From 2f24495ffe03a59fbe7fd79e34841ee9dfbe47ae Mon Sep 17 00:00:00 2001
From: Marco Arnulfo <marcoarnulfo1@gmail.com>
Date: Fri, 16 Oct 2026 13:05:37 +0200
Subject: [PATCH] Color effects recolour the points of a freeform gradient
 (fixes #2390)

---
 crates/color/src/lib.rs      | 11 +++++++++--
 crates/effects/src/adjust.rs | 16 ++++++++++++++++
 2 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/crates/color/src/lib.rs b/crates/color/src/lib.rs
index 6fc854ff0..ff10699be 100644
--- a/crates/color/src/lib.rs
+++ b/crates/color/src/lib.rs
@@ -387,7 +387,9 @@ impl Paint {
     }
     /// Apply `f` to the colours of this paint that can link to a swatch (a solid colour, each
     /// gradient stop) with their link and tint; `f` returns true when it changed them. A colour
-    /// left without a link gets tint 1. Returns whether anything changed.
+    /// left without a link gets tint 1. A freeform gradient's points, which it draws from, go
+    /// through `f` too, as unlinked colours (a link `f` gives them is dropped). Returns whether
+    /// anything changed.
     pub fn map_links(&mut self, f: &mut dyn FnMut(&mut Color, &mut Option<String>, &mut f32) -> bool) -> bool {
         let mut one = |c: &mut Color, link: &mut Option<String>, tint: &mut f32| {
             let changed = f(c, link, tint);
@@ -398,7 +400,12 @@ impl Paint {
         };
         match self {
             Paint::Solid { color, swatch, tint } => one(color, swatch, tint),
-            Paint::Gradient(g) => g.gradient.stops.iter_mut().fold(false, |ch, s| one(&mut s.color, &mut s.swatch, &mut s.tint) | ch),
+            Paint::Gradient(g) => {
+                let stops = g.gradient.stops.iter_mut().fold(false, |ch, s| one(&mut s.color, &mut s.swatch, &mut s.tint) | ch);
+                let points =
+                    g.freeform.iter_mut().flat_map(|ff| ff.points.iter_mut()).fold(false, |ch, p| one(&mut p.color, &mut None, &mut 1.0) | ch);
+                stops | points
+            }
             _ => false,
         }
     }
diff --git a/crates/effects/src/adjust.rs b/crates/effects/src/adjust.rs
index 85e8a2cd9..84ca9d3c1 100644
--- a/crates/effects/src/adjust.rs
+++ b/crates/effects/src/adjust.rs
@@ -490,4 +490,20 @@ mod tests {
         assert_eq!(out.appearance.items[0].paint(), p.appearance.items[0].paint());
         assert!(out.appearance.items[1].effects().is_empty());
     }
+
+    #[test]
+    fn adjust_recolours_the_points_of_a_freeform_gradient() {
+        use vectorcraft_doc::color::{Freeform, FreeformPoint, Gradient, GradientKind, GradientPaint};
+        let mut gp = GradientPaint::new(Gradient { kind: GradientKind::Freeform, ..Gradient::default() });
+        let pt = |x, c| FreeformPoint::new(kurbo::Point::new(x, 5.0), c);
+        gp.set_freeform(Freeform { points: vec![pt(2.0, Color::rgb(1.0, 0.0, 0.0)), pt(8.0, Color::rgb(0.0, 0.0, 1.0))], ..Default::default() });
+        let fill = Appearance::basic(Paint::Gradient(Box::new(gp)), Paint::None, 0.0);
+        let mut p = Node::path(NodeId(1), shapes::rectangle(Rect::new(0.0, 0.0, 10.0, 10.0)), fill);
+        p.appearance.effects.push(Effect { id: "adjust.hueSaturation".into(), params: json!({"hue": 120}), visible: true });
+        let out = adjust(&p, None, &mut |_, _| None).unwrap();
+        let Paint::Gradient(g) = out.appearance.fill_paint() else { panic!("a gradient fill") };
+        // The points are what a freeform gradient draws from, not its stops.
+        let hexes: Vec<String> = g.freeform.as_ref().unwrap().points.iter().map(|p| p.color.to_hex()).collect();
+        assert_eq!(hexes, ["#00ff00", "#ff0000"]);
+    }
 }