figcraft/crates/geom/src/tests.rs

use super::*;

fn area(p: &BezPath) -> f64 {
    p.area().abs()
}

#[test]
fn plain_rect_area() {
    let p = rounded_rect(100.0, 50.0, [0.0; 4], 0.0);
    assert!((area(&p) - 5000.0).abs() < 1e-6);
}

#[test]
fn rounded_rect_area_matches_circle_corners() {
    let r = 10.0;
    let p = rounded_rect(100.0, 50.0, [r; 4], 0.0);
    let expected = 5000.0 - 4.0 * r * r + PI * r * r;
    assert!((area(&p) - expected).abs() < 0.5, "{} vs {}", area(&p), expected);
}

#[test]
fn full_radius_is_capsule_and_bounds_hold() {
    let p = rounded_rect(100.0, 40.0, [1000.0; 4], 0.0);
    let b = p.bounding_box();
    assert!((b.width() - 100.0).abs() < 1e-6 && (b.height() - 40.0).abs() < 1e-6);
}

#[test]
fn smoothing_stays_in_bounds_and_reduces_area_less_than_sharp() {
    for s in [0.0, 0.3, 0.6, 1.0] {
        let p = rounded_rect(200.0, 120.0, [24.0, 0.0, 40.0, 8.0], s);
        let b = p.bounding_box();
        assert!(b.x0 >= -1e-6 && b.y0 >= -1e-6 && b.x1 <= 200.0 + 1e-6 && b.y1 <= 120.0 + 1e-6, "s={s} {b:?}");
        assert!(area(&p) < 200.0 * 120.0);
    }
    // More smoothing removes more area at the same radius.
    let a0 = area(&rounded_rect(200.0, 200.0, [40.0; 4], 0.0));
    let a1 = area(&rounded_rect(200.0, 200.0, [40.0; 4], 1.0));
    assert!(a1 < a0);
}

#[test]
fn degenerate_inputs_dont_panic() {
    let _ = rounded_rect(f64::NAN, -1.0, [f64::INFINITY; 4], f64::NAN);
    let _ = rounded_rect(0.0, 0.0, [5.0; 4], 0.5);
    let _ = polygon_points(0.0, 0.0, 0);
    let _ = star_points(10.0, 10.0, 1, -3.0);
    let _ = rounded_polygon(&[], 4.0);
    let _ = rounded_polygon(&[Point::ZERO, Point::ZERO, Point::ZERO], 4.0);
    let _ = smoothed_polygon(&[Point::ZERO, Point::ZERO, Point::ZERO], 4.0, 0.6);
    let _ = smoothed_polygon(&[Point::ZERO, Point::new(10.0, 0.0), Point::new(20.0, 0.0)], 4.0, 1.0);
    let _ = smoothed_polygon(&polygon_points(10.0, 10.0, 5), f64::INFINITY, f64::NAN);
    let _ = smoothed_polygon(&polygon_points(10.0, 10.0, 5), 3.0, f64::INFINITY);
    let _ = ellipse(f64::NAN, 10.0, f64::NAN, 100.0, 2.0);
}

#[test]
fn polygon_first_vertex_top_center() {
    let pts = polygon_points(100.0, 100.0, 3);
    assert_eq!(pts.len(), 3);
    assert!((pts[0].x - 50.0).abs() < 1e-9 && pts[0].y.abs() < 1e-9);
}

#[test]
fn star_has_twice_the_points() {
    assert_eq!(star_points(100.0, 100.0, 5, 0.38).len(), 10);
}

#[test]
fn rounded_polygon_shrinks_area() {
    let pts = polygon_points(100.0, 100.0, 6);
    let sharp = area(&rounded_polygon(&pts, 0.0));
    let round = area(&rounded_polygon(&pts, 10.0));
    assert!(round < sharp && round > sharp * 0.8);
}

#[test]
fn smoothed_polygon_matches_the_rectangle_corner() {
    // A four-sided polygon is a square turned 45°: smoothed, it has the rounded rectangle's area.
    let side = 50.0 * std::f64::consts::SQRT_2;
    let pts = polygon_points(100.0, 100.0, 4);
    for (r, s) in [(10.0, 0.0), (10.0, 0.6), (12.0, 1.0), (30.0, 0.6), (1000.0, 0.6)] {
        let poly = area(&smoothed_polygon(&pts, r, s));
        let rect = area(&rounded_rect(side, side, [r; 4], s));
        assert!((poly - rect).abs() < 0.05, "r={r} s={s}: {poly} vs {rect}");
    }
}

#[test]
fn smoothed_polygon_smooths_every_corner() {
    use kurbo::{ParamCurve, ParamCurveArclen, ParamCurveNearest};
    let near = |p: &BezPath, at: Point| p.segments().map(|seg| seg.nearest(at, 1e-9).distance_sq).fold(f64::INFINITY, f64::min);
    // (points, convex: smoothing only cuts area away)
    let shapes = [(polygon_points(100.0, 100.0, 3), true), (polygon_points(120.0, 80.0, 6), true), (star_points(100.0, 100.0, 5, 0.38), false)];
    for (pts, convex) in shapes {
        let plain = smoothed_polygon(&pts, 8.0, 0.0);
        assert_eq!(plain, rounded_polygon(&pts, 8.0), "no smoothing draws the plain rounded corners");
        let sharp = area(&rounded_polygon(&pts, 0.0));
        let mut last = area(&plain);
        for s in [0.3, 0.6, 1.0] {
            let p = smoothed_polygon(&pts, 8.0, s);
            let a = area(&p);
            assert!(if convex { a < last } else { (a - last).abs() > 1e-3 }, "s={s}: more smoothing changes the area ({a} after {last})");
            assert!((a - sharp).abs() < sharp * 0.2, "s={s}: the shape stays close to its points");
            last = a;
            // The outline has no kinks: each piece leaves in the direction the one before arrives.
            let segs: Vec<kurbo::PathSeg> = p.segments().filter(|seg| seg.arclen(1e-6) > 1e-6).collect();
            for (i, seg) in segs.iter().enumerate() {
                let next = segs[(i + 1) % segs.len()];
                let out = (seg.eval(1.0) - seg.eval(1.0 - 1e-6)).normalize();
                let into = (next.eval(1e-6) - next.eval(0.0)).normalize();
                assert!(out.dot(into) > 0.999, "s={s}: piece {i} joins the next smoothly ({out:?} then {into:?})");
            }
            let b = p.bounding_box();
            assert!(b.x0 >= -1e-6 && b.y0 >= -1e-6 && b.x1 <= 120.0 + 1e-6 && b.y1 <= 100.0 + 1e-6, "s={s} {b:?}");
            // Every vertex is cut off, and the middle of every edge is still on the outline.
            for (i, v) in pts.iter().enumerate() {
                let next = pts[(i + 1) % pts.len()];
                let mid = v.midpoint(next);
                assert!(near(&p, mid) < 1e-6, "s={s}: edge {i} keeps its middle");
                assert!(near(&p, *v) > 0.25, "s={s}: vertex {i} is rounded");
            }
        }
    }
}

#[test]
fn ellipse_ring_area() {
    let full = area(&ellipse(100.0, 100.0, 0.0, TAU, 0.0));
    assert!((full - PI * 2500.0).abs() < 2.0);
    let ring = ellipse(100.0, 100.0, 0.0, TAU, 0.5);
    // Winding area of a ring with a reversed inner contour: outer - inner.
    let a = ring.area().abs();
    assert!((a - PI * (2500.0 - 625.0)).abs() < 5.0, "{a}");
    let half = area(&ellipse(100.0, 100.0, 0.0, PI, 0.0));
    assert!((half - PI * 1250.0).abs() < 2.0);
}

#[test]
fn rotation_roundtrip() {
    for deg in [0.0, 30.0, -45.0, 90.0, 179.0] {
        let xf = from_position_rotation(10.0, 20.0, deg);
        assert!((rotation_degrees(xf) - deg).abs() < 1e-9, "{deg}");
        assert_eq!(translation(xf), Point::new(10.0, 20.0));
    }
}

#[test]
fn set_rotation_keeps_center() {
    let xf = from_position_rotation(10.0, 20.0, 0.0);
    let r = set_rotation_about_center(xf, 100.0, 50.0, 90.0);
    let c0 = xf * Point::new(50.0, 25.0);
    let c1 = r * Point::new(50.0, 25.0);
    assert!((c0 - c1).hypot() < 1e-9);
    assert!((rotation_degrees(r) - 90.0).abs() < 1e-9);
    // A flipped box stays flipped and reads back the rotation set, whichever way it was flipped.
    for flip in [Affine::FLIP_X, Affine::FLIP_Y] {
        for deg in [0.0, 30.0, -120.0] {
            let r = set_rotation_about_center(xf * flip, 100.0, 50.0, deg);
            assert!(is_flipped(r) && (rotation_degrees(r) - deg).abs() < 1e-9, "{deg}");
            assert!((xf * flip * Point::new(50.0, 25.0) - r * Point::new(50.0, 25.0)).hypot() < 1e-9);
        }
    }
}

#[test]
fn reverse_subpaths_preserves_open_and_closed() {
    let mut open = BezPath::new();
    open.move_to((0.0, 0.0));
    open.line_to((10.0, 0.0));
    open.line_to((10.0, 10.0));
    let r = <BezPath as ReverseSubpaths>::reverse_subpaths(&open);
    assert!(!r.elements().iter().any(|e| matches!(e, kurbo::PathEl::ClosePath)), "{:?}", r.elements());

    let mut closed = open.clone();
    closed.close_path();
    let r = <BezPath as ReverseSubpaths>::reverse_subpaths(&closed);
    assert!(matches!(r.elements().last(), Some(kurbo::PathEl::ClosePath)), "{:?}", r.elements());
}