ClipPathHelper(GraphicsContext* context, const DeprecatedPaintLayer& paintLayer, const DeprecatedPaintLayerPaintingInfo& paintingInfo, LayoutRect& rootRelativeBounds, bool& rootRelativeBoundsComputed,
        const LayoutPoint& offsetFromRoot, PaintLayerFlags paintFlags)
        : m_resourceClipper(0), m_paintLayer(paintLayer), m_context(context)
    {
        const ComputedStyle& style = paintLayer.layoutObject()->styleRef();

        // Clip-path, like border radius, must not be applied to the contents of a composited-scrolling container.
        // It must, however, still be applied to the mask layer, so that the compositor can properly mask the
        // scrolling contents and scrollbars.
        if (!paintLayer.layoutObject()->hasClipPath() || (paintLayer.needsCompositedScrolling() && !(paintFlags & PaintLayerPaintingChildClippingMaskPhase)))
            return;

        m_clipperState = SVGClipPainter::ClipperNotApplied;

        ASSERT(style.clipPath());
        if (style.clipPath()->type() == ClipPathOperation::SHAPE) {
            ShapeClipPathOperation* clipPath = toShapeClipPathOperation(style.clipPath());
            if (clipPath->isValid()) {
                if (!rootRelativeBoundsComputed) {
                    rootRelativeBounds = paintLayer.physicalBoundingBoxIncludingReflectionAndStackingChildren(paintingInfo.rootLayer, offsetFromRoot);
                    rootRelativeBoundsComputed = true;
                }
                m_clipPathRecorder.emplace(*context, *paintLayer.layoutObject(), clipPath->path(rootRelativeBounds));
            }
        } else if (style.clipPath()->type() == ClipPathOperation::REFERENCE) {
            ReferenceClipPathOperation* referenceClipPathOperation = toReferenceClipPathOperation(style.clipPath());
            Document& document = paintLayer.layoutObject()->document();
            // FIXME: It doesn't work with forward or external SVG references (https://bugs.webkit.org/show_bug.cgi?id=90405)
            Element* element = document.getElementById(referenceClipPathOperation->fragment());
            if (isSVGClipPathElement(element) && element->layoutObject()) {
                if (!rootRelativeBoundsComputed) {
                    rootRelativeBounds = paintLayer.physicalBoundingBoxIncludingReflectionAndStackingChildren(paintingInfo.rootLayer, offsetFromRoot);
                    rootRelativeBoundsComputed = true;
                }

                m_resourceClipper = toLayoutSVGResourceClipper(toLayoutSVGResourceContainer(element->layoutObject()));
                if (!SVGClipPainter(*m_resourceClipper).applyClippingToContext(*paintLayer.layoutObject(), rootRelativeBounds,
                    paintingInfo.paintDirtyRect, context, m_clipperState)) {
                    // No need to post-apply the clipper if this failed.
                    m_resourceClipper = 0;
                }
            }
        }
    }