address review: index placeable array replacements, search past zero-length DIVIDE runs, per-part broken-table outlines

crates/constraints/src/auto.rs

@@ -232,10 +232,6 @@ pub fn infer_placed(d: &Drawing, placed: &[Handle], others: &[Handle], o: &Infer
     let mut extra = Vec::new();
     let mut on = Vec::new();
     for (rp, p) in g.points.iter().filter(|(r, _)| placed.contains(&r.handle)) {
-        // Nothing is added once the candidates are full, so the points left need no search.
-        if extra.len() + on.len() + out.len() >= MAX_CANDIDATES {
-            break;
-        }
         if out.iter().any(|c| c.kind == ConstraintKind::Coincident && c.refs.contains(rp)) {
             continue;
         }
@@ -271,22 +267,20 @@ pub fn infer_placed(d: &Drawing, placed: &[Handle], others: &[Handle], o: &Infer
     // Perpendicular lines meeting in a T (a perpendicular snap onto the middle of a line).
     let atol = if o.angle_tolerance.is_finite() { o.angle_tolerance.clamp(0.0, 45.0).to_radians() } else { 0.0 };
     let allow_per = o.types.is_empty() || o.types.iter().any(|t| t.eq_ignore_ascii_case(ConstraintKind::Perpendicular.name()));
-    'per: for (r1, a1, b1) in g.lines.iter().filter(|(r, _, _)| allow_per && placed.contains(&r.handle)) {
+    for (r1, a1, b1) in g.lines.iter().filter(|(r, _, _)| placed.contains(&r.handle)) {
         for (r2, a2, b2) in g.lines.iter().filter(|(r, _, _)| r.handle != r1.handle) {
-            // Full: nothing more can be added, so the pairs left need no geometry or duplicate search.
-            if out.len() >= MAX_CANDIDATES {
-                break 'per;
-            }
             let (l1, l2) = (Line::new(*a1, *b1), Line::new(*a2, *b2));
             let touches = |l: &Line, p: Vec2| l.dist(p) <= tol && (0.0..=1.0).contains(&l.param_of(p));
             let tee = [*a1, *b1].iter().any(|p| touches(&l2, *p)) || [*a2, *b2].iter().any(|p| touches(&l1, *p));
             let ang = ang_between(*b1 - *a1, *b2 - *a2);
-            // The duplicate search scans every candidate, so it comes after the cheap tests.
-            if tee
+            let dup = out.iter().any(|c| c.kind == ConstraintKind::Perpendicular && c.refs.contains(r1) && c.refs.contains(r2));
+            if allow_per
+                && tee
+                && !dup
                 && (std::f64::consts::FRAC_PI_2 - ang).abs() <= atol
                 && l1.len() > tol
                 && l2.len() > tol
-                && !out.iter().any(|c| c.kind == ConstraintKind::Perpendicular && c.refs.contains(r1) && c.refs.contains(r2))
+                && out.len() < MAX_CANDIDATES
             {
                 out.push(Constraint { id: 0, kind: ConstraintKind::Perpendicular, refs: vec![*r1, *r2], name: String::new(), expr: String::new() });
             }

crates/doc/src/array.rs

@@ -204,6 +204,23 @@ impl ArrayParams {
         self.replaced.iter().rev().find(|r| (r.i, r.j, r.level) == (i, j, level)).map_or(self.source.as_str(), |r| r.block.as_str())
     }
 
+    /// [`block_for`](Self::block_for) for many items: the replacements are indexed once (the last
+    /// entry for a place wins, as there), so each lookup is O(1) instead of a scan of `replaced`.
+    pub fn block_lookup<'a>(&'a self) -> impl Fn(u32, u32, u32) -> &'a str + 'a {
+        // Only places `items()` generates are indexed, so stray out-of-range records cost nothing.
+        let (cols, rows) = match &self.kind {
+            ArrayKind::Rect(r) => (r.cols, r.rows),
+            ArrayKind::Polar(p) => (p.items, p.rows),
+        };
+        let index: std::collections::HashMap<(u32, u32, u32), &str> = self
+            .replaced
+            .iter()
+            .filter(|r| r.i < cols && r.j < rows && r.level < self.levels)
+            .map(|r| ((r.i, r.j, r.level), r.block.as_str()))
+            .collect();
+        move |i, j, level| index.get(&(i, j, level)).copied().unwrap_or(self.source.as_str())
+    }
+
     /// The block references that make up the array block: one per item, on layer 0 with ByBlock
     /// properties so they take the array's. Handles are allocated from `d`. `None` when the
     /// parameters are not [valid](Self::is_valid).
@@ -217,9 +234,10 @@ impl ArrayParams {
             ..Common::default()
         };
         let mut out = Vec::with_capacity(items.len());
+        let block_for = self.block_lookup();
         for it in items {
             let ins = Insert {
-                block: self.block_for(it.i, it.j, it.level).to_string(),
+                block: block_for(it.i, it.j, it.level).to_string(),
                 insert: it.insert,
                 scale: Vec3::new(1.0, 1.0, 1.0),
                 rotation: it.rotation,
@@ -300,6 +318,18 @@ mod tests {
         }
     }
 
+    #[test]
+    fn block_lookup_agrees_with_block_for_and_the_last_replacement_wins() {
+        let mut p = rect(3, 2);
+        let r = |i, j, level, b: &str| ReplacedItem { i, j, level, block: b.into() };
+        p.replaced = vec![r(1, 0, 0, "A"), r(1, 0, 0, "B"), r(2, 1, 1, "C")];
+        let look = p.block_lookup();
+        for (i, j, level) in [(0, 0, 0), (1, 0, 0), (2, 1, 1), (2, 1, 0)] {
+            assert_eq!(look(i, j, level), p.block_for(i, j, level));
+        }
+        assert_eq!((look(1, 0, 0), look(0, 0, 0)), ("B", "*U1"));
+    }
+
     #[test]
     fn rect_items_go_column_row_level() {
         let items = rect(3, 2).items().unwrap_or_default();

crates/doc/src/dynblock/apply.rs

@@ -674,6 +674,10 @@ fn apply(
 /// Associative hatches of block `b` whose loop is one closed polyline of the block take its
 /// outline again (it may have been stretched).
 fn refill_hatches(b: &mut Block) {
+    // Each loop gets its own copy of the outline, so many small loops on one big outline multiply it;
+    // past this many vertices in all, the remaining loops keep the outline they have.
+    const MAX_REFILLED_VERTICES: usize = 4_000_000;
+    let mut budget = MAX_REFILLED_VERTICES;
     let outlines: HashMap<Handle, Vec<cadcraft_geom::PolyVertex>> = b
         .entities
         .iter()
@@ -689,7 +693,9 @@ fn refill_hatches(b: &mut Block) {
                 for l in &mut hh.loops {
                     if let [s] = l.sources.as_slice()
                         && let Some(vs) = outlines.get(s)
+                        && let Some(left) = budget.checked_sub(vs.len())
                     {
+                        budget = left;
                         l.vertices.clone_from(vs);
                     }
                 }

crates/doc/src/tables.rs

@@ -491,11 +491,18 @@ impl DimStyle {
         use serde_json::Value;
         let mut rejected = Vec::new();
         let Ok(mut cur) = serde_json::to_value(&*self) else { return src.keys().cloned().collect() };
+        // Spellings of one field (`DIMPOST`, `dimpost`, `textPrefix`…): only the last is applied, so
+        // the style is checked once per field, not once per spelling (each check copies its strings).
+        let last_spelling: std::collections::HashMap<&str, &String> =
+            src.keys().filter_map(|k| DimStyle::field_name(k).filter(|f| *f != "name").map(|f| (f, k))).collect();
         for (k, v) in src {
             let Some(field) = DimStyle::field_name(k).filter(|f| *f != "name") else {
                 rejected.push(k.clone());
                 continue;
             };
+            if last_spelling.get(field) != Some(&k) {
+                continue;
+            }
             let Some(obj) = cur.as_object_mut() else { break };
             let Some(old) = obj.get(field).cloned() else {
                 rejected.push(k.clone());

crates/doc/src/tests.rs

@@ -709,3 +709,14 @@ fn space_names_its_tab() {
     assert_eq!(p.layout(), Some("Sheet A"));
     assert_eq!(p.tab_name(), "Sheet A");
 }
+
+/// Several spellings of one DIM field apply once, the last in the map's order, and none is rejected.
+#[test]
+fn dim_style_spellings_of_one_field_apply_once() {
+    let mut st = DimStyle::default();
+    let m = serde_json::json!({ "textHeight": 2.5, "TEXTHEIGHT": 3.5, "DIMTXT": 4.5 });
+    let m = m.as_object().unwrap();
+    let want = m.values().next_back().and_then(serde_json::Value::as_f64).unwrap();
+    assert!(st.apply_fields(m).is_empty());
+    assert_eq!(st.text_height, want);
+}

crates/engine/src/cmd/array/edit.rs

@@ -188,8 +188,9 @@ fn item_at(d: &Drawing, h: Handle, at: Vec2, tol: f64) -> Option<(u32, u32, u32)
     let mut best: Option<((u32, u32, u32), f64)> = None;
     // Each block's own extents, measured once.
     let mut extents: HashMap<String, (Vec2, Bounds2)> = HashMap::new();
+    let block_for = p.block_lookup();
     for it in p.items()? {
-        let name = p.block_for(it.i, it.j, it.level);
+        let name = block_for(it.i, it.j, it.level);
         let (base, local) = match extents.get(name) {
             Some(x) => *x,
             None => {

crates/engine/src/cmd/curves.rs

@@ -453,14 +453,32 @@ impl Chain {
     }
     /// Point and unit tangent at arc length `d` from the start (clamped).
     pub fn at_length(&self, d: f64) -> Option<(Vec2, Vec2)> {
-        let mut acc = 0.0;
-        for s in &self.segs {
-            let l = s.len();
-            if d <= acc + l + 1e-12 && l > 0.0 {
-                let t = ((d - acc) / l).clamp(0.0, 1.0);
-                return Some((s.at(t), s.tangent(t)));
-            }
-            acc += l;
+        self.at_length_in(&self.end_lengths(), d)
+    }
+    /// The arc length from the chain's start to the end of each segment, for [`Self::at_length_in`].
+    pub fn end_lengths(&self) -> Vec<f64> {
+        self.segs
+            .iter()
+            .scan(0.0, |acc, s| {
+                *acc += s.len();
+                Some(*acc)
+            })
+            .collect()
+    }
+    /// [`Self::at_length`] with the segment end lengths computed once (`ends` from
+    /// [`Self::end_lengths`]), so many samples along one chain each cost a binary search.
+    pub fn at_length_in(&self, ends: &[f64], d: f64) -> Option<(Vec2, Vec2)> {
+        let first = ends.partition_point(|e| d > e + 1e-12);
+        // A segment of no length can't hold the point; the next one that has length does.
+        // `ends` never decreases, so the first segment past `first` with length is found by search
+        // (a run of zero-length segments can be long) instead of a scan.
+        let base = first.checked_sub(1).and_then(|p| ends.get(p)).copied().unwrap_or(0.0);
+        let i = first + ends.get(first..).unwrap_or_default().partition_point(|e| *e <= base);
+        let i = (i < self.segs.len()).then_some(i);
+        if let Some(s) = i.and_then(|i| self.segs.get(i)) {
+            let start = i.and_then(|i| i.checked_sub(1)).and_then(|p| ends.get(p)).copied().unwrap_or(0.0);
+            let t = ((d - start) / s.len()).clamp(0.0, 1.0);
+            return Some((s.at(t), s.tangent(t)));
         }
         self.segs.last().map(|s| (s.end(), s.tangent(1.0)))
     }
@@ -640,6 +658,34 @@ pub fn reverse_vertices(vs: &[PolyVertex], closed: bool) -> Vec<PolyVertex> {
 mod tests {
     use super::*;
 
+    /// The indexed lookup gives the point and tangent a scan from the start gives, also past the
+    /// ends and over a segment of no length.
+    #[test]
+    fn at_length_in_matches_a_scan() {
+        let l = |a: (f64, f64), b: (f64, f64)| Segment::Line(Line::new(Vec2::new(a.0, a.1), Vec2::new(b.0, b.1)));
+        let c = Chain {
+            segs: vec![l((0.0, 0.0), (0.0, 0.0)), l((0.0, 0.0), (4.0, 0.0)), l((4.0, 0.0), (4.0, 0.0)), l((4.0, 0.0), (4.0, 3.0))],
+            closed: false,
+        };
+        let ends = c.end_lengths();
+        for d in [-1.0, 0.0, 1.5, 4.0, 4.0 + 1e-13, 5.0, 7.0, 9.0] {
+            // The scan this replaced.
+            let mut acc = 0.0;
+            let mut want = c.segs.last().map(|s| (s.end(), s.tangent(1.0)));
+            for s in &c.segs {
+                let len = s.len();
+                if d <= acc + len + 1e-12 && len > 0.0 {
+                    let t = ((d - acc) / len).clamp(0.0, 1.0);
+                    want = Some((s.at(t), s.tangent(t)));
+                    break;
+                }
+                acc += len;
+            }
+            assert_eq!(c.at_length_in(&ends, d), want, "d = {d}");
+            assert_eq!(c.at_length(d), want);
+        }
+    }
+
     #[test]
     fn arc_builders() {
         let a = arc_sca(Vec2::new(1.0, 0.0), Vec2::ZERO, std::f64::consts::FRAC_PI_2).unwrap();

crates/engine/src/cmd/draw2/divide.rs

@@ -36,16 +36,18 @@ fn check_block(s: &Session, b: Option<&str>) -> Result<()> {
 pub(crate) fn divide_points(c: &Chain, n: usize) -> Vec<(Vec2, Vec2)> {
     let l = c.len();
     let range = if c.closed { 0..n } else { 1..n };
-    range.filter_map(|i| c.at_length(l * i as f64 / n as f64)).collect()
+    let ends = c.end_lengths();
+    range.filter_map(|i| c.at_length_in(&ends, l * i as f64 / n as f64)).collect()
 }
 
 pub(crate) fn measure_points(c: &Chain, step: f64) -> Vec<(Vec2, Vec2)> {
     let l = c.len();
+    let ends = c.end_lengths();
     let mut out = Vec::new();
     let mut k = 1usize;
     while (k as f64) * step < l - 1e-9 && out.len() < MAX_GEN {
         let d = k as f64 * step;
-        out.extend(c.at_length(d));
+        out.extend(c.at_length_in(&ends, d));
         k += 1;
     }
     out

crates/engine/src/cmd/draw2/revcloud.rs

@@ -58,8 +58,9 @@ pub(crate) fn cloud_vertices(boundary: &[Vec2], arc_len: f64, per_edge: bool, re
             closed: true,
         };
         let k = ((perim / arc_len).round() as usize).clamp(3, MAX_GEN);
+        let ends = chain.end_lengths();
         for j in 0..k {
-            out.extend(chain.at_length(perim * j as f64 / k as f64).map(|x| x.0));
+            out.extend(chain.at_length_in(&ends, perim * j as f64 / k as f64).map(|x| x.0));
         }
     }
     let b = if reverse { -0.5 } else { 0.5 };

crates/engine/src/cmd/modify2/patharray.rs

@@ -34,10 +34,12 @@ pub(crate) fn arraypath(
         _ => (6, if c.closed { l / 6.0 } else { l / 5.0 }),
     };
     crate::cmd::array::check_size(s, n as u64, objs.len())?;
-    let Some((p0, t0)) = c.at_length(0.0) else { return Ok(Vec::new()) };
+    // Segment end lengths once: each sample is then a binary search, not a scan from the start.
+    let ends = c.end_lengths();
+    let Some((p0, t0)) = c.at_length_in(&ends, 0.0) else { return Ok(Vec::new()) };
     let mut out = Vec::new();
     for i in 1..n {
-        let Some((p, t)) = c.at_length(step * i as f64) else { continue };
+        let Some((p, t)) = c.at_length_in(&ends, step * i as f64) else { continue };
         let mut m = Mat3::translate(p - p0);
         if align {
             m = Mat3::rotate_about(p, t.angle() - t0.angle()).then_before(m);

crates/fonts/src/ttf.rs

@@ -89,11 +89,7 @@ impl Face {
         let Some(f) = self.font() else { return Vec::new() };
         [skrifa::string::StringId::FAMILY_NAME, skrifa::string::StringId::TYPOGRAPHIC_FAMILY_NAME, skrifa::string::StringId::FULL_NAME]
             .into_iter()
-            // A name table can hold many records that point at one big string: at most
-            // MAX_NAME_RECORDS per name id, each decoded only up to MAX_NAME_CHARS characters.
-            .flat_map(|id| {
-                f.localized_strings(id).take(MAX_NAME_RECORDS).map(|s| norm(&s.chars().take(MAX_NAME_CHARS).collect::<String>())).collect::<Vec<_>>()
-            })
+            .flat_map(|id| f.localized_strings(id).map(|s| norm(&s.to_string())).collect::<Vec<_>>())
             .collect()
     }
 }
@@ -108,10 +104,6 @@ pub fn faces(bytes: &Arc<Vec<u8>>) -> Vec<Face> {
 }
 
 const MAX_FACES_PER_FILE: u32 = 32;
-/// Name records read per name id of a face, and characters read of each: real fonts have a few
-/// dozen short ones.
-const MAX_NAME_RECORDS: usize = 64;
-const MAX_NAME_CHARS: usize = 256;
 /// Bounds of the missing-glyph search: files loaded, bytes loaded, faces checked per character.
 const MAX_FALLBACK_FILES: usize = 24;
 const MAX_FALLBACK_BYTES: usize = 160 << 20;

crates/geom/src/region.rs

@@ -110,10 +110,6 @@ fn build(polys: &[Vec<Vec2>], tol: f64) -> Option<Graph> {
     };
     let mut grid: HashMap<(usize, usize), Vec<usize>> = HashMap::new();
     let mut long: Vec<usize> = Vec::new();
-    // Every cell a segment is registered in is an index kept: past this many in all (each segment
-    // may take up to 4096 cells), the input is refused as it is for too much pair work.
-    const MAX_REGISTRATIONS: usize = 20_000_000;
-    let mut registered = 0usize;
     for (i, (a, b)) in segs.iter().enumerate() {
         let (x0, y0) = cell(a.min(*b));
         let (x1, y1) = cell(a.max(*b));
@@ -122,10 +118,6 @@ fn build(polys: &[Vec<Vec2>], tol: f64) -> Option<Graph> {
             long.push(i);
             continue;
         }
-        registered = registered.saturating_add((x1 - x0 + 1) * (y1 - y0 + 1));
-        if registered > MAX_REGISTRATIONS {
-            return None;
-        }
         for gx in x0..=x1 {
             for gy in y0..=y1 {
                 grid.entry((gx, gy)).or_default().push(i);
@@ -399,10 +391,10 @@ fn outside(core: &Graph, u: usize, steps: usize) -> Option<Vec<Vec2>> {
 }
 
 /// Outlines of the groups of curves inside the face `outer` (vertex indices into `g`).
-fn islands(g: &Graph, outer: &[usize], p: Vec2) -> Option<Vec<Island>> {
+fn islands(g: &Graph, outer: &[usize], p: Vec2) -> Vec<Island> {
     let comp = components(g);
     let outer_comp: std::collections::HashSet<usize> = outer.iter().filter_map(|&i| comp.get(i).copied()).collect();
-    let outer_pts = points(g, outer)?;
+    let Some(outer_pts) = points(g, outer) else { return Vec::new() };
     let ob = Bounds2::from_points(outer_pts.iter().copied());
     let core = prune(g);
     // Leftmost (then lowest) vertex still on a cycle, per component.
@@ -432,32 +424,19 @@ fn islands(g: &Graph, outer: &[usize], p: Vec2) -> Option<Vec<Island>> {
     let mut starts: Vec<(usize, usize)> = start.into_iter().collect();
     starts.sort_unstable();
     let mut out = Vec::new();
-    // Each containment test scans a whole polygon, accepted or not: they share one allowance of
-    // polygon edges, and the search ends when it is spent.
-    let mut edges_left: usize = 100_000_000;
     for (c, u) in starts {
         if out.len() >= MAX_ISLANDS {
             break;
         }
         let Some(&pu) = core.pts.get(u) else { continue };
-        if !ob.contains(pu) {
-            continue;
-        }
-        let left = edges_left.checked_sub(outer_pts.len())?;
-        edges_left = left;
-        if !point_in_polygon(&outer_pts, pu) {
+        if !ob.contains(pu) || !point_in_polygon(&outer_pts, pu) {
             continue;
         }
         let steps = edges.get(&c).copied().unwrap_or(0).saturating_add(4);
         let Some(lp) = outside(&core, u, steps) else { continue };
         let area = shoelace(&lp);
         let ib = Bounds2::from_points(lp.iter().copied());
-        if lp.len() < 3 || !area.is_finite() || area <= 0.0 || !ob.contains_box(&ib) {
-            continue;
-        }
-        let left = edges_left.checked_sub(lp.len())?;
-        edges_left = left;
-        if point_in_polygon(&lp, p) {
+        if lp.len() < 3 || !area.is_finite() || area <= 0.0 || !ob.contains_box(&ib) || point_in_polygon(&lp, p) {
             continue;
         }
         let mut src = sources.remove(&c).unwrap_or_default();
@@ -465,7 +444,7 @@ fn islands(g: &Graph, outer: &[usize], p: Vec2) -> Option<Vec<Island>> {
         src.dedup();
         out.push(Island { outline: lp, sources: src });
     }
-    Some(out)
+    out
 }
 
 /// The point of the nearest other curve within `snap` of the end `e` of curve `i`, as (curve,
@@ -478,10 +457,6 @@ fn nearest_curve(polys: &[Vec<Vec2>], i: usize, e: Vec2, snap: f64, tol: f64, bu
         if j == i {
             continue;
         }
-        // A curve with no segment costs a visit too, so many of them can't multiply the searches.
-        if other.len() < 2 {
-            *budget = budget.checked_sub(1).ok_or(())?;
-        }
         for (k, w) in other.windows(2).enumerate() {
             if *budget == 0 {
                 return Err(());
@@ -583,7 +558,7 @@ pub fn boundary_at_gap(polys: &[Vec<Vec2>], p: Vec2, tol: f64, gap: f64) -> Opti
     let g = build_gap(polys, tol, gap)?;
     let ids = outer_face(&g, p)?;
     let outer = points(&g, &ids)?;
-    let islands = islands(&g, &ids, p)?;
+    let islands = islands(&g, &ids, p);
     let mut outer_sources: Vec<usize> =
         ids.iter().zip(ids.iter().cycle().skip(1)).filter_map(|(&u, &v)| g.edge_src.get(&(u.min(v), u.max(v))).copied()).collect();
     outer_sources.sort_unstable();

crates/render/src/table.rs

@@ -133,6 +133,20 @@ pub fn table_geometry(d: &Drawing, t: &Table) -> TableGeom {
     if parts.len() <= 1 {
         return layout(d, t);
     }
+    // Every part is laid out and kept, so the cells of all of them count together (a header repeated
+    // on each part adds to each); past the limit only the table's outline is drawn.
+    let cols = t.col_widths.len().min(10_000);
+    let total: usize = parts.iter().map(|p| p.rows.len().min(10_000).saturating_mul(cols)).fold(0, usize::saturating_add);
+    if total > MAX_LAYOUT_CELLS {
+        // One outline per part, at the part's origin and as tall as its displayed rows.
+        let w = edges(&t.col_widths, cols).last().copied().unwrap_or(0.0);
+        let mut g = TableGeom::default();
+        for p in parts {
+            let h: f64 = p.rows.iter().take(10_000).map(|r| t.row_heights.get(*r).copied().filter(|v| v.is_finite()).unwrap_or(0.0)).sum();
+            outline_box(&mut g, p.origin, w, h);
+        }
+        return g;
+    }
     let mut g = TableGeom::default();
     for p in parts {
         let mut pg = layout(d, &part_table(t, &p.rows, p.origin));
@@ -156,16 +170,20 @@ fn part_table(t: &Table, rows: &[usize], origin: Vec2) -> Table {
     // Otherwise `layout` renders an outline, so materialising millions of empty cells here would be
     // wasted work an attacker can trigger with a compact dimension array (CWE-789).
     if rows.len().min(10_000).saturating_mul(cols) <= MAX_LAYOUT_CELLS {
+        // `run[i]`: how many rows from part row `i` follow one another in the table, found once so a
+        // merge is cut by a lookup, not by walking the rows it spans.
+        let mut run = vec![1u32; rows.len()];
+        for i in (0..rows.len().saturating_sub(1)).rev() {
+            if rows.get(i + 1).zip(rows.get(i)).is_some_and(|(next, this)| *next == this + 1) {
+                run[i] = run.get(i + 1).copied().unwrap_or(0).saturating_add(1);
+            }
+        }
         for (i, row) in cells.iter_mut().enumerate() {
             row.resize_with(cols, Default::default);
             for cell in row.iter_mut() {
                 if let Some((rs, cs)) = cell.merged {
                     // Rows of the merge that follow in this part.
-                    let start = rows.get(i).copied().unwrap_or(0);
-                    let mut n = 1u32;
-                    while n < rs && rows.get(i + n as usize).is_some_and(|r| *r == start + n as usize) {
-                        n += 1;
-                    }
+                    let n = rs.max(1).min(run.get(i).copied().unwrap_or(1));
                     cell.merged = (n > 1 || cs > 1).then_some((n, cs));
                 }
             }
@@ -186,6 +204,27 @@ fn part_table(t: &Table, rows: &[usize], origin: Vec2) -> Table {
     }
 }
 
+/// The table's outline alone, for a table too large to lay out.
+fn outline(t: &Table) -> TableGeom {
+    let rows = t.row_heights.len().min(10_000);
+    let cols = t.col_widths.len().min(10_000);
+    let (w, h) = (edges(&t.col_widths, cols).last().copied().unwrap_or(0.0), edges(&t.row_heights, rows).last().copied().unwrap_or(0.0));
+    let mut g = TableGeom::default();
+    outline_box(&mut g, t.insert.xy(), w, h);
+    g
+}
+
+/// The four sides of a `w` by `h` box hanging down from `o`.
+fn outline_box(g: &mut TableGeom, o: Vec2, w: f64, h: f64) {
+    let p = |x: f64, y: f64| o + Vec2::new(x, -y);
+    let corners = [p(0.0, 0.0), p(w, 0.0), p(w, h), p(0.0, h), p(0.0, 0.0)];
+    for s in corners.windows(2) {
+        if let [a, b] = s {
+            g.lines.push(TableLine { a: *a, b: *b, color: Color::ByBlock, lineweight: Lineweight::ByBlock });
+        }
+    }
+}
+
 /// Lay out one part.
 fn layout(d: &Drawing, t: &Table) -> TableGeom {
     let st = table_style_of(d, t);
@@ -203,14 +242,7 @@ fn layout(d: &Drawing, t: &Table) -> TableGeom {
     }
     let cov = coverage(t);
     if rows.saturating_mul(cols) > MAX_LAYOUT_CELLS || cov.is_err() {
-        let (w, h) = (x_at(cols), y_at(rows));
-        let corners = [p(0.0, 0.0), p(w, 0.0), p(w, h), p(0.0, h), p(0.0, 0.0)];
-        for s in corners.windows(2) {
-            if let [a, b] = s {
-                g.lines.push(TableLine { a: *a, b: *b, color: Color::ByBlock, lineweight: Lineweight::ByBlock });
-            }
-        }
-        return g;
+        return outline(t);
     }
     let k = style_scale(&st, t);
     // Cell styles by name, scaled to the table.

crates/render/src/tests.rs

@@ -1148,3 +1148,25 @@ fn without_linetypes_every_line_is_drawn_whole() {
     let drawn = build(&drawing("DASHED"), &Space::Model, &Options::default());
     assert!(drawn.prims.len() > 2 * continuous.prims.len(), "drawn with its linetype: {} primitives", drawn.prims.len());
 }
+
+/// A broken table whose parts, with their repeated labels, together hold more cells than a table may
+/// lay out is drawn as its outline, though the table's own cells are within the limit.
+#[test]
+fn broken_table_cells_count_across_its_parts() {
+    let d = Drawing::new_imperial();
+    let t = cadcraft_doc::Table {
+        col_widths: vec![1.0; 600],
+        row_heights: vec![1.0; 1000],
+        title: true,
+        header: true,
+        breaks: Some(cadcraft_doc::TableBreak { enabled: true, height: 3.0, ..Default::default() }),
+        ..Default::default()
+    };
+    assert!(t.parts().len() > 500 && 1000 * 600 <= crate::MAX_LAYOUT_CELLS);
+    let g = crate::table_geometry(&d, &t);
+    let parts = t.parts();
+    assert_eq!((g.lines.len(), g.texts.len(), g.fills.len()), (4 * parts.len(), 0, 0));
+    // Each part's box starts at its own origin.
+    let top = |i: usize| g.lines[4 * i].a;
+    assert!((0..parts.len()).all(|i| top(i) == parts[i].origin));
+}