clippy: pass closures without extra borrows to first_amvp_neighbour

Lower the cognitive complexity of segment_at, apply_mmco, derive_amvp,
plotted_extent and look_with_def by moving their per-segment, per-MMCO,
per-neighbour, per-stack and per-preset-style steps into helpers. The
expressions and their evaluation order are unchanged.

crates/engine/src/cmd/points.rs

@@ -658,6 +658,62 @@ pub fn vertex_at(doc: &deckcraft_model::Presentation, sel: &crate::Selection, sh
     None
 }
 
+/// The point at parameter `t` of segment `si`, scaled by `scale` into the shape's box.
+fn segment_point(segs: &[Seg], si: usize, p0: Point, t: f64, scale: (f64, f64)) -> Option<Point> {
+    let q = match segs.get(si)? {
+        Seg::L(p1) => p0.lerp(*p1, t),
+        Seg::Q(c, p1) => p0.lerp(*c, t).lerp(c.lerp(*p1, t), t),
+        Seg::C(c1, c2, p1) => {
+            let (a, b, c) = (p0.lerp(*c1, t), c1.lerp(*c2, t), c2.lerp(*p1, t));
+            a.lerp(b, t).lerp(b.lerp(c, t), t)
+        }
+        _ => return None,
+    };
+    Some(Point::new(q.x * scale.0, q.y * scale.1))
+}
+
+/// The vertex that ends segment `si` (a closing edge ends on the start).
+fn segment_end_vertex(segs: &[Seg], vs: &[usize], si: usize) -> Option<usize> {
+    if closes_onto_start(segs, si) {
+        let start = segs.get(..si).and_then(|s| s.iter().rposition(|x| matches!(x, Seg::M(_))));
+        start.and_then(|m| vs.iter().position(|v| *v == m))
+    } else {
+        vs.iter().position(|v| *v == si)
+    }
+}
+
+/// The distance and `t` of the point on segment `si` nearest `local`, if it lies within `tol`.
+fn nearest_on_segment(segs: &[Seg], si: usize, p0: Point, scale: (f64, f64), local: Point, tol: f64) -> Option<(f64, f64)> {
+    let at = |t: f64| segment_point(segs, si, p0, t, scale);
+    let mut near: Option<(f64, f64)> = None;
+    for k in 1..32 {
+        let t = k as f64 / 32.0;
+        if let Some(q) = at(t) {
+            let d = (q - local).hypot();
+            if d <= tol && near.is_none_or(|n| d < n.0) {
+                near = Some((d, t));
+            }
+        }
+    }
+    let (mut d, mut t) = near?;
+    // Narrow `t` down to the nearest place on the segment, where Add Point puts the point.
+    let mut step = 1.0 / 32.0;
+    for _ in 0..4 {
+        step /= 8.0;
+        let c = t;
+        for k in -8..=8 {
+            let u = (c + f64::from(k) * step).clamp(0.0, 1.0);
+            if let Some(q) = at(u) {
+                let e = (q - local).hypot();
+                if e < d {
+                    (d, t) = (e, u);
+                }
+            }
+        }
+    }
+    Some((d, t))
+}
+
 /// The segment of `sh`'s outline near slide point `p`: (path, index of the vertex ending it, t).
 pub fn segment_at(doc: &deckcraft_model::Presentation, sel: &crate::Selection, sh: &Shape, p: Point, tol: f64) -> Option<(usize, usize, f64)> {
     let Geom::Custom { paths } = &sh.geom else { return None };
@@ -665,57 +721,13 @@ pub fn segment_at(doc: &deckcraft_model::Presentation, sel: &crate::Selection, s
     let local = x.affine().inverse() * p;
     let mut best: Option<(f64, usize, usize, f64)> = None;
     for (pi, cp) in paths.iter().enumerate() {
-        let (sx, sy) = (if cp.w > 0.0 { x.w / cp.w } else { 1.0 }, if cp.h > 0.0 { x.h / cp.h } else { 1.0 });
+        let scale = (if cp.w > 0.0 { x.w / cp.w } else { 1.0 }, if cp.h > 0.0 { x.h / cp.h } else { 1.0 });
         let segs = parse(&cp.d);
         let vs = vertices(&segs);
         for si in 0..segs.len() {
             let Some(p0) = seg_start(&segs, si) else { continue };
-            let at = |t: f64| -> Option<Point> {
-                let q = match segs.get(si)? {
-                    Seg::L(p1) => p0.lerp(*p1, t),
-                    Seg::Q(c, p1) => p0.lerp(*c, t).lerp(c.lerp(*p1, t), t),
-                    Seg::C(c1, c2, p1) => {
-                        let (a, b, c) = (p0.lerp(*c1, t), c1.lerp(*c2, t), c2.lerp(*p1, t));
-                        a.lerp(b, t).lerp(b.lerp(c, t), t)
-                    }
-                    _ => return None,
-                };
-                Some(Point::new(q.x * sx, q.y * sy))
-            };
-            // The vertex that ends this segment (a closing edge ends on the start).
-            let end_vertex = if closes_onto_start(&segs, si) {
-                let start = segs.get(..si).and_then(|s| s.iter().rposition(|x| matches!(x, Seg::M(_))));
-                start.and_then(|m| vs.iter().position(|v| *v == m))
-            } else {
-                vs.iter().position(|v| *v == si)
-            };
-            let Some(ev) = end_vertex else { continue };
-            let mut near: Option<(f64, f64)> = None;
-            for k in 1..32 {
-                let t = k as f64 / 32.0;
-                if let Some(q) = at(t) {
-                    let d = (q - local).hypot();
-                    if d <= tol && near.is_none_or(|n| d < n.0) {
-                        near = Some((d, t));
-                    }
-                }
-            }
-            let Some((mut d, mut t)) = near else { continue };
-            // Narrow `t` down to the nearest place on the segment, where Add Point puts the point.
-            let mut step = 1.0 / 32.0;
-            for _ in 0..4 {
-                step /= 8.0;
-                let c = t;
-                for k in -8..=8 {
-                    let u = (c + f64::from(k) * step).clamp(0.0, 1.0);
-                    if let Some(q) = at(u) {
-                        let e = (q - local).hypot();
-                        if e < d {
-                            (d, t) = (e, u);
-                        }
-                    }
-                }
-            }
+            let Some(ev) = segment_end_vertex(&segs, &vs, si) else { continue };
+            let Some((d, t)) = nearest_on_segment(&segs, si, p0, scale, local, tol) else { continue };
             if best.is_none_or(|b| d < b.0) {
                 best = Some((d, pi, ev, t));
             }

crates/format/src/rtf.rs

@@ -126,155 +126,216 @@ fn advance(rtf: &str, i: usize, n: usize) -> usize {
     if rtf.is_char_boundary(i + n) { i + n } else { i + rtf.get(i..).and_then(|r| r.chars().next()).map_or(1, char::len_utf8) }
 }
 
+/// Group state: whether the text is being skipped, and the `\uc` fallback count.
+#[derive(Clone, Copy)]
+struct St {
+    skip: bool,
+    uc: usize,
+}
+
+/// Parser state for [`rtf_to_outline`]: the cursor, the group stack and the outline so far.
+struct Outline<'a> {
+    rtf: &'a str,
+    b: &'a [u8],
+    i: usize,
+    stack: Vec<St>,
+    st: St,
+    level: Option<u32>,
+    indent: i64,
+    pending_skip: usize,
+    line: String,
+    out: String,
+}
+
 /// Read an RTF outline into tab-indented outline text: a paragraph's outline level (or its left
 /// indent in 0.25" steps) becomes its number of tabs.
 pub fn rtf_to_outline(rtf: &str) -> String {
-    #[derive(Clone, Copy)]
-    struct St {
-        skip: bool,
-        uc: usize,
-    }
-    let b = rtf.as_bytes();
-    let mut stack: Vec<St> = vec![];
-    let mut st = St { skip: false, uc: 1 };
-    let (mut level, mut indent): (Option<u32>, i64) = (None, 0);
-    let mut line = String::new();
-    let mut out = String::new();
-    let mut pending_skip = 0usize;
-    let mut i = 0;
-    let flush = |line: &mut String, level: Option<u32>, indent: i64, out: &mut String| {
-        let text = line.trim();
-        if !text.is_empty() {
-            let n = level.map(|l| l as i64).unwrap_or(indent.saturating_add(180) / 360).clamp(0, 9) as usize;
-            out.push_str(&"\t".repeat(n));
-            out.push_str(text);
-            out.push('\n');
-        }
-        line.clear();
+    let mut p = Outline {
+        rtf,
+        b: rtf.as_bytes(),
+        i: 0,
+        stack: vec![],
+        st: St { skip: false, uc: 1 },
+        level: None,
+        indent: 0,
+        pending_skip: 0,
+        line: String::new(),
+        out: String::new(),
     };
-    while i < b.len() {
-        let c = b[i];
-        match c {
-            b'{' => {
-                stack.push(st);
-                i += 1;
-                // `{\*\dest …}`: an ignorable destination.
-                if b[i..].starts_with(b"\\*") {
-                    st.skip = true;
-                }
-            }
-            b'}' => {
-                st = stack.pop().unwrap_or(St { skip: false, uc: 1 });
-                i += 1;
-            }
-            b'\\' => {
-                i += 1;
-                let Some(&n) = b.get(i) else { break };
-                if n.is_ascii_alphabetic() {
-                    let s = i;
-                    while i < b.len() && b[i].is_ascii_alphabetic() {
-                        i += 1;
-                    }
-                    let word = &rtf[s..i];
-                    let ns = i;
-                    if i < b.len() && (b[i] == b'-' || b[i].is_ascii_digit()) {
-                        i += 1;
-                        while i < b.len() && b[i].is_ascii_digit() {
-                            i += 1;
-                        }
-                    }
-                    let arg: Option<i64> = rtf[ns..i].parse().ok();
-                    if i < b.len() && b[i] == b' ' {
-                        i += 1;
-                    }
-                    if pending_skip > 0 {
-                        pending_skip -= 1;
-                        continue;
-                    }
-                    if SKIP.contains(&word) {
-                        st.skip = true;
-                    }
-                    if st.skip {
-                        continue;
-                    }
-                    match word {
-                        "par" => {
-                            flush(&mut line, level, indent, &mut out);
-                        }
-                        "pard" => {
-                            level = None;
-                            indent = 0;
-                        }
-                        "outlinelevel" => level = arg.map(|a| a.clamp(0, 9) as u32),
-                        "li" => indent = arg.unwrap_or(0),
-                        "tab" | "line" => line.push(' '),
-                        "uc" => st.uc = arg.unwrap_or(1).clamp(0, 8) as usize,
-                        "u" => {
-                            let v = arg.unwrap_or(0);
-                            // RTF writes UTF-16 units as signed 16-bit values.
-                            push_utf16(&mut line, (v & 0xffff) as u32);
-                            pending_skip = 0;
-                            // Skip the fallback characters.
-                            let mut k = st.uc;
-                            while k > 0 && i < b.len() {
-                                if b[i] == b'\\' && b.get(i + 1) == Some(&b'\'') {
-                                    i = advance(rtf, i, 4);
-                                } else if b[i] == b'{' || b[i] == b'}' || b[i] == b'\\' {
-                                    break;
-                                } else {
-                                    i = advance(rtf, i, 1);
-                                }
-                                k -= 1;
-                            }
-                        }
-                        "emdash" => line.push('—'),
-                        "endash" => line.push('–'),
-                        "bullet" => line.push('•'),
-                        "lquote" => line.push('‘'),
-                        "rquote" => line.push('’'),
-                        "ldblquote" => line.push('“'),
-                        "rdblquote" => line.push('”'),
-                        _ => {}
-                    }
-                } else if n == b'\'' {
-                    let hex = rtf.get(i + 1..i + 3).filter(|h| h.bytes().all(|b| b.is_ascii_hexdigit())).and_then(|h| u8::from_str_radix(h, 16).ok());
-                    i = advance(rtf, i, 3);
-                    if !st.skip
-                        && let Some(h) = hex
-                        && h != 0
-                    {
-                        line.push(cp1252(h));
-                    }
-                } else {
-                    i += 1;
-                    if st.skip {
-                        continue;
-                    }
-                    match n {
-                        b'\\' | b'{' | b'}' => line.push(n as char),
-                        b'~' => line.push('\u{a0}'),
-                        b'_' => line.push('\u{2011}'),
-                        b'\n' | b'\r' => flush(&mut line, level, indent, &mut out),
-                        _ => {}
+    p.run();
+    p.flush();
+    finish_surrogates(p.out)
+}
+
+impl Outline<'_> {
+    fn run(&mut self) {
+        while self.i < self.b.len() {
+            match self.b[self.i] {
+                b'{' => self.open_group(),
+                b'}' => self.close_group(),
+                b'\\' => {
+                    self.i += 1;
+                    if !self.escape() {
+                        break;
                     }
                 }
-            }
-            b'\r' | b'\n' => i += 1,
-            _ => {
-                let s = i;
-                while i < b.len() && !matches!(b[i], b'{' | b'}' | b'\\' | b'\r' | b'\n') {
-                    i += 1;
-                }
-                if !st.skip
-                    && let Some(t) = rtf.get(s..i)
-                {
-                    line.push_str(&t.replace('\u{0}', ""));
-                }
+                b'\r' | b'\n' => self.i += 1,
+                _ => self.text(),
             }
         }
     }
-    flush(&mut line, level, indent, &mut out);
-    finish_surrogates(out)
+
+    /// `{`: push the group; `{\*\dest …}` is an ignorable destination.
+    fn open_group(&mut self) {
+        self.stack.push(self.st);
+        self.i += 1;
+        if self.b[self.i..].starts_with(b"\\*") {
+            self.st.skip = true;
+        }
+    }
+
+    fn close_group(&mut self) {
+        self.st = self.stack.pop().unwrap_or(St { skip: false, uc: 1 });
+        self.i += 1;
+    }
+
+    /// The character after a backslash: a control word, a hex escape or a symbol. False at the
+    /// end of the input.
+    fn escape(&mut self) -> bool {
+        let Some(&n) = self.b.get(self.i) else { return false };
+        if n.is_ascii_alphabetic() {
+            self.control_word();
+        } else if n == b'\'' {
+            self.hex_escape();
+        } else {
+            self.symbol(n);
+        }
+        true
+    }
+
+    fn control_word(&mut self) {
+        let rtf = self.rtf;
+        let s = self.i;
+        while self.i < self.b.len() && self.b[self.i].is_ascii_alphabetic() {
+            self.i += 1;
+        }
+        let word = &rtf[s..self.i];
+        let ns = self.i;
+        if self.i < self.b.len() && (self.b[self.i] == b'-' || self.b[self.i].is_ascii_digit()) {
+            self.i += 1;
+            while self.i < self.b.len() && self.b[self.i].is_ascii_digit() {
+                self.i += 1;
+            }
+        }
+        let arg: Option<i64> = rtf[ns..self.i].parse().ok();
+        if self.i < self.b.len() && self.b[self.i] == b' ' {
+            self.i += 1;
+        }
+        if self.pending_skip > 0 {
+            self.pending_skip -= 1;
+            return;
+        }
+        if SKIP.contains(&word) {
+            self.st.skip = true;
+        }
+        if !self.st.skip {
+            self.apply(word, arg);
+        }
+    }
+
+    fn apply(&mut self, word: &str, arg: Option<i64>) {
+        match word {
+            "par" => self.flush(),
+            "pard" => {
+                self.level = None;
+                self.indent = 0;
+            }
+            "outlinelevel" => self.level = arg.map(|a| a.clamp(0, 9) as u32),
+            "li" => self.indent = arg.unwrap_or(0),
+            "tab" | "line" => self.line.push(' '),
+            "uc" => self.st.uc = arg.unwrap_or(1).clamp(0, 8) as usize,
+            "u" => self.unicode(arg.unwrap_or(0)),
+            "emdash" => self.line.push('—'),
+            "endash" => self.line.push('–'),
+            "bullet" => self.line.push('•'),
+            "lquote" => self.line.push('‘'),
+            "rquote" => self.line.push('’'),
+            "ldblquote" => self.line.push('“'),
+            "rdblquote" => self.line.push('”'),
+            _ => {}
+        }
+    }
+
+    /// `\uN`: one UTF-16 unit, then the `\uc` fallback characters, which are skipped.
+    fn unicode(&mut self, v: i64) {
+        // RTF writes UTF-16 units as signed 16-bit values.
+        push_utf16(&mut self.line, (v & 0xffff) as u32);
+        self.pending_skip = 0;
+        let mut k = self.st.uc;
+        while k > 0 && self.i < self.b.len() {
+            if self.b[self.i] == b'\\' && self.b.get(self.i + 1) == Some(&b'\'') {
+                self.i = advance(self.rtf, self.i, 4);
+            } else if matches!(self.b[self.i], b'{' | b'}' | b'\\') {
+                break;
+            } else {
+                self.i = advance(self.rtf, self.i, 1);
+            }
+            k -= 1;
+        }
+    }
+
+    /// `\'hh`: one cp1252 byte.
+    fn hex_escape(&mut self) {
+        let hex =
+            self.rtf.get(self.i + 1..self.i + 3).filter(|h| h.bytes().all(|b| b.is_ascii_hexdigit())).and_then(|h| u8::from_str_radix(h, 16).ok());
+        self.i = advance(self.rtf, self.i, 3);
+        if !self.st.skip
+            && let Some(h) = hex
+            && h != 0
+        {
+            self.line.push(cp1252(h));
+        }
+    }
+
+    /// A one-character control symbol (`\\`, `\{`, `\~`, ...).
+    fn symbol(&mut self, n: u8) {
+        self.i += 1;
+        if self.st.skip {
+            return;
+        }
+        match n {
+            b'\\' | b'{' | b'}' => self.line.push(n as char),
+            b'~' => self.line.push('\u{a0}'),
+            b'_' => self.line.push('\u{2011}'),
+            b'\n' | b'\r' => self.flush(),
+            _ => {}
+        }
+    }
+
+    /// Plain text up to the next special character.
+    fn text(&mut self) {
+        let s = self.i;
+        while self.i < self.b.len() && !matches!(self.b[self.i], b'{' | b'}' | b'\\' | b'\r' | b'\n') {
+            self.i += 1;
+        }
+        if !self.st.skip
+            && let Some(t) = self.rtf.get(s..self.i)
+        {
+            self.line.push_str(&t.replace('\u{0}', ""));
+        }
+    }
+
+    /// Ends the current line: a non-empty line becomes one outline entry, indented by its level.
+    fn flush(&mut self) {
+        let text = self.line.trim();
+        if !text.is_empty() {
+            let n = self.level.map(|l| l as i64).unwrap_or(self.indent.saturating_add(180) / 360).clamp(0, 9) as usize;
+            self.out.push_str(&"\t".repeat(n));
+            self.out.push_str(text);
+            self.out.push('\n');
+        }
+        self.line.clear();
+    }
 }
 
 /// Push a UTF-16 unit; surrogate halves are parked as private markers (NUL plus four hex digits)

crates/h264/src/dpb.rs

@@ -301,6 +301,25 @@ impl Dpb {
         Ok(lists)
     }
 
+    /// Marks as unused every entry in state `mark` that `hit` selects.
+    fn unmark_where(&mut self, mark: RefMark, hit: impl Fn(&DpbEntry) -> bool) {
+        for e in &mut self.entries {
+            if e.mark == mark && hit(e) {
+                e.mark = RefMark::Unused;
+            }
+        }
+    }
+
+    /// Makes every short-term entry that `hit` selects a long-term one with index `idx`.
+    fn mark_long_where(&mut self, hit: impl Fn(&DpbEntry) -> bool, idx: u32) {
+        for e in &mut self.entries {
+            if e.mark == RefMark::Short && hit(e) {
+                e.mark = RefMark::Long;
+                e.long_term_frame_idx = idx;
+            }
+        }
+    }
+
     /// One memory management control operation; returns true for MMCO 5.
     fn apply_mmco(&mut self, m: &Mmco, cur_frame_num: u32, max_frame_num: u32, cur_long: &mut Option<u32>) -> bool {
         let mut had5 = false;
@@ -308,40 +327,17 @@ impl Dpb {
         match m.op {
             1 => {
                 let pn = curr_pic_num - (m.difference_of_pic_nums_minus1 as i32 + 1);
-                for e in &mut self.entries {
-                    if e.mark == RefMark::Short && Self::frame_num_wrap(e, cur_frame_num, max_frame_num) == pn {
-                        e.mark = RefMark::Unused;
-                    }
-                }
-            }
-            2 => {
-                for e in &mut self.entries {
-                    if e.mark == RefMark::Long && e.long_term_frame_idx == m.long_term_pic_num {
-                        e.mark = RefMark::Unused;
-                    }
-                }
+                self.unmark_where(RefMark::Short, |e| Self::frame_num_wrap(e, cur_frame_num, max_frame_num) == pn);
             }
+            2 => self.unmark_where(RefMark::Long, |e| e.long_term_frame_idx == m.long_term_pic_num),
             3 => {
                 let pn = curr_pic_num - (m.difference_of_pic_nums_minus1 as i32 + 1);
-                for e in &mut self.entries {
-                    if e.mark == RefMark::Long && e.long_term_frame_idx == m.long_term_frame_idx {
-                        e.mark = RefMark::Unused;
-                    }
-                }
-                for e in &mut self.entries {
-                    if e.mark == RefMark::Short && Self::frame_num_wrap(e, cur_frame_num, max_frame_num) == pn {
-                        e.mark = RefMark::Long;
-                        e.long_term_frame_idx = m.long_term_frame_idx;
-                    }
-                }
+                self.unmark_where(RefMark::Long, |e| e.long_term_frame_idx == m.long_term_frame_idx);
+                self.mark_long_where(|e| Self::frame_num_wrap(e, cur_frame_num, max_frame_num) == pn, m.long_term_frame_idx);
             }
             4 => {
                 let max = m.max_long_term_frame_idx_plus1;
-                for e in &mut self.entries {
-                    if e.mark == RefMark::Long && (max == 0 || e.long_term_frame_idx > max - 1) {
-                        e.mark = RefMark::Unused;
-                    }
-                }
+                self.unmark_where(RefMark::Long, |e| max == 0 || e.long_term_frame_idx > max - 1);
                 self.max_long_term_frame_idx = if max == 0 { None } else { Some(max - 1) };
             }
             5 => {
@@ -353,16 +349,9 @@ impl Dpb {
             }
             6 => {
                 // Only an index within the allowed range may be assigned (8.2.5.4.6).
-                let allowed = match self.max_long_term_frame_idx {
-                    Some(max) => m.long_term_frame_idx <= max,
-                    None => false,
-                };
+                let allowed = self.max_long_term_frame_idx.is_some_and(|max| m.long_term_frame_idx <= max);
                 if allowed {
-                    for e in &mut self.entries {
-                        if e.mark == RefMark::Long && e.long_term_frame_idx == m.long_term_frame_idx {
-                            e.mark = RefMark::Unused;
-                        }
-                    }
+                    self.unmark_where(RefMark::Long, |e| e.long_term_frame_idx == m.long_term_frame_idx);
                     *cur_long = Some(m.long_term_frame_idx);
                 }
             }

crates/hevc/src/mvpred.rs

@@ -74,16 +74,39 @@ impl<'a> SliceDecoder<'a> {
 
     /// Merge mode motion (8.5.3.2.2).
     pub fn derive_merge(&self, g: PbGeom, part: PartMode, merge_idx: usize) -> MvField {
-        let PbGeom { xc, yc, ncb, xp: xp0, yp: yp0, w: w0, h: h0, part_idx: part_idx0 } = g;
+        let (w0, h0) = (g.w, g.h);
+        // With a parallel merge level above 4x4, an 8x8 coding block shares one candidate set.
+        let g = if self.pps.log2_parallel_merge_level > 2 && g.ncb == 8 {
+            PbGeom { xp: g.xc, yp: g.yc, w: g.ncb, h: g.ncb, part_idx: 0, ..g }
+        } else {
+            g
+        };
+        let max = self.sh.max_num_merge_cand as usize;
+        let (list, n) = self.spatial_merge_candidates(&g, part);
+        if merge_idx < n {
+            return self.finish_merge(list[merge_idx], w0, h0);
+        }
+        let mut cands: Vec<MvField> = list[..n].to_vec();
+        cands.extend(self.temporal_merge_candidate(g.xp, g.yp, g.w, g.h));
+        if merge_idx < cands.len() {
+            return self.finish_merge(cands[merge_idx], w0, h0);
+        }
+        self.combined_merge_candidates(&mut cands, max);
+        if merge_idx < cands.len() {
+            return self.finish_merge(cands[merge_idx], w0, h0);
+        }
+        self.zero_merge_candidates(&mut cands, merge_idx);
+        self.finish_merge(cands[merge_idx], w0, h0)
+    }
+
+    /// The spatial candidates A1, B1, B0, A0 and B2 (8.5.3.2.3): the candidates, and how many.
+    fn spatial_merge_candidates(&self, g: &PbGeom, part: PartMode) -> ([MvField; 5], usize) {
+        let PbGeom { xp, yp, w, h, part_idx, .. } = *g;
         let pml = self.pps.log2_parallel_merge_level;
-        let (xp, yp, w, h, part_idx) = if pml > 2 && ncb == 8 { (xc, yc, ncb, ncb, 0) } else { (xp0, yp0, w0, h0, part_idx0) };
-        let g = PbGeom { xc, yc, ncb, xp, yp, w, h, part_idx };
         let same_mer = |xn: i32, yn: i32| (xp >> pml) == (xn >> pml) && (yp >> pml) == (yn >> pml);
-        let avail = |xn: i32, yn: i32| self.pb_avail(&g, xn, yn) && !same_mer(xn, yn);
+        let avail = |xn: i32, yn: i32| self.pb_avail(g, xn, yn) && !same_mer(xn, yn);
         let mut list: [MvField; 5] = [MvField::default(); 5];
         let mut n = 0;
-        let max = self.sh.max_num_merge_cand as usize;
-        // spatial candidates (8.5.3.2.3)
         let pa1 = (xp - 1, yp + h - 1);
         let av_a1 = avail(pa1.0, pa1.1) && !(matches!(part, PartMode::PNx2N | PartMode::PnLx2N | PartMode::PnRx2N) && part_idx == 1);
         let m_a1 = if av_a1 { self.mv_at(pa1.0, pa1.1) } else { MvField::default() };
@@ -130,10 +153,11 @@ impl<'a> SliceDecoder<'a> {
             list[n] = self.mv_at(pb2.0, pb2.1);
             n += 1;
         }
-        if merge_idx < n {
-            return self.finish_merge(list[merge_idx], w0, h0);
-        }
-        // temporal candidate
+        (list, n)
+    }
+
+    /// The temporal candidate (8.5.3.2.8): list 0 from the collocated picture, and list 1 for B slices.
+    fn temporal_merge_candidate(&self, xp: i32, yp: i32, w: i32, h: i32) -> Option<MvField> {
         let mut col = MvField::default();
         let mut col_avail = false;
         if let Some(mv) = self.temporal(xp, yp, w, h, 0, 0) {
@@ -148,30 +172,28 @@ impl<'a> SliceDecoder<'a> {
             col.ref_idx[1] = 0;
             col_avail = true;
         }
-        let mut cands: Vec<MvField> = list[..n].to_vec();
-        if col_avail {
-            cands.push(col);
-        }
-        if merge_idx < cands.len() {
-            return self.finish_merge(cands[merge_idx], w0, h0);
-        }
-        // combined bi-predictive candidates (8.5.3.2.4)
+        col_avail.then_some(col)
+    }
+
+    /// Combined bi-predictive candidates (8.5.3.2.4) from pairs of the original candidates.
+    fn combined_merge_candidates(&self, cands: &mut Vec<MvField>, max: usize) {
         let num_orig = cands.len();
-        if self.sh.is_b() && num_orig > 1 && num_orig < max {
-            let mut comb = 0;
-            while comb < num_orig * (num_orig - 1) && cands.len() < max {
-                let (i0, i1) = COMB[comb];
-                let (c0, c1) = (cands[i0], cands[i1]);
-                if c0.pred(0) && c1.pred(1) && (self.ref_pic(0, c0.ref_idx[0]).poc != self.ref_pic(1, c1.ref_idx[1]).poc || c0.mv[0] != c1.mv[1]) {
-                    cands.push(MvField { mv: [c0.mv[0], c1.mv[1]], ref_idx: [c0.ref_idx[0], c1.ref_idx[1]] });
-                }
-                comb += 1;
+        if !(self.sh.is_b() && num_orig > 1 && num_orig < max) {
+            return;
+        }
+        let mut comb = 0;
+        while comb < num_orig * (num_orig - 1) && cands.len() < max {
+            let (i0, i1) = COMB[comb];
+            let (c0, c1) = (cands[i0], cands[i1]);
+            if c0.pred(0) && c1.pred(1) && (self.ref_pic(0, c0.ref_idx[0]).poc != self.ref_pic(1, c1.ref_idx[1]).poc || c0.mv[0] != c1.mv[1]) {
+                cands.push(MvField { mv: [c0.mv[0], c1.mv[1]], ref_idx: [c0.ref_idx[0], c1.ref_idx[1]] });
             }
+            comb += 1;
         }
-        if merge_idx < cands.len() {
-            return self.finish_merge(cands[merge_idx], w0, h0);
-        }
-        // zero candidates (8.5.3.2.5)
+    }
+
+    /// Zero candidates (8.5.3.2.5) up to and including `merge_idx`.
+    fn zero_merge_candidates(&self, cands: &mut Vec<MvField>, merge_idx: usize) {
         let num_ref = if self.sh.is_b() { self.sh.num_ref_idx[0].min(self.sh.num_ref_idx[1]) } else { self.sh.num_ref_idx[0] } as usize;
         let mut zero_idx = 0;
         while cands.len() <= merge_idx {
@@ -179,7 +201,6 @@ impl<'a> SliceDecoder<'a> {
             cands.push(MvField { mv: [[0; 2]; 2], ref_idx: [r, if self.sh.is_b() { r } else { -1 }] });
             zero_idx += 1;
         }
-        self.finish_merge(cands[merge_idx], w0, h0)
     }
 
     fn finish_merge(&self, mut f: MvField, w: i32, h: i32) -> MvField {
@@ -240,68 +261,59 @@ impl<'a> SliceDecoder<'a> {
         if cur.long_term || col_diff == cur_diff { Some(mv) } else { Some(scale_mv(mv, col_diff, cur_diff)) }
     }
 
+    /// AMVP neighbour motion with the target's reference picture (no scaling), 8.5.3.2.7.
+    fn amvp_exact(&self, f: &MvField, l: usize, tpoc: i32) -> Option<[i16; 2]> {
+        let y = 1 - l;
+        if f.pred(l) && self.ref_pic(l, f.ref_idx[l]).poc == tpoc {
+            Some(f.mv[l])
+        } else if f.pred(y) && self.ref_pic(y, f.ref_idx[y]).poc == tpoc {
+            Some(f.mv[y])
+        } else {
+            None
+        }
+    }
+
+    /// AMVP neighbour motion with a long-term-compatible reference, scaled when both are short-term.
+    fn amvp_scaled(&self, f: &MvField, l: usize, tpoc: i32, tlt: bool, cur_poc: i32) -> Option<[i16; 2]> {
+        let y = 1 - l;
+        let pick = if f.pred(l) && self.ref_pic(l, f.ref_idx[l]).long_term == tlt {
+            Some((f.mv[l], self.ref_pic(l, f.ref_idx[l])))
+        } else if f.pred(y) && self.ref_pic(y, f.ref_idx[y]).long_term == tlt {
+            Some((f.mv[y], self.ref_pic(y, f.ref_idx[y])))
+        } else {
+            None
+        };
+        pick.map(|(mv, r)| if r.poc != tpoc && !r.long_term && !tlt { scale_mv(mv, cur_poc - r.poc, cur_poc - tpoc) } else { mv })
+    }
+
+    /// The first neighbour whose position is available and whose motion `pick` accepts.
+    fn first_amvp_neighbour(&self, pos: &[(i32, i32)], avail: &[bool], pick: impl Fn(&MvField) -> Option<[i16; 2]>) -> Option<[i16; 2]> {
+        pos.iter().zip(avail).find_map(|(&(x, y), &ok)| if ok { pick(&self.mv_at(x, y)) } else { None })
+    }
+
     /// AMVP predictor (8.5.3.2.6, 8.5.3.2.7).
     pub fn derive_amvp(&self, g: PbGeom, l: usize, ref_idx: usize, mvp_flag: usize) -> [i16; 2] {
         let PbGeom { xp, yp, w, h, .. } = g;
         let target = &self.refs[l][ref_idx];
         let (tpoc, tlt) = (target.poc, target.long_term);
         let cur_poc = self.pic.poc;
-        let y = 1 - l;
-        // exact reference match (no scaling)
-        let unscaled = |f: &MvField| -> Option<[i16; 2]> {
-            if f.pred(l) && self.ref_pic(l, f.ref_idx[l]).poc == tpoc {
-                Some(f.mv[l])
-            } else if f.pred(y) && self.ref_pic(y, f.ref_idx[y]).poc == tpoc {
-                Some(f.mv[y])
-            } else {
-                None
-            }
-        };
-        // long-term-compatible match, scaled when both references are short-term
-        let scaled = |f: &MvField| -> Option<[i16; 2]> {
-            let pick = if f.pred(l) && self.ref_pic(l, f.ref_idx[l]).long_term == tlt {
-                Some((f.mv[l], self.ref_pic(l, f.ref_idx[l])))
-            } else if f.pred(y) && self.ref_pic(y, f.ref_idx[y]).long_term == tlt {
-                Some((f.mv[y], self.ref_pic(y, f.ref_idx[y])))
-            } else {
-                None
-            };
-            pick.map(|(mv, r)| if r.poc != tpoc && !r.long_term && !tlt { scale_mv(mv, cur_poc - r.poc, cur_poc - tpoc) } else { mv })
-        };
+        let exact = |f: &MvField| self.amvp_exact(f, l, tpoc);
+        let scaled = |f: &MvField| self.amvp_scaled(f, l, tpoc, tlt, cur_poc);
         let pa = [(xp - 1, yp + h), (xp - 1, yp + h - 1)];
         let av_a = [self.pb_avail(&g, pa[0].0, pa[0].1), self.pb_avail(&g, pa[1].0, pa[1].1)];
         let is_scaled = av_a[0] || av_a[1];
-        let mut a = None;
-        for k in 0..2 {
-            if av_a[k] && a.is_none() {
-                a = unscaled(&self.mv_at(pa[k].0, pa[k].1));
-            }
-        }
+        let mut a = self.first_amvp_neighbour(&pa, &av_a, exact);
         if a.is_none() {
-            for k in 0..2 {
-                if av_a[k] && a.is_none() {
-                    a = scaled(&self.mv_at(pa[k].0, pa[k].1));
-                }
-            }
+            a = self.first_amvp_neighbour(&pa, &av_a, scaled);
         }
         let pb = [(xp + w, yp - 1), (xp + w - 1, yp - 1), (xp - 1, yp - 1)];
         let av_b = [0, 1, 2].map(|k| self.pb_avail(&g, pb[k].0, pb[k].1));
-        let mut b = None;
-        for k in 0..3 {
-            if av_b[k] && b.is_none() {
-                b = unscaled(&self.mv_at(pb[k].0, pb[k].1));
-            }
-        }
+        let mut b = self.first_amvp_neighbour(&pb, &av_b, exact);
         if !is_scaled && b.is_some() {
             a = b;
         }
         if !is_scaled {
-            b = None;
-            for k in 0..3 {
-                if av_b[k] && b.is_none() {
-                    b = scaled(&self.mv_at(pb[k].0, pb[k].1));
-                }
-            }
+            b = self.first_amvp_neighbour(&pb, &av_b, scaled);
         }
         let mut list: [[i16; 2]; 3] = [[0; 2]; 3];
         let mut n = 0;

crates/hevc/src/slicedec.rs

@@ -1366,84 +1366,106 @@ impl<'a> SliceDecoder<'a> {
 
     /// prediction_unit(): parse, derive motion, store it and predict. Returns merge_flag.
     fn prediction_unit(&mut self, g: PbGeom, part: PartMode, skip: bool) -> Result<bool> {
-        let PbGeom { xc, yc, ncb, xp, yp, w, h, part_idx } = g;
         let merge = if skip { true } else { self.dd(MERGE_FLAG) == 1 };
         let mvf = if merge {
-            let idx = if self.sh.max_num_merge_cand > 1 {
-                let mut i = 0;
-                if self.dd(MERGE_IDX) == 1 {
-                    i = 1;
-                    while i < self.sh.max_num_merge_cand - 1 && self.bypass() == 1 {
-                        i += 1;
-                    }
-                }
-                i
-            } else {
-                0
-            };
-            self.derive_merge(PbGeom { xc, yc, ncb, xp, yp, w, h, part_idx }, part, idx as usize)
+            let idx = self.merge_idx();
+            self.derive_merge(g, part, idx as usize)
         } else {
-            let pred_idc = if self.sh.is_b() {
-                if w + h != 12 {
-                    let depth = self.pic.blk_at(xc, yc).depth as usize;
-                    if self.dd(INTER_PRED_IDC + depth) == 1 { 2 } else { self.dd(INTER_PRED_IDC + 4) }
-                } else {
-                    self.dd(INTER_PRED_IDC + 4)
-                }
-            } else {
-                0
-            };
-            let mut ref_idx = [-1i8; 2];
-            let mut mvd = [[0i32; 2]; 2];
-            let mut mvp_flag = [0u32; 2];
-            for l in 0..2 {
-                let used = if l == 0 { pred_idc != 1 } else { pred_idc != 0 };
-                if !used {
-                    continue;
-                }
-                let nref = self.sh.num_ref_idx[l];
-                let mut ri = 0;
-                if nref > 1 {
-                    while ri < nref - 1 {
-                        let bin = if ri < 2 { self.dd(REF_IDX + ri as usize) } else { self.bypass() };
-                        if bin == 0 {
-                            break;
-                        }
-                        ri += 1;
-                    }
-                }
-                ref_idx[l] = ri as i8;
-                if l == 1 && self.sh.mvd_l1_zero && pred_idc == 2 {
-                    mvd[1] = [0, 0];
-                } else {
-                    mvd[l] = self.mvd_coding()?;
-                }
-                mvp_flag[l] = self.dd(MVP_FLAG);
-            }
-            let mut f = MvField { mv: [[0; 2]; 2], ref_idx };
-            for l in 0..2 {
-                if ref_idx[l] < 0 {
-                    continue;
-                }
-                let mvp = self.derive_amvp(PbGeom { xc, yc, ncb, xp, yp, w, h, part_idx }, l, ref_idx[l] as usize, mvp_flag[l] as usize);
-                // mvLX = (mvp + mvd) wrapped to 16 bits (8-94)
-                f.mv[l] = [(mvp[0] as i32 + mvd[l][0]) as i16, (mvp[1] as i32 + mvd[l][1]) as i16];
-            }
-            f
+            self.amvp_motion(g)?
         };
         for l in 0..2 {
             if mvf.ref_idx[l] >= 0 {
                 ensure!((mvf.ref_idx[l] as usize) < self.refs[l].len(), "reference index out of range");
             }
         }
-        // store motion
+        self.store_motion(g.xp, g.yp, g.w, g.h, mvf);
+        self.motion_compensate(g.xp, g.yp, g.w as usize, g.h as usize, &mvf);
+        Ok(merge)
+    }
+
+    /// merge_idx(): the merge candidate index, truncated unary (0 when there is one candidate).
+    fn merge_idx(&mut self) -> u32 {
+        if self.sh.max_num_merge_cand <= 1 {
+            return 0;
+        }
+        let mut i = 0;
+        if self.dd(MERGE_IDX) == 1 {
+            i = 1;
+            while i < self.sh.max_num_merge_cand - 1 && self.bypass() == 1 {
+                i += 1;
+            }
+        }
+        i
+    }
+
+    /// inter_pred_idc: 0 = list 0, 1 = list 1, 2 = both.
+    fn inter_pred_idc(&mut self, xc: i32, yc: i32, w: i32, h: i32) -> u32 {
+        if !self.sh.is_b() {
+            return 0;
+        }
+        if w + h != 12 {
+            let depth = self.pic.blk_at(xc, yc).depth as usize;
+            if self.dd(INTER_PRED_IDC + depth) == 1 { 2 } else { self.dd(INTER_PRED_IDC + 4) }
+        } else {
+            self.dd(INTER_PRED_IDC + 4)
+        }
+    }
+
+    /// ref_idx_lX: truncated unary, the first two bins context-coded.
+    fn ref_idx(&mut self, l: usize) -> u32 {
+        let nref = self.sh.num_ref_idx[l];
+        let mut ri = 0;
+        if nref > 1 {
+            while ri < nref - 1 {
+                let bin = if ri < 2 { self.dd(REF_IDX + ri as usize) } else { self.bypass() };
+                if bin == 0 {
+                    break;
+                }
+                ri += 1;
+            }
+        }
+        ri
+    }
+
+    /// The AMVP branch: parse each used list's reference index, mvd and predictor flag, then add
+    /// every mvd to its predictor.
+    fn amvp_motion(&mut self, g: PbGeom) -> Result<MvField> {
+        let pred_idc = self.inter_pred_idc(g.xc, g.yc, g.w, g.h);
+        let mut ref_idx = [-1i8; 2];
+        let mut mvd = [[0i32; 2]; 2];
+        let mut mvp_flag = [0u32; 2];
+        for l in 0..2 {
+            let used = if l == 0 { pred_idc != 1 } else { pred_idc != 0 };
+            if !used {
+                continue;
+            }
+            ref_idx[l] = self.ref_idx(l) as i8;
+            if l == 1 && self.sh.mvd_l1_zero && pred_idc == 2 {
+                mvd[1] = [0, 0];
+            } else {
+                mvd[l] = self.mvd_coding()?;
+            }
+            mvp_flag[l] = self.dd(MVP_FLAG);
+        }
+        let mut f = MvField { mv: [[0; 2]; 2], ref_idx };
+        for l in 0..2 {
+            if ref_idx[l] < 0 {
+                continue;
+            }
+            let mvp = self.derive_amvp(g, l, ref_idx[l] as usize, mvp_flag[l] as usize);
+            // mvLX = (mvp + mvd) wrapped to 16 bits (8-94)
+            f.mv[l] = [(mvp[0] as i32 + mvd[l][0]) as i16, (mvp[1] as i32 + mvd[l][1]) as i16];
+        }
+        Ok(f)
+    }
+
+    /// Writes a prediction block's motion into the picture's 4x4 motion field.
+    fn store_motion(&mut self, xp: i32, yp: i32, w: i32, h: i32, mvf: MvField) {
         let w4 = self.pic.w4;
         for by in (yp >> 2)..((yp + h) >> 2) {
             let o = by as usize * w4;
             self.pic.mvf[o + (xp >> 2) as usize..o + ((xp + w) >> 2) as usize].fill(mvf);
         }
-        self.motion_compensate(xp, yp, w as usize, h as usize, &mvf);
-        Ok(merge)
     }
 
     fn mvd_coding(&mut self) -> Result<[i32; 2]> {

crates/model/src/chart.rs

@@ -608,64 +608,73 @@ impl Chart {
         if ser.is_empty() {
             return (!secondary && self.kind != ChartType::Combo).then_some((0.0, 0.0));
         }
-        let (mut lo, mut hi) = (f64::INFINITY, f64::NEG_INFINITY);
+        let mut ext = (f64::INFINITY, f64::NEG_INFINITY);
         let has_stacked_or_percent = ser.iter().any(|s| {
             let k = self.series_kind(s);
             k.stacked() || k.percent()
         });
-
-        let mut percent = false;
-        if has_stacked_or_percent {
-            let n = ser.iter().map(|s| s.values.len()).max().unwrap_or(0);
-            let budget = (ser.len() * n).min(10_000_000);
-            let n_clamped = if ser.is_empty() { 0 } else { n.min(budget / ser.len()) };
-
-            for i in 0..n_clamped {
-                let (mut p, mut m, mut stacked) = (0.0, 0.0, false);
-                for s in &ser {
-                    let k = self.series_kind(s);
-                    let Some(v) = s.values.get(i).copied().flatten().filter(|v| v.is_finite()) else { continue };
-                    if k.percent() {
-                        percent = true;
-                    } else if k.stacked() {
-                        stacked = true;
-                        if v >= 0.0 { p += v } else { m += v }
-                    } else {
-                        hi = hi.max(v);
-                        lo = lo.min(v);
-                    }
-                }
-                if stacked {
-                    hi = hi.max(p);
-                    lo = lo.min(m);
-                }
-            }
+        let percent = if has_stacked_or_percent {
+            self.fold_stacked(&ser, &mut ext)
         } else {
             for s in &ser {
                 for v in s.values.iter().flatten().copied().filter(|v| v.is_finite()) {
-                    hi = hi.max(v);
-                    lo = lo.min(v);
+                    widen(&mut ext, v);
                 }
             }
-        }
+            false
+        };
         if !percent {
-            for s in &ser {
-                if self.series_kind(s).stacked() {
-                    continue;
-                }
-                for y in s.trendline_ys(crate::trendline::series_is_scatter(self.series_kind(s))) {
-                    hi = hi.max(y);
-                    lo = lo.min(y);
-                }
-            }
+            self.fold_trendlines(&ser, &mut ext);
         }
         if percent {
-            lo = lo.min(0.0);
-            hi = hi.max(1.0);
+            ext.0 = ext.0.min(0.0);
+            ext.1 = ext.1.max(1.0);
         }
+        let (lo, hi) = ext;
         Some(if lo <= hi { (lo, hi) } else { (0.0, 0.0) })
     }
 
+    /// Widens `ext` by the points of the stacked and 100 % series in `ser`; returns whether a
+    /// 100 % series is among them.
+    fn fold_stacked(&self, ser: &[&Series], ext: &mut (f64, f64)) -> bool {
+        let mut percent = false;
+        let n = ser.iter().map(|s| s.values.len()).max().unwrap_or(0);
+        let budget = (ser.len() * n).min(10_000_000);
+        let n_clamped = if ser.is_empty() { 0 } else { n.min(budget / ser.len()) };
+        for i in 0..n_clamped {
+            let (mut p, mut m, mut stacked) = (0.0, 0.0, false);
+            for s in ser {
+                let k = self.series_kind(s);
+                let Some(v) = s.values.get(i).copied().flatten().filter(|v| v.is_finite()) else { continue };
+                if k.percent() {
+                    percent = true;
+                } else if k.stacked() {
+                    stacked = true;
+                    if v >= 0.0 { p += v } else { m += v }
+                } else {
+                    widen(ext, v);
+                }
+            }
+            if stacked {
+                ext.1 = ext.1.max(p);
+                ext.0 = ext.0.min(m);
+            }
+        }
+        percent
+    }
+
+    /// Widens `ext` by the trendlines of the series in `ser` that are not stacked.
+    fn fold_trendlines(&self, ser: &[&Series], ext: &mut (f64, f64)) {
+        for s in ser {
+            if self.series_kind(s).stacked() {
+                continue;
+            }
+            for y in s.trendline_ys(crate::trendline::series_is_scatter(self.series_kind(s))) {
+                widen(ext, y);
+            }
+        }
+    }
+
     /// A waterfall's bars as (from, to) on the value axis: each point floats from the running
     /// total, a total point stands on zero and sets it.
     pub fn waterfall_bars(&self) -> Vec<(f64, f64)> {
@@ -1346,6 +1355,12 @@ impl Chart {
     }
 }
 
+/// Widens the (min, max) extent `ext` to include `v`.
+fn widen(ext: &mut (f64, f64), v: f64) {
+    ext.0 = ext.0.min(v);
+    ext.1 = ext.1.max(v);
+}
+
 /// Excel's QUARTILE.EXC position `p·(n+1)` (1-based) on sorted data, clamped to the ends.
 fn quantile_exc(v: &[f64], p: f64) -> f64 {
     let n = v.len();

crates/render/src/table.rs

@@ -147,6 +147,86 @@ pub fn look(ctx: &Ctx, t: &Table, r: usize, c: usize) -> CellLook {
     look_with_def(ctx, resolve_style(ctx, t), t, r, c)
 }
 
+/// Which parts of the table a cell sits in, for the preset styles.
+#[derive(Clone, Copy)]
+struct PresetPart {
+    header: bool,
+    total: bool,
+    first_col: bool,
+    last_col: bool,
+    banded: bool,
+}
+
+impl PresetPart {
+    /// In a header, total, first or last column: the parts a preset style makes strong.
+    fn strong(self) -> bool {
+        self.header || self.total || self.first_col || self.last_col
+    }
+}
+
+/// Tint `k` of accent `a`.
+fn tint(a: Rgba, k: i32) -> Rgba {
+    deckcraft_color::apply(a, &[ColorTransform::Tint(k)])
+}
+
+fn light1_look(a: Rgba, p: PresetPart, on: impl Fn(Rgba) -> Rgba) -> CellLook {
+    let fill = p.banded.then(|| tint(a, 20000));
+    CellLook { fill, text: fill.map(on), bold: p.strong(), border: if p.header { Some((a, 1.0)) } else { None }, sides: [None; 4], paint: None }
+}
+
+fn light2_look(a: Rgba, p: PresetPart) -> CellLook {
+    CellLook {
+        fill: if p.header { Some(a) } else { None },
+        text: if p.header { Some(Rgba::WHITE) } else { None },
+        bold: p.header || p.total || p.first_col,
+        border: Some((a, 1.0)),
+        sides: [None; 4],
+        paint: None,
+    }
+}
+
+fn dark1_look(a: Rgba, p: PresetPart) -> CellLook {
+    CellLook {
+        fill: Some(if p.header {
+            Rgba::BLACK
+        } else if p.banded {
+            deckcraft_color::apply(a, &[ColorTransform::Shade(60000)])
+        } else {
+            deckcraft_color::apply(a, &[ColorTransform::Shade(75000)])
+        }),
+        text: Some(Rgba::WHITE),
+        bold: p.header || p.total || p.first_col,
+        border: Some((Rgba::WHITE, 1.0)),
+        sides: [None; 4],
+        paint: None,
+    }
+}
+
+fn medium4_look(a: Rgba, p: PresetPart, on: impl Fn(Rgba) -> Rgba) -> CellLook {
+    let fill = if p.header || p.banded { tint(a, 40000) } else { tint(a, 20000) };
+    CellLook { fill: Some(fill), text: Some(on(fill)), bold: p.strong(), border: Some((a, 0.75)), sides: [None; 4], paint: None }
+}
+
+/// medium2: strong header, banded light tints, white grid.
+fn medium2_look(a: Rgba, p: PresetPart, on: impl Fn(Rgba) -> Rgba) -> CellLook {
+    let strong = p.strong();
+    let fill = if strong {
+        a
+    } else if p.banded {
+        tint(a, 40000)
+    } else {
+        tint(a, 20000)
+    };
+    CellLook {
+        fill: Some(fill),
+        text: Some(if strong { Rgba::WHITE } else { on(fill) }),
+        bold: strong,
+        border: Some((Rgba::WHITE, 1.0)),
+        sides: [None; 4],
+        paint: None,
+    }
+}
+
 pub fn look_with_def(ctx: &Ctx, def: Option<&TableStyleDef>, t: &Table, r: usize, c: usize) -> CellLook {
     if let Some(def) = def {
         return look_def(ctx, def, t, r, c);
@@ -160,8 +240,7 @@ pub fn look_with_def(ctx: &Ctx, def: Option<&TableStyleDef>, t: &Table, r: usize
     let body_r = if t.first_row { r.wrapping_sub(1) } else { r };
     let band = t.band_row && !header && !total && body_r % 2 == 0;
     let band_c = t.band_col && c.is_multiple_of(2);
-    let tint = |k: i32| deckcraft_color::apply(a, &[ColorTransform::Tint(k)]);
-    let white = Rgba::WHITE;
+    let p = PresetPart { header, total, first_col, last_col, banded: band || band_c };
     let text_color = ctx.color(&ColorRef::scheme(SchemeSlot::Tx1), None);
     // Text on a tinted cell never inherits the text colour, which a dark theme makes light and
     // unreadable on the light tint: PowerPoint's medium styles set it to the theme's dark colour
@@ -173,69 +252,11 @@ pub fn look_with_def(ctx: &Ctx, def: Option<&TableStyleDef>, t: &Table, r: usize
     match kind {
         "none" => CellLook { fill: None, text: None, bold: false, border: None, sides: [None; 4], paint: None },
         "grid" => CellLook { fill: None, text: None, bold: false, border: Some((text_color, 0.75)), sides: [None; 4], paint: None },
-        "light1" => {
-            let fill = (band || band_c).then(|| tint(20000));
-            CellLook {
-                fill,
-                text: fill.map(on),
-                bold: header || total || first_col || last_col,
-                border: if header { Some((a, 1.0)) } else { None },
-                sides: [None; 4],
-                paint: None,
-            }
-        }
-        "light2" => CellLook {
-            fill: if header { Some(a) } else { None },
-            text: if header { Some(white) } else { None },
-            bold: header || total || first_col,
-            border: Some((a, 1.0)),
-            sides: [None; 4],
-            paint: None,
-        },
-        "dark1" => CellLook {
-            fill: Some(if header {
-                Rgba::BLACK
-            } else if band || band_c {
-                deckcraft_color::apply(a, &[ColorTransform::Shade(60000)])
-            } else {
-                deckcraft_color::apply(a, &[ColorTransform::Shade(75000)])
-            }),
-            text: Some(white),
-            bold: header || total || first_col,
-            border: Some((white, 1.0)),
-            sides: [None; 4],
-            paint: None,
-        },
-        "medium4" => {
-            let fill = if header || band || band_c { tint(40000) } else { tint(20000) };
-            CellLook {
-                fill: Some(fill),
-                text: Some(on(fill)),
-                bold: header || total || first_col || last_col,
-                border: Some((a, 0.75)),
-                sides: [None; 4],
-                paint: None,
-            }
-        }
-        _ => {
-            // medium2: strong header, banded light tints, white grid.
-            let strong = header || total || first_col || last_col;
-            let fill = if strong {
-                a
-            } else if band || band_c {
-                tint(40000)
-            } else {
-                tint(20000)
-            };
-            CellLook {
-                fill: Some(fill),
-                text: Some(if strong { white } else { on(fill) }),
-                bold: strong,
-                border: Some((white, 1.0)),
-                sides: [None; 4],
-                paint: None,
-            }
-        }
+        "light1" => light1_look(a, p, on),
+        "light2" => light2_look(a, p),
+        "dark1" => dark1_look(a, p),
+        "medium4" => medium4_look(a, p, on),
+        _ => medium2_look(a, p, on),
     }
 }