ladybird/Userland/Libraries/LibWeb/SVG/SVGCircleElement.cpp

/*
 * Copyright (c) 2022, Sam Atkins <atkinssj@serenityos.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <LibWeb/Bindings/Intrinsics.h>
#include <LibWeb/CSS/Parser/Parser.h>
#include <LibWeb/Layout/Node.h>
#include <LibWeb/SVG/AttributeNames.h>
#include <LibWeb/SVG/AttributeParser.h>
#include <LibWeb/SVG/SVGCircleElement.h>
#include <LibWeb/SVG/SVGViewport.h>

namespace Web::SVG {

JS_DEFINE_ALLOCATOR(SVGCircleElement);

SVGCircleElement::SVGCircleElement(DOM::Document& document, DOM::QualifiedName qualified_name)
    : SVGGeometryElement(document, qualified_name)
{
}

void SVGCircleElement::initialize(JS::Realm& realm)
{
    Base::initialize(realm);
    WEB_SET_PROTOTYPE_FOR_INTERFACE(SVGCircleElement);
}

void SVGCircleElement::apply_presentational_hints(CSS::StyleProperties& style) const
{
    Base::apply_presentational_hints(style);
    auto parsing_context = CSS::Parser::ParsingContext { document(), CSS::Parser::ParsingContext::Mode::SVGPresentationAttribute };

    auto cx_attribute = attribute(SVG::AttributeNames::cx);
    if (auto cx_value = parse_css_value(parsing_context, cx_attribute.value_or(String {}), CSS::PropertyID::Cx))
        style.set_property(CSS::PropertyID::Cx, cx_value.release_nonnull());

    auto cy_attribute = attribute(SVG::AttributeNames::cy);
    if (auto cy_value = parse_css_value(parsing_context, cy_attribute.value_or(String {}), CSS::PropertyID::Cy))
        style.set_property(CSS::PropertyID::Cy, cy_value.release_nonnull());

    auto r_attribute = attribute(SVG::AttributeNames::r);
    if (auto r_value = parse_css_value(parsing_context, r_attribute.value_or(String {}), CSS::PropertyID::R))
        style.set_property(CSS::PropertyID::R, r_value.release_nonnull());
}

Gfx::Path SVGCircleElement::get_path(CSSPixelSize viewport_size)
{
    auto* node = layout_node();
    auto cx = float(node->computed_values().cx().to_px(*node, viewport_size.width()));
    auto cy = float(node->computed_values().cy().to_px(*node, viewport_size.height()));
    // Percentages refer to the normalized diagonal of the current SVG viewport
    // (see Units: https://svgwg.org/svg2-draft/coords.html#Units)
    auto r = float(node->computed_values().r().to_px(*node, normalized_diagonal_length(viewport_size)));

    // A zero radius disables rendering.
    if (r == 0)
        return {};

    Gfx::Path path;
    bool large_arc = false;
    bool sweep = true;

    // 1. A move-to command to the point cx+r,cy;
    path.move_to({ cx + r, cy });

    // 2. arc to cx,cy+r;
    path.arc_to({ cx, cy + r }, r, large_arc, sweep);

    // 3. arc to cx-r,cy;
    path.arc_to({ cx - r, cy }, r, large_arc, sweep);

    // 4. arc to cx,cy-r;
    path.arc_to({ cx, cy - r }, r, large_arc, sweep);

    // 5. arc with a segment-completing close path operation.
    path.arc_to({ cx + r, cy }, r, large_arc, sweep);

    return path;
}

// https://www.w3.org/TR/SVG11/shapes.html#CircleElementCXAttribute
JS::NonnullGCPtr<SVGAnimatedLength> SVGCircleElement::cx() const
{
    // FIXME: Create a proper animated value when animations are supported.
    auto make_length = [&] {
        if (auto const* style = computed_css_values(); style) {
            if (auto cx = style->length_percentage(CSS::PropertyID::Cx); cx.has_value())
                return SVGLength::from_length_percentage(realm(), *cx);
        }
        return SVGLength::create(realm(), 0, 0.0f);
    };
    return SVGAnimatedLength::create(realm(), make_length(), make_length());
}

// https://www.w3.org/TR/SVG11/shapes.html#CircleElementCYAttribute
JS::NonnullGCPtr<SVGAnimatedLength> SVGCircleElement::cy() const
{
    // FIXME: Create a proper animated value when animations are supported.
    auto make_length = [&] {
        if (auto const* style = computed_css_values(); style) {
            if (auto cy = style->length_percentage(CSS::PropertyID::Cy); cy.has_value())
                return SVGLength::from_length_percentage(realm(), *cy);
        }
        return SVGLength::create(realm(), 0, 0.0f);
    };
    return SVGAnimatedLength::create(realm(), make_length(), make_length());
}

// https://www.w3.org/TR/SVG11/shapes.html#CircleElementRAttribute
JS::NonnullGCPtr<SVGAnimatedLength> SVGCircleElement::r() const
{
    // FIXME: Create a proper animated value when animations are supported.
    auto make_length = [&] {
        if (auto const* style = computed_css_values(); style) {
            if (auto r = computed_css_values()->length_percentage(CSS::PropertyID::R); r.has_value())
                return SVGLength::from_length_percentage(realm(), *r);
        }
        return SVGLength::create(realm(), 0, 0.0f);
    };
    return SVGAnimatedLength::create(realm(), make_length(), make_length());
}

}