LibWeb: Add SVG <ellipse> element and test case :^)

Userland/Libraries/LibWeb/SVG/SVGEllipseElement.cpp

@@ -0,0 +1,78 @@
+/*
+ * Copyright (c) 2022, Sam Atkins <atkinssj@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include "SVGEllipseElement.h"
+#include <LibWeb/SVG/AttributeNames.h>
+#include <LibWeb/SVG/AttributeParser.h>
+
+namespace Web::SVG {
+
+SVGEllipseElement::SVGEllipseElement(DOM::Document& document, QualifiedName qualified_name)
+    : SVGGeometryElement(document, qualified_name)
+{
+}
+
+void SVGEllipseElement::parse_attribute(FlyString const& name, String const& value)
+{
+    SVGGeometryElement::parse_attribute(name, value);
+
+    if (name == SVG::AttributeNames::cx) {
+        m_center_x = AttributeParser::parse_coordinate(value);
+        m_path.clear();
+    } else if (name == SVG::AttributeNames::cy) {
+        m_center_y = AttributeParser::parse_coordinate(value);
+        m_path.clear();
+    } else if (name == SVG::AttributeNames::rx) {
+        m_radius_x = AttributeParser::parse_positive_length(value);
+        m_path.clear();
+    } else if (name == SVG::AttributeNames::ry) {
+        m_radius_y = AttributeParser::parse_positive_length(value);
+        m_path.clear();
+    }
+}
+
+Gfx::Path& SVGEllipseElement::get_path()
+{
+    if (m_path.has_value())
+        return m_path.value();
+
+    float rx = m_radius_x.value_or(0);
+    float ry = m_radius_y.value_or(0);
+    float cx = m_center_x.value_or(0);
+    float cy = m_center_y.value_or(0);
+    Gfx::Path path;
+
+    // A computed value of zero for either dimension, or a computed value of auto for both dimensions, disables rendering of the element.
+    if (rx == 0 || ry == 0) {
+        m_path = move(path);
+        return m_path.value();
+    }
+
+    Gfx::FloatPoint radii = { rx, ry };
+    double x_axis_rotation = 0;
+    bool large_arc = false;
+    bool sweep = true; // Note: Spec says it should be false, but it's wrong. https://github.com/w3c/svgwg/issues/765
+
+    // 1. A move-to command to the point cx+rx,cy;
+    path.move_to({ cx + rx, cy });
+
+    // 2. arc to cx,cy+ry;
+    path.elliptical_arc_to({ cx, cy + ry }, radii, x_axis_rotation, large_arc, sweep);
+
+    // 3. arc to cx-rx,cy;
+    path.elliptical_arc_to({ cx - rx, cy }, radii, x_axis_rotation, large_arc, sweep);
+
+    // 4. arc to cx,cy-ry;
+    path.elliptical_arc_to({ cx, cy - ry }, radii, x_axis_rotation, large_arc, sweep);
+
+    // 5. arc with a segment-completing close path operation.
+    path.elliptical_arc_to({ cx + rx, cy }, radii, x_axis_rotation, large_arc, sweep);
+
+    m_path = move(path);
+    return m_path.value();
+}
+
+}

Userland/Libraries/LibWeb/SVG/SVGEllipseElement.h

@@ -0,0 +1,33 @@
+/*
+ * Copyright (c) 2022, Sam Atkins <atkinssj@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibWeb/SVG/SVGGeometryElement.h>
+
+namespace Web::SVG {
+
+class SVGEllipseElement final : public SVGGeometryElement {
+public:
+    using WrapperType = Bindings::SVGEllipseElementWrapper;
+
+    SVGEllipseElement(DOM::Document&, QualifiedName);
+    virtual ~SVGEllipseElement() override = default;
+
+    virtual void parse_attribute(FlyString const& name, String const& value) override;
+
+    virtual Gfx::Path& get_path() override;
+
+private:
+    Optional<Gfx::Path> m_path;
+
+    Optional<float> m_center_x;
+    Optional<float> m_center_y;
+    Optional<float> m_radius_x;
+    Optional<float> m_radius_y;
+};
+
+}

Userland/Libraries/LibWeb/SVG/SVGEllipseElement.idl

@@ -0,0 +1,7 @@
+[Exposed=Window]
+interface SVGEllipseElement : SVGGeometryElement {
+    // [SameObject] readonly attribute SVGAnimatedLength cx;
+    // [SameObject] readonly attribute SVGAnimatedLength cy;
+    // [SameObject] readonly attribute SVGAnimatedLength rx;
+    // [SameObject] readonly attribute SVGAnimatedLength ry;
+};

Userland/Libraries/LibWeb/SVG/TagNames.h

@@ -12,6 +12,7 @@ namespace Web::SVG::TagNames {
 
 #define ENUMERATE_SVG_GRAPHICS_TAGS \
     __ENUMERATE_SVG_TAG(circle)     \
+    __ENUMERATE_SVG_TAG(ellipse)    \
     __ENUMERATE_SVG_TAG(g)          \
     __ENUMERATE_SVG_TAG(path)       \
     __ENUMERATE_SVG_TAG(rect)       \