address review: share one clip-work allowance between fill and stroke

crates/metafile/src/cliprect.rs

@@ -168,7 +168,7 @@ pub(crate) fn clip_raw(raw: Raw, clip: &[P]) -> Vec<Raw> {
                 return Vec::new();
             }
             let subs = flatten(&ops);
-            if too_much_work(&subs, clip) {
+            if too_much_work(&subs, clip, usize::from(fill.is_some()) + usize::from(stroke.is_some())) {
                 return Vec::new();
             }
             let mut out = Vec::new();
@@ -195,7 +195,7 @@ pub(crate) fn clip_raw(raw: Raw, clip: &[P]) -> Vec<Raw> {
                 return Vec::new();
             }
             let subs = flatten(&ops);
-            if too_much_work(&subs, clip) {
+            if too_much_work(&subs, clip, 1) {
                 return Vec::new();
             }
             let f = clip_fill(&subs, clip).unwrap_or_default();
@@ -248,9 +248,11 @@ pub(crate) fn flatten(ops: &[Op]) -> Vec<(Vec<P>, bool)> {
 }
 
 /// Whether cutting every subpath of one item by `clip` would exceed [`MAX_CLIP_WORK`]; the
-/// per-polygon check alone lets many small subpaths each spend the whole allowance.
-fn too_much_work(subs: &[(Vec<P>, bool)], clip: &[P]) -> bool {
-    subs.iter().map(|s| s.0.len() + 1).sum::<usize>().saturating_mul(clip.len()) > MAX_CLIP_WORK
+/// per-polygon check alone lets many small subpaths each spend the whole allowance. `passes` is
+/// how many clipping passes the item gets (fill and stroke each cut every subpath), so one item
+/// shares a single allowance between them.
+fn too_much_work(subs: &[(Vec<P>, bool)], clip: &[P], passes: usize) -> bool {
+    subs.iter().map(|s| s.0.len() + 1).sum::<usize>().saturating_mul(clip.len()).saturating_mul(passes) > MAX_CLIP_WORK
 }
 
 /// The clipped fill of every subpath, its clipping work shared by all of them: `None` (the whole

crates/metafile/src/tests.rs

@@ -2086,6 +2086,23 @@ fn clip_polygon_charges_actual_work_not_projected_growth() {
     assert!(clipped.len() > 100, "the intersection is kept: {}", clipped.len());
 }
 
+#[test]
+fn clip_work_is_shared_by_fill_and_stroke() {
+    use crate::canvas::Raw;
+    use crate::geom::Op;
+    // One zigzag subpath crossing a 512-gon's edge: about 510k point-edge tests per pass, so a
+    // fill alone fits the allowance but a fill plus a stroke would spend it twice.
+    let clip: Vec<(f64, f64)> =
+        (0..512).map(|i| (i as f64 / 512.0 * std::f64::consts::TAU).sin_cos()).map(|(s, c)| (100.0 + 100.0 * c, 100.0 + 100.0 * s)).collect();
+    let mut ops = vec![Op::M((0.0, 95.0))];
+    ops.extend((1..1000).map(|i| Op::L((i as f64 * 0.19, if i % 2 == 0 { 95.0 } else { 300.0 }))));
+    ops.push(Op::Z);
+    let raw = |fill, stroke| Raw::Path { ops: ops.clone(), fill, stroke, even_odd: false, region: None };
+    let black = [0, 0, 0, 255];
+    assert!(!crate::cliprect::clip_raw(raw(Some(black), None), &clip).is_empty(), "a fill alone is within the allowance");
+    assert!(crate::cliprect::clip_raw(raw(Some(black), Some((black, 1.0))), &clip).is_empty(), "fill and stroke share one allowance");
+}
+
 #[test]
 fn clip_work_is_bounded_across_subpaths() {
     use crate::canvas::Raw;