pathops: a huge stroke width with round joins no longer panics Outline Stroke

normalize_bez ran the sweep without the catch_unwind guard that Sweep::new has,
so an outline_stroke width of 1e200 or more with a round join panicked inside
linesweeper (Left == Ish). The panic is now a Degenerate error and the art is
left unchanged. Adds hostile-number tests for the pathops edit, stroke and
offset functions.

crates/pathops/tests/it/hostile_params.rs

@@ -0,0 +1,49 @@
+//! Absurd but finite or non-finite numeric parameters: no panic, hang or runaway allocation.
+
+use vectorcraft_geom::{PathData, Point, SubPath};
+use vectorcraft_pathops::*;
+
+const HOSTILE: [f64; 9] = [f64::NAN, f64::INFINITY, f64::NEG_INFINITY, 0.0, -0.0, 1e-300, 1e300, -1e300, f64::MAX];
+
+fn square() -> PathData {
+    PathData::single(SubPath::polyline(&[Point::new(0.0, 0.0), Point::new(10.0, 0.0), Point::new(10.0, 10.0), Point::new(0.0, 10.0)], true))
+}
+
+fn zigzag() -> PathData {
+    let pts: Vec<Point> = (0..40).map(|i| Point::new(i as f64 * 3.0, if i % 2 == 0 { 0.0 } else { 7.0 })).collect();
+    PathData::single(SubPath::polyline(&pts, false))
+}
+
+#[test]
+fn edit_functions_survive_hostile_numbers() {
+    for paths in [square(), zigzag()] {
+        for &v in &HOSTILE {
+            let _ = simplify(&paths, v);
+            let _ = simplify_with(&paths, &SimplifyOptions { tolerance: v, corner_angle_deg: v, straight_lines: false });
+            let _ = simplify_with(&paths, &SimplifyOptions { tolerance: 0.5, corner_angle_deg: v, straight_lines: true });
+            let _ = smooth(&paths, v);
+            let _ = smooth_level(&paths, v);
+            let _ = remove_redundant_points(&paths, v);
+            let _ = join(&[paths.clone(), zigzag()], v);
+            let _ = simplify_level_tolerance(v);
+            let _ = auto_simplify_level(v);
+        }
+    }
+}
+
+/// A stroke width of 1e200 or more with round joins used to panic inside the sweep (`Left == Ish`).
+#[test]
+fn stroke_and_offset_survive_hostile_numbers() {
+    for paths in [square(), zigzag()] {
+        for &w in &HOSTILE {
+            for &m in &[f64::NAN, 0.0, 1.0, 1e300] {
+                for join in [Join::Miter, Join::Round, Join::Bevel] {
+                    for cap in [Cap::Butt, Cap::Round] {
+                        let _ = outline_stroke(&paths, w, cap, join, m);
+                    }
+                    let _ = offset_path(&paths, w, join, m);
+                }
+            }
+        }
+    }
+}

crates/pathops/tests/it/main.rs

@@ -5,6 +5,7 @@
 #[path = "../common/mod.rs"]
 mod common;
 
+mod hostile_params;
 mod ops;
 mod pathfinder_pinned;
 mod prop_pathops;