address review: charge the pairwise boundary check only for areas

crates/measure/src/lib.rs

@@ -520,11 +520,12 @@ pub fn list(doc: &Document) -> Listing {
                 Some(b"PolygonDimension") => Kind::Area,
                 _ => continue,
             };
-            // The boundary check compares every pair of edges: charge it before reading the
-            // vertices, so a listing stops at its work bound rather than at a stall.
+            // An area's boundary check compares every pair of edges: charge it before reading the
+            // vertices, so a listing stops at its work bound rather than at a stall. Other kinds
+            // read their vertices once.
             let vertices = d.get(if kind == Kind::Distance { b"L".as_slice() } else { b"Vertices" }).map(|v| doc.resolve(v));
             let n = vertices.as_deref().and_then(Object::as_array).map_or(0, |a| a.len() / 2).min(MAX_POINTS);
-            work = work.saturating_add(n.saturating_mul(n));
+            work = work.saturating_add(if kind == Kind::Area { n.saturating_mul(n) } else { n.max(1) });
             if work > MAX_LISTED_WORK {
                 out.truncated = true;
                 return out;

crates/measure/src/tests.rs

@@ -511,3 +511,27 @@ fn listing_reads_a_shared_scale_once_and_bounds_boundary_checks() {
     assert!((5..areas).contains(&l.measurements.len()), "{} listed", l.measurements.len());
     assert!(l.unsupported.is_empty(), "{:?}", l.unsupported);
 }
+
+/// Perimeters and distances read their vertices once: only areas pay for the pairwise boundary
+/// check, so many maximal perimeters list in full.
+#[test]
+fn perimeters_are_charged_linear_work() {
+    let measure = "<< /Type /Measure /Subtype /RL /R (1 pt = 1 pt) /X [<< /Type /NumberFormat /U (pt) /C 1 /D 100 >>] /D [<< /Type /NumberFormat /U (pt) /C 1 /D 100 >>] /A [<< /Type /NumberFormat /U (pt) /C 1 /D 100 >>] >>";
+    let verts: Vec<String> = (0..MAX_POINTS).map(|i| format!("{} {}", 10 + i % 500, 10 + i / 500 * 3 + (i % 2))).collect();
+    let verts = verts.join(" ");
+    let lines = 40;
+    let annots: Vec<String> = (0..lines).map(|i| format!("{} 0 R", 6 + i)).collect();
+    let mut pdf = Pdf::new()
+        .obj("<< /Type /Catalog /Pages 2 0 R >>")
+        .obj("<< /Type /Pages /Kids [3 0 R] /Count 1 /MediaBox [0 0 612 792] >>")
+        .obj(format!("<< /Type /Page /Parent 2 0 R /Contents 4 0 R /Annots [{}] >>", annots.join(" ")))
+        .stream("", "")
+        .obj(measure);
+    for _ in 0..lines {
+        pdf = pdf.obj(format!("<< /Type /Annot /Subtype /PolyLine /IT /PolyLineDimension /Rect [0 0 612 792] /Vertices [{verts}] /Measure 5 0 R >>"));
+    }
+    let d = Document::open(Arc::new(pdf.build())).unwrap();
+    let l = list(&d);
+    assert!(!l.truncated, "{} listed", l.measurements.len());
+    assert_eq!(l.measurements.len() + l.unsupported.len(), lines, "{:?}", l.unsupported.first());
+}