CGContextGetPathBoundingBox(context);
    CGContextRestoreGState(context);

    return FloatRect(box);
}

}

#endif // ENABLE(SVG)