Effects: a path with its own Transform effect paints each copy with its own gradient (#2451)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/effects/src/lib.rs

@@ -69,7 +69,7 @@ pub use live::{expand_live, expand_live_deep, expanded_live_group, text_outliner
 pub use marks::{CROP_MARKS, crop_marks_art, has_crop_marks};
 pub use pixel::{PIXEL_EFFECTS, PixelFx, PixelSpace};
 pub use raster::{RasterFx, outset, raster_effects};
-pub use reshape::{expand_outlined, has_item_geometry, needs_outline, outline_art, outline_text, reshape};
+pub use reshape::{expand_outlined, has_gradient_copies, has_item_geometry, needs_outline, outline_art, outline_text, reshape};
 pub use revolve::{REVOLVE, has_revolve, revolve_art, revolve_options, validate_revolve};
 pub use solids::{
     EXTRUDE, INFLATE, ROTATE, ROTATION_PRESETS, SOLIDS, extrude_options, has_solid, inflate_options, is_three_d, solid_art, validate_solid,

crates/effects/src/reshape.rs

@@ -32,6 +32,17 @@ pub fn needs_outline(n: &Node) -> bool {
     )
 }
 
+/// Is `n` a path or compound path with a visible Transform effect that makes copies and a gradient
+/// in a fill or stroke? Such an object is drawn through its art ([`outline_art`]) so that each copy
+/// paints its gradient by itself ([`copy_with_gradients`]), as a group's copies do.
+pub fn has_gradient_copies(n: &Node) -> bool {
+    matches!(n.kind, NodeKind::Path { guide: false, clipping: false, .. } | NodeKind::Compound { .. })
+        && (n.appearance.has_unplaced_gradient() || n.appearance.has_placed_gradient())
+        && geometry_effects(n)
+            .iter()
+            .any(|e| e.id == "distort.transform" && crate::distort::transform_map(Rect::ZERO, &merged_params(&e.id, &e.params), 0).1 > 0)
+}
+
 /// Is `n` type without inline graphics that has a fill or stroke of its own that paints and has a
 /// visible geometry effect? Such an effect reshapes the whole outline that its fill or stroke
 /// paints ([`outline_text`], which leaves inline graphics out).
@@ -127,6 +138,16 @@ pub fn outline_art(n: &Node, symbol_art: Option<&Node>) -> Option<Node> {
             a.transform(*xf, false);
             Node::group(n.id, vec![Arc::new(a)])
         }
+        // The object as the one piece the copies of its Transform effect are made from.
+        _ if has_gradient_copies(n) => {
+            let mut one = n.clone();
+            one.opacity = 1.0;
+            one.blend = Default::default();
+            one.isolate = false;
+            one.extras_mut().mask = None;
+            one.appearance.effects.clear();
+            Node::group(n.id, vec![Arc::new(one)])
+        }
         _ if vectorcraft_doc::live::is_live(n) => vectorcraft_doc::live::expand_deep(n, Some(hook)),
         _ => return None,
     };
@@ -171,7 +192,7 @@ pub(crate) fn outline_nested_text(n: &mut Node, clipping: bool) {
 /// a geometry effect on a fill or stroke of its own ([`has_item_geometry`]), or has no art (a
 /// symbol instance without `symbol_art`).
 pub fn reshape(n: &Node, symbol_art: Option<&Node>) -> Option<Node> {
-    if (geometry_effects(n).is_empty() && n.projection().is_none() && !has_item_geometry(n)) || !needs_outline(n) {
+    if (geometry_effects(n).is_empty() && n.projection().is_none() && !has_item_geometry(n)) || !(needs_outline(n) || has_gradient_copies(n)) {
         return None;
     }
     as_art(n, symbol_art)

crates/render/src/fx.rs

@@ -68,11 +68,13 @@ pub(crate) fn has_fx(n: &Node) -> bool {
 
 /// Does `n` carry visible object-level effects that only apply through its art (type, images,
 /// symbol instances, live objects; Crop Marks and colour adjustments on anything), is it type with
-/// a geometry effect on a fill or stroke of its own ([`effects::has_item_geometry`]), or is it a
+/// a geometry effect on a fill or stroke of its own ([`effects::has_item_geometry`]), is it a path
+/// whose Transform effect copies it with a gradient ([`effects::has_gradient_copies`]), or is it a
 /// group or layer with an appearance of its own (see [`Renderer::draw_object_fx`])?
 pub(crate) fn has_object_fx(n: &Node) -> bool {
     (effects::needs_outline(n) && (visible(&n.appearance.effects) || n.projection().is_some()))
         || effects::has_item_geometry(n)
+        || effects::has_gradient_copies(n)
         || effects::has_container_appearance(n)
         || effects::has_crop_marks(n)
         || effects::has_adjustment(n)

crates/render/src/tests_objectfx.rs

@@ -697,3 +697,24 @@ fn a_strokes_own_glow_paints_around_that_stroke_only() {
     let worst = img.pixels.iter().zip(&mt.pixels).map(|(a, b)| a.abs_diff(*b)).max().unwrap();
     assert!(worst <= 4, "max channel difference {worst}");
 }
+
+#[test]
+fn a_path_with_its_own_transform_paints_each_copy_with_its_own_gradient() {
+    use vectorcraft_color::GradientGeom;
+    let stops = vec![GradientStop::new(0.0, Color::rgb(1.0, 0.0, 0.0)), GradientStop::new(1.0, Color::rgb(0.0, 0.0, 1.0))];
+    let ramp = GradientPaint::new(Gradient { kind: GradientKind::Linear, stops });
+    let geom = GradientGeom { start: Point::new(0.0, 50.0), end: Point::new(20.0, 50.0), aspect: 1.0, focal: None };
+    // Fitted to the box on each render, and placed on the object.
+    for paint in [ramp.clone(), GradientPaint { geom: Some(geom), ..ramp }] {
+        let square = shapes::rectangle(vectorcraft_geom::Rect::new(0.0, 40.0, 20.0, 60.0));
+        let mut n = Node::path(NodeId(0), square, Appearance::basic(Paint::Gradient(Box::new(paint)), Paint::None, 0.0));
+        n.appearance.effects = vec![fx("distort.transform", json!({"moveH": 40, "copies": 1}))];
+        let img = render(&doc_with(Document::new(100.0, 100.0), n));
+        let at = |x: usize| img.pixels.chunks(4).nth(50 * 100 + x).map(|p| (p[0], p[2])).unwrap_or_default();
+        // The left edge of each copy is red, its right edge blue.
+        for (left, right) in [(1, 18), (41, 58)] {
+            assert!(at(left).0 > 200 && at(left).1 < 60, "{:?} at {left}", at(left));
+            assert!(at(right).1 > 200 && at(right).0 < 60, "{:?} at {right}", at(right));
+        }
+    }
+}