C++ GraphicsContext::clipPath方法代码示例

bool RenderSVGResourceClipper::pathOnlyClipping(GraphicsContext& context, const AffineTransform& animatedLocalTransform, const FloatRect& objectBoundingBox)
{
    // If the current clip-path gets clipped itself, we have to fallback to masking.
    if (!style().svgStyle().clipperResource().isEmpty())
        return false;
    WindRule clipRule = RULE_NONZERO;
    Path clipPath = Path();

    // If clip-path only contains one visible shape or path, we can use path-based clipping. Invisible
    // shapes don't affect the clipping and can be ignored. If clip-path contains more than one
    // visible shape, the additive clipping may not work, caused by the clipRule. EvenOdd
    // as well as NonZero can cause self-clipping of the elements.
    // See also http://www.w3.org/TR/SVG/painting.html#FillRuleProperty
    for (Node* childNode = clipPathElement().firstChild(); childNode; childNode = childNode->nextSibling()) {
        RenderObject* renderer = childNode->renderer();
        if (!renderer)
            continue;
        // Only shapes or paths are supported for direct clipping. We need to fallback to masking for texts.
        if (renderer->isSVGText())
            return false;
        if (!childNode->isSVGElement() || !downcast<SVGElement>(*childNode).isSVGGraphicsElement())
            continue;
        SVGGraphicsElement& styled = downcast<SVGGraphicsElement>(*childNode);
        const RenderStyle& style = renderer->style();
        if (style.display() == NONE || style.visibility() != VISIBLE)
             continue;
        const SVGRenderStyle& svgStyle = style.svgStyle();
        // Current shape in clip-path gets clipped too. Fallback to masking.
        if (!svgStyle.clipperResource().isEmpty())
            return false;
        // Fallback to masking, if there is more than one clipping path.
        if (clipPath.isEmpty()) {
            styled.toClipPath(clipPath);
            clipRule = svgStyle.clipRule();
        } else
            return false;
    }
    // Only one visible shape/path was found. Directly continue clipping and transform the content to userspace if necessary.
    if (clipPathElement().clipPathUnits() == SVGUnitTypes::SVG_UNIT_TYPE_OBJECTBOUNDINGBOX) {
        AffineTransform transform;
        transform.translate(objectBoundingBox.x(), objectBoundingBox.y());
        transform.scaleNonUniform(objectBoundingBox.width(), objectBoundingBox.height());
        clipPath.transform(transform);
    }

    // Transform path by animatedLocalTransform.
    clipPath.transform(animatedLocalTransform);

    // The SVG specification wants us to clip everything, if clip-path doesn't have a child.
    if (clipPath.isEmpty())
        clipPath.addRect(FloatRect());
    context.clipPath(clipPath, clipRule);
    return true;
}

void BeginClipPathDisplayItem::replay(GraphicsContext& context) const
{
    context.save();
    context.clipPath(m_clipPath, AntiAliased);
}

void ClipPath::apply(GraphicsContext& context) const
{
    context.clipPath(m_path, m_windRule);
}