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bflatasticandClaude Opus 5.5
23f19a861b
The shared stroke geometry now has its own arc-length dash generator: a dash of length 0 becomes a dot that a round cap paints as a disc and a projecting cap as a square turned along the path (a butt cap paints nothing). Dashes restart per subpath, join across the start of closed subpaths, and a pattern too fine for the path draws solid. The canvas and raster export use it through line_outline; the stroke.set params doc says how to get dots. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
78 lines
2.9 KiB
Rust
78 lines
2.9 KiB
Rust
//! Pixel tests for the shared stroke geometry (`vectorcraft_effects::stroke`) on the canvas:
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//! dotted lines (zero-length dashes).
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use vectorcraft_color::{Color, Paint};
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use vectorcraft_doc::{Appearance, AppearanceItem, Dash, Document, LineCap, StrokeLayer};
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use vectorcraft_geom::{Point, Rect, shapes};
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use vectorcraft_testkit::fixtures::DocBuilder;
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use vectorcraft_testkit::raster::{Image, assert_similar, render_region};
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use vectorcraft_testkit::svg;
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/// Pixels per point in these tests.
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const S: f64 = 4.0;
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fn stroked(width: f64, f: impl FnOnce(&mut StrokeLayer)) -> Appearance {
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let mut st = StrokeLayer::new(Paint::solid(Color::BLACK), width);
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f(&mut st);
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Appearance { items: vec![AppearanceItem::Stroke(st)], effects: vec![] }
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}
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/// A horizontal line from x0 to x1 at y = 50 on a 100 × 100 artboard.
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fn line_doc(x0: f64, x1: f64, app: Appearance, opacity: f32) -> Document {
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let mut b = DocBuilder::new(100.0, 100.0);
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b.path(shapes::line(Point::new(x0, 50.0), Point::new(x1, 50.0)), app, |n| n.opacity = opacity);
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b.build()
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}
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fn render(d: &Document) -> Image {
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render_region(d, Rect::new(0.0, 0.0, 100.0, 100.0), S)
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}
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/// Is the pixel at document point (x, y) dark?
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fn dark(img: &Image, x: f64, y: f64) -> bool {
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img.over_white((x * S) as u32, (y * S) as u32)[0] < 128
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}
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fn dotted(cap: LineCap) -> Document {
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line_doc(
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20.0,
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80.0,
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stroked(4.0, |s| {
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s.cap = cap;
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s.dash = Some(Dash { pattern: vec![0.0, 6.0], offset: 0.0, align_corners: false });
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}),
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1.0,
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)
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}
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#[test]
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fn zero_length_dashes_draw_dots_with_a_round_cap_and_squares_with_a_projecting_cap() {
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let round = render(&dotted(LineCap::Round));
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// 60 pt with a dot every 6 pt: 11 separate dots along the centre line.
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let row: Vec<bool> = (0..round.width).map(|x| round.over_white(x, (50.0 * S) as u32)[0] < 128).collect();
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let runs = row.windows(2).filter(|w| !w[0] && w[1]).count();
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assert_eq!(runs, 11, "dots along the line");
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for k in 0..=10 {
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let x = 20.0 + 6.0 * k as f64;
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assert!(dark(&round, x, 50.0), "dot {k}");
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assert!(!dark(&round, x + 3.0, 50.0), "gap after dot {k}");
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}
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// A disc's corner region is empty; a square fills it.
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assert!(!dark(&round, 20.0 + 1.8, 50.0 + 1.8));
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let square = render(&dotted(LineCap::Square));
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assert!(dark(&square, 20.0 + 1.8, 50.0 + 1.8));
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assert!(dark(&square, 26.0 - 1.8, 50.0 - 1.8));
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// A butt cap gives a zero-length dash no area at all.
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assert_eq!(render(&dotted(LineCap::Butt)).ink(), 0);
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}
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#[test]
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fn dotted_lines_survive_svg_export_and_render_the_same() {
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for cap in [LineCap::Round, LineCap::Square] {
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let d = dotted(cap);
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let text = svg::export(&d, &Default::default());
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let back = svg::import(&text).unwrap();
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assert_similar(&render(&d), &render(&back), 0.05, 0.001);
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}
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}
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