LibWeb: Add support for the SVG gradient spreadMethod attribute

Author: https://github.com/MacDue
Commit: https://github.com/SerenityOS/serenity/commit/46f42d9755
Pull-request: https://github.com/SerenityOS/serenity/pull/20682

Userland/Libraries/LibWeb/SVG/AttributeParser.cpp

@@ -509,6 +509,21 @@ Optional<GradientUnits> AttributeParser::parse_gradient_units(StringView input)
     return {};
 }
 
+// https://svgwg.org/svg2-draft/pservers.html#RadialGradientElementSpreadMethodAttribute
+Optional<SpreadMethod> AttributeParser::parse_spread_method(StringView input)
+{
+    GenericLexer lexer { input };
+    lexer.ignore_while(whitespace);
+    auto spread_method_string = lexer.consume_until(whitespace);
+    if (spread_method_string == "pad"sv)
+        return SpreadMethod::Pad;
+    if (spread_method_string == "repeat"sv)
+        return SpreadMethod::Repeat;
+    if (spread_method_string == "reflect"sv)
+        return SpreadMethod::Reflect;
+    return {};
+}
+
 // https://drafts.csswg.org/css-transforms/#svg-syntax
 Optional<Vector<Transform>> AttributeParser::parse_transform()
 {

Userland/Libraries/LibWeb/SVG/AttributeParser.h

@@ -93,6 +93,12 @@ enum class GradientUnits {
     UserSpaceOnUse
 };
 
+enum class SpreadMethod {
+    Pad,
+    Repeat,
+    Reflect
+};
+
 class NumberPercentage {
 public:
     NumberPercentage(float value, bool is_percentage)
@@ -144,6 +150,7 @@ public:
     static Optional<Vector<Transform>> parse_transform(StringView input);
     static Optional<PreserveAspectRatio> parse_preserve_aspect_ratio(StringView input);
     static Optional<GradientUnits> parse_gradient_units(StringView input);
+    static Optional<SpreadMethod> parse_spread_method(StringView input);
 
 private:
     AttributeParser(StringView source);

Userland/Libraries/LibWeb/SVG/SVGGradientElement.cpp

@@ -22,6 +22,8 @@ void SVGGradientElement::attribute_changed(DeprecatedFlyString const& name, Depr
     SVGElement::attribute_changed(name, value);
     if (name == AttributeNames::gradientUnits) {
         m_gradient_units = AttributeParser::parse_gradient_units(value);
+    } else if (name == AttributeNames::spreadMethod) {
+        m_spread_method = AttributeParser::parse_spread_method(value);
     } else if (name == AttributeNames::gradientTransform) {
         if (auto transform_list = AttributeParser::parse_transform(value); transform_list.has_value()) {
             m_gradient_transform = transform_from_transform_list(*transform_list);
@@ -40,6 +42,15 @@ GradientUnits SVGGradientElement::gradient_units() const
     return GradientUnits::ObjectBoundingBox;
 }
 
+SpreadMethod SVGGradientElement::spread_method() const
+{
+    if (m_spread_method.has_value())
+        return *m_spread_method;
+    if (auto gradient = linked_gradient())
+        return gradient->spread_method();
+    return SpreadMethod::Pad;
+}
+
 Optional<Gfx::AffineTransform> SVGGradientElement::gradient_transform() const
 {
     if (m_gradient_transform.has_value())

Userland/Libraries/LibWeb/SVG/SVGGradientElement.h

@@ -20,6 +20,20 @@ struct SVGPaintContext {
     Gfx::AffineTransform transform;
 };
 
+inline Gfx::SVGGradientPaintStyle::SpreadMethod to_gfx_spread_method(SpreadMethod spread_method)
+{
+    switch (spread_method) {
+    case SpreadMethod::Pad:
+        return Gfx::SVGGradientPaintStyle::SpreadMethod::Pad;
+    case SpreadMethod::Reflect:
+        return Gfx::SVGGradientPaintStyle::SpreadMethod::Reflect;
+    case SpreadMethod::Repeat:
+        return Gfx::SVGGradientPaintStyle::SpreadMethod::Repeat;
+    default:
+        VERIFY_NOT_REACHED();
+    }
+}
+
 class SVGGradientElement : public SVGElement {
     WEB_PLATFORM_OBJECT(SVGGradientElement, SVGElement);
 
@@ -32,6 +46,8 @@ public:
 
     GradientUnits gradient_units() const;
 
+    SpreadMethod spread_method() const;
+
     Optional<Gfx::AffineTransform> gradient_transform() const;
 
 protected:
@@ -61,6 +77,7 @@ protected:
 
 private:
     Optional<GradientUnits> m_gradient_units = {};
+    Optional<SpreadMethod> m_spread_method = {};
     Optional<Gfx::AffineTransform> m_gradient_transform = {};
 };
 

Userland/Libraries/LibWeb/SVG/SVGLinearGradientElement.cpp

@@ -131,6 +131,7 @@ Optional<Gfx::PaintStyle const&> SVGLinearGradientElement::to_gfx_paint_style(SV
     }
 
     m_paint_style->set_gradient_transform(gradient_paint_transform(paint_context));
+    m_paint_style->set_spread_method(to_gfx_spread_method(spread_method()));
     return *m_paint_style;
 }
 

Userland/Libraries/LibWeb/SVG/SVGRadialGradientElement.cpp

@@ -172,6 +172,7 @@ Optional<Gfx::PaintStyle const&> SVGRadialGradientElement::to_gfx_paint_style(SV
         m_paint_style->set_end_radius(end_radius);
     }
     m_paint_style->set_gradient_transform(gradient_paint_transform(paint_context));
+    m_paint_style->set_spread_method(to_gfx_spread_method(spread_method()));
     return *m_paint_style;
 }