vaev-style: Update stroke handling in SVG rendering and add strokeOpacity property.

Author: sleepy-monax

src/vaev-engine/layout/base/fragment.cpp

@@ -81,6 +81,7 @@ struct GroupFrag : SVG::Frag {
         e("(GroupFrag)");
     }
 };
+
 } // namespace SVG
 
 struct SVGRootFrag : SVG::GroupFrag {

src/vaev-engine/layout/svg.cpp

@@ -86,22 +86,22 @@ struct Rectangle {
     }
 };
 
-Rc<Scene::Node> rectToSceneNode(Rectangle<f64> rect, Opt<Gfx::Fill> fill, Opt<Gfx::Fill> strokeColor, f64 strokeWidth) {
+Rc<Scene::Node> rectToSceneNode(Rectangle<f64> rect, Opt<Gfx::Fill> fill, Opt<Gfx::Stroke> const& stroke) {
     Gfx::Borders borders;
-    if (strokeColor and strokeWidth > 0) {
+    if (stroke) {
         borders = Gfx::Borders{
             Math::Radiif{},
-            Math::Insetsf{strokeWidth},
-            Array<Gfx::Fill, 4>::fill(*strokeColor),
+            Math::Insetsf{stroke->width},
+            Array<Gfx::Fill, 4>::fill(stroke->fill),
             Array<Gfx::BorderStyle, 4>::fill(Gfx::BorderStyle::SOLID),
         };
 
         // FIXME: needed due to mismatch between SVG's and Scene's box model
         // svg's stroke's center is at the shape's edges
-        rect.width += strokeWidth;
-        rect.height += strokeWidth;
-        rect.x -= strokeWidth / 2;
-        rect.y -= strokeWidth / 2;
+        rect.width += stroke->width;
+        rect.height += stroke->width;
+        rect.x -= stroke->width / 2;
+        rect.y -= stroke->width / 2;
     }
 
     return makeRc<Scene::Box>(
@@ -267,18 +267,33 @@ struct ShapeFrag : Frag {
         unreachable();
     }
 
+    Opt<Gfx::Stroke> _resolveStroke(SVGProps const& style, Gfx::Color currentColor) const {
+        Opt<Gfx::Color> color = Vaev::Layout::resolve(style.stroke, currentColor);
+        if (not color)
+            return NONE;
+
+        if (Math::epsilonEq(style.strokeOpacity, 0.))
+            return NONE;
+
+        color = color->withOpacity(style.strokeOpacity);
+
+        if (strokeWidth == 0_au)
+            return NONE;
+
+        return Gfx::Stroke{*color, static_cast<f64>(strokeWidth)};
+    }
+
     Rc<Scene::Node> toSceneNode(Gfx::Color currentColor) const {
-        Opt<Gfx::Color> resolvedFill = Vaev::Layout::resolve(box->style->svg->fill, currentColor).map([&](auto fill) {
-            return fill.withOpacity(box->style->svg->fillOpacity);
+        auto const& style = *box->style->svg;
+
+        Opt<Gfx::Color> resolvedFill = Vaev::Layout::resolve(style.fill, currentColor).map([&](auto fill) {
+            return fill.withOpacity(style.fillOpacity);
         });
-        Opt<Gfx::Color> resolvedStrokeColor = Vaev::Layout::resolve(box->style->svg->stroke, currentColor);
-        Opt<Gfx::Stroke> resolvedStroke =
-            resolvedStrokeColor
-                ? Opt<Gfx::Stroke>{{*resolvedStrokeColor, (f64)strokeWidth}}
-                : NONE;
+
+        Opt<Gfx::Stroke> resolvedStroke = _resolveStroke(style, currentColor);
 
         if (auto rect = shape.is<Rectangle<Au>>()) {
-            return rectToSceneNode(rect->cast<f64>(), resolvedFill, resolvedStrokeColor, (f64)strokeWidth);
+            return rectToSceneNode(rect->cast<f64>(), resolvedFill, resolvedStroke);
         } else if (auto circle = shape.is<Circle<Au>>()) {
             return circleToSceneNode(circle->cast<f64>(), resolvedFill, resolvedStroke);
         } else if (auto path = shape.is<Rc<Math::Path>>()) {

src/vaev-engine/style/props.cpp

@@ -3369,6 +3369,33 @@ export struct SVGStrokeProp {
     }
 };
 
+// https://svgwg.org/svg2-draft/painting.html#StrokeOpacity
+export struct SvgStrokeOpacityProp {
+    Number value = initial();
+
+    static Str name() { return "stroke-opacity"; }
+
+    static f64 initial() { return 1; }
+
+    void apply(SpecifiedValues& c) const {
+        c.svg.cow().strokeOpacity = value;
+    }
+
+    static f64 load(SpecifiedValues const& c) {
+        return c.svg->strokeOpacity;
+    }
+
+    Res<> parse(Cursor<Css::Sst>& c) {
+        auto maybePercent = parseValue<Percent>(c);
+        if (maybePercent) {
+            value = maybePercent.unwrap().value() / 100;
+        } else {
+            value = try$(parseValue<Number>(c));
+        }
+        return Ok();
+    }
+};
+
 // https://svgwg.org/svg2-draft/painting.html#FillOpacity
 export struct FillOpacityProp {
     Number value = initial();
@@ -3671,6 +3698,7 @@ using _StyleProp = Union<
     SVGFillProp,
     SVGDProp,
     SVGStrokeProp,
+    SvgStrokeOpacityProp,
     SVGViewBoxProp,
     FillOpacityProp,
     StrokeWidthProp

src/vaev-engine/values/svg.cpp

@@ -64,6 +64,7 @@ export struct SVGProps {
 
     Number fillOpacity = 1;
     PercentOr<Length> strokeWidth = Length{1_au};
+    Number strokeOpacity = 1;
     Union<String, None> d = NONE;
     Paint fill = Color{Gfx::BLACK};
     Paint stroke = NONE;