Merge pull request #3668 from Taha-Mahmoodi/fix/dither-followups

Gradients: dithered fills sample only what shows; review follow-ups to #3637

crates/engine/src/cmd/paint.rs

@@ -403,6 +403,10 @@ fn set_paint(s: &mut Session, p: &Value, fill: bool) -> Result<Value> {
     }
     check_keep_model(p, cmd)?;
     let paint = paint_from(s, p)?.ok_or_else(|| bad(cmd, "give color, none, swatch or gradient"))?;
+    // As `paint.editGradient`: a `dither` given applies to gradient fills only.
+    if !fill && matches!(&paint, Paint::Gradient(g) if g.gradient.dither) && p.get("swatch").is_none() {
+        return Err(bad(cmd, "`dither` applies to gradient fills (paint.setFill)"));
+    }
     apply_paint(s, p, paint, fill)
 }
 

crates/engine/src/cmd/pathops.rs

@@ -635,7 +635,7 @@ pub(crate) fn outlined_stroke(
         blend: st.blend,
         effects: st.effects.clone(),
         overprint: st.overprint,
-        ..vectorcraft_doc::appearance::FillLayer::new(st.paint.clone())
+        ..vectorcraft_doc::appearance::FillLayer::new(st.paint.stroke_as_fill())
     };
     n.appearance = Appearance { items: vec![AppearanceItem::Fill(fill)], ..Default::default() }.into();
     Some(n)

crates/engine/src/tests_gradient.rs

@@ -440,7 +440,29 @@ fn dither_is_a_fill_gradient_option_that_saves_and_loads() {
     s.execute("paint.setStroke", &json!({"gradient": {}})).unwrap();
     let before = node(&s, id).appearance.clone();
     assert!(s.execute("paint.editGradient", &json!({"dither": true, "stroke": true})).is_err());
+    assert!(s.execute("paint.setStroke", &json!({"gradient": {"dither": true}})).is_err());
     assert!(s.execute("paint.editGradient", &json!({"dither": "yes"})).is_err());
     assert!(s.execute("paint.setFill", &json!({"gradient": {"dither": 1}})).is_err());
     assert_eq!(node(&s, id).appearance, before);
 }
+
+/// A stroke ignores dither, so one that holds it anyway (swapped from a fill) outlines to a fill
+/// without it: Outline Stroke keeps the look.
+#[test]
+fn an_outlined_stroke_leaves_dither_behind() {
+    let mut s = session();
+    let id = rect(&mut s, 0.0, 0.0, 100.0, 100.0);
+    s.execute("paint.setStroke", &json!({"gradient": {}})).unwrap();
+    s.execute("paint.setFill", &json!({"gradient": {"dither": true}})).unwrap();
+    s.execute("paint.swap", &json!({})).unwrap();
+    let Paint::Gradient(st) = node(&s, id).appearance.stroke_paint() else { panic!("a gradient stroke") };
+    assert!(st.gradient.dither, "the swapped stroke keeps the option");
+    s.execute("object.path.outlineStroke", &json!({})).unwrap();
+    let mut fills = vec![];
+    s.doc().unwrap().doc.walk(|n| {
+        if let Paint::Gradient(g) = n.appearance.fill_paint() {
+            fills.push(g.gradient.dither);
+        }
+    });
+    assert_eq!(fills, [false, false], "the fill and the outline, neither dithered");
+}