From f69601b0ffd09da60cc90aabb2b713cf78bbc584 Mon Sep 17 00:00:00 2001 From: moppeeer Date: Wed, 14 Oct 2026 10:36:45 +0200 Subject: [PATCH] A linear gradient across a straight line runs along its length, on screen and in PDF alike Review fix from aiongg (72d7ea2e, with the line tests of 6db40bdb), ported to this branch: Fill::linear_axis gives screen and PDF one gradient axis, and a box with no extent along the gradient's angle takes its longer side. Co-authored-by: aiongg Co-Authored-By: Claude Opus 5.5 --- crates/doc/src/item.rs | 15 ++++++++++++ crates/engine/src/cmd/style.rs | 45 ++++++++++++++++++++++++++++++++++ crates/pdf/src/export.rs | 10 ++------ crates/render/src/lib.rs | 9 +++---- 4 files changed, 65 insertions(+), 14 deletions(-) diff --git a/crates/doc/src/item.rs b/crates/doc/src/item.rs index 1dc045e08..593edd170 100644 --- a/crates/doc/src/item.rs +++ b/crates/doc/src/item.rs @@ -32,6 +32,21 @@ impl Default for Fill { } impl Fill { + /// A linear gradient's axis on an object whose bounds (in its own space) are `b`: the + /// Gradient Swatch tool's vector, or the box's extent along the gradient's angle through its + /// centre. A box with no extent along that angle (a straight line, across it) takes its longer + /// side. + pub fn linear_axis(&self, b: Rect) -> (Point, Point) { + if let Some([x0, y0, x1, y1]) = self.gradient_vector { + return (Point::new(x0, y0), Point::new(x1, y1)); + } + let a = self.gradient_angle.unwrap_or(0.0).to_radians(); + let half = (b.width() * a.cos().abs() + b.height() * a.sin().abs()) / 2.0; + let half = if half > 1e-9 { half } else { b.width().max(b.height()).max(1e-3) / 2.0 }; + let d = designcraft_geom::Vec2::new(a.cos(), -a.sin()) * half; + (b.center() - d, b.center() + d) + } + pub fn none() -> Self { Fill { swatch: designcraft_color::swatch::NONE.into(), tint: 1.0, gradient_angle: None, gradient_vector: None, overprint: false } } diff --git a/crates/engine/src/cmd/style.rs b/crates/engine/src/cmd/style.rs index 08cb736a9..fdc11e805 100644 --- a/crates/engine/src/cmd/style.rs +++ b/crates/engine/src/cmd/style.rs @@ -1900,6 +1900,51 @@ mod gradient_stroke_tests { assert!(a > 215 && b < 40, "dragged: {a} {b}"); assert!(s.execute("object.gradient", &json!({"ids": [id], "target": "gap"})).is_err()); } + + /// A 20 pt horizontal line with a gradient on its stroke, drawn on screen and from its PDF. + fn line_with_stroke_gradient(g: serde_json::Value) -> (designcraft_render::Rendered, designcraft_render::Rendered) { + let mut s = crate::Session::new(); + s.execute("file.new", &json!({"width": 200, "height": 120, "facingPages": false})).unwrap(); + let id = s.execute("line.create", &json!({"a": [20, 60], "b": [180, 60]})).unwrap()["id"].as_u64().unwrap(); + s.execute("object.stroke", &json!({"ids": [id], "weight": 20})).unwrap(); + let mut g = g; + g["ids"] = json!([id]); + g["target"] = json!("stroke"); + s.execute("object.gradient", &g).unwrap(); + let d = s.doc().unwrap().doc.clone(); + let mut rr = designcraft_render::Renderer::new(); + let screen = rr.render_page(&d, &s.cache, 0, 1.0, false, &Default::default()).unwrap(); + let pdf = designcraft_pdf::export_pdf(&d, &s.cache, &Default::default()).unwrap(); + let mut p = crate::Session::new(); + p.execute("file.new", &json!({"width": 200, "height": 120, "facingPages": false})).unwrap(); + p.execute("file.place", &json!({"base64": crate::cmd::file::base64_encode(&pdf), "name": "line.pdf", "x": 0, "y": 0, "width": 200})).unwrap(); + let pd = p.doc().unwrap().doc.clone(); + let placed = rr.render_page(&pd, &p.cache, 0, 1.0, false, &Default::default()).unwrap(); + (screen, placed) + } + + #[test] + fn a_radial_gradient_on_a_straight_lines_stroke_shows_all_its_stops() { + // The line's box has no height: the gradient is a circle across the line's length. + let (screen, pdf) = line_with_stroke_gradient( + json!({"kind": "radial", "stops": [{"location": 0, "color": "#000000"}, {"location": 100, "color": "#ffffff"}]}), + ); + for (what, img) in [("screen", &screen), ("pdf", &pdf)] { + let (a, m, b) = along(img); + assert!(m < 40 && a > 180 && b > 180, "{what}: {a} {m} {b}"); + } + } + + #[test] + fn a_linear_gradient_across_a_straight_line_paints_its_stroke_alike_on_screen_and_in_pdf() { + let (screen, pdf) = + line_with_stroke_gradient(json!({"angle": 90, "stops": [{"location": 0, "color": "#ff0000"}, {"location": 100, "color": "#0000ff"}]})); + let (s, p) = (screen.pixel(100, 60), pdf.pixel(100, 60)); + // The line's box has no height: the gradient runs across the line's length, so the stroke + // shows its middle. + assert!(s[1] < 60 && s[0] > 80 && s[2] > 80, "screen: the stroke is painted, {s:?}"); + assert!((0..3).all(|i| s[i].abs_diff(p[i]) < 40), "screen {s:?}, pdf {p:?}"); + } } #[cfg(test)] diff --git a/crates/pdf/src/export.rs b/crates/pdf/src/export.rs index 64434732a..8da90186e 100644 --- a/crates/pdf/src/export.rs +++ b/crates/pdf/src/export.rs @@ -978,7 +978,7 @@ impl Exporter<'_> { /// A swatch fill (solid or gradient) in the item's inner space. `None` for [None]/unknown. fn fill_paint(&mut self, fill: &designcraft_doc::Fill, bounds: Rect) -> Option { - let (swatch, tint, angle) = (fill.swatch.as_str(), fill.tint, fill.gradient_angle); + let (swatch, tint) = (fill.swatch.as_str(), fill.tint); if let Some(g) = designcraft_color::swatch::resolve_gradient(&self.doc.swatches, swatch) { let kind = g.kind; let expanded = g.expanded_stops(); @@ -1036,13 +1036,7 @@ impl Exporter<'_> { .into() } _ => { - let a = angle.unwrap_or(0.0).to_radians(); - let half = ((bounds.width() * a.cos().abs() + bounds.height() * a.sin().abs()) / 2.0).max(1e-3); - let d = Vec2::new(a.cos(), -a.sin()) * half; - let (p0, p1) = match v { - Some([x0, y0, x1, y1]) => (designcraft_geom::Point::new(x0, y0), designcraft_geom::Point::new(x1, y1)), - None => (c - d, c + d), - }; + let (p0, p1) = fill.linear_axis(bounds); LinearGradient { x1: p0.x as f32, y1: p0.y as f32, diff --git a/crates/render/src/lib.rs b/crates/render/src/lib.rs index f4085b270..07b08a812 100644 --- a/crates/render/src/lib.rs +++ b/crates/render/src/lib.rs @@ -889,7 +889,7 @@ pub fn color_of(c: &designcraft_color::Color, alpha: f32) -> peniko::Color { /// Set a swatch fill (solid or gradient) as the paint. Returns false for [None]/unknown. fn set_fill_paint(ctx: &mut RenderContext, doc: &Document, fill: &designcraft_doc::Fill, bounds: Rect) -> bool { - let (swatch, tint, angle) = (fill.swatch.as_str(), fill.tint, fill.gradient_angle); + let (swatch, tint) = (fill.swatch.as_str(), fill.tint); if let Some(g) = designcraft_color::swatch::resolve_gradient(&doc.swatches, swatch) { let stops: Vec = g.expanded_stops().iter().map(|(o, c, a)| peniko::ColorStop::from((*o, color_of(c, *a)))).collect(); if stops.is_empty() { @@ -901,16 +901,13 @@ fn set_fill_paint(ctx: &mut RenderContext, doc: &Document, fill: &designcraft_do let r = Vec2::new(x1 - x0, y1 - y0).hypot().max(1e-3); peniko::Gradient::new_radial((x0, y0), r as f32).with_stops(stops.as_slice()) } - (_, Some([x0, y0, x1, y1])) => peniko::Gradient::new_linear((x0, y0), (x1, y1)).with_stops(stops.as_slice()), (designcraft_color::GradientKind::Radial, None) => { let r = bounds.width().max(bounds.height()) / 2.0; peniko::Gradient::new_radial(c, r as f32).with_stops(stops.as_slice()) } _ => { - let a = angle.unwrap_or(0.0).to_radians(); - let half = (bounds.width() * a.cos().abs() + bounds.height() * a.sin().abs()) / 2.0; - let d = Vec2::new(a.cos(), -a.sin()) * half; - peniko::Gradient::new_linear(c - d, c + d).with_stops(stops.as_slice()) + let (a, b) = fill.linear_axis(bounds); + peniko::Gradient::new_linear(a, b).with_stops(stops.as_slice()) } }; ctx.set_paint(grad);