Docs: keep the progress table in one piece

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

Cargo.lock

@@ -1109,6 +1109,7 @@ dependencies = [
 name = "deckcraft-render"
 version = "0.6.1"
 dependencies = [
+ "deckcraft-anim",
  "deckcraft-color",
  "deckcraft-fonts",
  "deckcraft-geom",

ROADMAP.md

@@ -128,6 +128,8 @@ app's JSON control channel (`deckcraft --control PORT`).
 
 | Date | What landed |
 |---|---|
+| 2026-10-13 | Slide transitions like PowerPoint: every transition and option measured frame by frame against PowerPoint's video export and retuned (curves, directions, soft edges, 3-D perspective, contents moving over backgrounds); PowerPoint's own XML elements and defaults read and written (diagonal Wipe, Zoom, Shape In/Out, Glitter Hexagons, Shred In/Out, Page Curl Single); `deckcraft-cli render-transition` renders frames headless |
+| 2026-10-13 | Wild text cases measured against PowerPoint (102 synthetic slides): bidi by run language, East Asian vertical text upright, mongolianVert/wordArtVert/wordArtVertRtl, underline styles and strikethrough at the font's metrics, centre/right/decimal tabs, East Asian, Thai, Hindi, Arabic and Hebrew numbering, small caps, all-caps "ß", transparent text, soft hyphens, kinsoku, rtlCol and just/dist anchoring, emoji presentation, fallback faces that no longer move the baseline |
 | 2026-10-12 | Objects off the slide show and can be selected and moved around it in Normal view, as in PowerPoint; the show, exports and thumbnails still clip to the slide (#270) |
 | 2026-10-12 | Korean, Japanese and Chinese input: IME composition shown in place and underlined, one undo step per composition, candidate window at the caret (slide text, notes, fields); interface text (title, notes, outline, sections, comments) borrows installed fonts for scripts the interface fonts lack (#101) |
 | 2026-10-12 | Selection Pane like PowerPoint (#133): front-most first, groups fold, drag and drop restacks among siblings, Bring Forward / Send Backward, Show All / Hide All, eye, rename in place, keyboard; Lock (pane padlock, canvas menu) keeps objects from moving, sizing or rotating and round-trips PowerPoint's locking attributes |
@@ -147,6 +149,7 @@ app's JSON control channel (`deckcraft --control PORT`).
 
 | Date | Change | Summary |
 |---|---|---|
+| 2026-10-13 | trivial | Progress log: wild text cases |
 | 2026-10-12 | trivial | Progress log: File tab (Backstage, #76) |
 | 2026-10-12 | trivial | Progress log: lines in scaled groups (#233) |
 | 2026-10-10 | minor | Readiness-by-audience table with hours to ~95% for full, mainstream and essentials |

apps/deckcraft-cli/src/main.rs

@@ -3,6 +3,7 @@
 //! ```text
 //! deckcraft-cli info FILE                       # slides, titles, layouts (JSON)
 //! deckcraft-cli render (FILE | --sample) [--slide N | --all] [--scale S] OUT.png|OUT_DIR
+//! deckcraft-cli render-transition FILE --slide N --t T[,T…] [--width PX] OUT.png   # transition frame(s)
 //! deckcraft-cli convert IN OUT                  # .deckcraft ⇄ .pptx, outline .txt, .png (first slide)
 //! deckcraft-cli run [--in FILE | --sample] [--cmd ID[=JSON]]... [--save OUT] [--export OUT] [--print]
 //! deckcraft-cli commands [FILTER]               # list commands (JSON)
@@ -34,6 +35,7 @@ macro_rules! outln {
 
 const USAGE: &str = "usage: deckcraft-cli info FILE
        deckcraft-cli render (FILE | --sample) [--slide N | --all] [--scale S] [--edit] OUT
+       deckcraft-cli render-transition FILE --slide N --t T[,T...] [--width PX] OUT.png
        deckcraft-cli convert IN OUT
        deckcraft-cli run [--in FILE | --sample] [--cmd ID[=JSON]]... [--save OUT] [--export OUT] [--print]
        deckcraft-cli commands [FILTER]
@@ -52,6 +54,7 @@ fn main() -> ExitCode {
         }
         Some("info") => report(info(rest)),
         Some("render") => report(render(rest)),
+        Some("render-transition") => report(render_transition(rest)),
         Some("convert") => report(convert(rest)),
         Some("run") => report(run(rest)),
         Some("commands") => {
@@ -161,6 +164,80 @@ fn render(args: &[String]) -> Result<(), String> {
     Ok(())
 }
 
+/// Frames of slide N's transition (0-based N; from slide N-1, or black for the first slide) at
+/// the given progress values. With several values, OUT gets `-t<value>` before its extension.
+fn render_transition(args: &[String]) -> Result<(), String> {
+    use deckcraft_engine::render;
+    let mut input = None;
+    let mut slide: Option<usize> = None;
+    let mut ts: Vec<f64> = Vec::new();
+    let mut width: Option<f64> = None;
+    let mut out = None;
+    let mut it = args.iter();
+    while let Some(a) = it.next() {
+        match a.as_str() {
+            "--slide" => slide = Some(it.next().and_then(|v| v.parse().ok()).ok_or("--slide needs a number")?),
+            "--t" => {
+                let v = it.next().ok_or("--t needs a value")?;
+                for x in v.split(',') {
+                    let t: f64 = x.trim().parse().map_err(|_| format!("bad --t value `{x}`"))?;
+                    if !t.is_finite() {
+                        return Err(format!("bad --t value `{x}`"));
+                    }
+                    ts.push(t);
+                }
+            }
+            "--width" => {
+                width = Some(it.next().and_then(|v| v.parse().ok()).filter(|w: &f64| w.is_finite() && *w >= 1.0).ok_or("--width needs pixels")?)
+            }
+            other if input.is_none() => input = Some(other.to_string()),
+            other => out = Some(other.to_string()),
+        }
+    }
+    let input = input.ok_or("render-transition needs a FILE")?;
+    let out = out.ok_or("render-transition needs an output path")?;
+    let i = slide.ok_or("render-transition needs --slide N")?;
+    if ts.is_empty() {
+        return Err("render-transition needs --t".into());
+    }
+    let mut s = Session::new();
+    open(&mut s, Some(&input), false)?;
+    let st = s.doc().map_err(|e| e.to_string())?;
+    let doc = &st.doc;
+    let n = doc.slides.len();
+    let Some(sl) = doc.slides.get(i) else { return Err(format!("no slide {i} (the deck has {n})")) };
+    let sw = doc.slide_size.width.max(1.0);
+    let w = width.unwrap_or(sw * 2.0).min(render::MAX_SIDE as f64);
+    let opts = render::RenderOpts { scale: w / sw, ..Default::default() };
+    let tr = sl.transition.clone().unwrap_or_default();
+    // Render both slides once and composite every frame from them (morph re-renders per frame).
+    let prev = i.checked_sub(1);
+    let cached = (tr.kind != "morph").then(|| {
+        let parts = render::uses_slide_parts(&tr.kind, &tr.option).then(|| render::SlideParts::render(doc, prev, i, &opts));
+        (prev.map(|p| render::render_slide(doc, p, &opts)), render::render_slide(doc, i, &opts), parts)
+    });
+    let aspect = sw / doc.slide_size.height.max(1.0);
+    for t in &ts {
+        let img = match &cached {
+            Some((old, new, parts)) => {
+                render::composite_transition(old.as_ref(), new, parts.as_ref(), &render::transition_frame(&tr.kind, &tr.option, *t, aspect))
+            }
+            None => render::render_transition(doc, i, *t, &opts),
+        };
+        let path = if ts.len() == 1 {
+            out.clone()
+        } else {
+            let p = std::path::Path::new(&out);
+            let stem = p.file_stem().and_then(|x| x.to_str()).unwrap_or("frame");
+            let name = format!("{stem}-t{t:.3}.png");
+            p.with_file_name(name).to_string_lossy().into_owned()
+        };
+        std::fs::write(&path, img.to_png()).map_err(|e| format!("{path}: {e}"))?;
+        outln!("{path} ({}×{}) {} {} t={t}", img.width, img.height, tr.kind, tr.option);
+    }
+    Ok(())
+}
+
 fn convert(args: &[String]) -> Result<(), String> {
     let (Some(input), Some(out)) = (args.first(), args.get(1)) else { return Err("convert needs IN and OUT".into()) };
     let mut s = Session::new();

crates/anim/src/lib.rs

@@ -14,24 +14,30 @@
 
 mod easing;
 mod effects;
+mod mesh;
 mod morph;
 mod path;
 mod show;
 mod timeline;
 mod transition;
+mod transition_fx;
+mod transition_geom;
 
 #[cfg(test)]
 mod tests;
+#[cfg(test)]
+mod transition_tests;
 
 pub use deckcraft_model::Rgba;
 use serde::{Deserialize, Serialize};
 
 pub use easing::ease;
+pub use mesh::{MeshVertex, layer_mesh};
 pub use morph::{MorphFrame, MorphPath, MorphText, morph_frame, morph_pairs, morph_xfrm};
 pub use path::{MotionPath, default_path};
 pub use show::{LinkJump, ShowAction, ShowState, safe_url, show_order};
 pub use timeline::{EffectTiming, Sequence, Timeline, TriggerPlay};
-pub use transition::{Layer, Source, transition_layers};
+pub use transition::{DEFAULT_ASPECT, Layer, Source, transition_frame, transition_layers, uses_slide_parts};
 
 /// Animation state of one shape (or one paragraph of a shape's text) at one moment of the show.
 ///

crates/anim/src/mesh.rs

@@ -0,0 +1,139 @@
+//! Triangle meshes for transition layers.
+//!
+//! A [`Layer`] is a textured quad. Drawn as two triangles, a trapezoid (a slide seen in
+//! perspective) bends its texture along the diagonal, because GPUs and simple rasterisers
+//! interpolate texture coordinates linearly in screen space. [`layer_mesh`] splits such quads into a
+//! grid whose vertices follow the projective map from the source rectangle to the quad, so the
+//! picture looks like a flat card turned in 3-D. Rectangles and parallelograms stay two triangles,
+//! wedges one: the per-frame cost stays a handful of vertices per layer.
+
+use crate::transition::Layer;
+
+/// One mesh vertex: position in slide-unit space (0..1, y down), texture coordinate (0..1) and
+/// opacity (the layer's alpha times its corner fade, interpolated).
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub struct MeshVertex {
+    pub pos: [f64; 2],
+    pub uv: [f64; 2],
+    pub a: f64,
+}
+
+/// Grid cells per side for quads that need a projective subdivision.
+const GRID: usize = 8;
+
+/// The triangles of a layer: vertices and index triples into them.
+pub fn layer_mesh(l: &Layer) -> (Vec<MeshVertex>, Vec<[u32; 3]>) {
+    let q = l.quad;
+    let uv = l.uv;
+    let fa = l.fade.map(|f| f * l.alpha);
+    // A wedge (triangle): the 4th corner repeats the 3rd.
+    if q[3] == q[2] && uv[3] == uv[2] {
+        let v = (0..3).map(|k| MeshVertex { pos: q[k], uv: uv[k], a: fa[k] }).collect();
+        return (v, vec![[0, 1, 2]]);
+    }
+    let affine = {
+        // Parallelogram: opposite edges equal.
+        let e1 = [q[1][0] - q[0][0], q[1][1] - q[0][1]];
+        let e2 = [q[2][0] - q[3][0], q[2][1] - q[3][1]];
+        (e1[0] - e2[0]).abs() < 1e-9 && (e1[1] - e2[1]).abs() < 1e-9
+    };
+    let h = if affine { None } else { square_to_quad(q) };
+    let Some(h) = h else {
+        let v = (0..4).map(|k| MeshVertex { pos: q[k], uv: uv[k], a: fa[k] }).collect();
+        return (v, vec![[0, 1, 2], [0, 2, 3]]);
+    };
+    // Small quads (tiles, shards) bend their texture too little to matter: fewer cells.
+    let span = q.iter().flat_map(|p| q.iter().map(move |r| (p[0] - r[0]).abs().max((p[1] - r[1]).abs()))).fold(0.0, f64::max);
+    let n = ((span * 2.0 * GRID as f64).ceil() as usize).clamp(1, GRID);
+    let mut v = Vec::with_capacity((n + 1) * (n + 1));
+    for j in 0..=n {
+        let b = j as f64 / n as f64;
+        for i in 0..=n {
+            let a = i as f64 / n as f64;
+            // Texture: bilinear in (a, b) over the four uv corners (exact for rectangles).
+            let top = lerp2(uv[0], uv[1], a);
+            let bot = lerp2(uv[3], uv[2], a);
+            let t = lerp2(top, bot, b);
+            let at = fa[0] + (fa[1] - fa[0]) * a;
+            let ab = fa[3] + (fa[2] - fa[3]) * a;
+            v.push(MeshVertex { pos: apply(&h, a, b), uv: t, a: at + (ab - at) * b });
+        }
+    }
+    let mut tris = Vec::with_capacity(n * n * 2);
+    let w = (n + 1) as u32;
+    for j in 0..n as u32 {
+        for i in 0..n as u32 {
+            let p = j * w + i;
+            tris.push([p, p + 1, p + w + 1]);
+            tris.push([p, p + w + 1, p + w]);
+        }
+    }
+    (v, tris)
+}
+
+fn lerp2(a: [f64; 2], b: [f64; 2], t: f64) -> [f64; 2] {
+    [a[0] + (b[0] - a[0]) * t, a[1] + (b[1] - a[1]) * t]
+}
+
+/// Projective map taking the unit square's corners (0,0), (1,0), (1,1), (0,1) to `q`'s tl, tr, br,
+/// bl (Heckbert's square-to-quad). `None` when the quad is degenerate.
+fn square_to_quad(q: [[f64; 2]; 4]) -> Option<[f64; 8]> {
+    let [[x0, y0], [x1, y1], [x2, y2], [x3, y3]] = q;
+    let sx = x0 - x1 + x2 - x3;
+    let sy = y0 - y1 + y2 - y3;
+    let (dx1, dx2, dy1, dy2) = (x1 - x2, x3 - x2, y1 - y2, y3 - y2);
+    let den = dx1 * dy2 - dx2 * dy1;
+    if !den.is_finite() || den.abs() < 1e-12 {
+        return None;
+    }
+    let g = (sx * dy2 - dx2 * sy) / den;
+    let h = (dx1 * sy - sx * dy1) / den;
+    let m = [x1 - x0 + g * x1, x3 - x0 + h * x3, x0, y1 - y0 + g * y1, y3 - y0 + h * y3, y0, g, h];
+    m.iter().all(|v| v.is_finite()).then_some(m)
+}
+
+fn apply(m: &[f64; 8], u: f64, v: f64) -> [f64; 2] {
+    let w = m[6] * u + m[7] * v + 1.0;
+    let w = if w.abs() < 1e-9 { 1e-9_f64.copysign(w) } else { w };
+    [(m[0] * u + m[1] * v + m[2]) / w, (m[3] * u + m[4] * v + m[5]) / w]
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::transition::{Layer, Source};
+
+    #[test]
+    fn rect_is_two_triangles() {
+        let (v, t) = layer_mesh(&Layer::full(Source::New, 1.0));
+        assert_eq!((v.len(), t.len()), (4, 2));
+    }
+
+    #[test]
+    fn trapezoid_is_subdivided_projectively() {
+        // A card turned about its left edge: the right edge is shorter.
+        let q = [[0.0, 0.0], [0.6, 0.2], [0.6, 0.8], [0.0, 1.0]];
+        let l = Layer::quad(Source::Old, [0.0, 0.0, 1.0, 1.0], q, 1.0);
+        let (v, t) = layer_mesh(&l);
+        assert_eq!(v.len(), (GRID + 1) * (GRID + 1));
+        assert_eq!(t.len(), GRID * GRID * 2);
+        // A small tile in perspective needs no more than a couple of triangles.
+        let small = Layer::quad(Source::Old, [0.0, 0.0, 1.0, 1.0], [[0.5, 0.5], [0.52, 0.505], [0.52, 0.515], [0.5, 0.52]], 1.0);
+        assert!(layer_mesh(&small).1.len() <= 2);
+        // Corners land on the quad's corners.
+        assert_eq!(v[0].pos, q[0]);
+        let last = v[v.len() - 1].pos;
+        assert!((last[0] - 0.6).abs() < 1e-9 && (last[1] - 0.8).abs() < 1e-9);
+        // The texture's middle column sits nearer the far (short) edge than halfway: foreshortening.
+        let mid = v[GRID / 2].pos[0];
+        assert!(mid > 0.3, "{mid}");
+    }
+
+    #[test]
+    fn degenerate_quads_do_not_blow_up() {
+        let q = [[0.5, 0.5]; 4];
+        let l = Layer::quad(Source::Old, [0.0, 0.0, 1.0, 1.0], q, 1.0);
+        let (v, _) = layer_mesh(&l);
+        assert!(v.iter().all(|p| p.pos[0].is_finite() && p.pos[1].is_finite()));
+    }
+}

crates/anim/src/transition.rs

@@ -1,15 +1,18 @@
 //! Slide transitions as layers of textured quads.
 //!
 //! A frame is drawn over black: each [`Layer`] maps part of a source image (old slide, new slide,
-//! or a solid colour) onto a quad in slide-unit space (0..1, y down). Fake 3-D comes from
-//! trapezoids; wedges are triangles (4th corner repeats the 3rd).
-
-use std::f64::consts::PI;
+//! their backgrounds or contents alone, or a solid colour) onto a quad in slide-unit space (0..1, y
+//! down), with an opacity per corner. Perspective comes from projecting 3-D cards
+//! ([`crate::layer_mesh`] keeps their textures straight); soft edges come from per-corner opacity
+//! ramps; wedges are triangles (4th corner repeats the 3rd).
+//!
+//! The motions, curves, directions and option meanings were measured frame by frame on
+//! PowerPoint's video export of synthetic decks (`plan/powerpoint/tools/synth_transitions.ps1`).
+//! The effects themselves live in [`crate::transition_fx`].
 
 use serde::{Deserialize, Serialize};
 
 use crate::clampf;
-use crate::easing::smooth;
 
 /// What a layer shows.
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, Serialize, Deserialize)]
@@ -20,6 +23,35 @@ pub enum Source {
     New,
     Black,
     White,
+    /// The outgoing slide's background (background fill plus master and layout graphics) alone.
+    OldBack,
+    /// The incoming slide's background alone.
+    NewBack,
+    /// The outgoing slide's own shapes alone, over transparency.
+    OldContent,
+    /// The incoming slide's own shapes alone, over transparency.
+    NewContent,
+}
+
+impl Source {
+    /// The whole-slide source to draw instead when the parts aren't available: a background
+    /// becomes its slide, content becomes nothing.
+    pub fn whole(self) -> Option<Source> {
+        match self {
+            Source::OldBack => Some(Source::Old),
+            Source::NewBack => Some(Source::New),
+            Source::OldContent | Source::NewContent => None,
+            s => Some(s),
+        }
+    }
+    /// Does this source need the slide rendered in parts (background / content)?
+    pub fn is_part(self) -> bool {
+        matches!(self, Source::OldBack | Source::NewBack | Source::OldContent | Source::NewContent)
+    }
+}
+
+fn ones() -> [f64; 4] {
+    [1.0; 4]
 }
 
 /// One textured quad of a transition frame.
@@ -34,12 +66,18 @@ pub struct Layer {
     /// are the corners of `src`; triangles and mirrored flaps carry their own. Draw with these.
     pub uv: [[f64; 2]; 4],
     pub alpha: f64,
+    /// Opacity of each corner (tl, tr, br, bl), multiplied by `alpha` and interpolated across the
+    /// quad: soft edges and feathered masks.
+    #[serde(default = "ones")]
+    pub fade: [f64; 4],
 }
 
-type R = [f64; 4];
-const FULL: R = [0.0, 0.0, 1.0, 1.0];
+pub(crate) type R = [f64; 4];
+pub(crate) type P = [f64; 2];
+pub(crate) type Q = [[f64; 2]; 4];
+pub(crate) const FULL: R = [0.0, 0.0, 1.0, 1.0];
 
-fn corners(r: R) -> [[f64; 2]; 4] {
+pub(crate) fn corners(r: R) -> Q {
     [[r[0], r[1]], [r[2], r[1]], [r[2], r[3]], [r[0], r[3]]]
 }
 
@@ -50,23 +88,39 @@ impl Layer {
     }
     /// `src` rectangle of the source drawn into the `dst` rectangle.
     pub fn rect(source: Source, src: R, dst: R, alpha: f64) -> Layer {
-        Layer { source, src, quad: corners(dst), uv: corners(src), alpha }
+        Layer { source, src, quad: corners(dst), uv: corners(src), alpha, fade: ones() }
     }
     /// `src` rectangle of the source drawn onto a quad.
-    pub fn quad(source: Source, src: R, quad: [[f64; 2]; 4], alpha: f64) -> Layer {
-        Layer { source, src, quad, uv: corners(src), alpha }
+    pub fn quad(source: Source, src: R, quad: Q, alpha: f64) -> Layer {
+        Layer { source, src, quad, uv: corners(src), alpha, fade: ones() }
     }
     /// The part of the source under `dst` drawn in place.
-    fn inplace(source: Source, dst: R, alpha: f64) -> Layer {
+    pub(crate) fn inplace(source: Source, dst: R, alpha: f64) -> Layer {
         Layer::rect(source, dst, dst, alpha)
     }
-    /// A triangle of the source drawn in place.
-    fn tri(source: Source, a: [f64; 2], b: [f64; 2], c: [f64; 2], alpha: f64) -> Layer {
-        let xs = [a[0], b[0], c[0]];
-        let ys = [a[1], b[1], c[1]];
+    /// A triangle with its own texture coordinates and corner opacities.
+    pub(crate) fn tri_uv(source: Source, p: [P; 3], uv: [P; 3], fade: [f64; 3], alpha: f64) -> Layer {
+        let xs = [uv[0][0], uv[1][0], uv[2][0]];
+        let ys = [uv[0][1], uv[1][1], uv[2][1]];
         let mn = |v: [f64; 3]| v.iter().copied().fold(f64::INFINITY, f64::min);
         let mx = |v: [f64; 3]| v.iter().copied().fold(f64::NEG_INFINITY, f64::max);
-        Layer { source, src: [mn(xs), mn(ys), mx(xs), mx(ys)], quad: [a, b, c, c], uv: [a, b, c, c], alpha }
+        Layer {
+            source,
+            src: [mn(xs), mn(ys), mx(xs), mx(ys)],
+            quad: [p[0], p[1], p[2], p[2]],
+            uv: [uv[0], uv[1], uv[2], uv[2]],
+            alpha,
+            fade: [fade[0], fade[1], fade[2], fade[2]],
+        }
+    }
+    /// With corner opacities.
+    pub(crate) fn faded(mut self, fade: [f64; 4]) -> Layer {
+        self.fade = fade;
+        self
+    }
+    /// A black copy of this layer's shape at `k` of its opacity: shading a card.
+    pub(crate) fn shade(&self, k: f64) -> Layer {
+        Layer { source: Source::Black, alpha: self.alpha * k.clamp(0.0, 1.0), ..*self }
     }
     fn sanitized(mut self) -> Layer {
         let f = |v: f64| if v.is_finite() { v.clamp(-1.0e6, 1.0e6) } else { 0.0 };
@@ -81,827 +135,48 @@ impl Layer {
             c[0] = c[0].clamp(0.0, 1.0);
             c[1] = c[1].clamp(0.0, 1.0);
         }
+        for a in self.fade.iter_mut() {
+            *a = clampf(*a, 0.0, 1.0, 0.0);
+        }
         self.alpha = clampf(self.alpha, 0.0, 1.0, 0.0);
         self
     }
 }
 
-// ---------- geometry helpers ----------
-
-fn offset(r: R, dx: f64, dy: f64) -> R {
-    [r[0] + dx, r[1] + dy, r[2] + dx, r[3] + dy]
-}
-
-fn moved(source: Source, dx: f64, dy: f64, alpha: f64) -> Layer {
-    Layer::rect(source, FULL, offset(FULL, dx, dy), alpha)
-}
-
-/// The whole source scaled about (cx, cy) and moved.
-fn scaled(source: Source, s: f64, cx: f64, cy: f64, dx: f64, dy: f64, alpha: f64) -> Layer {
-    let r = [cx + (0.0 - cx) * s + dx, cy + (0.0 - cy) * s + dy, cx + (1.0 - cx) * s + dx, cy + (1.0 - cy) * s + dy];
-    Layer::rect(source, FULL, r, alpha)
-}
-
-/// Rotate a point about a pivot (degrees).
-fn rot(p: [f64; 2], c: [f64; 2], deg: f64) -> [f64; 2] {
-    let (s, co) = deg.to_radians().sin_cos();
-    let (x, y) = (p[0] - c[0], p[1] - c[1]);
-    [c[0] + x * co - y * s, c[1] + x * s + y * co]
-}
-
-fn rot_quad(q: [[f64; 2]; 4], c: [f64; 2], deg: f64) -> [[f64; 2]; 4] {
-    [rot(q[0], c, deg), rot(q[1], c, deg), rot(q[2], c, deg), rot(q[3], c, deg)]
-}
-
-/// Horizontal perspective: left/right edges shortened by `li`/`ri` (fraction of height, each end).
-fn persp_h(r: R, li: f64, ri: f64) -> [[f64; 2]; 4] {
-    let h = r[3] - r[1];
-    [[r[0], r[1] + li * h], [r[2], r[1] + ri * h], [r[2], r[3] - ri * h], [r[0], r[3] - li * h]]
-}
-
-/// Vertical perspective: top/bottom edges shortened by `ti`/`bi` (fraction of width, each end).
-fn persp_v(r: R, ti: f64, bi: f64) -> [[f64; 2]; 4] {
-    let w = r[2] - r[0];
-    [[r[0] + ti * w, r[1]], [r[2] - ti * w, r[1]], [r[2] - bi * w, r[3]], [r[0] + bi * w, r[3]]]
-}
-
-/// Mirror a rectangle horizontally and/or vertically, or swap its axes (canonical → direction).
-fn map_rect(r: R, mx: bool, my: bool, swap: bool) -> R {
-    let mut r = if swap { [r[1], r[0], r[3], r[2]] } else { r };
-    if mx {
-        r = [1.0 - r[2], r[1], 1.0 - r[0], r[3]];
-    }
-    if my {
-        r = [r[0], 1.0 - r[3], r[2], 1.0 - r[1]];
-    }
-    r
-}
-
-/// Motion direction of an option: l, r, u, d and diagonals.
-fn dir(opt: &str, default: (f64, f64)) -> (f64, f64) {
-    let mut d = (0.0, 0.0);
-    if opt.contains('l') {
-        d.0 = -1.0;
-    }
-    if opt.contains('r') {
-        d.0 = 1.0;
-    }
-    if opt.contains('u') {
-        d.1 = -1.0;
-    }
-    if opt.contains('d') {
-        d.1 = 1.0;
-    }
-    if d == (0.0, 0.0) { default } else { d }
-}
-
-fn hash64(mut x: u64) -> u64 {
-    x = x.wrapping_add(0x9E37_79B9_7F4A_7C15);
-    x = (x ^ (x >> 30)).wrapping_mul(0xBF58_476D_1CE4_E5B9);
-    x = (x ^ (x >> 27)).wrapping_mul(0x94D0_49BB_1331_11EB);
-    x ^ (x >> 31)
-}
-
-/// Deterministic pseudo-random value in [0, 1).
-fn rnd(i: u64) -> f64 {
-    (hash64(i) >> 11) as f64 / (1u64 << 53) as f64
-}
-
-fn ramp(t: f64, order: f64, window: f64) -> f64 {
-    let w = window.clamp(0.01, 1.0);
-    ((t - order * (1.0 - w)) / w).clamp(0.0, 1.0)
-}
-
-fn grid(cols: usize, rows: usize) -> Vec<(usize, usize, R)> {
-    let mut v = Vec::with_capacity(cols * rows);
-    for r in 0..rows {
-        for c in 0..cols {
-            let cell = [c as f64 / cols as f64, r as f64 / rows as f64, (c + 1) as f64 / cols as f64, (r + 1) as f64 / rows as f64];
-            v.push((c, r, cell));
-        }
-    }
-    v
-}
-
-fn center(r: R) -> [f64; 2] {
-    [(r[0] + r[2]) / 2.0, (r[1] + r[3]) / 2.0]
-}
-
-fn scale_rect(r: R, s: f64) -> R {
-    let c = center(r);
-    let hw = (r[2] - r[0]) / 2.0 * s;
-    let hh = (r[3] - r[1]) / 2.0 * s;
-    [c[0] - hw, c[1] - hh, c[0] + hw, c[1] + hh]
-}
-
-// ---------- effects ----------
+/// Slide aspect assumed by [`transition_layers`] (16:9).
+pub const DEFAULT_ASPECT: f64 = 16.0 / 9.0;
 
 /// Layers of the transition `kind` (a [`deckcraft_model::anim::TRANSITIONS`] id) with `option` at
-/// progress `t` (0..1). Draw in order over black. At `t >= 1` the result is the new slide alone;
-/// at `t <= 0` (or NaN) the old slide alone. Morph returns a plain crossfade (the UI renders morph
-/// frames with [`crate::morph_frame`]).
+/// progress `t` (0..1) on a 16:9 slide. See [`transition_frame`].
 pub fn transition_layers(kind: &str, option: &str, t: f64) -> Vec<Layer> {
+    transition_frame(kind, option, t, DEFAULT_ASPECT)
+}
+
+/// Layers of the transition `kind` with `option` at linear progress `t` (0..1; the effect applies
+/// its own easing) on a slide `aspect` wide per unit of height. Draw in order over black. At
+/// `t >= 1` the result is the new slide alone; at `t <= 0` (or NaN) the old slide alone. Morph
+/// returns a plain crossfade (the UI renders morph frames with [`crate::morph_frame`]). Layers
+/// with [`Source::is_part`] sources need the slides rendered as background and content
+/// ([`uses_slide_parts`]).
+pub fn transition_frame(kind: &str, option: &str, t: f64, aspect: f64) -> Vec<Layer> {
     let t = clampf(t, 0.0, 1.0, 0.0);
+    let aspect = if aspect.is_finite() && aspect > 0.01 { aspect.min(100.0) } else { DEFAULT_ASPECT };
     let v = if t >= 1.0 {
         vec![Layer::full(Source::New, 1.0)]
     } else if t <= 0.0 {
         vec![Layer::full(Source::Old, 1.0)]
     } else {
-        layers(kind, option, t, 0)
+        crate::transition_fx::layers(kind, option, t, aspect, 0)
     };
-    v.into_iter().map(Layer::sanitized).filter(|l| l.alpha > 0.0).collect()
+    v.into_iter().map(Layer::sanitized).filter(|l| l.alpha > 0.0 && l.fade.iter().any(|a| *a > 0.0)).collect()
 }
 
-fn crossfade(t: f64) -> Vec<Layer> {
-    vec![Layer::full(Source::Old, 1.0), Layer::full(Source::New, t)]
-}
-
-const RANDOM_KINDS: &[&str] = &[
-    "fade",
-    "push",
-    "wipe",
-    "split",
-    "reveal",
-    "randomBar",
-    "shape",
-    "uncover",
-    "cover",
-    "fallOver",
-    "drape",
-    "curtains",
-    "wind",
-    "prestige",
-    "fracture",
-    "crush",
-    "peelOff",
-    "pageCurlDouble",
-    "airplane",
-    "origami",
-    "dissolve",
-    "checker",
-    "blinds",
-    "clock",
-    "ripple",
-    "honeycomb",
-    "glitter",
-    "vortex",
-    "shred",
-    "switch",
-    "flip",
-    "gallery",
-    "cube",
-    "doors",
-    "box",
-    "comb",
-    "zoom",
-    "pan",
-    "ferris",
-    "conveyor",
-    "rotate",
-    "window",
-    "orbit",
-    "flythrough",
-];
-
-fn layers(kind: &str, option: &str, t: f64, depth: u32) -> Vec<Layer> {
-    use Source::{Black, New, Old, White};
-    let o = option;
-    let s = smooth(t);
+/// Does `kind` animate the slides' backgrounds and contents separately (PowerPoint's Dynamic
+/// Content transitions and Reveal)? Then the frame uses [`Source::OldBack`] & co.
+pub fn uses_slide_parts(kind: &str, option: &str) -> bool {
     match kind {
-        "none" => vec![Layer::full(New, 1.0)],
-        "cut" => {
-            if o == "throughBlack" && t < 0.5 {
-                vec![Layer::full(Black, 1.0)]
-            } else {
-                vec![Layer::full(New, 1.0)]
-            }
-        }
-        "fade" if o == "throughBlack" => {
-            if t < 0.5 {
-                vec![Layer::full(Black, 1.0), Layer::full(Old, 1.0 - 2.0 * t)]
-            } else {
-                vec![Layer::full(Black, 1.0), Layer::full(New, 2.0 * t - 1.0)]
-            }
-        }
-        "fade" | "morph" => crossfade(t),
-        "push" | "pan" => {
-            let (dx, dy) = dir(o, (0.0, -1.0));
-            vec![moved(Old, dx * s, dy * s, 1.0), moved(New, dx * (s - 1.0), dy * (s - 1.0), 1.0)]
-        }
-        "uncover" => {
-            let (dx, dy) = dir(o, (-1.0, 0.0));
-            vec![Layer::full(New, 1.0), moved(Old, dx * s, dy * s, 1.0)]
-        }
-        "cover" => {
-            let (dx, dy) = dir(o, (-1.0, 0.0));
-            vec![Layer::full(Old, 1.0), moved(New, dx * (s - 1.0), dy * (s - 1.0), 1.0)]
-        }
-        "wipe" => wipe(o, t),
-        "split" => {
-            let horz = o.starts_with("horz");
-            let mut v = vec![Layer::full(Old, 1.0)];
-            let rects: Vec<R> = if o.ends_with("In") {
-                vec![[0.0, 0.0, s / 2.0, 1.0], [1.0 - s / 2.0, 0.0, 1.0, 1.0]]
-            } else {
-                vec![[0.5 - s / 2.0, 0.0, 0.5 + s / 2.0, 1.0]]
-            };
-            for r in rects {
-                v.push(Layer::inplace(New, map_rect(r, false, false, horz), 1.0));
-            }
-            v
-        }
-        "reveal" => {
-            let dx = if o.ends_with("Right") { 1.0 } else { -1.0 };
-            if o.starts_with("black") {
-                if t < 0.5 {
-                    vec![Layer::full(Black, 1.0), moved(Old, dx * t * 0.4, 0.0, 1.0 - 2.0 * t)]
-                } else {
-                    vec![Layer::full(Black, 1.0), moved(New, -dx * (1.0 - t) * 0.2, 0.0, 2.0 * t - 1.0)]
-                }
-            } else {
-                vec![Layer::full(New, 1.0), moved(Old, dx * s * 0.6, 0.0, 1.0 - t)]
-            }
-        }
-        "randomBar" => {
-            let horz = o == "horz";
-            let n = 48;
-            let mut v = vec![Layer::full(Old, 1.0)];
-            for i in 0..n {
-                if t > rnd(i as u64 + 17) * 0.98 {
-                    let r = [i as f64 / n as f64, 0.0, (i + 1) as f64 / n as f64, 1.0];
-                    v.push(Layer::inplace(New, map_rect(r, false, false, horz), 1.0));
-                }
-            }
-            v
-        }
-        "shape" => {
-            let form = match o {
-                "circle" | "diamond" | "plus" => o,
-                _ => "box",
-            };
-            let inward = o == "in";
-            if inward {
-                let mut v = vec![Layer::full(New, 1.0)];
-                v.extend(shape_form(Old, form, 1.0 - s));
-                v
-            } else {
-                let mut v = vec![Layer::full(Old, 1.0)];
-                v.extend(shape_form(New, form, s));
-                v
-            }
-        }
-        "flash" => {
-            if t < 0.5 {
-                vec![Layer::full(Old, 1.0), Layer::full(White, (2.0 * t).min(1.0))]
-            } else {
-                vec![Layer::full(New, 1.0), Layer::full(White, 2.0 - 2.0 * t)]
-            }
-        }
-        "fallOver" => {
-            let sg = if o == "r" { 1.0 } else { -1.0 };
-            let a = t * t * PI / 2.0;
-            let top = 1.0 - a.cos();
-            let ins = 0.12 * a.sin();
-            let sh = sg * 0.15 * a.sin();
-            let q = [[ins + sh, top], [1.0 - ins + sh, top], [1.0, 1.0], [0.0, 1.0]];
-            vec![Layer::full(New, 1.0), Layer::quad(Old, FULL, q, 1.0 - t.powi(3))]
-        }
-        "drape" => {
-            let k = t * t;
-            let q = [[0.0, 0.0], [1.0 - 0.3 * k, k], [1.0 - 0.3 * k, 1.0 + k], [0.0, 1.0]];
-            let q = if o == "r" { mirror_q(q) } else { q };
-            vec![Layer::full(New, 1.0), Layer::quad(Old, FULL, q, 1.0 - k)]
-        }
-        "curtains" => {
-            let w = 0.5 * (1.0 - s);
-            let lq = [[0.0, 0.0], [w, 0.12 * s], [w, 1.0 - 0.12 * s], [0.0, 1.0]];
-            let rq = [[1.0 - w, 0.12 * s], [1.0, 0.0], [1.0, 1.0], [1.0 - w, 1.0 - 0.12 * s]];
-            vec![
-                scaled(New, 0.9 + 0.1 * s, 0.5, 0.5, 0.0, 0.0, 1.0),
-                Layer::quad(Old, [0.0, 0.0, 0.5, 1.0], lq, 1.0),
-                Layer::quad(Old, [0.5, 0.0, 1.0, 1.0], rq, 1.0),
-            ]
-        }
-        "wind" => {
-            let d = if o == "r" { 1.0 } else { -1.0 };
-            let r = offset(FULL, d * 1.2 * s, -0.1 * s);
-            let q = [[r[0] + d * 0.2 * s, r[1]], [r[2] + d * 0.2 * s, r[1]], [r[2], r[3]], [r[0], r[3]]];
-            vec![moved(New, -d * 0.3 * (1.0 - s), 0.0, smooth((t * 1.5).min(1.0))), Layer::quad(Old, FULL, q, 1.0 - t)]
-        }
-        "prestige" => vec![scaled(Old, 1.0 - 0.3 * s, 0.5, 0.5, 0.0, 0.2 * s, 1.0 - t), scaled(New, 0.7 + 0.3 * s, 0.5, 0.5, 0.0, 0.0, s)],
-        "fracture" => {
-            let mut v = vec![Layer::full(New, 1.0)];
-            for (c, r, cell) in grid(8, 6) {
-                let i = (r * 8 + c) as u64;
-                let q = ramp(t, rnd(i + 101) * 0.5, 0.5);
-                let cc = center(cell);
-                let (dx, dy) = ((cc[0] - 0.5) * 1.5 * q, (cc[1] - 0.5) * 1.5 * q + 0.5 * q * q);
-                let quad = rot_quad(corners(offset(cell, dx, dy)), [cc[0] + dx, cc[1] + dy], (rnd(i + 7) - 0.5) * 180.0 * q);
-                v.push(Layer::quad(Old, cell, quad, 1.0 - q));
-            }
-            v
-        }
-        "crush" => {
-            let mut v = vec![Layer::full(New, 1.0)];
-            for (c, r, cell) in grid(4, 4) {
-                let i = (r * 4 + c) as u64;
-                let cc = center(cell);
-                let k = 1.0 - s;
-                let pos = [0.5 + (cc[0] - 0.5) * k, 0.5 + (cc[1] - 0.5) * k];
-                let half = scale_rect(cell, k * (0.8 + 0.2 * rnd(i + 3)));
-                let half = offset(half, pos[0] - cc[0], pos[1] - cc[1]);
-                let quad = rot_quad(corners(half), pos, (rnd(i + 5) - 0.5) * 60.0 * s);
-                v.push(Layer::quad(Old, cell, quad, 1.0 - t * t));
-            }
-            v
-        }
-        "peelOff" => {
-            let mut v = vec![Layer::full(New, 1.0)];
-            v.extend(peel(Old, [0.0, 0.0, 1.0, 1.0], s, o == "r"));
-            v
-        }
-        "pageCurlDouble" => {
-            let mut v = vec![Layer::full(New, 1.0)];
-            let left_first = o != "r";
-            v.extend(peel(Old, [0.0, 0.0, 0.5, 1.0], s, !left_first));
-            v.extend(peel(Old, [0.5, 0.0, 1.0, 1.0], s, left_first));
-            v
-        }
-        "airplane" => {
-            let d = if o == "r" { 1.0 } else { -1.0 };
-            let k = 1.0 - 0.8 * s;
-            let r = offset(scale_rect(FULL, k), d * 1.2 * s * s, -0.5 * s * s);
-            let q = persp_h(r, if d > 0.0 { 0.3 * s } else { 0.0 }, if d > 0.0 { 0.0 } else { 0.3 * s });
-            vec![Layer::full(New, 1.0), Layer::quad(Old, FULL, q, 1.0 - t * t)]
-        }
-        "origami" => {
-            let d = if o == "r" { 1.0 } else { -1.0 };
-            let mut v = vec![Layer::full(New, 1.0)];
-            if t < 0.5 {
-                let f = t * 2.0;
-                let w = 0.5 * (1.0 - 0.8 * f);
-                v.push(Layer::quad(Old, [0.0, 0.0, 0.5, 1.0], persp_h([0.5 - w, 0.0, 0.5, 1.0], 0.15 * f, 0.0), 1.0));
-                v.push(Layer::quad(Old, [0.5, 0.0, 1.0, 1.0], persp_h([0.5, 0.0, 0.5 + w, 1.0], 0.0, 0.15 * f), 1.0));
-            } else {
-                let f = (t - 0.5) * 2.0;
-                let r = offset(scale_rect([0.4, 0.0, 0.6, 1.0], 1.0 - 0.6 * f), d * f * 0.8, -0.3 * f);
-                v.push(Layer::quad(Old, FULL, persp_v(r, 0.1, 0.0), 1.0 - f));
-            }
-            v
-        }
-        "dissolve" => {
-            let mut v = vec![Layer::full(Old, 1.0)];
-            for (c, r, cell) in grid(32, 18) {
-                if t > rnd((r * 32 + c) as u64 + 991) * 0.98 {
-                    v.push(Layer::inplace(New, cell, 1.0));
-                }
-            }
-            v
-        }
-        "checker" => {
-            let vert = o == "vert";
-            let (n, m) = (10usize, 8usize);
-            let mut v = vec![Layer::full(Old, 1.0)];
-            for (c, r, cell) in grid(n, m) {
-                let across = if vert { c } else { r };
-                let f = (t * 2.0 - (across % 2) as f64 * 0.5).clamp(0.0, 1.0);
-                if f <= 0.0 {
-                    continue;
-                }
-                let rc = if vert {
-                    [cell[0], cell[1], cell[2], cell[1] + (cell[3] - cell[1]) * f]
-                } else {
-                    [cell[0], cell[1], cell[0] + (cell[2] - cell[0]) * f, cell[3]]
-                };
-                v.push(Layer::inplace(New, rc, 1.0));
-            }
-            v
-        }
-        "blinds" => {
-            let horz = o == "horz";
-            let n = 8;
-            let mut v = vec![Layer::full(Old, 1.0)];
-            for i in 0..n {
-                let x0 = i as f64 / n as f64;
-                let r = [x0, 0.0, x0 + s / n as f64, 1.0];
-                v.push(Layer::inplace(New, map_rect(r, false, false, horz), 1.0));
-            }
-            v
-        }
-        "clock" => clock(o, s),
-        "ripple" => {
-            let origin = match o {
-                "lu" => [0.0, 0.0],
-                "ru" => [1.0, 0.0],
-                "ld" => [0.0, 1.0],
-                "rd" => [1.0, 1.0],
-                _ => [0.5, 0.5],
-            };
-            let maxd = if origin == [0.5, 0.5] { 0.71 } else { 1.42 };
-            let mut v = vec![Layer::full(Old, 1.0)];
-            for (_, _, cell) in grid(24, 14) {
-                let cc = center(cell);
-                let d = ((cc[0] - origin[0]).powi(2) + (cc[1] - origin[1]).powi(2)).sqrt() / maxd;
-                let a = ramp(t, d.min(1.0), 0.3);
-                if a > 0.0 {
-                    let sc = 1.0 + 0.15 * (a * PI).sin();
-                    v.push(Layer::rect(New, cell, scale_rect(cell, sc), a));
-                }
-            }
-            v
-        }
-        "honeycomb" => {
-            let (cols, rows) = (12usize, 8usize);
-            let mut v = vec![Layer::full(Old, 1.0)];
-            for c in 0..cols {
-                let odd = c % 2 == 1;
-                let extra = if odd { 1 } else { 0 };
-                for r in 0..rows + extra {
-                    let y0 = (r as f64 - if odd { 0.5 } else { 0.0 }) / rows as f64;
-                    let cell = [c as f64 / cols as f64, y0.max(0.0), (c + 1) as f64 / cols as f64, (y0 + 1.0 / rows as f64).min(1.0)];
-                    let a = ramp(t, rnd((c * 64 + r) as u64 + 4242), 0.35);
-                    if a > 0.0 {
-                        v.push(Layer::rect(New, cell, scale_rect(cell, 0.3 + 0.7 * a), a));
-                    }
-                }
-            }
-            v
-        }
-        "glitter" => {
-            let (dx, dy) = dir(o, (-1.0, 0.0));
-            let mut v = vec![Layer::full(Old, 1.0)];
-            for (c, r, cell) in grid(20, 12) {
-                let cc = center(cell);
-                let grad = if dx < 0.0 {
-                    1.0 - cc[0]
-                } else if dx > 0.0 {
-                    cc[0]
-                } else if dy < 0.0 {
-                    1.0 - cc[1]
-                } else {
-                    cc[1]
-                };
-                let order = 0.6 * grad + 0.4 * rnd((r * 20 + c) as u64 + 77);
-                let a = ramp(t, order, 0.25);
-                if a > 0.0 {
-                    let quad = rot_quad(corners(cell), cc, (1.0 - a) * 90.0);
-                    v.push(Layer::quad(New, cell, quad, a));
-                }
-            }
-            v
-        }
-        "vortex" => {
-            let (dx, dy) = dir(o, (-1.0, 0.0));
-            let mut v = vec![Layer::full(New, 1.0)];
-            for (c, r, cell) in grid(16, 9) {
-                let i = (r * 16 + c) as u64;
-                let cc = center(cell);
-                let grad = 0.5 + 0.5 * ((cc[0] - 0.5) * -dx + (cc[1] - 0.5) * -dy);
-                let q = ramp(t, 0.5 * grad + 0.5 * rnd(i + 31), 0.4);
-                let ang = q * 2.0 * PI + rnd(i) * PI;
-                let rad = q * 1.2;
-                let (ox, oy) = (dx * q * 0.8 + rad * ang.cos() * 0.3, dy * q * 0.8 + rad * ang.sin() * 0.3);
-                let pos = [cc[0] + ox, cc[1] + oy];
-                let quad = rot_quad(corners(offset(scale_rect(cell, 1.0 - 0.5 * q), ox, oy)), pos, q * 360.0);
-                v.push(Layer::quad(Old, cell, quad, 1.0 - q));
-            }
-            v
-        }
-        "shred" => {
-            let mut v = vec![Layer::full(New, 1.0)];
-            if o == "particles" {
-                for (c, r, cell) in grid(24, 14) {
-                    let i = (r * 24 + c) as u64;
-                    let q = ramp(t, rnd(i + 555) * 0.6 + 0.4 * (1.0 - center(cell)[1]), 0.4);
-                    let dy = q * q * 1.2;
-                    let dx = (rnd(i + 9) - 0.5) * 0.3 * q;
-                    v.push(Layer::rect(Old, cell, offset(scale_rect(cell, 1.0 - 0.6 * q), dx, dy), 1.0 - q));
-                }
-            } else {
-                let n = 16;
-                for i in 0..n {
-                    let x0 = i as f64 / n as f64;
-                    let x1 = (i + 1) as f64 / n as f64;
-                    let q = ramp(t, i as f64 / n as f64 * 0.3 + 0.1 * rnd(i as u64), 0.7);
-                    let dy = if i % 2 == 0 { 1.1 * q * q } else { -1.1 * q * q };
-                    v.push(Layer::rect(Old, [x0, 0.0, x1, 1.0], [x0, dy, x1, 1.0 + dy], 1.0));
-                }
-            }
-            v
-        }
-        "switch" => {
-            let d = if o == "r" { 1.0 } else { -1.0 };
-            let k = (t * PI).sin();
-            let old = Layer::quad(
-                Old,
-                FULL,
-                persp_h(
-                    offset(scale_rect(FULL, 1.0 - 0.25 * t), d * 0.45 * k, 0.0),
-                    if d > 0.0 { 0.0 } else { 0.08 * k },
-                    if d > 0.0 { 0.08 * k } else { 0.0 },
-                ),
-                1.0,
-            );
-            let new = Layer::quad(
-                New,
-                FULL,
-                persp_h(
-                    offset(scale_rect(FULL, 0.75 + 0.25 * t), -d * 0.45 * k, 0.0),
-                    if d > 0.0 { 0.08 * k } else { 0.0 },
-                    if d > 0.0 { 0.0 } else { 0.08 * k },
-                ),
-                1.0,
-            );
-            if t < 0.5 { vec![new, old] } else { vec![old, new] }
-        }
-        "flip" => {
-            let a = PI * s;
-            let w = a.cos().abs();
-            let k = 0.1 * a.sin();
-            let r = [0.5 - w / 2.0, 0.0, 0.5 + w / 2.0, 1.0];
-            let right = o != "l";
-            if t < 0.5 {
-                let q = if right { persp_h(r, -k / 2.0, k) } else { persp_h(r, k, -k / 2.0) };
-                vec![Layer::quad(Old, FULL, q, 1.0)]
-            } else {
-                let q = if right { persp_h(r, k, -k / 2.0) } else { persp_h(r, -k / 2.0, k) };
-                vec![Layer::quad(New, FULL, q, 1.0)]
-            }
-        }
-        "gallery" | "conveyor" => {
-            let d = if o == "r" { 1.0 } else { -1.0 };
-            let k = (s * PI).sin();
-            let sc = 1.0 - if kind == "gallery" { 0.25 } else { 0.1 } * k;
-            let gap = if kind == "gallery" { 1.15 } else { 1.05 };
-            let old = offset(scale_rect(FULL, sc), d * s * gap, 0.0);
-            let new = offset(scale_rect(FULL, sc), d * (s - 1.0) * gap, 0.0);
-            let p = 0.08 * k;
-            vec![
-                Layer::quad(Old, FULL, if d > 0.0 { persp_h(old, 0.0, p) } else { persp_h(old, p, 0.0) }, 1.0),
-                Layer::quad(New, FULL, if d > 0.0 { persp_h(new, p, 0.0) } else { persp_h(new, 0.0, p) }, 1.0),
-            ]
-        }
-        "cube" | "box" | "rotate" => {
-            let (dx, dy) = dir(o, (-1.0, 0.0));
-            let vertical = dy != 0.0 && dx == 0.0;
-            let neg = if vertical { dy < 0.0 } else { dx < 0.0 };
-            let k = (s * PI).sin();
-            let (far_old, far_new, shared) = match kind {
-                "cube" => (0.18 * s, 0.18 * (1.0 - s), 0.05 * k),
-                "box" => (0.0, 0.0, 0.18 * k),
-                _ => (0.25 * s, 0.25 * (1.0 - s), 0.0),
-            };
-            // Canonical: moving toward -x; old on the left [0, 1-s], new on the right [1-s, 1].
-            let split = 1.0 - s;
-            let (old_q, new_q) = if kind == "rotate" {
-                if t < 0.5 {
-                    (Some(canon_q([0.0, 0.0, (1.0 - 2.0 * t).max(0.0), 1.0], far_old, 0.0)), None)
-                } else {
-                    (None, Some(canon_q([1.0 - (2.0 * t - 1.0), 0.0, 1.0, 1.0], 0.0, far_new)))
-                }
-            } else {
-                (Some(canon_q([0.0, 0.0, split, 1.0], far_old, shared)), Some(canon_q([split, 0.0, 1.0, 1.0], shared, far_new)))
-            };
-            let fix = |q: [[f64; 2]; 4]| -> [[f64; 2]; 4] {
-                let q = if neg { q } else { mirror_q(q) };
-                if vertical { swap_q(q) } else { q }
-            };
-            let mut v = vec![Layer::full(Black, 1.0)];
-            if let Some(q) = old_q {
-                v.push(Layer::quad(Old, FULL, fix(q), 1.0));
-            }
-            if let Some(q) = new_q {
-                v.push(Layer::quad(New, FULL, fix(q), 1.0));
-            }
-            v
-        }
-        "doors" | "window" => {
-            let horz = o == "horz";
-            let (zoom0, persp) = if kind == "doors" { (0.85, 0.1) } else { (0.6, 0.2) };
-            let w = 0.5 * (1.0 - s);
-            let k = persp * s;
-            let left = [[0.0, 0.0], [w, -k], [w, 1.0 + k], [0.0, 1.0]];
-            let right = [[1.0 - w, -k], [1.0, 0.0], [1.0, 1.0], [1.0 - w, 1.0 + k]];
-            let (l, r) = if horz { (swap_q(left), swap_q(right)) } else { (left, right) };
-            let (sl, sr) = if horz { ([0.0, 0.0, 1.0, 0.5], [0.0, 0.5, 1.0, 1.0]) } else { ([0.0, 0.0, 0.5, 1.0], [0.5, 0.0, 1.0, 1.0]) };
-            vec![scaled(New, zoom0 + (1.0 - zoom0) * s, 0.5, 0.5, 0.0, 0.0, s.max(0.2)), Layer::quad(Old, sl, l, 1.0), Layer::quad(Old, sr, r, 1.0)]
-        }
-        "comb" => {
-            let vert = o == "vert";
-            let n = 8;
-            let mut v = Vec::new();
-            for i in 0..n {
-                let a = i as f64 / n as f64;
-                let b = (i + 1) as f64 / n as f64;
-                let d = if i % 2 == 0 { 1.0 } else { -1.0 };
-                let band = if vert { [a, 0.0, b, 1.0] } else { [0.0, a, 1.0, b] };
-                let (ox, oy) = if vert { (0.0, d * s) } else { (d * s, 0.0) };
-                let (nx, ny) = if vert { (0.0, -d * (1.0 - s)) } else { (-d * (1.0 - s), 0.0) };
-                v.push(Layer::rect(Old, band, offset(band, ox, oy), 1.0));
-                v.push(Layer::rect(New, band, offset(band, nx, ny), 1.0));
-            }
-            v
-        }
-        "zoom" => {
-            if o == "out" {
-                vec![scaled(New, 1.5 - 0.5 * s, 0.5, 0.5, 0.0, 0.0, s), scaled(Old, 1.0 - 0.7 * s, 0.5, 0.5, 0.0, 0.0, 1.0 - t)]
-            } else {
-                vec![scaled(Old, 1.0 + s, 0.5, 0.5, 0.0, 0.0, 1.0 - t), scaled(New, s.max(0.01), 0.5, 0.5, 0.0, 0.0, s)]
-            }
-        }
-        "orbit" => {
-            let (dx, dy) = dir(o, (-1.0, 0.0));
-            let k = (s * PI).sin();
-            let old = scaled(Old, 1.0 - 0.4 * k, 0.5, 0.5, dx * s + dy.abs() * 0.15 * k, dy * s + dx.abs() * 0.15 * k, 1.0 - 0.5 * s);
-            let new = scaled(New, 1.0 - 0.4 * k, 0.5, 0.5, dx * (s - 1.0) - dy.abs() * 0.15 * k, dy * (s - 1.0) - dx.abs() * 0.15 * k, 0.5 + 0.5 * s);
-            if t < 0.5 { vec![new, old] } else { vec![old, new] }
-        }
-        "flythrough" => {
-            let bounce = o.ends_with("Bounce");
-            let ns = |base: f64| if bounce { base + 0.08 * (s * PI).sin() } else { base };
-            if o.starts_with("out") {
-                vec![scaled(Old, 1.0 - 0.5 * s, 0.5, 0.5, 0.0, 0.0, 1.0 - t), scaled(New, ns(1.5 - 0.5 * s), 0.5, 0.5, 0.0, 0.0, s)]
-            } else {
-                vec![scaled(New, ns(0.5 + 0.5 * s), 0.5, 0.5, 0.0, 0.0, s), scaled(Old, 1.0 + 1.5 * s, 0.5, 0.5, 0.0, 0.0, 1.0 - t)]
-            }
-        }
-        "ferris" => {
-            let d = if o == "r" { 1.0 } else { -1.0 };
-            let pivot = [0.5, 2.5];
-            let a = 50.0 * s * d;
-            let oq = rot_quad(corners(FULL), pivot, a);
-            let nq = rot_quad(corners(FULL), pivot, a - 50.0 * d);
-            vec![Layer::quad(Old, FULL, oq, 1.0), Layer::quad(New, FULL, nq, 1.0)]
-        }
-        "random" if depth == 0 => {
-            let h = option.bytes().fold(0x51ED_u64, |h, b| hash64(h ^ b as u64));
-            let k = RANDOM_KINDS.get((h % RANDOM_KINDS.len() as u64) as usize).copied().unwrap_or("fade");
-            let opt = deckcraft_model::anim::TRANSITIONS.iter().find(|x| x.0 == k).and_then(|x| x.4.first().copied()).unwrap_or("");
-            layers(k, opt, t, depth + 1)
-        }
-        _ => crossfade(t),
+        "pan" | "ferris" | "conveyor" | "rotate" | "window" | "orbit" | "flythrough" => true,
+        "reveal" => !option.starts_with("black"),
+        _ => false,
     }
 }
-
-fn mirror_q(q: [[f64; 2]; 4]) -> [[f64; 2]; 4] {
-    // Mirror x and keep the tl, tr, br, bl order (swap left/right corners).
-    let m = |p: [f64; 2]| [1.0 - p[0], p[1]];
-    [m(q[1]), m(q[0]), m(q[3]), m(q[2])]
-}
-
-fn swap_q(q: [[f64; 2]; 4]) -> [[f64; 2]; 4] {
-    // Transpose x/y; corners reordered so tl, tr, br, bl still map to the source's corners.
-    let s = |p: [f64; 2]| [p[1], p[0]];
-    [s(q[0]), s(q[3]), s(q[2]), s(q[1])]
-}
-
-fn canon_q(r: R, left_inset: f64, right_inset: f64) -> [[f64; 2]; 4] {
-    persp_h(r, left_inset, right_inset)
-}
-
-fn wipe(o: &str, t: f64) -> Vec<Layer> {
-    let mut v = vec![Layer::full(Source::Old, 1.0)];
-    let diag = o.len() == 2;
-    if diag {
-        // Diagonal: columns revealed by a slanted edge.
-        let (mx, my) = (o.contains('l'), o.contains('u'));
-        let n = 32;
-        for i in 0..n {
-            let x0 = i as f64 / n as f64;
-            let x1 = (i + 1) as f64 / n as f64;
-            let h = (2.0 * t - (x0 + x1) / 2.0).clamp(0.0, 1.0);
-            if h > 0.0 {
-                v.push(Layer::inplace(Source::New, map_rect([x0, 0.0, x1, h], mx, my, false), 1.0));
-            }
-        }
-        return v;
-    }
-    let (mx, swap) = match o {
-        "l" => (true, false),
-        "d" => (false, true),
-        "u" => (true, true),
-        _ => (false, false),
-    };
-    let soft = 0.15;
-    let e = t * (1.0 + soft);
-    let solid = (e - soft).clamp(0.0, 1.0);
-    if solid > 0.0 {
-        v.push(Layer::inplace(Source::New, map_rect([0.0, 0.0, solid, 1.0], mx, false, swap), 1.0));
-    }
-    let n = 6;
-    for k in 0..n {
-        let a = e - soft + soft * k as f64 / n as f64;
-        let b = e - soft + soft * (k + 1) as f64 / n as f64;
-        let (a, b) = (a.clamp(0.0, 1.0), b.clamp(0.0, 1.0));
-        if b > a {
-            let alpha = 1.0 - (k as f64 + 0.5) / n as f64;
-            v.push(Layer::inplace(Source::New, map_rect([a, 0.0, b, 1.0], mx, false, swap), alpha));
-        }
-    }
-    v
-}
-
-/// A centred shape of the source at size `f` (0 = nothing, 1 = covers the slide), as strips.
-fn shape_form(src: Source, form: &str, f: f64) -> Vec<Layer> {
-    let f = f.clamp(0.0, 1.0);
-    if f <= 0.0 {
-        return vec![];
-    }
-    match form {
-        "plus" => {
-            let h = f / 2.0;
-            vec![Layer::inplace(src, [0.0, 0.5 - h, 1.0, 0.5 + h], 1.0), Layer::inplace(src, [0.5 - h, 0.0, 0.5 + h, 1.0], 1.0)]
-        }
-        "circle" | "diamond" => {
-            let n = 40;
-            let r = if form == "circle" { f * 0.75 } else { f * 1.02 };
-            let mut v = Vec::new();
-            for i in 0..n {
-                let y0 = i as f64 / n as f64;
-                let y1 = (i + 1) as f64 / n as f64;
-                let dy = ((y0 + y1) / 2.0 - 0.5).abs();
-                let half = if form == "circle" { if r > dy { (r * r - dy * dy).sqrt() } else { 0.0 } } else { r - dy };
-                if half > 0.0 {
-                    let half = half.min(0.5);
-                    v.push(Layer::inplace(src, [0.5 - half, y0, 0.5 + half, y1], 1.0));
-                }
-            }
-            v
-        }
-        _ => vec![Layer::inplace(src, scale_rect(FULL, f), 1.0)],
-    }
-}
-
-/// A peeling page: the part of `area` not yet peeled stays, the peeled part shows as a mirrored flap.
-fn peel(src: Source, area: R, s: f64, toward_right: bool) -> Vec<Layer> {
-    let w = area[2] - area[0];
-    let p = s * w;
-    if toward_right {
-        let edge = area[0] + p;
-        let stay = [edge, area[1], area[2], area[3]];
-        let flap_src = [area[0], area[1], edge, area[3]];
-        let x2 = edge + p;
-        let flap = Layer {
-            source: src,
-            src: flap_src,
-            quad: [[x2, area[1]], [edge, area[1]], [edge, area[3]], [x2, area[3]]],
-            uv: corners(flap_src),
-            alpha: 0.85,
-        };
-        vec![Layer::inplace(src, stay, 1.0), flap]
-    } else {
-        let edge = area[2] - p;
-        let stay = [area[0], area[1], edge, area[3]];
-        let flap_src = [edge, area[1], area[2], area[3]];
-        let x2 = edge - p;
-        let flap = Layer {
-            source: src,
-            src: flap_src,
-            quad: [[edge, area[1]], [x2, area[1]], [x2, area[3]], [edge, area[3]]],
-            uv: corners(flap_src),
-            alpha: 0.85,
-        };
-        vec![Layer::inplace(src, stay, 1.0), flap]
-    }
-}
-
-/// Point on the unit square's boundary seen from the centre at angle `a` (radians, clockwise from
-/// 12 o'clock).
-fn boundary(a: f64) -> [f64; 2] {
-    let (dx, dy) = (a.sin(), -a.cos());
-    let m = dx.abs().max(dy.abs()).max(1e-9);
-    [0.5 + 0.5 * dx / m, 0.5 + 0.5 * dy / m]
-}
-
-fn clock(o: &str, s: f64) -> Vec<Layer> {
-    let mut v = vec![Layer::full(Source::Old, 1.0)];
-    let c = [0.5, 0.5];
-    let sweep = s * 2.0 * PI;
-    let (a0, a1) = match o {
-        "counterClockwise" => (-sweep, 0.0),
-        "wedge" => (-sweep / 2.0, sweep / 2.0),
-        _ => (0.0, sweep),
-    };
-    let span = a1 - a0;
-    if span <= 0.0 {
-        return v;
-    }
-    let n = ((span / (PI / 24.0)).ceil() as usize).clamp(1, 96);
-    let mut angles: Vec<f64> = (0..=n).map(|k| a0 + span * k as f64 / n as f64).collect();
-    // Square corners inside the sweep, so the fan reaches them.
-    for k in -8i32..=8 {
-        let a = PI / 4.0 + k as f64 * PI / 2.0;
-        if a > a0 && a < a1 {
-            angles.push(a);
-        }
-    }
-    angles.sort_by(f64::total_cmp);
-    for w in angles.windows(2) {
-        if let [x, y] = w
-            && y > x
-        {
-            v.push(Layer::tri(Source::New, c, boundary(*x), boundary(*y), 1.0));
-        }
-    }
-    v
-}

crates/anim/src/transition_geom.rs

@@ -0,0 +1,382 @@
+//! Geometry for transition effects: easing, 3-D cards, opacity fields, polygons.
+
+use std::f64::consts::PI;
+
+use crate::easing::{ease, smooth};
+use crate::transition::{FULL, Layer, P, Q, R, Source, corners};
+
+// ---------- easing ----------
+
+/// Smoothstep ease in-out (PowerPoint's fades).
+pub(crate) fn ss(x: f64) -> f64 {
+    smooth(x)
+}
+
+/// Quadratic ease in-out: velocity ramps up for the first half and down for the second
+/// (PowerPoint's moves: Push, Cover, Uncover, Pan…).
+pub(crate) fn q2(x: f64) -> f64 {
+    ease(x, 0.5, 0.5, 0.0)
+}
+
+/// Power ease in-out of degree `n` (2: quadratic, 3: cubic, 4: quartic).
+pub(crate) fn pow_inout(x: f64, n: f64) -> f64 {
+    let x = x.clamp(0.0, 1.0);
+    if x < 0.5 { 0.5 * (2.0 * x).powf(n) } else { 1.0 - 0.5 * (2.0 - 2.0 * x).powf(n) }
+}
+
+/// Quadratic ease-in.
+pub(crate) fn ein(x: f64) -> f64 {
+    let x = x.clamp(0.0, 1.0);
+    x * x
+}
+
+/// Quadratic ease-out.
+pub(crate) fn eout(x: f64) -> f64 {
+    let x = 1.0 - x.clamp(0.0, 1.0);
+    1.0 - x * x
+}
+
+/// Progress through the window [a, b] of t, clamped to 0..1.
+pub(crate) fn win(t: f64, a: f64, b: f64) -> f64 {
+    if b <= a {
+        return if t >= b { 1.0 } else { 0.0 };
+    }
+    ((t - a) / (b - a)).clamp(0.0, 1.0)
+}
+
+// ---------- randomness ----------
+
+pub(crate) fn hash64(mut x: u64) -> u64 {
+    x = x.wrapping_add(0x9E37_79B9_7F4A_7C15);
+    x = (x ^ (x >> 30)).wrapping_mul(0xBF58_476D_1CE4_E5B9);
+    x = (x ^ (x >> 27)).wrapping_mul(0x94D0_49BB_1331_11EB);
+    x ^ (x >> 31)
+}
+
+/// Deterministic pseudo-random value in [0, 1).
+pub(crate) fn rnd(i: u64) -> f64 {
+    (hash64(i) >> 11) as f64 / (1u64 << 53) as f64
+}
+
+// ---------- 2-D ----------
+
+pub(crate) fn offset(r: R, dx: f64, dy: f64) -> R {
+    [r[0] + dx, r[1] + dy, r[2] + dx, r[3] + dy]
+}
+
+pub(crate) fn center(r: R) -> P {
+    [(r[0] + r[2]) / 2.0, (r[1] + r[3]) / 2.0]
+}
+
+pub(crate) fn scale_rect(r: R, s: f64) -> R {
+    scale_rect_about(r, s, center(r))
+}
+
+pub(crate) fn scale_rect_about(r: R, s: f64, c: P) -> R {
+    [c[0] + (r[0] - c[0]) * s, c[1] + (r[1] - c[1]) * s, c[0] + (r[2] - c[0]) * s, c[1] + (r[3] - c[1]) * s]
+}
+
+/// The whole source moved by (dx, dy).
+pub(crate) fn moved(source: Source, dx: f64, dy: f64, alpha: f64) -> Layer {
+    Layer::rect(source, FULL, offset(FULL, dx, dy), alpha)
+}
+
+/// The whole source scaled by `s` about (cx, cy) and moved.
+pub(crate) fn scaled(source: Source, s: f64, cx: f64, cy: f64, dx: f64, dy: f64, alpha: f64) -> Layer {
+    Layer::rect(source, FULL, offset(scale_rect_about(FULL, s, [cx, cy]), dx, dy), alpha)
+}
+
+/// Rotate a point about a pivot by `deg` (clockwise on screen), in a slide `a` wide per unit of
+/// height, so angles and shapes stay true.
+pub(crate) fn rot(p: P, c: P, deg: f64, a: f64) -> P {
+    let (s, co) = deg.to_radians().sin_cos();
+    let (x, y) = ((p[0] - c[0]) * a, p[1] - c[1]);
+    [c[0] + (x * co - y * s) / a, c[1] + x * s + y * co]
+}
+
+pub(crate) fn rot_quad(q: Q, c: P, deg: f64, a: f64) -> Q {
+    [rot(q[0], c, deg, a), rot(q[1], c, deg, a), rot(q[2], c, deg, a), rot(q[3], c, deg, a)]
+}
+
+/// Motion direction of an option: l, r, u, d and diagonals.
+pub(crate) fn dir(opt: &str, default: (f64, f64)) -> (f64, f64) {
+    let mut d = (0.0, 0.0);
+    if opt.contains('l') {
+        d.0 = -1.0;
+    }
+    if opt.contains('r') {
+        d.0 = 1.0;
+    }
+    if opt.contains('u') {
+        d.1 = -1.0;
+    }
+    if opt.contains('d') {
+        d.1 = 1.0;
+    }
+    if d == (0.0, 0.0) { default } else { d }
+}
+
+/// A rectangle with a soft border `f` wide (slide units) fading out to nothing: the rectangle at
+/// full opacity, four edge ramps and four corner ramps. `src` maps onto `dst`; the border samples
+/// the texture's edge.
+pub(crate) fn soft_rect(source: Source, src: R, dst: R, f: f64, alpha: f64) -> Vec<Layer> {
+    let mut v = vec![Layer::rect(source, src, dst, alpha)];
+    if f <= 1e-6 {
+        return v;
+    }
+    let (l, t, r, b) = (dst[0], dst[1], dst[2], dst[3]);
+    let (fx, fy) = (f, f * 16.0 / 9.0);
+    let uv_at = |x: f64, y: f64| -> P {
+        let u = if r > l { src[0] + (x.clamp(l, r) - l) / (r - l) * (src[2] - src[0]) } else { src[0] };
+        let w = if b > t { src[1] + (y.clamp(t, b) - t) / (b - t) * (src[3] - src[1]) } else { src[1] };
+        [u, w]
+    };
+    let mut q = |pts: Q, fade: [f64; 4]| {
+        let uv = pts.map(|p| uv_at(p[0], p[1]));
+        let xs = uv.map(|p| p[0]);
+        let ys = uv.map(|p| p[1]);
+        let mn = |a: [f64; 4]| a.iter().copied().fold(f64::INFINITY, f64::min);
+        let mx = |a: [f64; 4]| a.iter().copied().fold(f64::NEG_INFINITY, f64::max);
+        v.push(Layer { source, src: [mn(xs), mn(ys), mx(xs), mx(ys)], quad: pts, uv, alpha, fade });
+    };
+    q([[l, t - fy], [r, t - fy], [r, t], [l, t]], [0.0, 0.0, 1.0, 1.0]);
+    q([[l, b], [r, b], [r, b + fy], [l, b + fy]], [1.0, 1.0, 0.0, 0.0]);
+    q([[l - fx, t], [l, t], [l, b], [l - fx, b]], [0.0, 1.0, 1.0, 0.0]);
+    q([[r, t], [r + fx, t], [r + fx, b], [r, b]], [1.0, 0.0, 0.0, 1.0]);
+    q([[l - fx, t - fy], [l, t - fy], [l, t], [l - fx, t]], [0.0, 0.0, 1.0, 0.0]);
+    q([[r, t - fy], [r + fx, t - fy], [r + fx, t], [r, t]], [0.0, 0.0, 0.0, 1.0]);
+    q([[r, b], [r + fx, b], [r + fx, b + fy], [r, b + fy]], [1.0, 0.0, 0.0, 0.0]);
+    q([[l - fx, b], [l, b], [l, b + fy], [l - fx, b + fy]], [0.0, 1.0, 0.0, 0.0]);
+    v
+}
+
+// ---------- opacity fields ----------
+
+/// The source shown in place through an opacity field `f(x, y)` (0..1) sampled on an `n` × `m`
+/// grid: each cell is a quad with its corners' opacities. Cells with nothing to show are left out
+/// and runs of fully opaque cells merge, so most frames stay small.
+pub(crate) fn field(source: Source, n: usize, m: usize, f: &dyn Fn(f64, f64) -> f64) -> Vec<Layer> {
+    let (n, m) = (n.clamp(1, 256), m.clamp(1, 256));
+    let mut vals = vec![0.0; (n + 1) * (m + 1)];
+    for j in 0..=m {
+        for i in 0..=n {
+            let v = f(i as f64 / n as f64, j as f64 / m as f64);
+            if let Some(x) = vals.get_mut(j * (n + 1) + i) {
+                *x = if v.is_finite() { v.clamp(0.0, 1.0) } else { 0.0 };
+            }
+        }
+    }
+    let at = |i: usize, j: usize| vals.get(j * (n + 1) + i).copied().unwrap_or(0.0);
+    let mut out = Vec::new();
+    for j in 0..m {
+        let (y0, y1) = (j as f64 / m as f64, (j + 1) as f64 / m as f64);
+        let mut run: Option<usize> = None;
+        for i in 0..=n {
+            let full = i < n && at(i, j) >= 1.0 && at(i + 1, j) >= 1.0 && at(i, j + 1) >= 1.0 && at(i + 1, j + 1) >= 1.0;
+            if full {
+                run.get_or_insert(i);
+                continue;
+            }
+            if let Some(s) = run.take() {
+                out.push(Layer::inplace(source, [s as f64 / n as f64, y0, i as f64 / n as f64, y1], 1.0));
+            }
+            if i == n {
+                break;
+            }
+            let c = [at(i, j), at(i + 1, j), at(i + 1, j + 1), at(i, j + 1)];
+            if c.iter().all(|v| *v <= 0.0) {
+                continue;
+            }
+            out.push(Layer::inplace(source, [i as f64 / n as f64, y0, (i + 1) as f64 / n as f64, y1], 1.0).faded(c));
+        }
+    }
+    out
+}
+
+/// Opacity of a soft edge at position `p` when the edge's middle is at `c` and it ramps over `w`.
+pub(crate) fn edge(c: f64, p: f64, w: f64) -> f64 {
+    if w <= 1e-9 {
+        return if p <= c { 1.0 } else { 0.0 };
+    }
+    ((c - p) / w + 0.5).clamp(0.0, 1.0)
+}
+
+/// Point on the unit square's boundary seen from its centre at angle `ang` (radians, clockwise
+/// from 12 o'clock, measured on a slide `a` wide per unit of height).
+pub(crate) fn boundary(ang: f64, a: f64) -> P {
+    let (dx, dy) = (ang.sin() / a, -ang.cos());
+    let m = (dx.abs() / 0.5).max(dy.abs() / 0.5).max(1e-9);
+    [0.5 + dx / m, 0.5 + dy / m]
+}
+
+/// The source shown in place through an angular opacity field `f(angle)` (radians clockwise from
+/// 12 o'clock, 0..2π): a fan of thin wedges from the centre.
+pub(crate) fn fan(source: Source, a: f64, steps: usize, f: &dyn Fn(f64) -> f64) -> Vec<Layer> {
+    let n = steps.clamp(8, 720);
+    let mut angles: Vec<f64> = (0..=n).map(|k| 2.0 * PI * k as f64 / n as f64).collect();
+    // The square's corners, so wedges reach them.
+    for c in [[1.0, 0.0], [1.0, 1.0], [0.0, 1.0], [0.0, 0.0]] {
+        let ang = ((c[0] - 0.5) * a).atan2(-(c[1] - 0.5));
+        angles.push(ang.rem_euclid(2.0 * PI));
+    }
+    angles.sort_by(f64::total_cmp);
+    angles.dedup_by(|x, y| (*x - *y).abs() < 1e-9);
+    let mut out = Vec::new();
+    let c = [0.5, 0.5];
+    for w in angles.windows(2) {
+        let [x, y] = w else { continue };
+        let (fx, fy) = (f(*x).clamp(0.0, 1.0), f(*y).clamp(0.0, 1.0));
+        if fx <= 0.0 && fy <= 0.0 {
+            continue;
+        }
+        let (bx, by) = (boundary(*x, a), boundary(*y, a));
+        out.push(Layer::tri_uv(source, [c, bx, by], [c, bx, by], [(fx + fy) / 2.0, fx, fy], 1.0));
+    }
+    out
+}
+
+// ---------- polygons ----------
+
+/// Keep the part of a convex polygon where `n · p <= d`.
+pub(crate) fn clip(poly: &[P], n: P, d: f64) -> Vec<P> {
+    let mut out = Vec::with_capacity(poly.len() + 2);
+    let side = |p: P| n[0] * p[0] + n[1] * p[1] - d;
+    for (i, p) in poly.iter().enumerate() {
+        let q = poly.get((i + 1) % poly.len()).copied().unwrap_or(*p);
+        let (sp, sq) = (side(*p), side(q));
+        if sp <= 0.0 {
+            out.push(*p);
+        }
+        if (sp < 0.0 && sq > 0.0) || (sp > 0.0 && sq < 0.0) {
+            let k = sp / (sp - sq);
+            out.push([p[0] + (q[0] - p[0]) * k, p[1] + (q[1] - p[1]) * k]);
+        }
+    }
+    out
+}
+
+/// A convex polygon as triangles: vertices drawn at `map(p)` with texture coordinate `p`.
+pub(crate) fn poly_layers(source: Source, poly: &[P], alpha: f64, map: &dyn Fn(P) -> P) -> Vec<Layer> {
+    let Some(first) = poly.first().copied() else { return vec![] };
+    poly.windows(2)
+        .skip(1)
+        .filter_map(|w| match w {
+            [b, c] => Some(Layer::tri_uv(source, [map(first), map(*b), map(*c)], [first, *b, *c], [1.0; 3], alpha)),
+            _ => None,
+        })
+        .collect()
+}
+
+pub(crate) fn rect_poly(r: R) -> Vec<P> {
+    corners(r).to_vec()
+}
+
+// ---------- 3-D ----------
+
+/// A point in the 3-D scene: x right and y down in slide heights (the slide spans x ∈ [−a/2, a/2],
+/// y ∈ [−½, ½] at z = 0), z away from the viewer.
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub(crate) struct V3 {
+    pub x: f64,
+    pub y: f64,
+    pub z: f64,
+}
+
+pub(crate) fn v3(x: f64, y: f64, z: f64) -> V3 {
+    V3 { x, y, z }
+}
+
+impl V3 {
+    pub fn add(self, o: V3) -> V3 {
+        v3(self.x + o.x, self.y + o.y, self.z + o.z)
+    }
+    pub fn sub(self, o: V3) -> V3 {
+        v3(self.x - o.x, self.y - o.y, self.z - o.z)
+    }
+    /// Rotate about the vertical axis through `c` (degrees; positive turns the right side away).
+    pub fn yaw(self, c: V3, deg: f64) -> V3 {
+        let (s, co) = deg.to_radians().sin_cos();
+        let p = self.sub(c);
+        v3(p.x * co - p.z * s, p.y, p.x * s + p.z * co).add(c)
+    }
+    /// Rotate about the horizontal axis through `c` (degrees; positive turns the top away).
+    pub fn pitch(self, c: V3, deg: f64) -> V3 {
+        let (s, co) = deg.to_radians().sin_cos();
+        let p = self.sub(c);
+        v3(p.x, p.y * co + p.z * s, -p.y * s + p.z * co).add(c)
+    }
+    /// Rotate in the screen plane about `c` (degrees, clockwise).
+    pub fn roll(self, c: V3, deg: f64) -> V3 {
+        let (s, co) = deg.to_radians().sin_cos();
+        let p = self.sub(c);
+        v3(p.x * co - p.y * s, p.x * s + p.y * co, p.z).add(c)
+    }
+}
+
+/// A perspective camera looking at the slide plane from `d` slide heights away.
+#[derive(Clone, Copy, Debug)]
+pub(crate) struct Cam {
+    pub a: f64,
+    pub d: f64,
+}
+
+impl Cam {
+    pub fn p(&self, v: V3) -> P {
+        let k = self.d / (self.d + v.z).max(self.d * 0.02);
+        [v.x * k / self.a + 0.5, v.y * k + 0.5]
+    }
+    /// The 3-D corners (tl, tr, br, bl) of the unit-space rectangle `r` lying on the slide plane.
+    pub fn rect(&self, r: R) -> [V3; 4] {
+        corners(r).map(|p| v3((p[0] - 0.5) * self.a, p[1] - 0.5, 0.0))
+    }
+    /// The unit-space point of a 3-D point on the slide plane.
+    pub fn unit(&self, x: f64, y: f64) -> V3 {
+        v3((x - 0.5) * self.a, y - 0.5, 0.0)
+    }
+    pub fn quad(&self, c: [V3; 4]) -> Q {
+        c.map(|v| self.p(v))
+    }
+}
+
+/// Signed area of a quad (positive: front side facing the viewer).
+pub(crate) fn area(q: &Q) -> f64 {
+    let mut s = 0.0;
+    for i in 0..4 {
+        let (a, b) = (q[i], q[(i + 1) % 4]);
+        s += a[0] * b[1] - b[0] * a[1];
+    }
+    s / 2.0
+}
+
+/// A card: `src` of the source mapped onto 3-D corners, if it faces the viewer; `shade` (0..1)
+/// darkens it. Seen from behind it is left out unless `back` is set (then drawn mirrored).
+pub(crate) fn card(cam: &Cam, source: Source, src: R, c: [V3; 4], alpha: f64, shade: f64, back: bool) -> Vec<Layer> {
+    let q = cam.quad(c);
+    if !q.iter().all(|p| p[0].is_finite() && p[1].is_finite()) {
+        return vec![];
+    }
+    let front = area(&q) > 0.0;
+    if !front && !back {
+        return vec![];
+    }
+    let l = Layer::quad(source, src, q, alpha);
+    let mut v = vec![l];
+    if shade > 0.001 {
+        v.push(l.shade(shade));
+    }
+    v
+}
+
+/// How much a card facing along `n` (unit normal toward the viewer is (0, 0, −1)) is darkened by
+/// the light behind the viewer: 0 facing straight on.
+pub(crate) fn facing_shade(c: [V3; 4], k: f64) -> f64 {
+    let u = c[1].sub(c[0]);
+    let w = c[3].sub(c[0]);
+    let n = v3(u.y * w.z - u.z * w.y, u.z * w.x - u.x * w.z, u.x * w.y - u.y * w.x);
+    let len = (n.x * n.x + n.y * n.y + n.z * n.z).sqrt();
+    if len < 1e-12 {
+        return 0.0;
+    }
+    let cos = (n.z / len).abs();
+    (k * (1.0 - cos)).clamp(0.0, 1.0)
+}

crates/anim/src/transition_tests.rs

@@ -0,0 +1,230 @@
+//! Transition curves and geometry against values measured on PowerPoint's video export
+//! (`plan/powerpoint/tools/synth_transitions.ps1`, 2 s transitions, 30 fps).
+
+#![allow(clippy::unwrap_used, clippy::expect_used, clippy::panic)]
+
+use deckcraft_model::anim::TRANSITIONS;
+
+use crate::transition::{Layer, Source, transition_frame, transition_layers, uses_slide_parts};
+use crate::transition_geom::{edge, pow_inout, q2, ss};
+
+const A: f64 = 16.0 / 9.0;
+
+fn near(a: f64, b: f64, tol: f64) -> bool {
+    (a - b).abs() <= tol
+}
+
+fn of(ls: &[Layer], src: Source) -> Vec<&Layer> {
+    ls.iter().filter(|l| l.source == src).collect()
+}
+
+fn left(l: &Layer) -> f64 {
+    l.quad.iter().map(|p| p[0]).fold(f64::INFINITY, f64::min)
+}
+
+fn top(l: &Layer) -> f64 {
+    l.quad.iter().map(|p| p[1]).fold(f64::INFINITY, f64::min)
+}
+
+#[test]
+fn fade_follows_powerpoints_s_curve() {
+    // Measured share of the new slide in a 2 s Fade at t = 0.25, 0.5, 0.75: 0.155, 0.49, 0.82.
+    for (t, want) in [(0.25, 0.155), (0.5, 0.49), (0.75, 0.82)] {
+        let ls = transition_layers("fade", "smoothly", t);
+        let new = of(&ls, Source::New);
+        assert!(near(new[0].alpha, want, 0.04), "t={t}: {}", new[0].alpha);
+    }
+    // Through black: the old slide is gone to black at the middle, then the new one fades in.
+    let mid = transition_layers("fade", "throughBlack", 0.5);
+    assert!(mid.iter().all(|l| l.source == Source::Black));
+    let q = transition_layers("fade", "throughBlack", 0.25);
+    assert!(near(of(&q, Source::Old)[0].alpha, 0.5, 0.01));
+}
+
+#[test]
+fn push_moves_both_slides_with_an_eased_curve() {
+    for (o, dx, dy) in [("l", -1.0, 0.0), ("r", 1.0, 0.0), ("u", 0.0, -1.0), ("d", 0.0, 1.0)] {
+        for t in [0.25, 0.5, 0.75] {
+            let ls = transition_layers("push", o, t);
+            let (old, new) = (of(&ls, Source::Old)[0], of(&ls, Source::New)[0]);
+            let s = q2(t);
+            assert!(near(old.quad[0][0], dx * s, 1e-9) && near(old.quad[0][1], dy * s, 1e-9), "{o} {t}");
+            assert!(near(new.quad[0][0], dx * (s - 1.0), 1e-9) && near(new.quad[0][1], dy * (s - 1.0), 1e-9), "{o} {t}");
+        }
+    }
+    // Ease in-out: slow at both ends.
+    assert!(q2(0.1) < 0.05 && q2(0.9) > 0.95 && near(q2(0.5), 0.5, 1e-9));
+}
+
+#[test]
+fn cover_and_uncover_match_measured_positions() {
+    // Offset of the new slide in Cover Left (fraction of the width) at measured times.
+    for (t, off) in [(0.445, 0.655), (0.495, 0.512), (0.544, 0.359), (0.643, 0.134), (0.742, 0.046)] {
+        let ls = transition_layers("cover", "l", t);
+        assert!(near(left(of(&ls, Source::New)[0]), off, 0.05), "cover t={t}");
+    }
+    // Offset of the old slide in Uncover Left.
+    for (t, off) in [(0.244, -0.06), (0.343, -0.14), (0.442, -0.32), (0.508, -0.5), (0.558, -0.63)] {
+        let ls = transition_layers("uncover", "l", t);
+        assert!(near(left(of(&ls, Source::Old)[0]), off, 0.05), "uncover t={t}");
+    }
+    // Diagonal Cover shoots in and settles slowly.
+    for (t, off) in [(0.142, 0.728), (0.257, 0.49), (0.356, 0.29), (0.455, 0.146), (0.604, 0.053)] {
+        let ls = transition_layers("cover", "lu", t);
+        let n = of(&ls, Source::New)[0];
+        assert!(near(left(n), off, 0.06) && near(top(n), off, 0.06), "cover lu t={t}");
+    }
+    assert!(near(pow_inout(0.25, 3.0), 0.0625, 1e-9));
+}
+
+#[test]
+fn wipe_has_a_wide_soft_edge() {
+    // Measured along a row of Wipe Right at t = 0.5: about half-way through at x = 0.6, nearly
+    // nothing at the right edge, fully new on the left third.
+    let c = -0.4 + 1.8 * 1.05 * 0.5;
+    assert!(near(edge(c, 0.6, 0.8), 0.49, 0.1));
+    assert!(edge(c, 1.0, 0.8) < 0.1);
+    assert!(edge(c, 0.2, 0.8) > 0.8);
+    // Directions: "r" starts on the left, "l" on the right, "u" at the bottom, "d" at the top,
+    // diagonals at the opposite corner.
+    let first = |o: &str| {
+        let ls = transition_layers("wipe", o, 0.15);
+        let n = of(&ls, Source::New);
+        assert!(!n.is_empty(), "{o}");
+        let cx = n.iter().map(|l| (l.quad[0][0] + l.quad[2][0]) / 2.0).sum::<f64>() / n.len() as f64;
+        let cy = n.iter().map(|l| (l.quad[0][1] + l.quad[2][1]) / 2.0).sum::<f64>() / n.len() as f64;
+        (cx, cy)
+    };
+    assert!(first("r").0 < 0.3 && first("l").0 > 0.7);
+    assert!(first("u").1 > 0.7 && first("d").1 < 0.3);
+    let ru = first("ru");
+    assert!(ru.0 < 0.4 && ru.1 > 0.6, "{ru:?}");
+}
+
+#[test]
+fn split_and_shape_open_from_the_middle() {
+    for o in ["horzOut", "vertOut"] {
+        let ls = transition_layers("split", o, 0.2);
+        let n = of(&ls, Source::New);
+        assert!(n.iter().all(|l| {
+            let c = [(l.quad[0][0] + l.quad[2][0]) / 2.0, (l.quad[0][1] + l.quad[2][1]) / 2.0];
+            if o.starts_with("horz") { (c[1] - 0.5).abs() < 0.4 } else { (c[0] - 0.5).abs() < 0.4 }
+        }));
+    }
+    // Shape In is done with the old slide at half time; Shape Out starts the new one then.
+    assert!(of(&transition_layers("shape", "in", 0.55), Source::Old).is_empty());
+    assert!(of(&transition_layers("shape", "out", 0.45), Source::New).is_empty());
+}
+
+#[test]
+fn dynamic_content_curves() {
+    // Pan: the new content's offset (fraction of the width) at measured times.
+    for (t, off) in [(0.6, 0.134), (0.7, 0.086), (0.8, 0.039), (0.9, 0.011)] {
+        let ls = transition_layers("pan", "l", t);
+        assert!(near(left(of(&ls, Source::NewContent)[0]), off, 0.07), "pan t={t}");
+    }
+    // The backgrounds cross-fade under the moving contents.
+    let ls = transition_layers("pan", "l", 0.5);
+    assert_eq!(ls.first().map(|l| l.source), Some(Source::OldBack));
+    assert!(of(&ls, Source::NewBack)[0].alpha > 0.5);
+    // Ferris Wheel: the old content drops (top edge, slide heights) as measured.
+    for (t, dy) in [(0.147, 0.06), (0.246, 0.17), (0.345, 0.36), (0.444, 0.70)] {
+        let ls = transition_layers("ferris", "l", t);
+        let q = of(&ls, Source::OldContent)[0].quad;
+        let cy = q.iter().map(|p| p[1]).sum::<f64>() / 4.0 - 0.5;
+        assert!(near(cy, dy, 0.08), "ferris t={t}: {cy}");
+    }
+    for k in ["pan", "ferris", "conveyor", "rotate", "window", "orbit", "flythrough"] {
+        assert!(uses_slide_parts(k, ""), "{k}");
+    }
+    assert!(uses_slide_parts("reveal", "smoothlyLeft") && !uses_slide_parts("reveal", "blackLeft"));
+    assert!(!uses_slide_parts("cube", "l") && !uses_slide_parts("push", "l"));
+}
+
+#[test]
+fn cube_turns_toward_the_option() {
+    // Cube Left at the middle: the shared edge is near the middle, the old face on the left.
+    let ls = transition_frame("cube", "l", 0.5, A);
+    let (o, n) = (of(&ls, Source::Old)[0], of(&ls, Source::New)[0]);
+    let o_right = o.quad.iter().map(|p| p[0]).fold(f64::NEG_INFINITY, f64::max);
+    assert!(near(o_right, left(n), 0.02), "shared edge: {o_right} vs {}", left(n));
+    assert!(o_right > 0.3 && o_right < 0.7);
+    // Up: the new face comes from below.
+    let ls = transition_frame("cube", "u", 0.5, A);
+    assert!(top(of(&ls, Source::New)[0]) > top(of(&ls, Source::Old)[0]));
+}
+
+#[test]
+fn switch_swaps_the_cards_past_halfway() {
+    let order = |t: f64| {
+        let ls = transition_frame("switch", "l", t, A);
+        let pos = |s: Source| ls.iter().position(|l| l.source == s);
+        (pos(Source::Old), pos(Source::New))
+    };
+    let (o, n) = order(0.3);
+    assert!(o > n, "old in front early");
+    let (o, n) = order(0.8);
+    assert!(n > o, "new in front late");
+}
+
+#[test]
+fn clock_hand_sweeps_at_constant_speed() {
+    // The share of the slide covered grows linearly.
+    let area = |t: f64| {
+        let ls = transition_layers("clock", "clockwise", t);
+        of(&ls, Source::New)
+            .iter()
+            .map(|l| {
+                let [a, b, c, _] = l.quad;
+                ((b[0] - a[0]) * (c[1] - a[1]) - (c[0] - a[0]) * (b[1] - a[1])).abs() / 2.0 * (l.fade[0] + l.fade[1] + l.fade[2]) / 3.0
+            })
+            .sum::<f64>()
+    };
+    let (a1, a2, a3) = (area(0.25), area(0.5), area(0.75));
+    assert!(near(a2 - a1, a3 - a2, 0.08), "{a1} {a2} {a3}");
+    assert!(near(a2, 0.5, 0.08), "{a2}");
+}
+
+#[test]
+fn options_change_the_frame() {
+    // Every option of a transition draws something different from its other options midway.
+    for (id, _, _, _, opts) in TRANSITIONS {
+        if matches!(*id, "morph" | "none" | "random") || opts.len() < 2 {
+            continue;
+        }
+        for (i, a) in opts.iter().enumerate() {
+            for b in opts.iter().skip(i + 1) {
+                let differs = [0.2, 0.35, 0.5, 0.8].iter().any(|t| transition_layers(id, a, *t) != transition_layers(id, b, *t));
+                assert!(differs, "{id}: {a} vs {b}");
+            }
+        }
+    }
+}
+
+#[test]
+fn frames_stay_cheap() {
+    // Per frame, the show draws these meshes from cached slide textures: keep them small.
+    for (id, _, _, _, opts) in TRANSITIONS {
+        let mut options: Vec<&str> = opts.to_vec();
+        options.push("");
+        for o in options {
+            for t in [0.1, 0.3, 0.5, 0.7, 0.9] {
+                let tris: usize = transition_frame(id, o, t, A).iter().map(|l| crate::layer_mesh(l).1.len()).sum();
+                assert!(tris < 30_000, "{id}/{o} t={t}: {tris} triangles");
+            }
+        }
+    }
+}
+
+#[test]
+fn hostile_aspects_are_safe() {
+    for a in [f64::NAN, 0.0, -3.0, 1e9, f64::INFINITY] {
+        for (id, ..) in TRANSITIONS {
+            for l in transition_frame(id, "", 0.4, a) {
+                assert!(l.quad.iter().all(|p| p[0].is_finite() && p[1].is_finite()));
+                assert!(l.fade.iter().all(|f| (0.0..=1.0).contains(f)));
+            }
+        }
+    }
+    assert!(near(ss(0.5), 0.5, 1e-12));
+}

crates/fonts/src/fallback.rs

@@ -17,6 +17,11 @@ use skrifa::raw::TableProvider;
 use crate::script::{ScriptTag, script_of};
 use crate::{CRAFT_FONTS, FontDb, FontFace};
 
+/// Variation selector 15: text presentation.
+const TEXT_SELECTOR: char = '\u{FE0E}';
+/// Combining enclosing keycap.
+const KEYCAP: char = '\u{20E3}';
+
 /// Characters that never decide a face: they're drawn by whatever face the cluster gets.
 fn ignorable(c: char) -> bool {
     c.is_whitespace()
@@ -24,20 +29,72 @@ fn ignorable(c: char) -> bool {
         || matches!(c as u32, 0x200B..=0x200F | 0x202A..=0x202E | 0x2060..=0x2069 | 0xFE00..=0xFE0F | 0xFEFF | 0xE0100..=0xE01EF)
 }
 
-/// Is the cluster an emoji drawn in colour: a pictograph that defaults to emoji presentation, or
-/// any sequence with an emoji presentation selector (U+FE0F), a zero-width joiner between
-/// pictographs, a skin tone modifier, regional indicators (flags) or a keycap?
+/// Is the cluster an emoji drawn in colour: a pictograph that defaults to emoji presentation
+/// (Unicode's Emoji_Presentation, including BMP ones such as ⭐ ✅ ☔ ⌚ ⏩), or a sequence with an
+/// emoji presentation selector (U+FE0F), a zero-width joiner between pictographs, a skin tone
+/// modifier or regional indicators (flags)? Keycaps ("1️⃣") are not: PowerPoint draws them as text
+/// (an outlined key), as it draws ♥ ✔ ☎ ⬆ ▶ without a selector.
 pub fn is_emoji_cluster(cluster: &[char]) -> bool {
-    if cluster.contains(&'\u{FE0E}') {
+    if cluster.contains(&'\u{FE0E}') || cluster.contains(&'\u{20E3}') {
         return false;
     }
     let pictographic = |c: char| matches!(c as u32, 0x1F000..=0x1FAFF | 0x2600..=0x27BF | 0x2B00..=0x2BFF | 0x2190..=0x21FF | 0x2300..=0x23FF);
-    let default_emoji =
-        |c: char| matches!(c as u32, 0x1F300..=0x1F64F | 0x1F680..=0x1F6FF | 0x1F900..=0x1F9FF | 0x1FA70..=0x1FAFF | 0x1F1E6..=0x1F1FF);
+    let default_emoji = |c: char| {
+        matches!(
+            c as u32,
+            0x1F300..=0x1F64F
+                | 0x1F680..=0x1F6FF
+                | 0x1F900..=0x1F9FF
+                | 0x1FA70..=0x1FAFF
+                | 0x1F1E6..=0x1F1FF
+                | 0x1F004
+                | 0x1F0CF
+                | 0x1F18E
+                | 0x1F191..=0x1F19A
+                | 0x1F201
+                | 0x1F21A
+                | 0x1F22F
+                | 0x1F232..=0x1F236
+                | 0x1F238..=0x1F23A
+                | 0x1F250..=0x1F251
+                | 0x231A..=0x231B
+                | 0x23E9..=0x23EC
+                | 0x23F0
+                | 0x23F3
+                | 0x25FD..=0x25FE
+                | 0x2614..=0x2615
+                | 0x2648..=0x2653
+                | 0x267F
+                | 0x2693
+                | 0x26A1
+                | 0x26AA..=0x26AB
+                | 0x26BD..=0x26BE
+                | 0x26C4..=0x26C5
+                | 0x26CE
+                | 0x26D4
+                | 0x26EA
+                | 0x26F2..=0x26F3
+                | 0x26F5
+                | 0x26FA
+                | 0x26FD
+                | 0x2705
+                | 0x270A..=0x270B
+                | 0x2728
+                | 0x274C
+                | 0x274E
+                | 0x2753..=0x2755
+                | 0x2757
+                | 0x2795..=0x2797
+                | 0x27B0
+                | 0x27BF
+                | 0x2B1B..=0x2B1C
+                | 0x2B50
+                | 0x2B55
+        )
+    };
     cluster.iter().any(|&c| default_emoji(c))
-        || (cluster.contains(&'\u{FE0F}') && cluster.iter().any(|&c| pictographic(c) || c.is_ascii_digit() || c == '#' || c == '*'))
+        || (cluster.contains(&'\u{FE0F}') && cluster.iter().any(|&c| pictographic(c)))
         || (cluster.contains(&'\u{200D}') && cluster.iter().any(|&c| pictographic(c)))
-        || cluster.contains(&'\u{20E3}')
 }
 
 /// Does `face` draw every character of the cluster?
@@ -86,12 +143,13 @@ impl FontDb {
         if let Some(f) = chain.iter().find(|f| covers_cluster(f, cluster)) {
             return f.clone();
         }
-        // Text presentation (U+FE0E): a plain face, not a colour emoji one.
-        if cluster.contains(&'\u{FE0E}') {
-            let faces = self.read_faces();
-            if let Some(f) = faces.iter().find(|f| !f.is_color() && covers_cluster(f, cluster)) {
-                return f.clone();
-            }
+        // Text presentation (U+FE0E) and keycaps: a plain face, not a colour emoji one.
+        let text_style = cluster.contains(&TEXT_SELECTOR) || cluster.contains(&KEYCAP);
+        if text_style
+            && let Some(key) = cluster.iter().copied().find(|c| !ignorable(*c))
+            && let Some(f) = self.plain_face_for(key, cluster)
+        {
+            return f;
         }
         let first = || chain.first().cloned().unwrap_or_else(|| self.face(crate::DEFAULT_FAMILY, style));
         let Some(key) = cluster.iter().copied().find(|c| !ignorable(*c)) else { return first() };
@@ -124,11 +182,23 @@ impl FontDb {
             }
         }
         let exclude = chain.first().map(|f| f.id()).unwrap_or(u32::MAX);
-        match self.fallback_for(key, exclude) {
+        let f = match self.fallback_for(key, exclude) {
             Some(f) if covers_cluster(&f, cluster) => f,
             Some(f) if chain.iter().all(|c| !c.covers(key)) => f,
-            _ => first(),
+            // A letter with marks the run's font lacks (stacked combining marks): a loaded plain
+            // face that draws the whole cluster, as PowerPoint draws the marks, before the run's
+            // font with missing-glyph boxes.
+            _ => self.read_faces().iter().find(|f| !f.is_color() && covers_cluster(f, cluster)).cloned().unwrap_or_else(first),
+        };
+        // A pictograph that defaults to text presentation (⚠ ♥ ⬆ ▶) whose first fallback is the
+        // colour emoji font: PowerPoint draws it from a plain symbol font.
+        if f.is_color()
+            && !is_emoji_cluster(cluster)
+            && let Some(plain) = self.plain_face_for(key, cluster)
+        {
+            return plain;
         }
+        f
     }
 
     /// An installed (non-bundled) face covering the cluster, loading one from the system catalog

crates/fonts/src/fontdb.rs

@@ -134,6 +134,12 @@ pub struct FontFace {
     /// Windows ascent over the Windows ascent plus descent (OS/2 `usWinAscent`/`usWinDescent`),
     /// the split PowerPoint uses (computed by `line_split`).
     pub line_split: f64,
+    /// Underline position (top edge, below the baseline) and thickness in font units (`post`
+    /// table; 0.1 and 0.05 em when the font has none). PowerPoint draws single underlines there.
+    pub underline: (f64, f64),
+    /// Strikethrough position (top edge, above the baseline) and thickness in font units (OS/2;
+    /// 0.26 and 0.05 em when the font has none). PowerPoint draws single strikethroughs there.
+    pub strikeout: (f64, f64),
     pub shaper: harfrust::ShaperData,
     /// Variable fonts: the named instance's axis settings (user units; empty = default instance),
     /// the normalised location and the shaper's view of it.
@@ -586,6 +592,8 @@ fn make_face(bytes: FontBytes, index: u32, family: String, style: String, coords
         cap_height: m.cap_height.map(|v| v as f64).filter(|v| *v > 0.0).unwrap_or(m.ascent as f64 * 0.72),
         x_height: m.x_height.map(|v| v as f64).filter(|v| *v > 0.0).unwrap_or(m.ascent as f64 * 0.5),
         line_split: line_split(&f, m.ascent as f64, -(m.descent as f64), m.units_per_em.max(1) as f64),
+        underline: underline_metrics(m.underline, m.units_per_em.max(1) as f64),
+        strikeout: strikeout_metrics(m.strikeout, m.units_per_em.max(1) as f64),
         shaper,
         coords,
         location,
@@ -597,6 +605,30 @@ fn make_face(bytes: FontBytes, index: u32, family: String, style: String, coords
     })
 }
 
+/// The underline's top edge below the baseline and its thickness, font units, from the `post`
+/// table (its position is the top edge: Arial's -217/2048 is where PowerPoint's underline starts,
+/// 10 px below the baseline at 96 pt); fonts without a usable one get 0.1 em and 0.05 em.
+fn underline_metrics(d: Option<skrifa::metrics::Decoration>, upem: f64) -> (f64, f64) {
+    match d {
+        Some(d) if d.thickness > 0.0 && (d.thickness as f64) < upem * 0.3 && (d.offset as f64).abs() < upem * 0.5 => {
+            (-(d.offset as f64), d.thickness as f64)
+        }
+        _ => (upem * 0.1, upem * 0.05),
+    }
+}
+
+/// The strikethrough's top edge above the baseline and its thickness, font units, from OS/2 (its
+/// position is the top edge: Arial's 530/2048 is where PowerPoint's strikethrough starts, 25 px
+/// above the baseline at 96 pt); fonts without a usable one get 0.26 em and 0.05 em.
+fn strikeout_metrics(d: Option<skrifa::metrics::Decoration>, upem: f64) -> (f64, f64) {
+    match d {
+        Some(d) if d.thickness > 0.0 && (d.thickness as f64) < upem * 0.3 && d.offset > 0.0 && (d.offset as f64) < upem => {
+            (d.offset as f64, d.thickness as f64)
+        }
+        _ => (upem * 0.26, upem * 0.05),
+    }
+}
+
 /// The named style part of a style with axis settings (`Bold {wght:650}` → `Bold`).
 pub fn base_style(style: &str) -> &str {
     style.split('{').next().unwrap_or(style).trim()
@@ -1060,6 +1092,79 @@ impl FontDb {
         None
     }
 
+    /// A loaded plain (not colour) face drawing all of `cluster`, loading an installed plain font
+    /// that covers `key` if none is loaded yet. Misses are remembered.
+    pub(crate) fn plain_face_for(&self, key: char, cluster: &[char]) -> Option<Arc<FontFace>> {
+        // Symbol fonts first (PowerPoint draws ⚠ ♥ ⬆ from the system's symbol font), then the
+        // usual fallback families in order, then any other.
+        let rank = |f: &FontFace| {
+            if f.family.contains("Symbol") {
+                return 0;
+            }
+            #[cfg(not(target_arch = "wasm32"))]
+            if let Some(i) = SYSTEM_FALLBACKS.iter().position(|s| s.eq_ignore_ascii_case(&f.family)) {
+                return i + 1;
+            }
+            1000
+        };
+        let pick = |db: &FontDb| {
+            let faces = db.read_faces();
+            let mut v: Vec<&Arc<FontFace>> = faces.iter().filter(|f| !f.is_color() && crate::covers_cluster(f, cluster)).collect();
+            v.sort_by_key(|f| (rank(f), f.italic, (f.weight - 400.0).abs() as i32));
+            v.first().map(|f| (*f).clone())
+        };
+        #[cfg(not(target_arch = "wasm32"))]
+        {
+            let cataloged: Vec<String> = self.read_catalog().iter().map(|e| e.family.clone()).collect();
+            for fam in SYSTEM_FALLBACKS.iter().filter(|f| f.contains("Symbol")) {
+                if !self.is_loaded(fam) && cataloged.iter().any(|f| f.eq_ignore_ascii_case(fam)) {
+                    self.load_cataloged(fam);
+                }
+            }
+        }
+        if let Some(f) = pick(self) {
+            return Some(f);
+        }
+        #[cfg(not(target_arch = "wasm32"))]
+        if self.system_plain_fallback(key) {
+            return pick(self);
+        }
+        let _ = key;
+        None
+    }
+
+    /// Load an installed font without colour tables covering `c`. True if one was loaded.
+    #[cfg(not(target_arch = "wasm32"))]
+    fn system_plain_fallback(&self, c: char) -> bool {
+        static MISSES: Mutex<Option<std::collections::HashSet<char>>> = Mutex::new(None);
+        if c.is_control() || c.is_whitespace() {
+            return false;
+        }
+        if !self.sys.lock().unwrap_or_else(|e| e.into_inner()).enabled {
+            return false;
+        }
+        if MISSES.lock().unwrap_or_else(|e| e.into_inner()).get_or_insert_with(Default::default).contains(&c) {
+            return false;
+        }
+        let mut paths: Vec<std::path::PathBuf> = self.read_catalog().iter().map(|e| e.path.clone()).collect();
+        paths.sort();
+        paths.dedup();
+        for p in paths {
+            if std::fs::metadata(&p).map(|m| m.len() > 40 << 20).unwrap_or(true) {
+                continue;
+            }
+            let Ok(data) = std::fs::read(&p) else { continue };
+            let hit = enumerate_faces(&data).iter().any(|(i, _, _, _)| {
+                !has_color_tables(&data, *i) && skrifa::FontRef::from_index(&data, *i).is_ok_and(|f| f.charmap().map(c).is_some())
+            });
+            if hit && self.add_font(data) > 0 {
+                return true;
+            }
+        }
+        MISSES.lock().unwrap_or_else(|e| e.into_inner()).get_or_insert_with(Default::default).insert(c);
+        false
+    }
+
     /// Load an installed colour font covering `c`. True if one was loaded.
     #[cfg(not(target_arch = "wasm32"))]
     fn system_color_fallback(&self, c: char) -> bool {

crates/fonts/src/lib.rs

@@ -141,10 +141,15 @@ mod tests {
     #[test]
     fn emoji_clusters_are_recognised() {
         let c = |s: &str| s.chars().collect::<Vec<char>>();
-        for yes in ["😀", "👍🏽", "❤\u{FE0F}", "👨\u{200D}👩\u{200D}👧", "🇯🇵", "1\u{FE0F}\u{20E3}", "🏳\u{FE0F}\u{200D}🌈"] {
+        // As PowerPoint draws them: emoji-presentation characters (⭐ ✅ ☔ ⌚ ⏩) in colour even
+        // without a selector, text-presentation ones (♥ ✔ ☎ ⬆ ▶) as text unless U+FE0F asks, and
+        // keycaps always as text.
+        for yes in ["😀", "👍🏽", "❤\u{FE0F}", "👨\u{200D}👩\u{200D}👧", "🇯🇵", "🏳\u{FE0F}\u{200D}🌈", "⭐", "✅", "☔", "⌚", "⏩", "🀄"]
+        {
             assert!(is_emoji_cluster(&c(yes)), "{yes:?}");
         }
-        for no in ["a", "1", "❤", "☺\u{FE0E}", "😀\u{FE0E}", "字", "→"] {
+        for no in ["a", "1", "❤", "☺\u{FE0E}", "😀\u{FE0E}", "字", "→", "♥", "✔", "☎", "⬆", "▶", "1\u{FE0F}\u{20E3}", "#\u{20E3}"]
+        {
             assert!(!is_emoji_cluster(&c(no)), "{no:?}");
         }
     }

crates/model/src/anim.rs

@@ -63,7 +63,7 @@ pub static TRANSITIONS: &[(&str, &str, &str, u32, &[&str])] = &[
     ("fracture", "Fracture", "Exciting", 2000, &[]),
     ("crush", "Crush", "Exciting", 2000, &[]),
     ("peelOff", "Peel Off", "Exciting", 1500, &["l", "r"]),
-    ("pageCurlDouble", "Page Curl", "Exciting", 1500, &["l", "r"]),
+    ("pageCurlDouble", "Page Curl", "Exciting", 1500, &["l", "r", "singleL", "singleR"]),
     ("airplane", "Airplane", "Exciting", 2000, &["l", "r"]),
     ("origami", "Origami", "Exciting", 2000, &["l", "r"]),
     ("dissolve", "Dissolve", "Exciting", 1200, &[]),
@@ -72,9 +72,9 @@ pub static TRANSITIONS: &[(&str, &str, &str, u32, &[&str])] = &[
     ("clock", "Clock", "Exciting", 2000, &["clockwise", "counterClockwise", "wedge"]),
     ("ripple", "Ripple", "Exciting", 1400, &["center", "lu", "ru", "ld", "rd"]),
     ("honeycomb", "Honeycomb", "Exciting", 3000, &[]),
-    ("glitter", "Glitter", "Exciting", 2500, &["l", "r", "u", "d"]),
+    ("glitter", "Glitter", "Exciting", 2500, &["l", "r", "u", "d", "hexL", "hexR", "hexU", "hexD"]),
     ("vortex", "Vortex", "Exciting", 3000, &["l", "r", "u", "d"]),
-    ("shred", "Shred", "Exciting", 2000, &["strips", "particles"]),
+    ("shred", "Shred", "Exciting", 2000, &["stripsIn", "stripsOut", "particlesIn", "particlesOut"]),
     ("switch", "Switch", "Exciting", 1250, &["l", "r"]),
     ("flip", "Flip", "Exciting", 1250, &["l", "r"]),
     ("gallery", "Gallery", "Exciting", 1500, &["l", "r"]),
@@ -82,7 +82,7 @@ pub static TRANSITIONS: &[(&str, &str, &str, u32, &[&str])] = &[
     ("doors", "Doors", "Exciting", 1400, &["vert", "horz"]),
     ("box", "Box", "Exciting", 1250, &["l", "r", "u", "d"]),
     ("comb", "Comb", "Exciting", 1000, &["horz", "vert"]),
-    ("zoom", "Zoom", "Exciting", 1000, &["in", "out"]),
+    ("zoom", "Zoom", "Exciting", 1000, &["in", "out", "rotate"]),
     ("random", "Random", "Exciting", 2000, &[]),
     ("pan", "Pan", "Dynamic Content", 1000, &["u", "d", "l", "r"]),
     ("ferris", "Ferris Wheel", "Dynamic Content", 2000, &["l", "r"]),
@@ -93,6 +93,101 @@ pub static TRANSITIONS: &[(&str, &str, &str, u32, &[&str])] = &[
     ("flythrough", "Fly Through", "Dynamic Content", 1000, &["in", "out", "inBounce", "outBounce"]),
 ];
 
+/// The Effect Options label PowerPoint shows for a transition option. Options are stored as the
+/// file format's values: for moving transitions (Push, Wipe, Cover, Pan, Cube…) the direction
+/// things move, so "l" is the effect coming "From Right"; Glitter and the preset effects (Fall
+/// Over, Wind…) name the side itself; Ripple names where the wave heads.
+pub fn transition_option_label(kind: &str, option: &str) -> String {
+    let side = |c: char| match c {
+        'l' => "Left",
+        'r' => "Right",
+        'u' => "Top",
+        _ => "Bottom",
+    };
+    let opposite = |c: char| match c {
+        'l' => 'r',
+        'r' => 'l',
+        'u' => 'd',
+        _ => 'u',
+    };
+    let corner = |o: &str, flip: bool| -> Option<String> {
+        let mut cs = o.chars();
+        let (h, v) = (cs.next()?, cs.next()?);
+        let (h, v) = if flip { (opposite(h), opposite(v)) } else { (h, v) };
+        Some(format!("From {}-{}", side(v), side(h)))
+    };
+    let moving = matches!(
+        kind,
+        "push"
+            | "wipe"
+            | "cover"
+            | "uncover"
+            | "pan"
+            | "vortex"
+            | "cube"
+            | "box"
+            | "rotate"
+            | "orbit"
+            | "gallery"
+            | "conveyor"
+            | "ferris"
+            | "switch"
+            | "flip"
+    );
+    match (kind, option) {
+        (_, "horz") => "Horizontal".into(),
+        (_, "vert") => "Vertical".into(),
+        ("split", o) => format!("{} {}", if o.starts_with("horz") { "Horizontal" } else { "Vertical" }, if o.ends_with("In") { "In" } else { "Out" }),
+        ("fade" | "cut", "throughBlack") => "Through Black".into(),
+        ("fade", _) => "Smoothly".into(),
+        ("cut", _) => "Cut".into(),
+        ("clock", "counterClockwise") => "Counterclockwise".into(),
+        ("clock", "wedge") => "Wedge".into(),
+        ("clock", _) => "Clockwise".into(),
+        ("zoom", "rotate") => "Zoom and Rotate".into(),
+        ("ripple", "center") => "Center".into(),
+        ("ripple", o) => corner(o, true).unwrap_or_else(|| "Center".into()),
+        ("glitter", o) => {
+            let (pat, d) = match o.strip_prefix("hex") {
+                Some(d) => ("Hexagons", d.to_ascii_lowercase()),
+                None => ("Diamonds", o.to_string()),
+            };
+            format!("{pat} From {}", side(d.chars().next().unwrap_or('l')))
+        }
+        ("pageCurlDouble", o) => match o {
+            "singleL" => "Single Left".into(),
+            "singleR" => "Single Right".into(),
+            "r" => "Double Right".into(),
+            _ => "Double Left".into(),
+        },
+        ("shred", o) => {
+            format!("{} {}", if o.starts_with("particles") { "Particles" } else { "Strips" }, if o.ends_with("Out") { "Out" } else { "In" })
+        }
+        ("reveal", o) => format!(
+            "{} {}",
+            if o.starts_with("black") { "Through Black" } else { "Smoothly" },
+            if o.ends_with("Right") { "From Right" } else { "From Left" }
+        ),
+        ("flythrough", o) => {
+            format!("{}{}", if o.starts_with("out") { "Out" } else { "In" }, if o.ends_with("Bounce") { " with Bounce" } else { "" })
+        }
+        ("morph", o) => match o {
+            "words" => "Words".into(),
+            "characters" => "Characters".into(),
+            _ => "Objects".into(),
+        },
+        (_, o) if o.len() == 2 && moving => corner(o, true).unwrap_or_default(),
+        (_, o) if o.len() == 1 && moving => format!("From {}", side(opposite(o.chars().next().unwrap_or('l')))),
+        (_, "l") => "Left".into(),
+        (_, "r") => "Right".into(),
+        (_, "u") => "Top".into(),
+        (_, "d") => "Bottom".into(),
+        (_, "in") => "In".into(),
+        (_, "out") => "Out".into(),
+        (_, o) => o.to_string(),
+    }
+}
+
 #[derive(Clone, Copy, Debug, Default, PartialEq, Eq, Serialize, Deserialize)]
 #[serde(rename_all = "camelCase")]
 pub enum AnimClass {
@@ -291,3 +386,29 @@ pub static ANIMATIONS: &[(&str, &str, AnimClass, u32, u32, &[&str])] = &[
 pub fn animation_info(effect: &str, class: AnimClass) -> Option<&'static (&'static str, &'static str, AnimClass, u32, u32, &'static [&'static str])> {
     ANIMATIONS.iter().find(|a| a.0 == effect && a.2 == class).or_else(|| ANIMATIONS.iter().find(|a| a.0 == effect))
 }
+
+#[cfg(test)]
+mod option_label_tests {
+    use super::*;
+
+    #[test]
+    fn transition_option_labels() {
+        assert_eq!(transition_option_label("push", "l"), "From Right");
+        assert_eq!(transition_option_label("push", "u"), "From Bottom");
+        assert_eq!(transition_option_label("wipe", "r"), "From Left");
+        assert_eq!(transition_option_label("cover", "ru"), "From Bottom-Left");
+        assert_eq!(transition_option_label("ripple", "ru"), "From Bottom-Left");
+        assert_eq!(transition_option_label("glitter", "hexU"), "Hexagons From Top");
+        assert_eq!(transition_option_label("glitter", "l"), "Diamonds From Left");
+        assert_eq!(transition_option_label("wind", "l"), "Left");
+        assert_eq!(transition_option_label("pageCurlDouble", "singleR"), "Single Right");
+        assert_eq!(transition_option_label("shred", "particlesOut"), "Particles Out");
+        assert_eq!(transition_option_label("zoom", "rotate"), "Zoom and Rotate");
+        assert_eq!(transition_option_label("split", "vertIn"), "Vertical In");
+        for (id, _, _, _, opts) in TRANSITIONS {
+            for o in opts.iter() {
+                assert!(!transition_option_label(id, o).is_empty(), "{id}/{o}");
+            }
+        }
+    }
+}

crates/model/src/text.rs

@@ -55,6 +55,10 @@ pub enum TextDir {
     Vertical270,
     Stacked,
     EaVertical,
+    /// `mongolianVert`: turned like `vert`, lines running from left to right.
+    MongolianVertical,
+    /// `wordArtVertRtl`: stacked, lines running from right to left.
+    StackedRtl,
 }
 
 impl TextDir {
@@ -65,14 +69,18 @@ impl TextDir {
             TextDir::Vertical270 => "vert270",
             TextDir::Stacked => "wordArtVert",
             TextDir::EaVertical => "eaVert",
+            TextDir::MongolianVertical => "mongolianVert",
+            TextDir::StackedRtl => "wordArtVertRtl",
         }
     }
     pub fn from_xml(s: &str) -> Option<Self> {
         Some(match s {
             "horz" => TextDir::Horizontal,
-            "vert" | "mongolianVert" => TextDir::Vertical,
+            "vert" => TextDir::Vertical,
+            "mongolianVert" => TextDir::MongolianVertical,
             "vert270" => TextDir::Vertical270,
-            "wordArtVert" | "wordArtVertRtl" => TextDir::Stacked,
+            "wordArtVert" => TextDir::Stacked,
+            "wordArtVertRtl" => TextDir::StackedRtl,
             "eaVert" => TextDir::EaVertical,
             _ => return None,
         })

crates/pptx/src/maps.rs

@@ -17,7 +17,12 @@ pub fn transition_from_xml(e: &El) -> Option<(String, String)> {
     Some((k, if has_opts { o } else { String::new() }))
 }
 
+/// Preset transitions (`p15:prstTrans`) whose "Left" option PowerPoint writes with `invX="1"`
+/// (the others write it for "Right"), as observed on PowerPoint's own files.
+const INVX_LEFT: &[&str] = &["wind", "airplane", "origami"];
+
 fn transition_from_xml_raw(e: &El) -> Option<(String, String)> {
+    // Defaults are what PowerPoint leaves out: e.g. it writes Push Left as `<p:push/>`.
     let dir = |d: &str| e.attr("dir").unwrap_or(d).to_string();
     let k = |s: &str| s.to_string();
     Some(match e.local() {
@@ -25,16 +30,22 @@ fn transition_from_xml_raw(e: &El) -> Option<(String, String)> {
         "cut" => (k("cut"), if e.bool("thruBlk") == Some(true) { k("throughBlack") } else { String::new() }),
         "push" => (k("push"), dir("l")),
         "wipe" => (k("wipe"), dir("l")),
+        // Diagonal wipes.
+        "strips" => (k("wipe"), dir("lu")),
         "split" => {
             let o = e.attr("orient").unwrap_or("horz");
             let d = e.attr("dir").unwrap_or("out");
             (k("split"), format!("{o}{}", if d == "in" { "In" } else { "Out" }))
         }
-        "randomBar" => (k("randomBar"), dir("vert")),
+        "randomBar" => (k("randomBar"), dir("horz")),
         "circle" => (k("shape"), k("circle")),
         "diamond" => (k("shape"), k("diamond")),
         "plus" => (k("shape"), k("plus")),
-        "zoom" => (k("zoom"), dir("in")),
+        // Shape In / Out (the slide zooming in a box).
+        "zoom" => (k("shape"), if e.attr("dir") == Some("in") { k("in") } else { k("out") }),
+        // The Zoom transition, and its Zoom and Rotate option.
+        "warp" => (k("zoom"), if e.attr("dir") == Some("in") { k("in") } else { k("out") }),
+        "newsflash" => (k("zoom"), k("rotate")),
         "pull" => (k("uncover"), dir("l")),
         "cover" => (k("cover"), dir("l")),
         "checker" => (k("checker"), dir("horz")),
@@ -47,14 +58,22 @@ fn transition_from_xml_raw(e: &El) -> Option<(String, String)> {
         "switch" => (k("switch"), dir("r")),
         "flip" => (k("flip"), dir("r")),
         "ripple" => (k("ripple"), dir("center")),
-        "doors" => (k("doors"), dir("vert")),
-        "window" => (k("window"), dir("vert")),
+        "doors" => (k("doors"), dir("horz")),
+        "window" => (k("window"), dir("horz")),
         "ferris" => (k("ferris"), dir("l")),
         "gallery" => (k("gallery"), dir("l")),
         "conveyor" => (k("conveyor"), dir("l")),
-        "pan" => (k("pan"), dir("d")),
-        "glitter" => (k("glitter"), dir("l")),
-        "shred" => (k("shred"), if e.attr("pattern") == Some("crush") { k("particles") } else { k("strips") }),
+        "pan" => (k("pan"), dir("l")),
+        "glitter" => {
+            let d = dir("l");
+            if e.attr("pattern") == Some("hexagon") { (k("glitter"), format!("hex{}", d.to_ascii_uppercase())) } else { (k("glitter"), d) }
+        }
+        "shred" => {
+            // `crush` is what DeckCraft wrote before it knew PowerPoint's `rectangle`.
+            let particles = matches!(e.attr("pattern"), Some("rectangle" | "crush"));
+            let out = e.attr("dir") == Some("out");
+            (k("shred"), format!("{}{}", if particles { "particles" } else { "strips" }, if out { "Out" } else { "In" }))
+        }
         "reveal" => {
             let black = e.bool("thruBlk") == Some(true);
             let right = e.attr("dir") == Some("r");
@@ -78,11 +97,16 @@ fn transition_from_xml_raw(e: &El) -> Option<(String, String)> {
         }
         "prstTrans" => {
             let prst = e.attr("prst").unwrap_or("fallOver");
+            let inv = e.bool("invX") == Some(true);
+            if prst == "pageCurlSingle" {
+                return Some((k("pageCurlDouble"), if inv { k("singleR") } else { k("singleL") }));
+            }
             let known = deckcraft_model::anim::TRANSITIONS.iter().any(|t| t.0 == prst);
             if !known {
                 return None;
             }
-            (k(prst), if e.bool("invX") == Some(true) { k("r") } else { k("l") })
+            let left = if INVX_LEFT.contains(&prst) { inv } else { !inv };
+            (k(prst), if left { k("l") } else { k("r") })
         }
         "morph" => (
             k("morph"),
@@ -119,7 +143,10 @@ pub fn transition_to_xml(w: &mut W, kind: &str, option: &str) -> Option<&'static
         "fade" => w.empty("p:fade", A::new().t("thruBlk", option == "throughBlack")),
         "cut" => w.empty("p:cut", A::new().t("thruBlk", option == "throughBlack")),
         "push" => w.empty("p:push", A::new().a("dir", lrud("u"))),
-        "wipe" => w.empty("p:wipe", A::new().a("dir", lrud("r"))),
+        "wipe" => match option {
+            "lu" | "ru" | "ld" | "rd" => w.empty("p:strips", A::new().a("dir", option)),
+            _ => w.empty("p:wipe", A::new().a("dir", lrud("r"))),
+        },
         "split" => {
             let (o, d) = match option {
                 "vertIn" => ("vert", "in"),
@@ -136,7 +163,13 @@ pub fn transition_to_xml(w: &mut W, kind: &str, option: &str) -> Option<&'static
             "in" | "out" => w.empty("p:zoom", A::new().a("dir", option)),
             _ => w.empty0("p:circle"),
         },
-        "zoom" => w.empty("p:zoom", A::new().a("dir", if option == "out" { "out" } else { "in" })),
+        "zoom" => match option {
+            "rotate" => w.empty0("p:newsflash"),
+            _ => {
+                w.empty("p14:warp", A::new().a("dir", if option == "out" { "out" } else { "in" }));
+                return Some("p14");
+            }
+        },
         "uncover" => w.empty("p:pull", A::new().a("dir", eight("l"))),
         "cover" => w.empty("p:cover", A::new().a("dir", eight("l"))),
         "checker" => w.empty("p:checker", A::new().a("dir", hv("horz"))),
@@ -160,9 +193,15 @@ pub fn transition_to_xml(w: &mut W, kind: &str, option: &str) -> Option<&'static
             w.empty0("p14:flash");
             return Some("p14");
         }
-        "vortex" | "glitter" => {
-            let name = if kind == "vortex" { "p14:vortex" } else { "p14:glitter" };
-            w.empty(name, A::new().a("dir", lrud("l")));
+        "vortex" => {
+            w.empty("p14:vortex", A::new().a("dir", lrud("l")));
+            return Some("p14");
+        }
+        "glitter" => {
+            let hex = option.starts_with("hex");
+            let d = option.trim_start_matches("hex").to_ascii_lowercase();
+            let d = if matches!(d.as_str(), "l" | "r" | "u" | "d") { d } else { "l".to_string() };
+            w.empty("p14:glitter", A::new().a("dir", d).o("pattern", hex.then_some("hexagon")));
             return Some("p14");
         }
         "switch" | "flip" | "gallery" | "conveyor" | "ferris" => {
@@ -194,7 +233,11 @@ pub fn transition_to_xml(w: &mut W, kind: &str, option: &str) -> Option<&'static
             return Some("p14");
         }
         "shred" => {
-            w.empty("p14:shred", A::new().a("pattern", if option == "particles" { "crush" } else { "strip" }));
+            let particles = option.starts_with("particles");
+            w.empty(
+                "p14:shred",
+                A::new().a("pattern", if particles { "rectangle" } else { "strip" }).a("dir", if option.ends_with("Out") { "out" } else { "in" }),
+            );
             return Some("p14");
         }
         "reveal" => {
@@ -215,8 +258,13 @@ pub fn transition_to_xml(w: &mut W, kind: &str, option: &str) -> Option<&'static
             );
             return Some("p14");
         }
+        "pageCurlDouble" if option.starts_with("single") => {
+            w.empty("p15:prstTrans", A::new().a("prst", "pageCurlSingle").t("invX", option == "singleR"));
+            return Some("p15");
+        }
         "fallOver" | "drape" | "curtains" | "wind" | "prestige" | "fracture" | "crush" | "peelOff" | "pageCurlDouble" | "airplane" | "origami" => {
-            w.empty("p15:prstTrans", A::new().a("prst", kind).t("invX", option == "r"));
+            let inv = if INVX_LEFT.contains(&kind) { option == "l" } else { option == "r" };
+            w.empty("p15:prstTrans", A::new().a("prst", kind).t("invX", inv));
             return Some("p15");
         }
         "morph" => {
@@ -342,16 +390,7 @@ mod tests {
                 assert!(!ns.is_empty());
                 let d = parse(w.s.as_bytes()).unwrap();
                 let (k, opt) = transition_from_xml(&d.root).unwrap_or_else(|| panic!("no read for {kind}"));
-                // `shape` in/out are written as zoom; everything else must come back.
-                if *kind == "shape" && (o == "in" || o == "out") {
-                    assert_eq!(k, "zoom");
-                    continue;
-                }
                 assert_eq!(k, *kind, "kind for {kind}/{o}");
-                // PresentationML wipes have no diagonal directions.
-                if *kind == "wipe" && o.len() == 2 {
-                    continue;
-                }
                 if !o.is_empty() {
                     assert_eq!(opt, o, "option for {kind}");
                 }

crates/pptx/src/read/dml.rs

@@ -616,5 +616,13 @@ mod tests {
         assert_eq!(b.vert, Some(TextDir::Vertical270));
         assert_eq!(b.columns, Some(2));
         assert_eq!(b.autofit, Some(AutoFit::Shrink { font_scale: 0.625, line_reduction: 0.2 }));
+        // mongolianVert is its own direction (PowerPoint runs its lines left to right) and is
+        // written back as it was read.
+        let d = parse(br#"<a:bodyPr vert="mongolianVert"/>"#).unwrap();
+        let b = body_pr(&d.root);
+        assert_eq!(b.vert, Some(TextDir::MongolianVertical));
+        assert_eq!(b.vert.map(|v| v.xml()), Some("mongolianVert"));
+        let d = parse(br#"<a:bodyPr vert="wordArtVertRtl"/>"#).unwrap();
+        assert_eq!(body_pr(&d.root).vert.map(|v| v.xml()), Some("wordArtVertRtl"));
     }
 }

crates/pptx/tests/roundtrip.rs

@@ -857,3 +857,135 @@ fn wordart_warps_and_their_adjusts_round_trip() {
     assert_eq!(inflate.warp.as_deref(), Some("textInflate"));
     assert!(inflate.warp_adj.is_empty());
 }
+
+/// Slide XML of a deck exported with one slide per transition (kind, option, ms, advance after).
+fn transition_deck(list: &[(&str, &str, u32, Option<u32>)]) -> (Presentation, Vec<String>) {
+    let mut p = defaults::new_presentation(None);
+    let base = p.slides[0].as_ref().clone();
+    p.slides.clear();
+    for (kind, option, ms, adv) in list {
+        let mut s = base.clone();
+        s.id = SlideId(p.alloc_id());
+        s.transition = Some(Transition {
+            kind: kind.to_string(),
+            option: option.to_string(),
+            duration_ms: *ms,
+            advance_on_click: adv.is_none(),
+            advance_after_ms: *adv,
+            ..Default::default()
+        });
+        p.slides.push(Arc::new(s));
+    }
+    let bytes = deckcraft_pptx::export(&p).expect("export");
+    let mut zip = zip::ZipArchive::new(std::io::Cursor::new(bytes)).expect("zip");
+    let xml = (1..=list.len())
+        .map(|i| {
+            let mut x = String::new();
+            std::io::Read::read_to_string(&mut zip.by_name(&format!("ppt/slides/slide{i}.xml")).expect("slide"), &mut x).expect("read");
+            x
+        })
+        .collect();
+    (p, xml)
+}
+
+#[test]
+fn transition_xml_matches_powerpoints_elements() {
+    // The elements, attributes and namespaces PowerPoint itself writes for these effect options
+    // (observed on files it saved), inside `mc:AlternateContent` with a `p:fade` fallback for
+    // the 2010+ effects.
+    let cases: &[(&str, &str, &[&str], &str)] = &[
+        ("wipe", "ru", &[r#"<p:strips dir="ru"/>"#], "p14"),
+        ("wipe", "u", &[r#"<p:wipe dir="u"/>"#], "p14"),
+        ("zoom", "in", &[r#"<p14:warp dir="in"/>"#], "p14"),
+        ("zoom", "rotate", &["<p:newsflash/>"], "p14"),
+        ("shape", "out", &[r#"<p:zoom dir="out"/>"#], "p14"),
+        ("glitter", "hexD", &[r#"<p14:glitter dir="d" pattern="hexagon"/>"#], "p14"),
+        ("shred", "particlesOut", &[r#"<p14:shred pattern="rectangle" dir="out"/>"#], "p14"),
+        ("wind", "l", &[r#"<p15:prstTrans prst="wind" invX="1"/>"#], "p15"),
+        ("wind", "r", &[r#"<p15:prstTrans prst="wind"/>"#], "p15"),
+        ("fallOver", "r", &[r#"<p15:prstTrans prst="fallOver" invX="1"/>"#], "p15"),
+        ("pageCurlDouble", "singleR", &[r#"<p15:prstTrans prst="pageCurlSingle" invX="1"/>"#], "p15"),
+        ("orbit", "u", &[r#"<p14:prism dir="u" isContent="1" isInverted="1"/>"#], "p14"),
+        ("vortex", "r", &[r#"<p14:vortex dir="r"/>"#], "p14"),
+        ("morph", "words", &[r#"<p159:morph option="byWord"/>"#], "p159"),
+    ];
+    let list: Vec<(&str, &str, u32, Option<u32>)> = cases.iter().map(|c| (c.0, c.1, 2000, Some(1000))).collect();
+    let (p, xml) = transition_deck(&list);
+    for ((kind, option, wants, req), x) in cases.iter().zip(&xml) {
+        for w in *wants {
+            assert!(x.contains(w), "{kind}/{option}: {w} in {x}");
+        }
+        assert!(x.contains(&format!(r#"Requires="{req}""#)), "{kind}/{option}");
+        assert!(x.contains(r#"p14:dur="2000""#) && x.contains(r#"advTm="1000""#) && x.contains(r#"advClick="0""#), "{kind}/{option}");
+        assert!(x.contains("<mc:Fallback>"), "{kind}/{option}");
+    }
+    // Back in, everything is as it was.
+    let bytes = deckcraft_pptx::export(&p).expect("export");
+    let q = deckcraft_pptx::import(&bytes).expect("import");
+    for ((kind, option, ..), s) in cases.iter().zip(&q.slides) {
+        let t = s.transition.as_ref().expect("transition");
+        assert_eq!(
+            (t.kind.as_str(), t.option.as_str(), t.duration_ms, t.advance_after_ms, t.advance_on_click),
+            (*kind, *option, 2000, Some(1000), false)
+        );
+    }
+}
+
+#[test]
+fn transition_defaults_read_like_powerpoint() {
+    // PowerPoint leaves out an option when it is the element's default; these are its defaults.
+    let cases: &[(&str, &str, &str)] = &[
+        ("<p:push/>", "push", "l"),
+        ("<p:wipe/>", "wipe", "l"),
+        ("<p:strips/>", "wipe", "lu"),
+        ("<p:randomBar/>", "randomBar", "horz"),
+        ("<p:checker/>", "checker", "horz"),
+        ("<p:blinds/>", "blinds", "horz"),
+        ("<p:comb/>", "comb", "horz"),
+        ("<p:zoom/>", "shape", "out"),
+        (r#"<p:zoom dir="in"/>"#, "shape", "in"),
+        ("<p:split/>", "split", "horzOut"),
+        ("<p14:doors/>", "doors", "horz"),
+        ("<p14:window/>", "window", "horz"),
+        ("<p14:pan/>", "pan", "l"),
+        ("<p14:warp/>", "zoom", "out"),
+        ("<p14:glitter/>", "glitter", "l"),
+        ("<p14:shred/>", "shred", "stripsIn"),
+        ("<p14:reveal/>", "reveal", "smoothlyLeft"),
+        ("<p14:prism/>", "cube", "l"),
+        (r#"<p15:prstTrans prst="airplane"/>"#, "airplane", "r"),
+        (r#"<p15:prstTrans prst="peelOff"/>"#, "peelOff", "l"),
+        (r#"<p15:prstTrans prst="pageCurlSingle"/>"#, "pageCurlDouble", "singleL"),
+    ];
+    let (_, xml) = transition_deck(&[("fade", "smoothly", 2000, None)]);
+    let Some(x) = xml.first() else { panic!("no slide") };
+    let start = x.find("<mc:AlternateContent").expect("transition");
+    let end = x.find("</mc:AlternateContent>").expect("transition end") + "</mc:AlternateContent>".len();
+    let p14 = r#"xmlns:p14="http://schemas.microsoft.com/office/powerpoint/2010/main""#;
+    let p15 = r#"xmlns:p15="http://schemas.microsoft.com/office/powerpoint/2012/main""#;
+    for (el, kind, option) in cases {
+        let tr = format!(r#"<p:transition {p14} {p15} spd="slow" p14:dur="2000">{el}</p:transition>"#);
+        let edited = format!("{}{}{}", &x[..start], tr, &x[end..]);
+        let mut p = defaults::new_presentation(None);
+        let base = p.slides[0].as_ref().clone();
+        p.slides = vec![Arc::new(base)];
+        let bytes = deckcraft_pptx::export(&p).expect("export");
+        let mut zip = zip::ZipArchive::new(std::io::Cursor::new(bytes)).expect("zip");
+        let mut out = zip::ZipWriter::new(std::io::Cursor::new(Vec::new()));
+        for i in 0..zip.len() {
+            let mut f = zip.by_index(i).expect("entry");
+            let name = f.name().to_string();
+            let mut data = vec![];
+            std::io::Read::read_to_end(&mut f, &mut data).expect("read");
+            if name == "ppt/slides/slide1.xml" {
+                data = edited.clone().into_bytes();
+            }
+            out.start_file(name, zip::write::SimpleFileOptions::default()).expect("start");
+            std::io::Write::write_all(&mut out, &data).expect("write");
+        }
+        let bytes = out.finish().expect("finish").into_inner();
+        let q = deckcraft_pptx::import(&bytes).expect("import");
+        let t = q.slides[0].transition.as_ref().expect("transition");
+        assert_eq!((t.kind.as_str(), t.option.as_str(), t.duration_ms), (*kind, *option, 2000), "{el}");
+    }
+}

crates/render/Cargo.toml

@@ -13,6 +13,7 @@ deckcraft-geom = { workspace = true }
 deckcraft-color = { workspace = true }
 deckcraft-metafile = { workspace = true }
 deckcraft-model = { workspace = true }
+deckcraft-anim = { workspace = true }
 deckcraft-fonts = { workspace = true }
 deckcraft-text = { workspace = true }
 vello_cpu = { workspace = true }

crates/render/src/lib.rs

@@ -23,6 +23,7 @@ mod pathgrad;
 mod placed;
 mod ramp;
 mod table;
+mod transition;
 mod warp;
 
 use std::collections::HashMap;
@@ -41,12 +42,14 @@ use kurbo::{Affine, BezPath, PathEl, Point, Rect, Shape as _, Vec2};
 use vello_common::filter_effects::{EdgeMode, Filter, FilterPrimitive};
 use vello_cpu::{RenderContext, Resources, peniko};
 
+pub use deckcraft_anim::{transition_frame, transition_layers, uses_slide_parts};
 pub use extent::{Region, TILE, layout_extent, pasteboard_region, slide_extent};
 pub use images::{decode as decode_image, gif_frame};
 pub use morph_path::PathMorph;
 pub use morph_text::TextMorph;
 pub use placed::{Placed, PlacedLink, PlacedText, place_slide};
 pub use table::row_heights as table_row_heights;
+pub use transition::{SlideParts, composite_transition, render_transition};
 
 /// Largest pixmap side we render (vello_cpu uses u16 sizes).
 pub const MAX_SIDE: u32 = 16_000;
@@ -329,6 +332,30 @@ pub fn render_slide_drawn(pres: &Presentation, index: usize, opts: &RenderOpts)
     }
 }
 
+/// Which part of a slide [`render_slide_part`] draws.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub enum SlidePart {
+    /// The background fill with the master and layout graphics.
+    Backdrop,
+    /// The slide's own shapes over transparency.
+    Content,
+}
+
+/// Render one part of slide `index` (transitions that move the contents over the backgrounds).
+/// A panic inside the renderer becomes a transparent image (logged), never a crash.
+pub fn render_slide_part(pres: &Presentation, index: usize, part: SlidePart, opts: &RenderOpts) -> Image {
+    let Some(slide) = pres.slides.get(index) else { return Image::default() };
+    match std::panic::catch_unwind(std::panic::AssertUnwindSafe(|| RENDERER.with(|r| r.borrow_mut().slide_part(pres, slide, index, part, opts)))) {
+        Ok(img) => img,
+        Err(_) => {
+            log::error!("rendering part of slide {index} panicked; showing nothing");
+            RENDERER.with(|r| *r.borrow_mut() = Renderer::default());
+            let (w, h) = output_size(pres, opts);
+            Image { width: w as u32, height: h as u32, pixels: vec![0; w as usize * h as usize * 4] }
+        }
+    }
+}
+
 /// Render a frame between slides `old` and `new` (indices into `pres.slides`), e.g. of Morph: the
 /// backdrop (background, master and layout graphics) of `old` cross-fading into that of `new` by
 /// `mix` (0..1), then `shapes` in order, each resolved against the slide it comes from (`true`:
@@ -550,6 +577,25 @@ impl Renderer {
         self.finish(ctx, w, h)
     }
 
+    fn slide_part(&mut self, pres: &Presentation, slide: &Slide, index: usize, part: SlidePart, opts: &RenderOpts) -> Image {
+        let (mut ctx, w, h, view) = Self::canvas(pres, opts, needs_filters(pres, slide));
+        let f = Frame { pres, opts, fields: Self::fields(pres, index, opts) };
+        if let Some(rctx) = Ctx::for_slide(pres, slide) {
+            match part {
+                SlidePart::Backdrop => self.backdrop(&mut ctx, &f, &rctx, slide, view),
+                SlidePart::Content => {
+                    // Shapes filled with the background (`useBgFill`) still show it.
+                    let (fill, ph) = resolve::background(&rctx, Some(slide));
+                    self.bg = Some((fill, ph, view));
+                    for s in &slide.shapes {
+                        self.shape(&mut ctx, &f, &rctx, s, view, 0);
+                    }
+                }
+            }
+        }
+        self.finish(ctx, w, h)
+    }
+
     #[allow(clippy::too_many_arguments)]
     fn blend(
         &mut self,
@@ -1353,7 +1399,7 @@ pub fn draw_layout_with(ctx: &mut RenderContext, l: &deckcraft_text::TextLayout,
         }
         ctx.set_transform(m * Affine::translate(ps.offset));
         ctx.set_paint(color(d.color, ps.opacity));
-        ctx.fill_rect(&d.rect);
+        fill_deco(ctx, d);
     };
     for d in l.decos.iter().filter(|d| d.behind) {
         deco(ctx, d);
@@ -1380,7 +1426,7 @@ pub fn draw_layout_with(ctx: &mut RenderContext, l: &deckcraft_text::TextLayout,
         // its bottom, from its first to its last character), as in PowerPoint.
         let mut grads: Vec<(usize, peniko::Gradient)> = Vec::new();
         for (gid, x, y) in &run.glyphs {
-            let at = m * Affine::translate((*x, *y));
+            let at = m * glyph_place(run, *gid, *x, *y);
             let Some(g) = run.gradient.as_ref().filter(|g| !g.stops.is_empty()) else {
                 draw_glyph(ctx, run, *gid, at, ps.opacity);
                 continue;
@@ -1401,6 +1447,37 @@ pub fn draw_layout_with(ctx: &mut RenderContext, l: &deckcraft_text::TextLayout,
     }
 }
 
+/// Where glyph `gid` of `run` with its pen at (`x`, `y`) is drawn, in text space: there, turned a
+/// quarter turn back about its em box's centre when it stands upright in vertical text.
+pub(crate) fn glyph_place(run: &deckcraft_text::GlyphRun, gid: u32, x: f64, y: f64) -> Affine {
+    let at = Affine::translate((x, y));
+    match run.upright_centre(gid, x, y) {
+        Some((cx, cy)) => Affine::translate((cx, cy)) * Affine::rotate(-std::f64::consts::FRAC_PI_2) * Affine::translate((-cx, -cy)) * at,
+        None => at,
+    }
+}
+
+/// Fill an underline, strikethrough or highlight with the current paint and transform: its box,
+/// its dashes, or its zigzag stroked.
+pub(crate) fn fill_deco(ctx: &mut RenderContext, d: &deckcraft_text::Deco) {
+    if let Some((pts, w)) = d.wave() {
+        let mut path = BezPath::new();
+        for (i, p) in pts.iter().enumerate() {
+            if i == 0 {
+                path.move_to(*p);
+            } else {
+                path.line_to(*p);
+            }
+        }
+        ctx.set_stroke(kurbo::Stroke::new(w.max(0.01)));
+        ctx.stroke_path(&path);
+        return;
+    }
+    for r in d.pieces() {
+        ctx.fill_rect(&r);
+    }
+}
+
 /// The line of paragraph `para` holding a glyph on baseline `y` (the nearest baseline).
 fn line_at(l: &deckcraft_text::TextLayout, para: usize, y: f64) -> usize {
     l.lines
@@ -1451,7 +1528,7 @@ fn text_effect(ctx: &mut RenderContext, run: &deckcraft_text::GlyphRun, which: T
             continue;
         }
         // The offset is in slide space: a shadow falls the same way whatever the text's rotation.
-        let at = pre_translate(m * Affine::translate((*x, *y)), offset * px) * skew * Affine::scale(k);
+        let at = pre_translate(m * glyph_place(run, *gid, *x, *y), offset * px) * skew * Affine::scale(k);
         ctx.set_transform(at);
         ctx.fill_path(&path);
         if grow > 0.0 {

crates/render/src/morph_text.rs

@@ -219,7 +219,7 @@ pub(crate) fn draw(
         for d in &l.decos {
             ctx.set_transform(place);
             ctx.set_paint(color(d.color, alpha));
-            ctx.fill_rect(&d.rect);
+            crate::fill_deco(ctx, d);
         }
     }
 }

crates/render/src/tests.rs

@@ -1644,3 +1644,65 @@ fn a_fill_overlay_blends_over_the_fill() {
     let (over, _) = draw([200, 100, 50], "over");
     assert!((over[0] as i32 - 128).abs() <= 3 && (over[1] as i32 - 128).abs() <= 3, "{over:?}");
 }
+
+#[test]
+fn dotted_and_wavy_underlines_draw_their_pattern() {
+    // Underlined spaces only, so the underline is the only ink: a red line under "      ".
+    let row_runs = |u: &str| {
+        let mut sh = Shape { id: ShapeId(760), xfrm: Some(Xfrm::new(0.0, 0.0, 900.0, 300.0)), text_box: true, ..Default::default() };
+        let mut t = TextBody::from_text("            ");
+        let props = &mut t.paragraphs[0].runs[0].props;
+        props.size = Some(96.0);
+        props.underline = Some(u.into());
+        props.fill = Some(deckcraft_model::style::Fill::solid(ColorRef::rgb(deckcraft_color::Rgba::rgb(255, 0, 0))));
+        sh.text = Some(t);
+        let p = deck_with(vec![sh]);
+        let img = render_slide(&p, 0, &RenderOpts { scale: 1.0, ..Default::default() });
+        let red = |x: u32, y: u32| {
+            let px = img.pixel(x, y);
+            px[0] > 150 && px[1] < 120
+        };
+        // The ink's rows, and the number of separate red stretches along the most inked row.
+        let rows: Vec<u32> = (0..300).filter(|&y| (0..900).any(|x| red(x, y))).collect();
+        let best = rows.iter().copied().max_by_key(|&y| (0..900).filter(|&x| red(x, y)).count()).unwrap_or(0);
+        let stretches = (1..900).filter(|&x| red(x, best) && !red(x - 1, best)).count();
+        (rows.len(), stretches)
+    };
+    let (sng_rows, sng_runs) = row_runs("sng");
+    assert_eq!(sng_runs, 1, "a single line is one stretch");
+    let (_, dotted_runs) = row_runs("dotted");
+    assert!(dotted_runs > 10, "dots: {dotted_runs}");
+    let (wavy_rows, _) = row_runs("wavy");
+    assert!(wavy_rows > sng_rows, "a wave spans more rows ({wavy_rows}) than a single line ({sng_rows})");
+}
+
+#[test]
+fn east_asian_vertical_text_stands_ideographs_upright() {
+    // "一" is a horizontal stroke. In eaVert text it stays horizontal (upright) while the line runs
+    // down the shape; in vert it lies on its side like Latin text.
+    let ink = |dir: deckcraft_model::text::TextDir| {
+        let mut sh = Shape { id: ShapeId(770), xfrm: Some(Xfrm::new(100.0, 50.0, 200.0, 400.0)), text_box: true, ..Default::default() };
+        let mut t = TextBody::from_text("一");
+        t.body.vert = Some(dir);
+        let props = &mut t.paragraphs[0].runs[0].props;
+        props.size = Some(80.0);
+        props.fill = Some(deckcraft_model::style::Fill::solid(ColorRef::rgb(deckcraft_color::Rgba::rgb(0, 0, 0))));
+        sh.text = Some(t);
+        let p = deck_with(vec![sh]);
+        let img = render_slide(&p, 0, &RenderOpts { scale: 1.0, ..Default::default() });
+        let (mut x0, mut y0, mut x1, mut y1) = (u32::MAX, u32::MAX, 0, 0);
+        for y in 0..540 {
+            for x in 0..960 {
+                if img.pixel(x, y)[0] < 128 {
+                    (x0, y0, x1, y1) = (x0.min(x), y0.min(y), x1.max(x), y1.max(y));
+                }
+            }
+        }
+        assert!(x1 >= x0 && y1 >= y0, "no ink for {dir:?}");
+        (x1 - x0, y1 - y0)
+    };
+    let (w, h) = ink(deckcraft_model::text::TextDir::EaVertical);
+    assert!(w > h * 3, "eaVert: upright stroke {w}x{h}");
+    let (w, h) = ink(deckcraft_model::text::TextDir::Vertical);
+    assert!(h > w * 3, "vert: stroke on its side {w}x{h}");
+}

crates/render/src/transition.rs

@@ -0,0 +1,517 @@
+//! Slide transition frames without a GPU: the layers of [`deckcraft_anim::transition_layers`]
+//! composited on the CPU from two rendered slide images. The slide show draws the same layers with
+//! the UI toolkit's meshes; this is the headless twin used by the CLI, comparisons and tests.
+
+use deckcraft_anim::{Layer, Source, layer_mesh, transition_frame, uses_slide_parts};
+use deckcraft_model::{Presentation, ShapeId};
+
+use crate::{Image, RenderOpts, ShapeState, SlidePart, render_blend, render_slide, render_slide_part};
+
+/// The two slides of a transition rendered as background and content, for the transitions that
+/// move contents over the backgrounds ([`deckcraft_anim::uses_slide_parts`]). `None` parts of the
+/// old slide (the show's first slide) are black and nothing.
+#[derive(Clone, Debug, Default)]
+pub struct SlideParts {
+    pub old_back: Option<Image>,
+    pub old_content: Option<Image>,
+    pub new_back: Image,
+    pub new_content: Image,
+}
+
+impl SlideParts {
+    /// Render the parts of slides `old` and `new`.
+    pub fn render(pres: &Presentation, old: Option<usize>, new: usize, opts: &RenderOpts) -> SlideParts {
+        SlideParts {
+            old_back: old.map(|i| render_slide_part(pres, i, SlidePart::Backdrop, opts)),
+            old_content: old.map(|i| render_slide_part(pres, i, SlidePart::Content, opts)),
+            new_back: render_slide_part(pres, new, SlidePart::Backdrop, opts),
+            new_content: render_slide_part(pres, new, SlidePart::Content, opts),
+        }
+    }
+}
+
+/// Composite transition `layers` over black into an image the size of `new`. `old` is the outgoing
+/// slide (`None`: black, as when the show starts); `parts` the slides' backgrounds and contents
+/// (without them, a background draws its whole slide and content draws nothing).
+pub fn composite_transition(old: Option<&Image>, new: &Image, parts: Option<&SlideParts>, layers: &[Layer]) -> Image {
+    let (w, h) = (new.width, new.height);
+    let n = (w as usize).saturating_mul(h as usize);
+    let mut out = Image { width: w, height: h, pixels: [0u8, 0, 0, 255].repeat(n) };
+    for l in layers {
+        let src = match (l.source.is_part(), parts) {
+            (true, None) => match l.source.whole() {
+                Some(s) => s,
+                None => continue,
+            },
+            _ => l.source,
+        };
+        let tex = match (src, parts) {
+            (Source::Old, _) => old.map(Tex::Image).unwrap_or(Tex::Solid([0.0, 0.0, 0.0])),
+            (Source::New, _) => Tex::Image(new),
+            (Source::Black, _) => Tex::Solid([0.0, 0.0, 0.0]),
+            (Source::White, _) => Tex::Solid([255.0, 255.0, 255.0]),
+            (Source::OldBack, Some(p)) => p.old_back.as_ref().map(Tex::Image).unwrap_or(Tex::Solid([0.0, 0.0, 0.0])),
+            (Source::NewBack, Some(p)) => Tex::Image(&p.new_back),
+            (Source::OldContent, Some(p)) => match &p.old_content {
+                Some(i) => Tex::Image(i),
+                None => continue,
+            },
+            (Source::NewContent, Some(p)) => Tex::Image(&p.new_content),
+            (_, None) => continue,
+        };
+        draw_layer(&mut out, l, &tex);
+    }
+    out
+}
+
+/// The frame of slide `index`'s transition at progress `t` (0..1): the previous slide (black for
+/// the first) going out, slide `index` coming in, at `opts`' scale and size. Morph frames are
+/// rendered shape by shape like the show does.
+pub fn render_transition(pres: &Presentation, index: usize, t: f64, opts: &RenderOpts) -> Image {
+    let Some(slide) = pres.slides.get(index) else { return Image::default() };
+    let (kind, option) = slide.transition.as_ref().map(|tr| (tr.kind.as_str(), tr.option.as_str())).unwrap_or(("none", ""));
+    let prev = index.checked_sub(1).filter(|i| pres.slides.get(*i).is_some());
+    if kind == "morph"
+        && let Some(from) = prev
+        && let Some(a) = pres.slides.get(from)
+    {
+        let tt = if t.is_finite() { t.clamp(0.0, 1.0) } else { 0.0 };
+        if tt < 1.0 {
+            let m = deckcraft_anim::morph_frame(pres, a, slide, tt, &|_| false);
+            let f = |id: ShapeId| ShapeState { opacity: m.opacity_of(id), ..Default::default() };
+            let o = RenderOpts { state: Some(&f), ..copy_opts(opts) };
+            let text: Vec<crate::TextMorph> =
+                m.text.iter().map(|x| crate::TextMorph { old: x.old, new: x.new, from: x.from, to: x.to, chars: x.chars, t: m.mix }).collect();
+            let paths: Vec<crate::PathMorph> = m
+                .paths
+                .iter()
+                .map(|x| crate::PathMorph { id: x.id, from: x.from.clone(), from_box: x.from_box, to_box: x.to_box, t: m.mix })
+                .collect();
+            return render_blend(pres, from, index, m.mix, &m.shapes, &text, &paths, &o);
+        }
+    }
+    let new = render_slide(pres, index, opts);
+    let old = prev.map(|i| render_slide(pres, i, opts));
+    let parts = uses_slide_parts(kind, option).then(|| SlideParts::render(pres, prev, index, opts));
+    let aspect = pres.slide_size.width / pres.slide_size.height.max(1.0);
+    composite_transition(old.as_ref(), &new, parts.as_ref(), &transition_frame(kind, option, t, aspect))
+}
+
+fn copy_opts<'a>(o: &RenderOpts<'a>) -> RenderOpts<'a> {
+    RenderOpts {
+        scale: o.scale,
+        edit: o.edit,
+        show_hidden: o.show_hidden,
+        state: o.state,
+        skip: o.skip,
+        skip_text: o.skip_text,
+        gif_times: o.gif_times,
+        threads: o.threads,
+        offset: o.offset,
+        size: o.size,
+        clear: o.clear,
+        date_text: o.date_text.clone(),
+        now: o.now,
+    }
+}
+
+enum Tex<'a> {
+    Image(&'a Image),
+    /// Straight RGB, opaque.
+    Solid([f32; 3]),
+}
+
+impl Tex<'_> {
+    /// Premultiplied RGBA (0..255) at texture coordinate (u, v), bilinear, clamped to the edge.
+    fn sample(&self, u: f64, v: f64) -> [f32; 4] {
+        match self {
+            Tex::Solid(c) => [c[0], c[1], c[2], 255.0],
+            Tex::Image(img) => {
+                let (w, h) = (img.width as usize, img.height as usize);
+                if w == 0 || h == 0 {
+                    return [0.0; 4];
+                }
+                let x = (u * w as f64 - 0.5).clamp(0.0, (w - 1) as f64);
+                let y = (v * h as f64 - 0.5).clamp(0.0, (h - 1) as f64);
+                let (x0, y0) = (x.floor() as usize, y.floor() as usize);
+                let (x1, y1) = ((x0 + 1).min(w - 1), (y0 + 1).min(h - 1));
+                let (fx, fy) = ((x - x0 as f64) as f32, (y - y0 as f64) as f32);
+                let px = |xx: usize, yy: usize| -> [f32; 4] {
+                    let i = (yy * w + xx) * 4;
+                    match img.pixels.get(i..i + 4) {
+                        Some(p) => [p[0] as f32, p[1] as f32, p[2] as f32, p[3] as f32],
+                        None => [0.0; 4],
+                    }
+                };
+                let (a, b, c, d) = (px(x0, y0), px(x1, y0), px(x0, y1), px(x1, y1));
+                let mut o = [0.0f32; 4];
+                for k in 0..4 {
+                    let top = a[k] + (b[k] - a[k]) * fx;
+                    let bot = c[k] + (d[k] - c[k]) * fx;
+                    o[k] = top + (bot - top) * fy;
+                }
+                o
+            }
+        }
+    }
+}
+
+fn draw_layer(out: &mut Image, l: &Layer, tex: &Tex) {
+    if !(l.alpha.is_finite() && l.alpha > 0.0) {
+        return;
+    }
+    let (verts, tris) = layer_mesh(l);
+    let (w, h) = (out.width as f64, out.height as f64);
+    for t in tris {
+        let (Some(a), Some(b), Some(c)) = (verts.get(t[0] as usize), verts.get(t[1] as usize), verts.get(t[2] as usize)) else { continue };
+        let p = [[a.pos[0] * w, a.pos[1] * h], [b.pos[0] * w, b.pos[1] * h], [c.pos[0] * w, c.pos[1] * h]];
+        let uv = [a.uv, b.uv, c.uv];
+        let al = [a.a, b.a, c.a].map(|x| if x.is_finite() { x.clamp(0.0, 1.0) } else { 0.0 });
+        if al.iter().all(|x| *x <= 0.0) {
+            continue;
+        }
+        fill_triangle(out, p, uv, al, tex);
+    }
+}
+
+/// Rasterise one textured triangle: pixel centres inside it take the texture's colour at the
+/// barycentric texture coordinate, at the interpolated opacity, blended source-over.
+fn fill_triangle(out: &mut Image, p: [[f64; 2]; 3], uv: [[f64; 2]; 3], al: [f64; 3], tex: &Tex) {
+    let area = (p[1][0] - p[0][0]) * (p[2][1] - p[0][1]) - (p[2][0] - p[0][0]) * (p[1][1] - p[0][1]);
+    if !area.is_finite() || area.abs() < 1e-12 {
+        return;
+    }
+    let (w, h) = (out.width as i64, out.height as i64);
+    let minx = p.iter().map(|q| q[0]).fold(f64::INFINITY, f64::min).floor().max(0.0) as i64;
+    let maxx = (p.iter().map(|q| q[0]).fold(f64::NEG_INFINITY, f64::max).ceil() as i64).min(w);
+    let miny = p.iter().map(|q| q[1]).fold(f64::INFINITY, f64::min).floor().max(0.0) as i64;
+    let maxy = (p.iter().map(|q| q[1]).fold(f64::NEG_INFINITY, f64::max).ceil() as i64).min(h);
+    if minx >= maxx || miny >= maxy {
+        return;
+    }
+    let edge = |a: [f64; 2], b: [f64; 2], x: f64, y: f64| (b[0] - a[0]) * (y - a[1]) - (b[1] - a[1]) * (x - a[0]);
+    let width = out.width as usize;
+    for y in miny..maxy {
+        // Sample a hair off the pixel centre so a point on an edge shared by two triangles falls
+        // in exactly one of them (no double-blended seams).
+        let fy = y as f64 + 0.5 + 2.31e-6;
+        for x in minx..maxx {
+            let fx = x as f64 + 0.5 + 1.17e-6;
+            let w0 = edge(p[1], p[2], fx, fy) / area;
+            let w1 = edge(p[2], p[0], fx, fy) / area;
+            let w2 = edge(p[0], p[1], fx, fy) / area;
+            if w0 < 0.0 || w1 < 0.0 || w2 < 0.0 {
+                continue;
+            }
+            let u = w0 * uv[0][0] + w1 * uv[1][0] + w2 * uv[2][0];
+            let v = w0 * uv[0][1] + w1 * uv[1][1] + w2 * uv[2][1];
+            let alpha = (w0 * al[0] + w1 * al[1] + w2 * al[2]) as f32;
+            if alpha <= 0.0 {
+                continue;
+            }
+            let s = tex.sample(u, v);
+            let i = (y as usize * width + x as usize) * 4;
+            let Some(d) = out.pixels.get_mut(i..i + 4) else { continue };
+            let sa = s[3] * alpha / 255.0;
+            for k in 0..4 {
+                let src = s[k] * alpha;
+                let v = src + d[k] as f32 * (1.0 - sa);
+                d[k] = v.round().clamp(0.0, 255.0) as u8;
+            }
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn solid(w: u32, h: u32, c: [u8; 4]) -> Image {
+        Image { width: w, height: h, pixels: c.repeat((w * h) as usize) }
+    }
+
+    #[test]
+    fn layers_composite_in_order() {
+        let old = solid(40, 20, [255, 0, 0, 255]);
+        let new = solid(40, 20, [0, 0, 255, 255]);
+        let img = composite_transition(Some(&old), &new, None, &deckcraft_anim::transition_layers("cover", "l", 0.0));
+        assert_eq!(img.pixel(20, 10), [255, 0, 0, 255]);
+        let img = composite_transition(Some(&old), &new, None, &deckcraft_anim::transition_layers("cover", "l", 1.0));
+        assert_eq!(img.pixel(20, 10), [0, 0, 255, 255]);
+    }
+
+    #[test]
+    fn missing_old_slide_is_black() {
+        let new = solid(10, 10, [0, 255, 0, 255]);
+        let img = composite_transition(None, &new, None, &[Layer::full(Source::Old, 1.0)]);
+        assert_eq!(img.pixel(5, 5), [0, 0, 0, 255]);
+    }
+
+    #[test]
+    fn half_alpha_blends() {
+        let old = solid(10, 10, [200, 0, 0, 255]);
+        let new = solid(10, 10, [0, 0, 200, 255]);
+        let l = [Layer::full(Source::Old, 1.0), Layer::full(Source::New, 0.5)];
+        let p = composite_transition(Some(&old), &new, None, &l).pixel(5, 5);
+        assert!((p[0] as i32 - 100).abs() <= 1 && (p[2] as i32 - 100).abs() <= 1, "{p:?}");
+    }
+
+    // ---------- golden-ish frames on synthetic slides ----------
+
+    const W: u32 = 160;
+    const H: u32 = 90;
+    const OLD: [u8; 4] = [220, 40, 40, 255];
+    const NEW: [u8; 4] = [30, 60, 200, 255];
+
+    #[derive(Clone, Copy, Debug, PartialEq)]
+    enum Is {
+        Old,
+        New,
+        Black,
+        White,
+        /// Something between (a blend).
+        Mix,
+    }
+
+    fn classify(p: [u8; 4]) -> Is {
+        let d = |c: [u8; 4]| (p[0] as i32 - c[0] as i32).abs() + (p[1] as i32 - c[1] as i32).abs() + (p[2] as i32 - c[2] as i32).abs();
+        let near = 40;
+        if d(OLD) < near {
+            Is::Old
+        } else if d(NEW) < near {
+            Is::New
+        } else if d([0, 0, 0, 255]) < near {
+            Is::Black
+        } else if d([255, 255, 255, 255]) < near {
+            Is::White
+        } else {
+            // A face shaded in 3-D: a darker copy of one of the slides.
+            let shaded = |c: [u8; 4]| {
+                let dot = |a: [u8; 4], b: [u8; 4]| (0..3).map(|i| a[i] as f64 * b[i] as f64).sum::<f64>();
+                let k = dot(p, c) / dot(c, c);
+                (0.3..=1.05).contains(&k) && (0..3).all(|i| (p[i] as f64 - k * c[i] as f64).abs() < 14.0)
+            };
+            if shaded(OLD) {
+                Is::Old
+            } else if shaded(NEW) {
+                Is::New
+            } else {
+                Is::Mix
+            }
+        }
+    }
+
+    fn frame(kind: &str, option: &str, t: f64) -> Image {
+        let old = solid(W, H, OLD);
+        let new = solid(W, H, NEW);
+        composite_transition(Some(&old), &new, None, &transition_frame(kind, option, t, 16.0 / 9.0))
+    }
+
+    fn at(img: &Image, x: f64, y: f64) -> Is {
+        let px = ((x * W as f64) as u32).min(W - 1);
+        let py = ((y * H as f64) as u32).min(H - 1);
+        classify(img.pixel(px, py))
+    }
+
+    /// (kind, option, t, x, y, what PowerPoint shows there), read off PowerPoint's own frames.
+    const PROBES: &[(&str, &str, f64, f64, f64, Is)] = &[
+        ("fade", "smoothly", 0.1, 0.5, 0.5, Is::Old),
+        ("fade", "smoothly", 0.5, 0.5, 0.5, Is::Mix),
+        ("fade", "smoothly", 0.9, 0.5, 0.5, Is::New),
+        ("fade", "throughBlack", 0.5, 0.5, 0.5, Is::Black),
+        ("cut", "throughBlack", 0.3, 0.5, 0.5, Is::Black),
+        ("cut", "", 0.3, 0.5, 0.5, Is::New),
+        // Push / Cover / Uncover: "l" moves things toward the left; the new slide comes from the right.
+        ("push", "l", 0.25, 0.97, 0.5, Is::New),
+        ("push", "l", 0.25, 0.1, 0.5, Is::Old),
+        ("push", "r", 0.25, 0.03, 0.5, Is::New),
+        ("push", "u", 0.25, 0.5, 0.97, Is::New),
+        ("push", "d", 0.25, 0.5, 0.03, Is::New),
+        ("cover", "l", 0.5, 0.75, 0.5, Is::New),
+        ("cover", "l", 0.5, 0.25, 0.5, Is::Old),
+        ("cover", "rd", 0.5, 0.05, 0.05, Is::New),
+        ("cover", "rd", 0.2, 0.97, 0.97, Is::Old),
+        ("uncover", "l", 0.5, 0.25, 0.5, Is::Old),
+        ("uncover", "l", 0.5, 0.75, 0.5, Is::New),
+        ("uncover", "lu", 0.5, 0.5, 0.5, Is::New),
+        // Wipe "r" sweeps rightward with a soft edge; "u" upward; diagonals from a corner.
+        ("wipe", "r", 0.5, 0.05, 0.5, Is::New),
+        ("wipe", "r", 0.5, 0.97, 0.5, Is::Old),
+        ("wipe", "l", 0.5, 0.97, 0.5, Is::New),
+        ("wipe", "u", 0.5, 0.5, 0.97, Is::New),
+        ("wipe", "u", 0.5, 0.5, 0.03, Is::Old),
+        ("wipe", "d", 0.5, 0.5, 0.03, Is::New),
+        ("wipe", "ru", 0.5, 0.03, 0.97, Is::New),
+        ("wipe", "ru", 0.5, 0.97, 0.03, Is::Old),
+        ("wipe", "r", 0.5, 0.55, 0.5, Is::Mix),
+        // Split: Out opens from the middle, In closes from the edges.
+        ("split", "horzOut", 0.5, 0.5, 0.5, Is::New),
+        ("split", "horzOut", 0.5, 0.5, 0.02, Is::Old),
+        ("split", "horzIn", 0.5, 0.5, 0.02, Is::New),
+        ("split", "horzIn", 0.5, 0.5, 0.5, Is::Old),
+        ("split", "vertOut", 0.5, 0.5, 0.5, Is::New),
+        ("split", "vertOut", 0.5, 0.02, 0.5, Is::Old),
+        ("split", "vertIn", 0.5, 0.02, 0.5, Is::New),
+        // Shape: grows from the centre; In shrinks the old slide over the first half, Out grows
+        // the new one over the second.
+        ("shape", "circle", 0.5, 0.5, 0.5, Is::New),
+        ("shape", "circle", 0.5, 0.02, 0.03, Is::Old),
+        ("shape", "diamond", 0.5, 0.5, 0.5, Is::New),
+        ("shape", "diamond", 0.5, 0.02, 0.03, Is::Old),
+        ("shape", "plus", 0.5, 0.5, 0.05, Is::New),
+        ("shape", "plus", 0.5, 0.05, 0.05, Is::Old),
+        ("shape", "in", 0.25, 0.5, 0.5, Is::Old),
+        ("shape", "in", 0.25, 0.05, 0.05, Is::New),
+        ("shape", "in", 0.75, 0.5, 0.5, Is::New),
+        ("shape", "out", 0.25, 0.5, 0.5, Is::Old),
+        ("shape", "out", 0.75, 0.5, 0.5, Is::New),
+        ("shape", "out", 0.75, 0.05, 0.05, Is::Old),
+        // Flash: white in the middle.
+        ("flash", "", 0.3, 0.5, 0.5, Is::White),
+        // Clock: a hand sweeping from 12 o'clock.
+        ("clock", "clockwise", 0.25, 0.6, 0.15, Is::New),
+        ("clock", "clockwise", 0.25, 0.4, 0.15, Is::Old),
+        ("clock", "counterClockwise", 0.25, 0.4, 0.15, Is::New),
+        ("clock", "counterClockwise", 0.25, 0.6, 0.15, Is::Old),
+        ("clock", "wedge", 0.5, 0.5, 0.05, Is::New),
+        ("clock", "wedge", 0.5, 0.5, 0.95, Is::Old),
+        // Ripple: from the centre, or from the corner opposite the option.
+        ("ripple", "center", 0.5, 0.5, 0.5, Is::New),
+        ("ripple", "center", 0.5, 0.02, 0.03, Is::Old),
+        ("ripple", "ru", 0.4, 0.03, 0.97, Is::New),
+        ("ripple", "ru", 0.4, 0.97, 0.03, Is::Old),
+        // Comb: the old slide's bands slide off, the bottom band first.
+        ("comb", "horz", 0.5, 0.5, 0.97, Is::New),
+        ("comb", "horz", 0.5, 0.5, 0.03, Is::Old),
+        // Glitter "l": the sweep starts on the left.
+        ("glitter", "l", 0.45, 0.03, 0.5, Is::New),
+        ("glitter", "l", 0.45, 0.97, 0.5, Is::Old),
+        ("glitter", "r", 0.45, 0.97, 0.5, Is::New),
+        // Vortex "l": the old slide whirls off toward the left, its right side first.
+        ("vortex", "l", 0.25, 0.03, 0.5, Is::Old),
+        ("vortex", "l", 0.97, 0.03, 0.5, Is::New),
+        // Cube / Box "l": the new face comes in from the right.
+        ("cube", "l", 0.5, 0.85, 0.5, Is::New),
+        ("cube", "l", 0.5, 0.15, 0.5, Is::Old),
+        ("cube", "r", 0.5, 0.15, 0.5, Is::New),
+        ("box", "l", 0.25, 0.97, 0.5, Is::New),
+        ("box", "l", 0.25, 0.3, 0.5, Is::Old),
+        ("cube", "u", 0.5, 0.5, 0.9, Is::New),
+        ("cube", "d", 0.5, 0.5, 0.1, Is::New),
+        // Switch "l": the old card is pulled out to the left, the new one to the right.
+        ("switch", "l", 0.25, 0.97, 0.5, Is::New),
+        ("switch", "l", 0.25, 0.3, 0.5, Is::Old),
+        ("switch", "r", 0.25, 0.03, 0.5, Is::New),
+        // Gallery "l": the slides travel left along the wall.
+        ("gallery", "l", 0.6, 0.9, 0.5, Is::New),
+        // Flip: the old face, then the new one.
+        ("flip", "l", 0.2, 0.5, 0.5, Is::Old),
+        ("flip", "l", 0.8, 0.5, 0.5, Is::New),
+        // Doors open in the middle, the new slide coming forward between them.
+        ("doors", "vert", 0.9, 0.5, 0.5, Is::New),
+        // Fall Over: the old slide tips backward, uncovering the new one at the top first.
+        ("fallOver", "l", 0.6, 0.5, 0.03, Is::New),
+        ("fallOver", "l", 0.6, 0.5, 0.97, Is::Old),
+        // Peel Off "l": from the bottom-right corner.
+        ("peelOff", "l", 0.4, 0.98, 0.98, Is::New),
+        ("peelOff", "l", 0.4, 0.03, 0.03, Is::Old),
+        ("peelOff", "r", 0.4, 0.02, 0.98, Is::New),
+        // Page Curl: the far half rolls up first.
+        ("pageCurlDouble", "l", 0.5, 0.9, 0.5, Is::New),
+        ("pageCurlDouble", "l", 0.5, 0.1, 0.5, Is::Old),
+        ("pageCurlDouble", "r", 0.5, 0.1, 0.5, Is::New),
+        ("pageCurlDouble", "singleL", 0.6, 0.95, 0.5, Is::New),
+        ("pageCurlDouble", "singleL", 0.6, 0.05, 0.5, Is::Old),
+        // Airplane "l": a dart with its nose to the right, hanging low.
+        ("airplane", "l", 0.5, 0.15, 0.1, Is::New),
+        ("airplane", "l", 0.5, 0.8, 0.68, Is::Old),
+        ("airplane", "r", 0.5, 0.2, 0.68, Is::Old),
+        // Origami "l": the bird flies off to the left.
+        ("origami", "l", 0.75, 0.97, 0.5, Is::New),
+        // Fracture: shards fall, the top first.
+        ("fracture", "", 0.6, 0.5, 0.05, Is::New),
+        // Crush: the old slide crumples toward the centre.
+        ("crush", "", 0.5, 0.03, 0.03, Is::New),
+        ("crush", "", 0.5, 0.45, 0.5, Is::Old),
+        // Curtains part in the middle.
+        ("curtains", "", 0.4, 0.5, 0.5, Is::New),
+        ("curtains", "", 0.4, 0.02, 0.5, Is::Old),
+        // Zoom and Rotate: the new slide spins in from the centre over the old one.
+        ("zoom", "rotate", 0.2, 0.03, 0.03, Is::Old),
+        ("zoom", "out", 0.8, 0.5, 0.5, Is::New),
+        ("dissolve", "", 0.02, 0.5, 0.5, Is::Old),
+        ("dissolve", "", 0.99, 0.5, 0.5, Is::New),
+    ];
+
+    #[test]
+    fn frames_match_powerpoint_probes() {
+        let mut bad = Vec::new();
+        for (kind, option, t, x, y, want) in PROBES {
+            let got = at(&frame(kind, option, *t), *x, *y);
+            if got != *want {
+                bad.push(format!("{kind}/{option} t={t} ({x},{y}): want {want:?}, got {got:?}"));
+            }
+        }
+        assert!(bad.is_empty(), "{}", bad.join("\n"));
+    }
+
+    #[test]
+    fn every_transition_starts_old_and_ends_new() {
+        for (kind, _, _, _, opts) in deckcraft_model::anim::TRANSITIONS {
+            let mut options: Vec<&str> = opts.to_vec();
+            options.push("");
+            for o in options {
+                assert_eq!(at(&frame(kind, o, 0.0), 0.5, 0.5), Is::Old, "{kind}/{o}");
+                assert_eq!(at(&frame(kind, o, 1.0), 0.5, 0.5), Is::New, "{kind}/{o}");
+                for t in [0.25, 0.5, 0.75] {
+                    let img = frame(kind, o, t);
+                    assert_eq!((img.width, img.height), (W, H));
+                }
+            }
+        }
+    }
+
+    #[test]
+    fn dynamic_content_moves_contents_over_backgrounds() {
+        // Old: red background with a white content square in the middle; new: blue background
+        // with a yellow square.
+        let content = |c: [u8; 4]| {
+            let mut img = solid(W, H, [0, 0, 0, 0]);
+            for y in 35..55u32 {
+                for x in 70..90u32 {
+                    let i = ((y * W + x) * 4) as usize;
+                    if let Some(p) = img.pixels.get_mut(i..i + 4) {
+                        p.copy_from_slice(&c);
+                    }
+                }
+            }
+            img
+        };
+        let parts = SlideParts {
+            old_back: Some(solid(W, H, OLD)),
+            old_content: Some(content([255, 255, 255, 255])),
+            new_back: solid(W, H, NEW),
+            new_content: content([255, 220, 0, 255]),
+        };
+        let old = solid(W, H, OLD);
+        let new = solid(W, H, NEW);
+        let f = |kind: &str, o: &str, t: f64| composite_transition(Some(&old), &new, Some(&parts), &transition_frame(kind, o, t, 16.0 / 9.0));
+        // Pan left at the middle: the backgrounds blend, the old square has moved left.
+        let img = f("pan", "l", 0.5);
+        let bg = img.pixel(5, 5);
+        assert!(bg[0] > 60 && bg[2] > 60, "{bg:?}");
+        assert_eq!(img.pixel(80, 45), bg, "the middle shows background only");
+        // Pan right: the new square arrives from the left.
+        let img = f("pan", "r", 0.6);
+        assert!((0..80).any(|x| {
+            let p = img.pixel(x, 45);
+            p[0] > 200 && p[1] > 180 && p[2] < 80
+        }));
+        // Reveal: the new content is in place near the end.
+        let p = f("reveal", "smoothlyLeft", 0.97).pixel(80, 45);
+        assert!(p[0] > 200 && p[1] > 180, "{p:?}");
+        // Without parts the dynamic transitions still draw whole slides.
+        let img = composite_transition(Some(&old), &new, None, &transition_frame("pan", "l", 0.5, 16.0 / 9.0));
+        assert_ne!(img.pixel(80, 45), [0, 0, 0, 255]);
+    }
+}

crates/render/src/warp.rs

@@ -140,10 +140,12 @@ pub(crate) fn draw(ctx: &mut RenderContext, l: &TextLayout, tr: Rect, m: Affine,
         }
         let y = (d.rect.y0 + d.rect.y1) / 2.0;
         let Some(li) = line_of(l, d.para, y) else { return };
-        let path = warp_path(&d.rect.to_path(0.1), tol, seg, &|p| mapper.map(li, p));
         ctx.set_transform(m * Affine::translate(ps.offset));
         ctx.set_paint(color(d.color, ps.opacity));
-        ctx.fill_path(&path);
+        for r in d.pieces() {
+            let path = warp_path(&r.to_path(0.1), tol, seg, &|p| mapper.map(li, p));
+            ctx.fill_path(&path);
+        }
     };
     for d in l.decos.iter().filter(|d| d.behind) {
         deco(ctx, d);

crates/text/src/bidi.rs

@@ -6,7 +6,7 @@
 //! [`visual_order`] rule L2). Rule L4 (mirrored brackets) is applied by the shaper, which draws
 //! mirrorable characters in right-to-left items with their mirrored glyphs.
 
-use unicode_bidi::BidiClass::{self, AL, AN, B, BN, FSI, LRE, LRI, LRO, PDF, PDI, R, RLE, RLI, RLO, S, WS};
+use unicode_bidi::BidiClass::{self, AL, AN, B, BN, CS, EN, ES, ET, FSI, L, LRE, LRI, LRO, NSM, ON, PDF, PDI, R, RLE, RLI, RLO, S, WS};
 use unicode_bidi::{BidiInfo, Level, bidi_class};
 
 /// Does anything in the text need the full algorithm? (Strong right-to-left, Arabic numbers or
@@ -27,6 +27,149 @@ pub(crate) fn levels(text: &str, chars: &[char], rtl: bool) -> Vec<u8> {
     text.char_indices().map(|(b, _)| info.levels.get(b).map(|l| l.number()).unwrap_or(base)).collect()
 }
 
+/// Is `lang` (BCP 47) a language written right to left? Its runs resolve neutral characters and
+/// digits the right-to-left way (see [`levels_lang`]).
+pub(crate) fn is_rtl_lang(lang: &str) -> bool {
+    let primary = lang.split(['-', '_']).next().unwrap_or("").to_ascii_lowercase();
+    matches!(primary.as_str(), "ar" | "he" | "iw" | "fa" | "ur" | "yi" | "ji" | "ps" | "sd" | "ug" | "dv" | "syr" | "ckb" | "arc")
+}
+
+/// How a character resolves before levels are assigned.
+#[derive(Clone, Copy, PartialEq, Eq, Debug)]
+enum Dir {
+    L,
+    R,
+    /// A number inside right-to-left text: kept left to right, placed with the right-to-left text.
+    Num,
+    /// Not resolved yet (neutral).
+    Open,
+}
+
+/// Embedding levels as PowerPoint resolves them: the language of each character's run
+/// (`rtl_lang`, from `a:rPr/@lang`) decides how neutral characters and digits go, where UAX #9
+/// would look at the surrounding text only. Observed on desktop PowerPoint:
+/// - in a run of a left-to-right language (or none), digits and punctuation are left to right,
+///   and a space takes the direction of the character before it (so the space after a Hebrew word
+///   travels with that word);
+/// - in a run of a right-to-left language (Hebrew, Arabic…), punctuation and spaces between text
+///   of one direction take it, everywhere else they are right to left; digits are a number in
+///   right-to-left text unless left-to-right text precedes them.
+///
+/// Paragraphs with explicit embeddings or isolates keep the plain algorithm ([`levels`]).
+pub(crate) fn levels_lang(text: &str, chars: &[char], rtl: bool, rtl_lang: &[bool]) -> Vec<u8> {
+    let base = u8::from(rtl);
+    let any_rtl_lang = rtl_lang.iter().any(|r| *r);
+    if !rtl && !any_rtl_lang && !needs_bidi(chars) {
+        return vec![0; chars.len()];
+    }
+    let classes: Vec<BidiClass> = chars.iter().map(|c| bidi_class(*c)).collect();
+    if classes.iter().any(|c| matches!(c, LRE | RLE | LRO | RLO | PDF | LRI | RLI | FSI | PDI)) {
+        return levels(text, chars, rtl);
+    }
+    let n = chars.len();
+    let rl = |i: usize| rtl_lang.get(i).copied().unwrap_or(false);
+    let sos = if rtl { Dir::R } else { Dir::L };
+    // W1: combining marks take the class of the character they sit on.
+    let mut cls = classes;
+    for i in 0..n {
+        if cls.get(i) == Some(&NSM) {
+            let prev = if i == 0 { if rtl { R } else { L } } else { cls.get(i - 1).copied().unwrap_or(L) };
+            if let Some(c) = cls.get_mut(i) {
+                *c = prev;
+            }
+        }
+    }
+    let mut dir = vec![Dir::Open; n];
+    // Strong letters and digits.
+    let mut last_strong: Option<BidiClass> = None;
+    for i in 0..n {
+        let c = cls.get(i).copied().unwrap_or(ON);
+        let d = match c {
+            L => Dir::L,
+            R | AL => Dir::R,
+            AN => Dir::Num,
+            EN if !rl(i) => Dir::L,
+            // W7: European digits after left-to-right text are left to right.
+            EN if last_strong == Some(L) => Dir::L,
+            EN => Dir::Num,
+            _ => Dir::Open,
+        };
+        if matches!(c, L | R | AL) {
+            last_strong = Some(c);
+        }
+        if let Some(x) = dir.get_mut(i) {
+            *x = d;
+        }
+    }
+    // W4/W5 in right-to-left runs: a separator between digits, and currency or percent signs next
+    // to them, belong to the number.
+    for i in 0..n {
+        if !rl(i) || dir.get(i) != Some(&Dir::Open) {
+            continue;
+        }
+        let c = cls.get(i).copied().unwrap_or(ON);
+        let num = |j: Option<usize>| j.and_then(|j| dir.get(j)).is_some_and(|d| *d == Dir::Num);
+        let joined = match c {
+            ES | CS => num(i.checked_sub(1)) && num(Some(i + 1)),
+            ET => num(i.checked_sub(1)) || (i + 1..n).find(|&j| cls.get(j) != Some(&ET)).is_some_and(|j| num(Some(j))),
+            _ => false,
+        };
+        if joined && let Some(x) = dir.get_mut(i) {
+            *x = Dir::Num;
+        }
+    }
+    // Punctuation in left-to-right runs is left to right.
+    for i in 0..n {
+        if !rl(i)
+            && dir.get(i) == Some(&Dir::Open)
+            && !matches!(cls.get(i), Some(WS | S))
+            && let Some(x) = dir.get_mut(i)
+        {
+            *x = Dir::L;
+        }
+    }
+    // Neutrals in right-to-left runs: the direction around them when both sides agree, else
+    // right to left. Unresolved spaces of left-to-right runs are looked through.
+    let strong_at = |dir: &[Dir], j: usize| match dir.get(j) {
+        Some(Dir::L) => Some(Dir::L),
+        Some(Dir::R | Dir::Num) => Some(Dir::R),
+        _ => None,
+    };
+    let mut i = 0;
+    while i < n {
+        if !(rl(i) && dir.get(i) == Some(&Dir::Open)) {
+            i += 1;
+            continue;
+        }
+        let start = i;
+        while i < n && rl(i) && dir.get(i) == Some(&Dir::Open) {
+            i += 1;
+        }
+        let before = (0..start).rev().find_map(|j| strong_at(&dir, j)).unwrap_or(sos);
+        let after = (i..n).find_map(|j| strong_at(&dir, j)).unwrap_or(sos);
+        let d = if before == after { before } else { Dir::R };
+        for x in dir.get_mut(start..i).into_iter().flatten() {
+            *x = d;
+        }
+    }
+    // Spaces in left-to-right runs follow the character before them.
+    let mut prev = Dir::L;
+    for d in dir.iter_mut() {
+        if *d == Dir::Open {
+            *d = prev;
+        }
+        prev = if *d == Dir::Num { Dir::R } else { *d };
+    }
+    dir.iter()
+        .map(|d| match (d, base % 2 == 1) {
+            (Dir::L, false) | (Dir::R, true) => base,
+            (Dir::L, true) | (Dir::R, false) | (Dir::Open, _) => base + 1,
+            (Dir::Num, false) => base + 2,
+            (Dir::Num, true) => base + 1,
+        })
+        .collect()
+}
+
 /// Whitespace-like for rule L1: reset to the paragraph level when trailing a line or preceding a
 /// segment/paragraph separator.
 fn l1_whitespace(c: BidiClass) -> bool {
@@ -131,6 +274,40 @@ mod tests {
         assert_eq!(lv("ab", true), vec![2, 2]);
     }
 
+    /// Visual string of `s` laid out on one line with every character in a run of language
+    /// direction `rtl_lang`, as PowerPoint orders it.
+    fn vis_lang(s: &str, rtl: bool, rtl_lang: bool) -> String {
+        let chars: Vec<char> = s.chars().collect();
+        let l = levels_lang(s, &chars, rtl, &vec![rtl_lang; chars.len()]);
+        visual_order(&line_levels(&chars, &l, u8::from(rtl))).iter().map(|&i| chars[i]).collect()
+    }
+
+    #[test]
+    fn run_language_decides_neutrals_like_powerpoint() {
+        // Observed in PowerPoint with each space highlighted. An English run: the space after a
+        // Hebrew word goes with it, punctuation is left to right.
+        assert_eq!(vis_lang("x אב גד y", false, false), "x  דג באy");
+        assert_eq!(vis_lang("אב גד x y", false, false), " דג באx y");
+        assert_eq!(vis_lang("x אב, גד! y", false, false), "x בא, דג! y");
+        // Digits after Hebrew stay left to right in an English run.
+        assert_eq!(vis_lang("אב 12", false, false), " בא12");
+        // A Hebrew run: neutrals between different directions are right to left, and digits are
+        // a number inside the right-to-left text.
+        assert_eq!(vis_lang("אב גד x y", false, true), " דג באx y");
+        assert_eq!(vis_lang("12 אב 34 x", false, true), " 34 בא 12x");
+        assert_eq!(vis_lang("x אב, גד! y", false, true), "x !דג ,בא y");
+        // Between two left-to-right words a Hebrew run's space stays left to right.
+        assert_eq!(vis_lang("Version 2.0 ok", false, true), "Version 2.0 ok");
+        // An English sentence in a right-to-left paragraph keeps its full stop at its end.
+        assert_eq!(vis_lang("Hello world.", true, false), "Hello world.");
+        // Right-to-left runs keep W4: "45.6%" is one number.
+        assert_eq!(vis_lang("אב 45.6% גד", false, true), "דג 45.6% בא");
+        // Without right-to-left text or runs, the fast path.
+        let chars: Vec<char> = "plain, text".chars().collect();
+        assert_eq!(levels_lang("plain, text", &chars, false, &[false; 11]), vec![0; 11]);
+        assert!(is_rtl_lang("he-IL") && is_rtl_lang("ar") && is_rtl_lang("FA-ir") && !is_rtl_lang("en-US") && !is_rtl_lang(""));
+    }
+
     #[test]
     fn l1_resets_trailing_whitespace_and_tabs() {
         let chars: Vec<char> = "ab\tcd  ".chars().collect();

crates/text/src/lib.rs

@@ -54,11 +54,31 @@ pub struct GlyphRun {
     pub para: usize,
     pub chars: (usize, usize),
     pub link: bool,
-    /// Alpha of the fill (0–1).
+    /// Opacity of the fill on top of `color`'s own alpha (0 for no fill).
     pub alpha: f64,
     pub gradient: Option<deckcraft_model::style::Gradient>,
     /// Shadow and glow behind the glyphs (`a:rPr/a:effectLst`).
     pub effects: Option<RunEffects>,
+    /// East Asian vertical text (`eaVert`): each glyph stands upright, turned a quarter turn
+    /// back about the centre of its em box ([`GlyphRun::upright_centre`]) inside text that is
+    /// laid out turned a quarter turn.
+    pub upright: bool,
+}
+
+/// Share of the size the ideographic em box's centre sits above the baseline (CJK fonts put the
+/// em box from 0.88 em above to 0.12 em below it).
+pub const UPRIGHT_CENTRE: f64 = 0.38;
+
+impl GlyphRun {
+    /// The point an upright glyph at pen position (`x`, `y`) turns about: the centre of its em box,
+    /// `advance` wide (`None` when the run is not upright).
+    pub fn upright_centre(&self, gid: u32, x: f64, y: f64) -> Option<(f64, f64)> {
+        if !self.upright {
+            return None;
+        }
+        let adv = self.face.advance(gid) * self.size / self.face.upem.max(1.0);
+        Some((x + adv / 2.0, y - self.size * UPRIGHT_CENTRE))
+    }
 }
 
 /// A text run's shadow and glow, colours resolved.
@@ -93,6 +113,150 @@ pub struct Deco {
     pub behind: bool,
     /// Paragraph the decoration belongs to (by-paragraph animation).
     pub para: usize,
+    /// How the line fills `rect`.
+    pub line: DecoLine,
+}
+
+/// How an underline fills its box.
+#[derive(Clone, Copy, Debug, Default, PartialEq)]
+pub enum DecoLine {
+    /// The whole box.
+    #[default]
+    Solid,
+    /// Dashes or dots across the box's height, from its left end.
+    Dashed(Dash),
+    /// A zigzag between the box's top and bottom: `stroke` wide, one wave every `period`.
+    Wave { stroke: f64, period: f64 },
+}
+
+/// Dash patterns of the dotted and dashed underlines, in units of the line's thickness. Measured
+/// on PowerPoint's export: dots and their gaps as long as the line is thick, dashes three
+/// thicknesses long with gaps of two.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub enum Dash {
+    Dot,
+    Dash,
+    Long,
+    DotDash,
+    DotDotDash,
+}
+
+impl Dash {
+    /// On, off, on, off… lengths in thicknesses.
+    fn pattern(self) -> &'static [f64] {
+        match self {
+            Dash::Dot => &[1.0, 1.0],
+            Dash::Dash => &[3.0, 2.0],
+            Dash::Long => &[6.0, 2.0],
+            Dash::DotDash => &[3.0, 2.0, 1.0, 2.0],
+            Dash::DotDotDash => &[3.0, 2.0, 1.0, 2.0, 1.0, 2.0],
+        }
+    }
+}
+
+impl Deco {
+    /// The filled boxes of a solid or dashed line (dashes start at the box's left end). A wavy
+    /// line gives a thin box along its middle, for drawing that can't stroke a path.
+    pub fn pieces(&self) -> Vec<Rect> {
+        let r = self.rect;
+        match self.line {
+            DecoLine::Solid => vec![r],
+            DecoLine::Wave { stroke, .. } => {
+                let c = (r.y0 + r.y1) / 2.0;
+                vec![Rect::new(r.x0, c - stroke / 2.0, r.x1, c + stroke / 2.0)]
+            }
+            DecoLine::Dashed(d) => {
+                let unit = r.height().max(0.1);
+                let pat = d.pattern();
+                let mut out = Vec::new();
+                let mut x = r.x0;
+                let mut k = 0usize;
+                while x < r.x1 && out.len() < 10_000 {
+                    let len = pat.get(k % pat.len()).copied().unwrap_or(1.0) * unit;
+                    if k.is_multiple_of(2) {
+                        out.push(Rect::new(x, r.y0, (x + len).min(r.x1), r.y1));
+                    }
+                    x += len;
+                    k += 1;
+                }
+                out
+            }
+        }
+    }
+
+    /// The zigzag of a wavy underline, left to right from the box's top, and its stroke width;
+    /// None for other lines.
+    pub fn wave(&self) -> Option<(Vec<Point>, f64)> {
+        let DecoLine::Wave { stroke, period } = self.line else { return None };
+        let r = self.rect;
+        let half = (period / 2.0).max(0.1);
+        let n = ((r.width().max(0.0) / half).ceil() as usize).min(20_000);
+        let pts = (0..=n)
+            .map(|i| {
+                let x = (r.x0 + i as f64 * half).min(r.x1);
+                Point::new(x, if i % 2 == 0 { r.y0 } else { r.y1 })
+            })
+            .collect();
+        Some((pts, stroke))
+    }
+}
+
+/// An underline style (`a:rPr/@u`).
+#[derive(Clone, Copy, Debug, PartialEq)]
+enum Underline {
+    Single,
+    Double,
+    Heavy,
+    /// Dotted or dashed, heavy or not.
+    Dashed(Dash, bool),
+    /// Wavy, heavy or not.
+    Wavy(bool),
+}
+
+impl Underline {
+    fn from_xml(u: &str) -> Option<Self> {
+        Some(match u {
+            "none" => return None,
+            // PowerPoint underlines the spaces of a "words" underline too.
+            "words" => Underline::Single,
+            // At text sizes PowerPoint's double wave reads as two straight lines.
+            "dbl" | "wavyDbl" => Underline::Double,
+            "heavy" => Underline::Heavy,
+            "dotted" => Underline::Dashed(Dash::Dot, false),
+            "dottedHeavy" => Underline::Dashed(Dash::Dot, true),
+            "dash" => Underline::Dashed(Dash::Dash, false),
+            "dashHeavy" => Underline::Dashed(Dash::Dash, true),
+            "dashLong" => Underline::Dashed(Dash::Long, false),
+            "dashLongHeavy" => Underline::Dashed(Dash::Long, true),
+            "dotDash" => Underline::Dashed(Dash::DotDash, false),
+            "dotDashHeavy" => Underline::Dashed(Dash::DotDash, true),
+            "dotDotDash" => Underline::Dashed(Dash::DotDotDash, false),
+            "dotDotDashHeavy" => Underline::Dashed(Dash::DotDotDash, true),
+            "wavy" => Underline::Wavy(false),
+            "wavyHeavy" => Underline::Wavy(true),
+            _ => Underline::Single,
+        })
+    }
+
+    /// The boxes of this underline below the baseline (top, bottom, fill), from the font's
+    /// underline position `p` and thickness `t` at the run's size. Measured on PowerPoint's export
+    /// (Arial 96 pt: p = 10.2, t = 7.0): single at p..p+t; heavy from p-t to p+0.55t; double as two
+    /// lines 0.55t thick spanning p-t..p+t; wavy a thin zigzag from p-0.6t to p+1.1t, a wave every
+    /// 3.9t.
+    fn boxes(self, p: f64, t: f64) -> Vec<(f64, f64, DecoLine)> {
+        let heavy = (p - t, p + 0.55 * t);
+        match self {
+            Underline::Single => vec![(p, p + t, DecoLine::Solid)],
+            Underline::Heavy => vec![(heavy.0, heavy.1, DecoLine::Solid)],
+            Underline::Double => vec![(p - t, p - 0.45 * t, DecoLine::Solid), (p + 0.45 * t, p + t, DecoLine::Solid)],
+            Underline::Dashed(d, false) => vec![(p, p + t, DecoLine::Dashed(d))],
+            Underline::Dashed(d, true) => vec![(heavy.0, heavy.1, DecoLine::Dashed(d))],
+            Underline::Wavy(h) => {
+                let stroke = (t * 0.15).max(0.4) * if h { 2.0 } else { 1.0 };
+                vec![(p - 0.6 * t, p + 1.1 * t, DecoLine::Wave { stroke, period: t * 3.9 })]
+            }
+        }
+    }
 }
 
 #[derive(Clone, Debug, Default)]
@@ -187,7 +351,7 @@ struct Style {
     baseline: f64,
     spacing: f64,
     caps: Caps,
-    underline: Option<Rgba>,
+    underline: Option<(Rgba, Underline)>,
     strike: Option<Strike>,
     highlight: Option<Rgba>,
     outline: Option<(Rgba, f64)>,
@@ -227,6 +391,8 @@ struct Cell {
     head: usize,
     /// A grapheme starts here: carets stand and lines break only before such cells.
     boundary: bool,
+    /// Drawn upright in East Asian vertical text.
+    upright: bool,
 }
 
 impl Cell {
@@ -269,7 +435,8 @@ fn make_style(ctx: &Ctx, r: &RunProps, scale: f64, prompt: Option<Rgba>) -> Styl
     let fake_italic = italic && !face.italic;
     let size = (r.size.unwrap_or(18.0) * scale).clamp(0.5, 4000.0);
     let (mut color, alpha, gradient) = match &r.fill {
-        Some(Fill::Solid { color }) => (ctx.color(color, None), color.alpha(), None),
+        // The resolved colour carries the fill's transparency (`a:alpha`): it is applied once.
+        Some(Fill::Solid { color }) => (ctx.color(color, None), 1.0, None),
         Some(Fill::Gradient(g)) => {
             // Colours resolved here (theme, colour map), so the renderer needs no colour scheme.
             let mut g = g.clone();
@@ -292,7 +459,8 @@ fn make_style(ctx: &Ctx, r: &RunProps, scale: f64, prompt: Option<Rgba>) -> Styl
     };
     let ea = slot_family(&r.font_ea, if major { "+mj-ea" } else { "+mn-ea" });
     let cs = slot_family(&r.font_cs, if major { "+mj-cs" } else { "+mn-cs" });
-    let underline = r.underline.as_deref().filter(|u| *u != "none").map(|_| r.underline_color.as_ref().map(|c| ctx.color(c, None)).unwrap_or(color));
+    let underline =
+        r.underline.as_deref().and_then(Underline::from_xml).map(|u| (r.underline_color.as_ref().map(|c| ctx.color(c, None)).unwrap_or(color), u));
     let outline = r.outline.as_ref().and_then(|l| match &l.fill {
         Some(Fill::Solid { color: c }) => Some((ctx.color(c, None), l.width.unwrap_or(0.75))),
         _ => None,
@@ -404,37 +572,129 @@ fn alpha_num(n: u32, upper: bool) -> String {
     if upper { s.to_uppercase() } else { s }
 }
 
-/// Text of an auto-number bullet: `arabicPeriod` 3 → "3.".
+/// Letters of a numbering alphabet: 1 → the first, past the end the letter doubles ("aa"), as
+/// the Latin alphabetic schemes do.
+fn letters(list: &[char], n: u32) -> String {
+    let len = list.len().max(1) as u32;
+    let Some(i) = n.checked_sub(1) else { return String::new() };
+    let c = list.get((i % len) as usize).copied().unwrap_or('?');
+    std::iter::repeat_n(c, (i / len + 1).min(50) as usize).collect()
+}
+
+/// `n` written with the digits `zero..zero+9` (Thai, Devanagari, full-width digits).
+fn digits_in(n: u32, zero: char) -> String {
+    n.to_string().chars().map(|d| d.to_digit(10).and_then(|v| char::from_u32(zero as u32 + v)).unwrap_or(d)).collect()
+}
+
+const CJK_DIGITS: [char; 10] = ['〇', '一', '二', '三', '四', '五', '六', '七', '八', '九'];
+
+/// Chinese numerals: 10 → 十, 11 → 十一, 25 → 二十五, 105 → 一百零五.
+fn chinese_num(n: u32) -> String {
+    if n == 0 || n > 99_999 {
+        return n.to_string();
+    }
+    let units = ['\0', '十', '百', '千', '万'];
+    let ds: Vec<u32> = n.to_string().chars().filter_map(|c| c.to_digit(10)).collect();
+    let mut out = String::new();
+    let mut zero = false;
+    for (i, d) in ds.iter().enumerate() {
+        let place = ds.len() - 1 - i;
+        if *d == 0 {
+            zero = true;
+            continue;
+        }
+        if zero {
+            out.push('零');
+            zero = false;
+        }
+        // "十" alone for 10–19, not "一十".
+        if !(*d == 1 && place == 1 && i == 0) {
+            out.push(CJK_DIGITS.get(*d as usize).copied().unwrap_or('?'));
+        }
+        if let Some(u) = units.get(place).filter(|u| **u != '\0') {
+            out.push(*u);
+        }
+    }
+    out
+}
+
+/// Text of an auto-number bullet: `arabicPeriod` 3 → "3.". The East Asian, Thai, Hindi, Arabic
+/// and Hebrew schemes are written as PowerPoint draws them: `ea1ChsPeriod` 10 → "十．",
+/// `ea1JpnKorPeriod` 10 → "一〇．" (digit by digit), `arabicDbPeriod` 13 → "１３．",
+/// `thaiAlphaParenR` 4 → "ง)", `hindiAlpha1Period` 1 → "क.", `arabic2Minus` 10 → "ي-"
+/// (abjad order), `circleNumWdWhitePlain` 13 → "③" (those circles go to ten).
 pub fn autonum(scheme: &str, n: u32) -> String {
-    let (core, upper) = if scheme.starts_with("romanUc") {
-        (roman(n, true), true)
+    const THAI: [char; 41] = [
+        'ก', 'ข', 'ค', 'ง', 'จ', 'ฉ', 'ช', 'ซ', 'ฌ', 'ญ', 'ฎ', 'ฏ', 'ฐ', 'ฑ', 'ฒ', 'ณ', 'ด', 'ต', 'ถ', 'ท', 'ธ', 'น', 'บ', 'ป', 'ผ', 'ฝ', 'พ', 'ฟ',
+        'ภ', 'ม', 'ย', 'ร', 'ล', 'ว', 'ศ', 'ษ', 'ส', 'ห', 'ฬ', 'อ', 'ฮ',
+    ];
+    const HINDI_VOWELS: [char; 11] = ['अ', 'आ', 'इ', 'ई', 'उ', 'ऊ', 'ऋ', 'ए', 'ऐ', 'ओ', 'औ'];
+    const HINDI_CONSONANTS: [char; 33] = [
+        'क', 'ख', 'ग', 'घ', 'ङ', 'च', 'छ', 'ज', 'झ', 'ञ', 'ट', 'ठ', 'ड', 'ढ', 'ण', 'त', 'थ', 'द', 'ध', 'न', 'प', 'फ', 'ब', 'भ', 'म', 'य', 'र', 'ल',
+        'व', 'श', 'ष', 'स', 'ह',
+    ];
+    const ARABIC_ALPHABET: [char; 28] =
+        ['ا', 'ب', 'ت', 'ث', 'ج', 'ح', 'خ', 'د', 'ذ', 'ر', 'ز', 'س', 'ش', 'ص', 'ض', 'ط', 'ظ', 'ع', 'غ', 'ف', 'ق', 'ك', 'ل', 'م', 'ن', 'ه', 'و', 'ي'];
+    const ARABIC_ABJAD: [char; 28] =
+        ['ا', 'ب', 'ج', 'د', 'ه', 'و', 'ز', 'ح', 'ط', 'ي', 'ك', 'ل', 'م', 'ن', 'س', 'ع', 'ف', 'ص', 'ق', 'ر', 'ش', 'ت', 'ث', 'خ', 'ذ', 'ض', 'ظ', 'غ'];
+    const HEBREW: [char; 22] = ['א', 'ב', 'ג', 'ד', 'ה', 'ו', 'ז', 'ח', 'ט', 'י', 'כ', 'ל', 'מ', 'נ', 'ס', 'ע', 'פ', 'צ', 'ק', 'ר', 'ש', 'ת'];
+    let circled = |first: u32, count: u32| char::from_u32(first + n.saturating_sub(1) % count).map(String::from).unwrap_or_else(|| n.to_string());
+    let core = if scheme.starts_with("romanUc") {
+        roman(n, true)
     } else if scheme.starts_with("romanLc") {
-        (roman(n, false), false)
+        roman(n, false)
     } else if scheme.starts_with("alphaUc") {
-        (alpha_num(n, true), true)
+        alpha_num(n, true)
     } else if scheme.starts_with("alphaLc") {
-        (alpha_num(n, false), false)
+        alpha_num(n, false)
+    } else if scheme.starts_with("circleNumWdWhite") {
+        return circled(0x2460, 10);
+    } else if scheme.starts_with("circleNumWdBlack") {
+        return circled(0x2776, 10);
     } else if scheme.starts_with("circleNum") {
-        let c = char::from_u32(0x2460 + n.saturating_sub(1).min(19)).unwrap_or('•');
-        return c.to_string();
+        return char::from_u32(0x2460 + n.saturating_sub(1).min(19)).map(String::from).unwrap_or_else(|| n.to_string());
+    } else if scheme.starts_with("ea1Chs") || scheme.starts_with("ea1Cht") {
+        chinese_num(n)
+    } else if scheme.starts_with("ea1Jpn") {
+        n.to_string().chars().map(|d| d.to_digit(10).and_then(|v| CJK_DIGITS.get(v as usize).copied()).unwrap_or(d)).collect()
+    } else if scheme.starts_with("arabicDb") {
+        digits_in(n, '０')
+    } else if scheme.starts_with("thaiAlpha") {
+        letters(&THAI, n)
+    } else if scheme.starts_with("thaiNum") {
+        digits_in(n, '๐')
+    } else if scheme.starts_with("hindiAlpha1") {
+        letters(&HINDI_CONSONANTS, n)
+    } else if scheme.starts_with("hindiAlpha") {
+        letters(&HINDI_VOWELS, n)
+    } else if scheme.starts_with("hindiNum") {
+        digits_in(n, '०')
+    } else if scheme.starts_with("arabic1") {
+        letters(&ARABIC_ALPHABET, n)
+    } else if scheme.starts_with("arabic2") {
+        letters(&ARABIC_ABJAD, n)
+    } else if scheme.starts_with("hebrew2") {
+        letters(&HEBREW, n)
     } else {
-        (n.to_string(), false)
+        n.to_string()
     };
-    let _ = upper;
+    // East Asian schemes end with a full-width full stop.
+    let wide = scheme.starts_with("ea1") || scheme.starts_with("arabicDb");
     if scheme.ends_with("ParenBoth") {
         format!("({core})")
     } else if scheme.ends_with("ParenR") {
         format!("{core})")
     } else if scheme.ends_with("Period") {
-        format!("{core}.")
+        format!("{core}{}", if wide { '．' } else { '.' })
     } else if scheme.ends_with("Minus") {
-        format!("- {core} -")
+        format!("{core}-")
     } else {
         core
     }
 }
 
-fn shape_para(ctx: &Ctx, shape: &Shape, body: &TextBody, pi: usize, scale: f64, opts: &Opts, number: Option<u32>) -> ParaShaped {
+#[allow(clippy::too_many_arguments)]
+fn shape_para(ctx: &Ctx, shape: &Shape, body: &TextBody, pi: usize, scale: f64, opts: &Opts, number: Option<u32>, vertical: Upright) -> ParaShaped {
     let db = FontDb::global();
     let Some(para) = body.paragraphs.get(pi) else {
         let face = db.face("Inter", "Regular");
@@ -471,7 +731,7 @@ fn shape_para(ctx: &Ctx, shape: &Shape, body: &TextBody, pi: usize, scale: f64,
         char_style.extend(std::iter::repeat_n(si, t.chars().count()));
         text.push_str(&t);
     }
-    let cells = shape_cells(ctx, &text, &char_style, &styles, &mut faces, rtl);
+    let cells = shape_cells(ctx, &text, &char_style, &styles, &mut faces, rtl, vertical);
     let lead = para.runs.first().map(|r| resolve::run(ctx, shape, para, &r.props)).unwrap_or_else(|| resolve::run(ctx, shape, para, &para.end_props));
     let lead_style = make_style(ctx, &lead, scale, opts.prompt_color);
     let lead_size = lead_style.size;
@@ -552,7 +812,16 @@ fn run_effects(ctx: &Ctx, r: &RunProps, scale: f64) -> Option<RunEffects> {
     (shadow.is_some() || glow.is_some()).then_some(RunEffects { shadow, glow })
 }
 
-fn shape_cells(ctx: &Ctx, text: &str, char_style: &[usize], styles: &[Style], faces: &mut Vec<Arc<FontFace>>, rtl: bool) -> Vec<Cell> {
+#[allow(clippy::too_many_arguments)]
+fn shape_cells(
+    ctx: &Ctx,
+    text: &str,
+    char_style: &[usize],
+    styles: &[Style],
+    faces: &mut Vec<Arc<FontFace>>,
+    rtl: bool,
+    vertical: Upright,
+) -> Vec<Cell> {
     let db = FontDb::global();
     let chars: Vec<char> = text.chars().collect();
     let n = chars.len();
@@ -560,7 +829,9 @@ fn shape_cells(ctx: &Ctx, text: &str, char_style: &[usize], styles: &[Style], fa
     let mut byte_of: Vec<usize> = text.char_indices().map(|(b, _)| b).collect();
     byte_of.push(text.len());
     let char_at_byte: HashMap<usize, usize> = byte_of.iter().enumerate().map(|(i, b)| (*b, i)).collect();
-    let levels = bidi::levels(text, &chars, rtl);
+    let style_rtl: Vec<bool> = styles.iter().map(|st| st.lang.as_deref().is_some_and(bidi::is_rtl_lang)).collect();
+    let rtl_lang: Vec<bool> = char_style.iter().map(|&si| style_rtl.get(si).copied().unwrap_or(false)).collect();
+    let levels = bidi::levels_lang(text, &chars, rtl, &rtl_lang);
     let scripts = script::resolve(&chars);
     let mut boundary = vec![false; n];
     let mut graphemes: Vec<(usize, usize)> = Vec::new();
@@ -602,7 +873,11 @@ fn shape_cells(ctx: &Ctx, text: &str, char_style: &[usize], styles: &[Style], fa
             .filter(|f| deckcraft_fonts::covers_cluster(f, cluster));
         let face = match (sym_face, prev.as_ref()) {
             (Some(f), _) => f,
-            (None, Some(p)) if neutral && deckcraft_fonts::covers_cluster(p, cluster) && char_style.get(a.wrapping_sub(1)) == Some(&si) => p.clone(),
+            (None, Some(p))
+                if neutral && !p.is_color() && deckcraft_fonts::covers_cluster(p, cluster) && char_style.get(a.wrapping_sub(1)) == Some(&si) =>
+            {
+                p.clone()
+            }
             (None, _) => {
                 let chain = chains.entry((si, slot, sc)).or_insert_with(|| face_chain(ctx, st, slot, sc));
                 db.cascade(cluster, chain, st.style_name)
@@ -624,25 +899,118 @@ fn shape_cells(ctx: &Ctx, text: &str, char_style: &[usize], styles: &[Style], fa
             adv: 0.0,
             head: i,
             boundary: boundary.get(i).copied().unwrap_or(true),
+            upright: false,
         })
         .collect();
+    // In East Asian vertical text, ideographs, kana, Hangul, full-width forms and the like stand
+    // upright (a whole grapheme at a time); other text lies on its side.
+    if vertical != Upright::None {
+        for &(a, b) in &graphemes {
+            let up = chars.get(a).is_some_and(|c| if vertical == Upright::All { !c.is_whitespace() } else { is_upright(*c) });
+            for c in cells.get_mut(a..b).into_iter().flatten() {
+                c.upright = up;
+            }
+        }
+    }
     // Items: maximal ranges of one level, face, script and shaping style (case mapping, language).
     let upper = |i: usize| styles.get(char_style.get(i).copied().unwrap_or(0)).is_some_and(|st| st.caps != Caps::None);
     let lang = |i: usize| styles.get(char_style.get(i).copied().unwrap_or(0)).and_then(|st| st.lang.as_deref());
     let kern = |i: usize| styles.get(char_style.get(i).copied().unwrap_or(0)).is_some_and(|st| st.kern);
-    let key = |i: usize| (levels.get(i).copied(), char_face.get(i).copied(), scripts.get(i).map(|s| s.0), upper(i), lang(i), kern(i));
+    let up = |i: usize| cells.get(i).is_some_and(|c| c.upright);
+    let key = |i: usize| (levels.get(i).copied(), char_face.get(i).copied(), scripts.get(i).map(|s| s.0), upper(i), lang(i), kern(i), up(i));
+    let mut items: Vec<(usize, usize)> = Vec::new();
     let mut a = 0;
     while a < n {
         let mut b = a + 1;
         while b < n && key(b) == key(a) {
             b += 1;
         }
-        shape_item(&mut cells, styles, faces, text, &byte_of, &char_at_byte, a..b, scripts.get(a).and_then(|s| s.0), lang(a), upper(a));
+        items.push((a, b));
         a = b;
     }
+    // Upright glyphs keep their horizontal forms: PowerPoint turns "、", "。" and "「" as they are
+    // (no `vert` alternates).
+    for (a, b) in items {
+        shape_item(&mut cells, styles, faces, text, &byte_of, &char_at_byte, a..b, scripts.get(a).and_then(|s| s.0), lang(a), upper(a));
+    }
+    // Stacked text: each character takes one em down the line, centred across it (PowerPoint
+    // stacks 18 pt Latin letters about 18 pt apart, a space only its own width).
+    if vertical == Upright::All {
+        for i in 0..n {
+            let Some(c) = cells.get(i) else { continue };
+            if !c.upright || c.head != i || c.glyphs.is_empty() {
+                continue;
+            }
+            let size = styles.get(c.style).map(|st| st.size).unwrap_or(18.0);
+            let width: f64 = (i..n).take_while(|&j| cells.get(j).is_some_and(|d| d.head == i)).filter_map(|j| cells.get(j)).map(|d| d.adv).sum();
+            let pad = (size - width) / 2.0;
+            if let Some(c) = cells.get_mut(i) {
+                for g in &mut c.glyphs {
+                    g.1 += pad;
+                }
+            }
+            for j in i..n {
+                match cells.get_mut(j) {
+                    Some(d) if d.head == i => d.adv = if j == i { size } else { 0.0 },
+                    _ => break,
+                }
+            }
+        }
+    }
     cells
 }
 
+/// A character in capitals (`cap="all"`/`"small"`): its uppercase when that is one character.
+/// PowerPoint leaves characters whose capital is a sequence as they are: "ß" stays "ß" (not "SS"),
+/// "fi" and "ʼn" stay.
+fn caps_char(ch: char) -> char {
+    let mut up = ch.to_uppercase();
+    match (up.next(), up.next()) {
+        (Some(u), None) => u,
+        _ => ch,
+    }
+}
+
+/// Does `c` stand upright in East Asian vertical text? Ideographs, kana, Hangul, Bopomofo, CJK
+/// symbols and punctuation, full-width forms, enclosed and compatibility CJK, circled numbers
+/// and emoji (Unicode's Vertical_Orientation U and T, roughly); Latin, digits and the rest of the
+/// half-width text lie on their side as in `vert`.
+fn is_upright(c: char) -> bool {
+    matches!(c as u32,
+        0x1100..=0x11FF
+            | 0x2460..=0x24FF
+            | 0x2E80..=0x2FFF
+            | 0x3000..=0x303F
+            | 0x3040..=0x30FF
+            | 0x3100..=0x312F
+            | 0x3130..=0x318F
+            | 0x3190..=0x31FF
+            | 0x3200..=0x33FF
+            | 0x3400..=0x4DBF
+            | 0x4E00..=0x9FFF
+            | 0xA960..=0xA97F
+            | 0xAC00..=0xD7FF
+            | 0xF900..=0xFAFF
+            | 0xFE10..=0xFE1F
+            | 0xFE30..=0xFE6F
+            | 0xFF01..=0xFF60
+            | 0xFFE0..=0xFFE6
+            | 0x1F000..=0x1FAFF
+            | 0x20000..=0x3FFFF
+    )
+}
+
+/// Which characters stand upright in vertical text.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+enum Upright {
+    /// None (horizontal text, vert, vert270, mongolianVert).
+    None,
+    /// Ideographs, kana and the like (eaVert).
+    Cjk,
+    /// Every character, one under the other (wordArtVert).
+    All,
+}
+
 /// Size of superscript and subscript text relative to the run's size.
 const SUB_SUPER: f64 = 0.66;
 
@@ -686,7 +1054,7 @@ fn shape_item(
     let (Some(&b0), Some(&b1)) = (byte_of.get(range.start), byte_of.get(range.end)) else { return };
     let features = shaping_features(cells.get(range.clone()).unwrap_or(&[]), styles, script);
     let params = ShapeParams { features: &features, rtl, script, language: lang };
-    let glyphs = deckcraft_fonts::shape_range(face, text, b0..b1, &params, |ch| if upper { ch.to_uppercase().next().unwrap_or(ch) } else { ch });
+    let glyphs = deckcraft_fonts::shape_range(face, text, b0..b1, &params, |ch| if upper { caps_char(ch) } else { ch });
     let upem = face.upem.max(1.0);
     let scale_of = |cell: &Cell| {
         let st = styles.get(cell.style);
@@ -896,31 +1264,50 @@ fn is_hangul(c: char) -> bool {
     matches!(c, '\u{1100}'..='\u{11FF}' | '\u{3130}'..='\u{318F}' | '\u{A960}'..='\u{A97F}' | '\u{AC00}'..='\u{D7FF}')
 }
 
-/// Closing East Asian punctuation that may hang past the end of a line (`hangingPunct`).
+/// East Asian commas and full stops, the punctuation PowerPoint lets hang past the end of a line
+/// (`hangingPunct`). Closing brackets don't hang: "「。」" overflowing by its "」" moves to the next
+/// line whole.
 fn is_hanging_punct(c: char) -> bool {
+    matches!(c, '、' | '。' | '，' | '．' | '､' | '｡')
+}
+
+/// Small kana, the prolonged sound mark and iteration marks: PowerPoint keeps them off the start
+/// of a line (strict Japanese line breaking), where UAX #14's default allows a break before them.
+fn is_cj_nonstarter(c: char) -> bool {
     matches!(
         c,
-        '、' | '。'
-            | '，'
-            | '．'
-            | '：'
-            | '；'
-            | '！'
-            | '？'
-            | '）'
-            | '」'
-            | '』'
-            | '】'
-            | '〕'
-            | '〉'
-            | '》'
-            | '〙'
-            | '〛'
-            | '｝'
-            | '］'
-            | '｣'
-            | '､'
-            | '｡'
+        'ぁ' | 'ぃ'
+            | 'ぅ'
+            | 'ぇ'
+            | 'ぉ'
+            | 'っ'
+            | 'ゃ'
+            | 'ゅ'
+            | 'ょ'
+            | 'ゎ'
+            | 'ゕ'
+            | 'ゖ'
+            | 'ァ'
+            | 'ィ'
+            | 'ゥ'
+            | 'ェ'
+            | 'ォ'
+            | 'ッ'
+            | 'ャ'
+            | 'ュ'
+            | 'ョ'
+            | 'ヮ'
+            | 'ヵ'
+            | 'ヶ'
+            | 'ー'
+            | '々'
+            | '〻'
+            | 'ゝ'
+            | 'ゞ'
+            | 'ヽ'
+            | 'ヾ'
+            | '\u{31F0}'..='\u{31FF}'
+            | 'ｧ'..='ｰ'
     )
 }
 
@@ -951,7 +1338,12 @@ fn break_opportunities(text: &str, latin_break: bool) -> (Vec<bool>, Vec<bool>)
     let chars: Vec<char> = text.chars().collect();
     for (i, w) in chars.windows(2).enumerate() {
         let (prev, next) = (w[0], w[1]);
-        let keep = if is_hangul(prev) && is_hangul(next) { false } else { latin_break || !matches!(prev, '/' | '\\') || next.is_whitespace() };
+        // PowerPoint never breaks after a zero-width space, nor before an em dash (only after it).
+        let keep = if (is_hangul(prev) && is_hangul(next)) || prev == '\u{200B}' || next == '\u{2014}' || is_cj_nonstarter(next) {
+            false
+        } else {
+            latin_break || !matches!(prev, '/' | '\\') || next.is_whitespace()
+        };
         if !keep
             && !mandatory.get(i + 1).copied().unwrap_or(false)
             && let Some(a) = allowed.get_mut(i + 1)
@@ -974,7 +1366,7 @@ fn break_lines(
     first_w: f64,
     rest_w: f64,
     wrap: bool,
-    tab_stops: &[f64],
+    tab_stops: &[Tab],
     default_tab: f64,
     x0_first: f64,
     x0_rest: f64,
@@ -1003,7 +1395,11 @@ fn break_lines(
                 next = i + 1;
                 break;
             }
-            let adv = if c == '\t' { tab_advance(x0 + x, tab_stops, default_tab) } else { p.cells.get(i).map(|c| c.adv).unwrap_or(0.0) };
+            let adv = if c == '\t' {
+                tab_advance(x0 + x, tab_stops, default_tab, tab_segment(&p.cells, i))
+            } else {
+                p.cells.get(i).map(|c| c.adv).unwrap_or(0.0)
+            };
             let breakable = |j: usize| p.cells.get(j).is_none_or(|c| c.breakable(j));
             if i > start && allowed.get(i).copied().unwrap_or(false) && breakable(i) {
                 last_break = Some(i);
@@ -1015,6 +1411,15 @@ fn break_lines(
                 next = i + 1;
                 break;
             }
+            // A tab that would run past the end moves to the next line (and to its first stop there).
+            if wrap && c == '\t' && x + adv > avail + 0.01 && i > start {
+                end = i;
+                next = i;
+                while end > start && p.cells.get(end - 1).is_some_and(|c| c.ch == ' ') {
+                    end -= 1;
+                }
+                break;
+            }
             if wrap && x + adv > avail + 0.01 && !c.is_whitespace() && i > start {
                 // Break at the last opportunity, or force mid-word (between clusters).
                 let b = last_break
@@ -1056,10 +1461,72 @@ fn break_lines(
     lines
 }
 
-fn tab_advance(x: f64, stops: &[f64], default_tab: f64) -> f64 {
+/// How a tab stop aligns the text after it (`a:tab/@algn`).
+#[derive(Clone, Copy, Debug, PartialEq)]
+enum TabAlign {
+    Left,
+    Center,
+    Right,
+    /// The first "." of the text sits at the stop (text without one ends there).
+    Decimal,
+}
+
+#[derive(Clone, Copy, Debug, PartialEq)]
+struct Tab {
+    pos: f64,
+    align: TabAlign,
+}
+
+fn tabs_of(props: &ParaProps) -> Vec<Tab> {
+    props
+        .tabs
+        .as_ref()
+        .map(|t| {
+            t.iter()
+                .map(|s| Tab {
+                    pos: s.pos,
+                    align: match s.align.as_str() {
+                        "ctr" => TabAlign::Center,
+                        "r" => TabAlign::Right,
+                        "dec" => TabAlign::Decimal,
+                        _ => TabAlign::Left,
+                    },
+                })
+                .collect()
+        })
+        .unwrap_or_default()
+}
+
+/// Width of the text after the tab at cell `i` up to the next tab or line break, and the width of
+/// that text before its first ".".
+fn tab_segment(cells: &[Cell], i: usize) -> (f64, f64) {
+    let mut w = 0.0;
+    let mut dec = None;
+    for c in cells.iter().skip(i + 1) {
+        if matches!(c.ch, '\t' | '\u{b}' | '\n') {
+            break;
+        }
+        if c.ch == '.' && dec.is_none() {
+            dec = Some(w);
+        }
+        w += c.adv;
+    }
+    (w, dec.unwrap_or(w))
+}
+
+/// Advance of a tab at `x` (from the start edge) to the next stop, placing the text after it
+/// (`seg`: its width, and its width before the decimal point) as the stop aligns it but never
+/// moving back, as PowerPoint does; past the last stop, to the next default stop.
+fn tab_advance(x: f64, stops: &[Tab], default_tab: f64, seg: (f64, f64)) -> f64 {
     for s in stops {
-        if *s > x + 0.5 {
-            return s - x;
+        if s.pos > x + 0.5 {
+            let to = s.pos - x;
+            return match s.align {
+                TabAlign::Left => to,
+                TabAlign::Right => (to - seg.0).max(0.0),
+                TabAlign::Center => (to - seg.0 / 2.0).max(0.0),
+                TabAlign::Decimal => (to - seg.1).max(0.0),
+            };
         }
     }
     let d = if default_tab > 1.0 { default_tab } else { 72.0 };
@@ -1094,11 +1561,22 @@ pub fn layout(ctx: &Ctx, shape: &Shape, body: &TextBody, opts: &Opts) -> TextLay
     l
 }
 
+#[allow(clippy::too_many_arguments)]
 fn layout_scaled(ctx: &Ctx, shape: &Shape, body: &TextBody, bp: &BodyProps, opts: &Opts, scale: f64, reduce: f64) -> TextLayout {
     let r = opts.rect;
     let vert = bp.vert.unwrap_or(TextDir::Horizontal);
+    // East Asian vertical text: CJK stands upright in text turned a quarter turn; stacked text
+    // stands every character upright, one under the other.
+    let upright_text = match vert {
+        TextDir::EaVertical => Upright::Cjk,
+        TextDir::Stacked | TextDir::StackedRtl => Upright::All,
+        _ => Upright::None,
+    };
+    // Mongolian vertical and stacked text: turned like vert, their lines run from left to right
+    // (as PowerPoint draws both).
+    let lines_ltr = matches!(vert, TextDir::MongolianVertical | TextDir::Stacked);
     let rotation = match vert {
-        TextDir::Vertical | TextDir::EaVertical | TextDir::Stacked => 90.0,
+        TextDir::Vertical | TextDir::EaVertical | TextDir::Stacked | TextDir::StackedRtl | TextDir::MongolianVertical => 90.0,
         TextDir::Vertical270 => 270.0,
         TextDir::Horizontal => 0.0,
     } + bp.rot.unwrap_or(0.0);
@@ -1147,7 +1625,7 @@ fn layout_scaled(ctx: &Ctx, shape: &Shape, body: &TextBody, bp: &BodyProps, opts
             }
             None
         };
-        shaped_paras.push(shape_para(ctx, shape, body, pi, scale, opts, number));
+        shaped_paras.push(shape_para(ctx, shape, body, pi, scale, opts, number, upright_text));
     }
     for (pi, p) in shaped_paras.iter().enumerate() {
         let props = &p.props;
@@ -1166,7 +1644,7 @@ fn layout_scaled(ctx: &Ctx, shape: &Shape, body: &TextBody, bp: &BodyProps, opts
             (margin + indent).max(0.0)
         };
         let rest_x = margin;
-        let tabs: Vec<f64> = props.tabs.as_ref().map(|t| t.iter().map(|s| s.pos).collect()).unwrap_or_default();
+        let tabs = tabs_of(props);
         let first_w = (col_w - first_x - mr).max(1.0);
         let rest_w = (col_w - rest_x - mr).max(1.0);
         let raw = break_lines(p, first_w, rest_w, wrap, &tabs, props.default_tab.unwrap_or(72.0), first_x, rest_x);
@@ -1179,7 +1657,11 @@ fn layout_scaled(ctx: &Ctx, shape: &Shape, body: &TextBody, bp: &BodyProps, opts
             for c in p.cells.get(rl.start..rl.end.max(rl.start)).unwrap_or(&[]) {
                 if let (Some(st), Some(face)) = (p.styles.get(c.style), p.faces.get(c.face)) {
                     let sz = st.size;
-                    let (a, d) = line_metrics(face, sz);
+                    // The run's own fonts set the line; a fallback face (emoji, a symbol or a
+                    // script the run's fonts lack) does not move the baseline in PowerPoint.
+                    let own = Arc::ptr_eq(face, &st.face)
+                        || [st.ea.as_deref(), st.cs.as_deref(), st.sym.as_deref()].into_iter().flatten().any(|f| face.family.eq_ignore_ascii_case(f));
+                    let (a, d) = line_metrics(if own { face } else { &st.face }, sz);
                     asc = asc.max(a);
                     desc = desc.max(d);
                     size = size.max(sz);
@@ -1208,8 +1690,16 @@ fn layout_scaled(ctx: &Ctx, shape: &Shape, body: &TextBody, bp: &BodyProps, opts
             // Logical advances; tabs measure from the start edge.
             let mut adv = Vec::with_capacity(n);
             let mut x = 0.0;
-            for c in line_cells {
-                let a = if c.ch == '\t' { tab_advance(x0 + x, &tabs, props.default_tab.unwrap_or(72.0)) } else { c.adv };
+            // A line that breaks at a soft hyphen ends with a visible hyphen.
+            let shy_end = li + 1 < raw.len() && line_cells.last().is_some_and(|c| c.ch == '\u{AD}');
+            for (k, c) in line_cells.iter().enumerate() {
+                let a = if shy_end && k + 1 == n {
+                    p.faces.get(c.face).zip(p.styles.get(c.style)).map(|(f, st)| measure_str(f, st.size, "-").0).unwrap_or(0.0)
+                } else if c.ch == '\t' {
+                    tab_advance(x0 + x, &tabs, props.default_tab.unwrap_or(72.0), tab_segment(&p.cells, rl.start + k))
+                } else {
+                    c.adv
+                };
                 adv.push(a);
                 x += a;
             }
@@ -1338,6 +1828,10 @@ fn layout_scaled(ctx: &Ctx, shape: &Shape, body: &TextBody, bp: &BodyProps, opts
     }
     let total = y;
     out.content_height = total;
+    // Where column `c` starts: from the left, or from the right with `rtlCol` (PowerPoint puts the
+    // first column on the right).
+    let rtl_cols = bp.rtl_col.unwrap_or(false) && ncols > 1;
+    let col_x = |c: usize| (if rtl_cols { ncols.saturating_sub(1 + c) } else { c }) as f64 * (col_w + col_gap);
     // Columns: distribute lines by height.
     let col_h = if ncols > 1 { inner.height() } else { f64::INFINITY };
     let mut col = 0usize;
@@ -1353,16 +1847,20 @@ fn layout_scaled(ctx: &Ctx, shape: &Shape, body: &TextBody, bp: &BodyProps, opts
             li.top -= dy;
             li.baseline -= dy;
             li.bottom -= dy;
-            li.shift_x(col as f64 * (col_w + col_gap));
+        }
+        let cx = col_x(col);
+        if cx != 0.0 {
+            li.shift_x(cx);
         }
     }
     let used_h = if ncols > 1 { all_lines.iter().map(|(l, ..)| l.bottom).fold(0.0, f64::max) } else { total };
     out.overflow = used_h > inner.height() + 0.5 || (ncols > 1 && all_lines.last().is_some_and(|(l, ..)| l.bottom > inner.height() + 0.5));
     let anchor = bp.anchor.unwrap_or(Anchor::Top);
     let dy = match anchor {
-        Anchor::Top | Anchor::Justified | Anchor::Distributed => 0.0,
+        Anchor::Top => 0.0,
         Anchor::Middle => (inner.height() - used_h) / 2.0,
-        Anchor::Bottom => inner.height() - used_h,
+        // PowerPoint draws justified and distributed anchoring at the bottom.
+        Anchor::Bottom | Anchor::Justified | Anchor::Distributed => inner.height() - used_h,
     };
     // anchorCtr: centre the block horizontally.
     let dx = if bp.anchor_ctr.unwrap_or(false) { ((inner.width() - out.content_width) / 2.0).max(0.0) } else { 0.0 };
@@ -1374,8 +1872,15 @@ fn layout_scaled(ctx: &Ctx, shape: &Shape, body: &TextBody, bp: &BodyProps, opts
         line.baseline += oy;
         line.bottom += oy;
         line.shift_x(ox);
+        if lines_ltr {
+            // The line's place mirrored across the box: the first line ends up on the left.
+            let d = inner.y0 + inner.y1 - line.top - line.bottom;
+            line.top += d;
+            line.baseline += d;
+            line.bottom += d;
+        }
         let Some(p) = shaped_paras.get(line.para) else { continue };
-        if let Some((s, bx, by)) = bullet.take()
+        if let Some((s, bx, _)) = bullet.take()
             && let Some((_, st)) = p.bullet.as_ref()
         {
             let (_, g) = measure_str(&st.face, st.size, &s);
@@ -1383,10 +1888,7 @@ fn layout_scaled(ctx: &Ctx, shape: &Shape, body: &TextBody, bp: &BodyProps, opts
                 face: st.face.clone(),
                 size: st.size,
                 color: st.color,
-                glyphs: g
-                    .into_iter()
-                    .map(|(gid, x)| (gid, ox + bx + x + if line.column > 0 { line.column as f64 * (col_w + col_gap) } else { 0.0 }, by + oy))
-                    .collect(),
+                glyphs: g.into_iter().map(|(gid, x)| (gid, ox + bx + x + col_x(line.column), line.baseline)).collect(),
                 cells: vec![],
                 fake_bold: false,
                 fake_italic: false,
@@ -1397,11 +1899,12 @@ fn layout_scaled(ctx: &Ctx, shape: &Shape, body: &TextBody, bp: &BodyProps, opts
                 alpha: st.alpha,
                 gradient: None,
                 effects: None,
+                upright: false,
             });
         }
         // Group visually consecutive cells by (style, face).
         let mut cur: Option<GlyphRun> = None;
-        let mut cur_key = (usize::MAX, usize::MAX);
+        let mut cur_key = (usize::MAX, usize::MAX, false, false);
         for &k in &place.order {
             let ci = line.start + k;
             let Some(cell) = p.cells.get(ci) else { continue };
@@ -1410,7 +1913,8 @@ fn layout_scaled(ctx: &Ctx, shape: &Shape, body: &TextBody, bp: &BodyProps, opts
             let base_y = line.baseline - st.baseline * st.size;
             let size = if st.baseline != 0.0 { st.size * SUB_SUPER } else { st.size };
             let size = if st.caps == Caps::Small && cell.ch.is_lowercase() { size * 0.8 } else { size };
-            let key = (cell.style, cell.face);
+            // Small capitals are drawn smaller than the capitals beside them: a run of their own.
+            let key = (cell.style, cell.face, st.caps == Caps::Small && cell.ch.is_lowercase(), cell.upright);
             if key != cur_key {
                 if let Some(r) = cur.take() {
                     out.runs.push(r);
@@ -1431,12 +1935,19 @@ fn layout_scaled(ctx: &Ctx, shape: &Shape, body: &TextBody, bp: &BodyProps, opts
                     alpha: st.alpha,
                     gradient: st.gradient.clone(),
                     effects: st.effects,
+                    upright: cell.upright,
                 });
                 cur_key = key;
             }
             if let Some(r) = cur.as_mut() {
                 r.chars = (r.chars.0.min(ci), r.chars.1.max(ci + 1));
-                if cell.head == ci && !cell.glyphs.is_empty() {
+                if cell.ch == '\u{AD}' && cx1 - cx > 0.01 {
+                    // The soft hyphen a line breaks at is drawn as a hyphen.
+                    if let Some(f) = p.faces.get(cell.face) {
+                        r.glyphs.push((f.glyph_for('-'), cx, base_y));
+                        r.cells.push((ci, cell.ch));
+                    }
+                } else if cell.head == ci && !cell.glyphs.is_empty() {
                     // The cluster's glyphs start at its leftmost cell; kashida (right-to-left
                     // only) fills the gap on the cluster's left with tatweel glyphs.
                     let cells_of =
@@ -1469,20 +1980,49 @@ fn layout_scaled(ctx: &Ctx, shape: &Shape, body: &TextBody, bp: &BodyProps, opts
                 continue;
             }
             if let Some(hl) = st.highlight {
-                out.decos.push(Deco { rect: Rect::new(cx, line.top, cx1, line.bottom), color: hl, behind: true, para: line.para });
+                out.decos.push(Deco {
+                    rect: Rect::new(cx, line.top, cx1, line.bottom),
+                    color: hl,
+                    behind: true,
+                    para: line.para,
+                    line: DecoLine::Solid,
+                });
             }
             if !cell.ch.is_whitespace() || st.underline.is_some() {
-                if let Some(uc) = st.underline {
-                    let t = (st.size * 0.06).max(0.5);
-                    let uy = line.baseline + st.size * 0.12;
-                    out.decos.push(Deco { rect: Rect::new(cx, uy, cx1, uy + t), color: uc, behind: false, para: line.para });
+                if let Some((uc, u)) = st.underline {
+                    // At the underline position and thickness of the run's own font.
+                    let k = st.size / st.face.upem.max(1.0);
+                    let (p, t) = (st.face.underline.0 * k, (st.face.underline.1 * k).max(0.5));
+                    for (y0, y1, kind) in u.boxes(p, t) {
+                        out.decos.push(Deco {
+                            rect: Rect::new(cx, line.baseline + y0, cx1, line.baseline + y1),
+                            color: uc,
+                            behind: false,
+                            para: line.para,
+                            line: kind,
+                        });
+                    }
                 }
                 if let Some(sk) = st.strike {
-                    let t = (st.size * 0.05).max(0.5);
-                    let sy = line.baseline - st.size * 0.3;
-                    out.decos.push(Deco { rect: Rect::new(cx, sy, cx1, sy + t), color: st.color, behind: false, para: line.para });
+                    // At the strikeout position and thickness of the run's own font.
+                    let k = st.size / st.face.upem.max(1.0);
+                    let t = (st.face.strikeout.1 * k).max(0.5);
+                    let sy = line.baseline - st.face.strikeout.0 * k;
+                    out.decos.push(Deco {
+                        rect: Rect::new(cx, sy, cx1, sy + t),
+                        color: st.color,
+                        behind: false,
+                        para: line.para,
+                        line: DecoLine::Solid,
+                    });
                     if sk == Strike::Double {
-                        out.decos.push(Deco { rect: Rect::new(cx, sy - t * 2.0, cx1, sy - t), color: st.color, behind: false, para: line.para });
+                        out.decos.push(Deco {
+                            rect: Rect::new(cx, sy - t * 2.0, cx1, sy - t),
+                            color: st.color,
+                            behind: false,
+                            para: line.para,
+                            line: DecoLine::Solid,
+                        });
                     }
                 }
             }
@@ -1511,13 +2051,15 @@ fn layout_scaled(ctx: &Ctx, shape: &Shape, body: &TextBody, bp: &BodyProps, opts
 fn merge_decos(v: Vec<Deco>) -> Vec<Deco> {
     let mut out: Vec<Deco> = Vec::with_capacity(v.len());
     for d in v {
-        if let Some(last) = out.last_mut()
-            && last.color == d.color
-            && last.behind == d.behind
-            && (last.rect.y0 - d.rect.y0).abs() < 0.01
-            && (last.rect.y1 - d.rect.y1).abs() < 0.01
-            && (last.rect.x1 - d.rect.x0).abs() < 0.5
-        {
+        // Lines drawn together (a double underline, a strikethrough) interleave: look a few back.
+        if let Some(last) = out.iter_mut().rev().take(4).find(|last| {
+            last.color == d.color
+                && last.behind == d.behind
+                && last.line == d.line
+                && (last.rect.y0 - d.rect.y0).abs() < 0.01
+                && (last.rect.y1 - d.rect.y1).abs() < 0.01
+                && (last.rect.x1 - d.rect.x0).abs() < 0.5
+        }) {
             last.rect.x1 = d.rect.x1;
             continue;
         }

crates/text/src/tests.rs

@@ -101,11 +101,55 @@ fn pairs_are_kerned_only_from_the_kern_size() {
     assert!((above - off).abs() < 0.01, "40 pt is below a 48 pt threshold");
 }
 
+/// Width of the first paragraph "AVATAR WAVE" (kerned from 12 pt) when a second paragraph's run
+/// has character spacing `spc`.
+fn kerned_width_beside_spacing(family: &str, spc: f64) -> f64 {
+    let (p, mut sh) = setup("AVATAR WAVE", 2000.0, 300.0);
+    let t = sh.text.as_mut().unwrap();
+    let mut second = t.paragraphs[0].clone();
+    second.runs[0].props.spacing = Some(spc);
+    t.paragraphs.push(second);
+    for para in &mut t.paragraphs {
+        para.props.bullet = Some(Bullet::None);
+        for r in &mut para.runs {
+            r.props.font = Some(family.into());
+            r.props.size = Some(40.0);
+            r.props.kern = Some(12.0);
+        }
+    }
+    let l = lay(&p, &sh, 2000.0, 300.0);
+    l.lines[0].extent.1 - l.lines[0].extent.0
+}
+
+#[test]
+fn character_spacing_in_the_body_keeps_kerning() {
+    let kerns = |f: &FontFace| {
+        let w = |feat: &[deckcraft_fonts::Feature]| deckcraft_fonts::shape(f, "AVATAR", feat, |c| c).iter().map(|g| g.x_advance).sum::<i32>();
+        w(&[]) != w(&deckcraft_fonts::feature("-kern").into_iter().collect::<Vec<_>>())
+    };
+    let Some(family) = first_family(LATIN_FAMILIES, kerns) else {
+        eprintln!("skipped: no font that kerns AVATAR");
+        return;
+    };
+    let (_, off) = glyphs_and_width(&family, "AVATAR WAVE", Some(0.0));
+    let (_, on) = glyphs_and_width(&family, "AVATAR WAVE", Some(12.0));
+    assert!(on < off);
+    // Spacing elsewhere in the box leaves the pairs kerned (Calibri, Segoe UI, Times New Roman in
+    // PowerPoint; only Arial drops them).
+    for spc in [0.0, 0.5, -1.0, 0.6, 2.0] {
+        let w = kerned_width_beside_spacing(&family, spc);
+        assert!((w - on).abs() < 0.01, "{family} spc {spc}: {w} vs {on}");
+    }
+}
+
 #[test]
 fn ligatures_stay_for_scripts_that_need_them() {
     let has = |f: &[deckcraft_fonts::Feature], tag: &str| f.iter().any(|x| Some(*x) == deckcraft_fonts::feature(tag));
-    let cells =
-        |s: &str| s.chars().map(|ch| Cell { ch, style: 0, face: 0, level: 0, glyphs: vec![], adv: 0.0, head: 0, boundary: true }).collect::<Vec<_>>();
+    let cells = |s: &str| {
+        s.chars()
+            .map(|ch| Cell { ch, style: 0, face: 0, level: 0, glyphs: vec![], adv: 0.0, head: 0, boundary: true, upright: false })
+            .collect::<Vec<_>>()
+    };
     let latin = shaping_features(&cells("office"), &[], Some(*b"Latn"));
     assert!(has(&latin, "-liga") && has(&latin, "-clig") && has(&latin, "-kern"));
     // Arabic needs its ligatures; emoji sequences are joined by them.
@@ -264,7 +308,11 @@ fn arabic_face() -> Option<Arc<FontFace>> {
 
 #[test]
 fn rtl_mixed_string_is_reordered_per_line() {
-    let (p, sh) = bidi_setup(vec![Run::new(MIXED)], 2000.0, true, Align::Right);
+    // An Arabic run (PowerPoint tags typed Arabic `ar-…`): its digits and brackets go with the
+    // right-to-left text.
+    let mut run = Run::new(MIXED);
+    run.props.lang = Some("ar-SA".into());
+    let (p, sh) = bidi_setup(vec![run], 2000.0, true, Align::Right);
     let l = lay(&p, &sh, 2000.0, 300.0);
     assert_eq!(l.lines.len(), 1);
     let line = &l.lines[0];
@@ -293,6 +341,20 @@ fn rtl_mixed_string_is_reordered_per_line() {
     assert_eq!(line.levels[10], 2);
 }
 
+#[test]
+fn an_english_run_keeps_digits_and_brackets_left_to_right() {
+    // The same text in a run without a right-to-left language: PowerPoint keeps "2024 (Retrait) "
+    // one left-to-right stretch, its number on the left.
+    let (p, sh) = bidi_setup(vec![Run::new(MIXED)], 2000.0, true, Align::Right);
+    let l = lay(&p, &sh, 2000.0, 300.0);
+    let line = &l.lines[0];
+    let mid = |k: usize| (line.edges[k].0 + line.edges[k].1) / 2.0;
+    assert!(mid(0) > mid(10), "first Arabic word right of the Latin");
+    assert!(mid(4) < mid(10), "number left of the Latin word");
+    assert!(mid(9) < mid(10) && mid(17) > mid(16), "brackets around Retrait, unmirrored");
+    assert!(mid(19) < mid(4), "last Arabic word on the left");
+}
+
 #[test]
 fn rtl_paragraph_starts_at_the_right_with_the_bullet_outside() {
     let (p, mut sh) = bidi_setup(vec![Run::new("مرحبا بكم")], 400.0, true, Align::Right);
@@ -781,3 +843,376 @@ fn symbol_font_characters_draw_in_the_sym_font() {
     // The letters around it keep the run's font.
     assert!(families.iter().all(|(f, c)| c.0 == 1 || !f.eq_ignore_ascii_case(symbol)), "{families:?}");
 }
+
+#[test]
+fn small_capitals_draw_smaller_than_the_capitals_beside_them() {
+    let (p, mut sh) = setup("HxHx", 2000.0, 300.0);
+    let para = &mut sh.text.as_mut().unwrap().paragraphs[0];
+    para.props.bullet = Some(Bullet::None);
+    para.runs[0].props.caps = Some(Caps::Small);
+    para.runs[0].props.size = Some(40.0);
+    let l = lay(&p, &sh, 2000.0, 300.0);
+    let sizes: Vec<(usize, f64)> = l.runs.iter().map(|r| (r.glyphs.len(), r.size)).collect();
+    // H at 40 pt, x as a capital at 80 % (four runs: the size changes at every letter).
+    assert_eq!(sizes, vec![(1, 40.0), (1, 32.0), (1, 40.0), (1, 32.0)]);
+}
+
+#[test]
+fn capitals_keep_characters_whose_capital_is_a_sequence() {
+    assert_eq!(caps_char('a'), 'A');
+    assert_eq!(caps_char('dž'), 'DŽ');
+    // PowerPoint draws "ß", "fi" and "ʼn" unchanged in all caps.
+    assert_eq!(caps_char('ß'), 'ß');
+    assert_eq!(caps_char('\u{FB01}'), '\u{FB01}');
+    assert_eq!(caps_char('ʼn'), 'ʼn');
+    let (p, mut sh) = setup("aß", 2000.0, 300.0);
+    let para = &mut sh.text.as_mut().unwrap().paragraphs[0];
+    para.runs[0].props.caps = Some(Caps::All);
+    let l = lay(&p, &sh, 2000.0, 300.0);
+    let r = l.runs.iter().find(|r| !r.cells.is_empty()).unwrap();
+    let face = &r.face;
+    if face.covers('ß') {
+        assert_eq!(r.glyphs[1].0, face.glyph_for('ß'), "ß is not drawn as S");
+    }
+}
+
+#[test]
+fn transparent_text_is_faded_once() {
+    let (p, mut sh) = setup("Faded", 2000.0, 300.0);
+    let run = &mut sh.text.as_mut().unwrap().paragraphs[0].runs[0];
+    run.props.fill = Some(deckcraft_model::Fill::solid(
+        deckcraft_model::ColorRef::rgb(deckcraft_color::Rgba::rgb(255, 0, 0)).with(deckcraft_color::ColorTransform::Alpha(40000)),
+    ));
+    let l = lay(&p, &sh, 2000.0, 300.0);
+    let r = l.runs.iter().find(|r| !r.cells.is_empty()).unwrap();
+    // 60 % transparency: 40 % opaque in all, not 40 % of 40 %.
+    let opacity = r.color.a as f64 / 255.0 * r.alpha;
+    assert!((opacity - 0.4).abs() < 0.01, "{opacity}");
+}
+
+/// One paragraph `text` with tab stops `tabs` (position, `algn`), no bullet or indent.
+fn tabbed(text: &str, tabs: &[(f64, &str)], w: f64) -> TextLayout {
+    let (p, mut sh) = setup(text, w, 300.0);
+    let para = &mut sh.text.as_mut().unwrap().paragraphs[0];
+    for r in &mut para.runs {
+        r.props.size = Some(18.0);
+    }
+    let pp = &mut para.props;
+    pp.bullet = Some(Bullet::None);
+    pp.margin_left = Some(0.0);
+    pp.indent = Some(0.0);
+    pp.default_tab = Some(72.0);
+    pp.tabs = Some(tabs.iter().map(|(pos, a)| deckcraft_model::text::TabStop { pos: *pos, align: a.to_string() }).collect());
+    lay(&p, &sh, w, 300.0)
+}
+
+#[test]
+fn tab_stops_align_the_text_after_them() {
+    let x0 = |l: &TextLayout| l.inner.x0;
+    // Right: the text ends at the stop. Centre: centred on it. Decimal: the "." at the stop.
+    let l = tabbed("a\tright", &[(200.0, "r")], 600.0);
+    assert!((l.lines[0].extent.1 - x0(&l) - 200.0).abs() < 0.01, "{:?}", l.lines[0].extent);
+    let l = tabbed("a\tmid", &[(200.0, "ctr")], 600.0);
+    let (s, e) = (l.lines[0].edges[2].0, l.lines[0].edges[4].1);
+    assert!(((s + e) / 2.0 - x0(&l) - 200.0).abs() < 0.01);
+    let l = tabbed("x\t1234.567", &[(150.0, "dec")], 600.0);
+    assert!((l.lines[0].edges[6].0 - x0(&l) - 150.0).abs() < 0.01, "the point sits at the stop");
+    // Text without a point ends at a decimal stop.
+    let l = tabbed("x\t12,5", &[(150.0, "dec")], 600.0);
+    assert!((l.lines[0].extent.1 - x0(&l) - 150.0).abs() < 0.01);
+    // Text wider than the room before a right stop starts where the tab is; it never moves back.
+    let l = tabbed("x\twider than the gap", &[(20.0, "r")], 600.0);
+    assert!((l.lines[0].edges[2].0 - l.lines[0].edges[0].1).abs() < 0.01);
+    // A left stop and then default stops every 72 pt.
+    let l = tabbed("a\tb\tc", &[(30.0, "l")], 600.0);
+    assert!((l.lines[0].edges[2].0 - x0(&l) - 30.0).abs() < 0.01);
+    assert!((l.lines[0].edges[4].0 - x0(&l) - 72.0).abs() < 0.01);
+}
+
+#[test]
+fn a_tab_past_the_end_moves_to_the_next_line() {
+    // PowerPoint: "abcdefghij\tk\tl\tm…" in a narrow box puts the tab that doesn't fit on the next
+    // line, so the text after it lands on that line's first stop.
+    let l = tabbed("abcdefghij\tk", &[], 130.0);
+    assert_eq!(l.lines.len(), 2);
+    assert_eq!(l.lines[1].start, 10, "the tab starts the second line: {:?}", l.lines.iter().map(|x| (x.start, x.end, x.extent)).collect::<Vec<_>>());
+    assert!((l.lines[1].edges[1].0 - l.inner.x0 - 72.0).abs() < 0.01);
+}
+
+/// Underline decorations of "ab cd" underlined `u` at 40 pt.
+fn underline_decos(u: &str) -> (TextLayout, Vec<Deco>) {
+    let (p, mut sh) = setup("ab cd", 2000.0, 300.0);
+    let para = &mut sh.text.as_mut().unwrap().paragraphs[0];
+    para.props.bullet = Some(Bullet::None);
+    para.runs[0].props.size = Some(40.0);
+    para.runs[0].props.underline = Some(u.into());
+    let l = lay(&p, &sh, 2000.0, 300.0);
+    let d = l.decos.iter().filter(|d| !d.behind).cloned().collect();
+    (l, d)
+}
+
+#[test]
+fn underlines_sit_at_the_font_underline_in_their_style() {
+    let (l, sng) = underline_decos("sng");
+    let r = l.runs.iter().find(|r| !r.cells.is_empty()).unwrap();
+    let k = 40.0 / r.face.upem;
+    let base = l.lines[0].baseline;
+    assert_eq!(sng.len(), 1);
+    assert!((sng[0].rect.y0 - base - r.face.underline.0 * k).abs() < 0.01, "top at the font's underline position");
+    assert!((sng[0].rect.height() - (r.face.underline.1 * k).max(0.5)).abs() < 0.01);
+    let t = sng[0].rect.height();
+    // Double: two thin lines spanning from one thickness above the single line to its bottom.
+    let (_, dbl) = underline_decos("dbl");
+    assert_eq!(dbl.len(), 2);
+    assert!((dbl[0].rect.y0 - (sng[0].rect.y0 - t)).abs() < 0.01 && (dbl[1].rect.y1 - sng[0].rect.y1).abs() < 0.01);
+    // Heavy is thicker; dotted is dots as long as the line is thick.
+    let (_, heavy) = underline_decos("heavy");
+    assert!(heavy[0].rect.height() > t * 1.4);
+    let (_, dotted) = underline_decos("dotted");
+    assert_eq!(dotted[0].line, DecoLine::Dashed(Dash::Dot));
+    let pieces = dotted[0].pieces();
+    assert!(pieces.len() > 3);
+    assert!((pieces[0].width() - t).abs() < 0.01 && (pieces[1].x0 - pieces[0].x1 - t).abs() < 0.01);
+    // Wavy: a zigzag between the box's top and bottom.
+    let (_, wavy) = underline_decos("wavy");
+    let (pts, w) = wavy[0].wave().expect("a wave");
+    assert!(pts.len() > 4 && w > 0.0 && w < t);
+    assert!(pts[0].y < pts[1].y);
+    // "words" underlines the spaces too, as PowerPoint draws it: one line.
+    let (_, words) = underline_decos("words");
+    assert_eq!(words.len(), 1);
+}
+
+#[test]
+fn no_break_after_a_zero_width_space_or_before_an_em_dash() {
+    let (allowed, _) = break_opportunities("ab\u{200B}cd", false);
+    assert!(!allowed[3], "PowerPoint does not break after a zero-width space");
+    let (allowed, _) = break_opportunities("ab\u{2014}cd", false);
+    assert!(!allowed[2] && allowed[3], "an em dash ends a line, never starts one");
+}
+
+#[test]
+fn a_line_broken_at_a_soft_hyphen_shows_a_hyphen() {
+    let (p, mut sh) = setup("Soft\u{AD}hyphenated\u{AD}words", 150.0, 300.0);
+    let para = &mut sh.text.as_mut().unwrap().paragraphs[0];
+    para.props.bullet = Some(Bullet::None);
+    para.runs[0].props.size = Some(24.0);
+    let l = lay(&p, &sh, 150.0, 300.0);
+    assert!(l.lines.len() >= 2);
+    let first = &l.lines[0];
+    let shy = first.end - 1;
+    assert_eq!(first.end, 5, "breaks after the soft hyphen: {:?}", l.lines.iter().map(|x| (x.start, x.end)).collect::<Vec<_>>());
+    let (x0, x1) = first.edges[shy - first.start];
+    assert!(x1 - x0 > 2.0, "the hyphen takes room");
+    let r = l.runs.iter().find(|r| r.cells.iter().any(|c| c.0 == shy)).expect("a glyph for the soft hyphen");
+    assert_eq!(r.glyphs[r.cells.iter().position(|c| c.0 == shy).unwrap()].0, r.face.glyph_for('-'));
+    // Soft hyphens draw only where a line ends; in a wide box, nowhere.
+    let ends: Vec<usize> = l.lines.iter().map(|x| x.end.saturating_sub(1)).collect();
+    for r in &l.runs {
+        for (g, c) in r.glyphs.iter().zip(&r.cells) {
+            assert!(c.1 != '\u{AD}' || ends.contains(&c.0) || g.0 != r.face.glyph_for('-'), "mid-line soft hyphen drawn");
+        }
+    }
+    let wide = lay(&p, &sh, 2000.0, 300.0);
+    assert_eq!(wide.lines.len(), 1);
+    assert!(wide.runs.iter().all(|r| r.cells.iter().all(|c| c.1 != '\u{AD}' || r.glyphs.iter().all(|g| g.0 != r.face.glyph_for('-')))));
+}
+
+#[test]
+fn small_kana_and_closing_brackets_follow_powerpoint_kinsoku() {
+    // "っ" and "ー" never start a line: the character before them moves down too.
+    let w = one_line("あいうえお") + 0.5;
+    for (text, first) in [("あいうえおっかき", "あいうえ"), ("あいうえおーかき", "あいうえ"), ("あいうえおかき", "あいうえお")]
+    {
+        let lines = wrapped(text, w, |p| p.hanging_punct = Some(true));
+        assert_eq!(lines[0], first, "{text}: {lines:?}");
+    }
+    // A closing bracket doesn't hang like "。" does: "「。」" overflowing by "」" moves down whole.
+    let w = one_line("あいうえ「。") + 0.5;
+    let lines = wrapped("あいうえ「。」かき", w, |p| p.hanging_punct = Some(true));
+    assert_eq!(lines[0], "あいうえ", "{lines:?}");
+}
+
+#[test]
+fn autonumber_schemes_follow_powerpoint() {
+    // As PowerPoint's export draws them (start values as in the probe deck).
+    for (scheme, n, want) in [
+        ("ea1ChsPlain", 4, "四"),
+        ("ea1ChsPeriod", 10, "十．"),
+        ("ea1ChtPeriod", 21, "二十一．"),
+        ("ea1JpnKorPeriod", 10, "一〇．"),
+        ("ea1JpnChsDbPeriod", 13, "一三．"),
+        ("arabicDbPlain", 10, "１０"),
+        ("arabicDbPeriod", 13, "１３．"),
+        ("circleNumDbPlain", 13, "⑬"),
+        ("circleNumWdWhitePlain", 13, "③"),
+        ("circleNumWdBlackPlain", 2, "❷"),
+        ("thaiAlphaPeriod", 1, "ก."),
+        ("thaiAlphaParenR", 4, "ง)"),
+        ("thaiAlphaParenBoth", 7, "(ช)"),
+        ("thaiNumPeriod", 10, "๑๐."),
+        ("hindiAlphaPeriod", 4, "ई."),
+        ("hindiAlpha1Period", 1, "क."),
+        ("hindiNumParenR", 13, "१३)"),
+        ("hebrew2Minus", 1, "א-"),
+        ("arabic1Minus", 13, "ش-"),
+        ("arabic2Minus", 10, "ي-"),
+        ("arabicPlain", 10, "10"),
+    ] {
+        assert_eq!(autonum(scheme, n), want, "{scheme} {n}");
+    }
+    assert_eq!(chinese_num(105), "一百零五");
+    assert_eq!(chinese_num(20), "二十");
+    // Past the end of an alphabet the letter doubles, like "aa".
+    assert_eq!(autonum("hebrew2Minus", 23), "אא-");
+    assert_eq!(autonum("thaiAlphaPeriod", 0), ".");
+}
+
+#[test]
+fn east_asian_vertical_text_marks_cjk_upright() {
+    let (p, mut sh) = setup("日本、ABC 12", 300.0, 600.0);
+    sh.text.as_mut().unwrap().body.vert = Some(deckcraft_model::text::TextDir::EaVertical);
+    let l = lay(&p, &sh, 300.0, 600.0);
+    assert_eq!(l.rotation, 90.0);
+    let upright: Vec<bool> = l
+        .runs
+        .iter()
+        .filter(|r| !r.cells.is_empty())
+        .flat_map(|r| r.cells.iter().map(move |c| (c.1, r.upright)))
+        .filter(|(c, _)| *c != ' ')
+        .map(|(_, u)| u)
+        .collect();
+    assert_eq!(upright, vec![true, true, true, false, false, false, false, false]);
+    // In vert nothing stands upright.
+    sh.text.as_mut().unwrap().body.vert = Some(deckcraft_model::text::TextDir::Vertical);
+    let l = lay(&p, &sh, 300.0, 600.0);
+    assert!(l.runs.iter().all(|r| !r.upright));
+    assert!(is_upright('あ') && is_upright('、') && is_upright('Ａ') && !is_upright('A') && !is_upright('1'));
+}
+
+#[test]
+fn mongolian_lines_run_left_to_right_and_stacked_letters_stand_one_em_apart() {
+    let (p, mut sh) = setup("one\ntwo", 200.0, 400.0);
+    sh.text.as_mut().unwrap().body.vert = Some(deckcraft_model::text::TextDir::Vertical);
+    let v = lay(&p, &sh, 200.0, 400.0);
+    sh.text.as_mut().unwrap().body.vert = Some(deckcraft_model::text::TextDir::MongolianVertical);
+    let m = lay(&p, &sh, 200.0, 400.0);
+    assert_eq!(m.rotation, 90.0);
+    // In layout space (turned a quarter turn) vert puts the first line at the top, which shows on
+    // the right; mongolianVert mirrors the line places, so the first line shows on the left.
+    assert!(v.lines[0].top < v.lines[1].top);
+    assert!(m.lines[0].top > m.lines[1].top);
+    let mid = (m.inner.y0 + m.inner.y1) / 2.0;
+    assert!(((m.lines[0].top + m.lines[0].bottom) / 2.0 - mid + ((v.lines[0].top + v.lines[0].bottom) / 2.0 - mid)).abs() < 0.01);
+    // Stacked: every letter upright, one em apart.
+    let (p, mut sh) = setup("Lil", 200.0, 400.0);
+    let t = sh.text.as_mut().unwrap();
+    t.body.vert = Some(deckcraft_model::text::TextDir::Stacked);
+    t.paragraphs[0].runs[0].props.size = Some(20.0);
+    let s = lay(&p, &sh, 200.0, 400.0);
+    assert!(s.runs.iter().filter(|r| !r.cells.is_empty()).all(|r| r.upright));
+    // Its lines run left to right too.
+    let (p2, mut sh2) = setup("one\ntwo", 200.0, 400.0);
+    sh2.text.as_mut().unwrap().body.vert = Some(deckcraft_model::text::TextDir::Stacked);
+    let st = lay(&p2, &sh2, 200.0, 400.0);
+    assert!(st.lines[0].top > st.lines[1].top);
+    // wordArtVertRtl stacks the same way with lines from right to left.
+    sh2.text.as_mut().unwrap().body.vert = Some(deckcraft_model::text::TextDir::StackedRtl);
+    let sr = lay(&p2, &sh2, 200.0, 400.0);
+    assert!(sr.lines[0].top < sr.lines[1].top);
+    assert!(sr.runs.iter().filter(|r| !r.cells.is_empty()).all(|r| r.upright));
+    let e = &s.lines[0].edges;
+    assert!((e[1].1 - e[1].0 - 20.0).abs() < 0.01 && (e[2].1 - e[2].0 - 20.0).abs() < 0.01, "{e:?}");
+}
+
+#[test]
+fn symbols_after_an_emoji_keep_a_text_face() {
+    // "✅ ⚠ ™": PowerPoint draws ✅ (emoji presentation) in colour and the symbols after it as text.
+    let db = FontDb::global();
+    if !db.cascade(&['✅'], &[], "Regular").is_color() {
+        return;
+    }
+    let (p, sh) = bidi_setup(vec![Run::new("✅ ⚠ ™")], 2000.0, false, Align::Left);
+    let l = lay(&p, &sh, 2000.0, 300.0);
+    for r in &l.runs {
+        for (_, c) in &r.cells {
+            assert_eq!(r.face.is_color(), *c == '✅', "{c:?} drawn with {}", r.face.family);
+        }
+    }
+}
+
+#[test]
+fn fallback_faces_do_not_move_the_baseline() {
+    // PowerPoint keeps a line's baseline and pitch from the run's own font when an emoji, a symbol
+    // or a script the font lacks is drawn from another face.
+    let base = |text: &str| {
+        let (p, sh) = bidi_setup(vec![Run::new(text)], 2000.0, false, Align::Left);
+        let l = lay(&p, &sh, 2000.0, 300.0);
+        (l.lines[0].baseline, l.lines[0].bottom)
+    };
+    let plain = base("Hxg Hxg");
+    for text in ["Hxg \u{1F600} Hxg", "Hxg \u{0E2A}\u{0E27}\u{0E31}\u{0E2A}", "Hxg \u{222B}\u{2211}"] {
+        let b = base(text);
+        assert!((b.0 - plain.0).abs() < 0.01 && (b.1 - plain.1).abs() < 0.01, "{text:?}: {b:?} vs {plain:?}");
+    }
+}
+
+#[test]
+fn strikethrough_sits_at_the_font_strikeout_position() {
+    let (p, mut sh) = setup("Struck", 2000.0, 300.0);
+    let para = &mut sh.text.as_mut().unwrap().paragraphs[0];
+    para.props.bullet = Some(Bullet::None);
+    para.runs[0].props.size = Some(96.0);
+    para.runs[0].props.strike = Some(Strike::Single);
+    let l = lay(&p, &sh, 2000.0, 300.0);
+    let r = l.runs.iter().find(|r| !r.cells.is_empty()).unwrap();
+    let k = 96.0 / r.face.upem;
+    let d = l.decos.iter().find(|d| !d.behind).expect("a strikethrough");
+    assert!((l.lines[0].baseline - d.rect.y0 - r.face.strikeout.0 * k).abs() < 0.01, "top at the strikeout position");
+    assert!((d.rect.height() - (r.face.strikeout.1 * k).max(0.5)).abs() < 0.01);
+}
+
+#[test]
+fn rtl_columns_start_on_the_right_and_just_anchoring_sits_at_the_bottom() {
+    let text = "word ".repeat(200);
+    let (p, mut sh) = setup(&text, 400.0, 200.0);
+    let t = sh.text.as_mut().unwrap();
+    t.body.columns = Some(2);
+    t.body.col_spacing = Some(20.0);
+    t.paragraphs[0].runs[0].props.size = Some(12.0);
+    let ltr = lay(&p, &sh, 400.0, 200.0);
+    sh.text.as_mut().unwrap().body.rtl_col = Some(true);
+    let rtl = lay(&p, &sh, 400.0, 200.0);
+    let first = |l: &TextLayout| l.lines.iter().find(|x| x.column == 0).map(|x| x.extent.0).unwrap();
+    let second = |l: &TextLayout| l.lines.iter().find(|x| x.column == 1).map(|x| x.extent.0).unwrap();
+    assert!(first(&ltr) < second(&ltr));
+    assert!(first(&rtl) > second(&rtl), "with rtlCol the first column is on the right");
+    // anchor="just" and "dist" draw like "b".
+    let (p, mut sh) = setup("one line", 400.0, 300.0);
+    sh.text.as_mut().unwrap().body.anchor = Some(Anchor::Bottom);
+    let b = lay(&p, &sh, 400.0, 300.0).lines[0].top;
+    for a in [Anchor::Justified, Anchor::Distributed] {
+        sh.text.as_mut().unwrap().body.anchor = Some(a);
+        assert!((lay(&p, &sh, 400.0, 300.0).lines[0].top - b).abs() < 0.01, "{a:?}");
+    }
+}
+
+#[test]
+fn stacked_combining_marks_take_a_face_that_draws_them() {
+    // A letter with marks the run's font lacks draws in a face that has them all (no boxes).
+    let db = FontDb::global();
+    let cluster = ['Z', '\u{0334}', '\u{0321}', '\u{031B}'];
+    let run_face = db.face("Inter", "Regular");
+    let f = db.cascade(&cluster, std::slice::from_ref(&run_face), "Regular");
+    if !deckcraft_fonts::covers_cluster(&run_face, &cluster) && ["DejaVu Sans", "Segoe UI"].iter().any(|fam| db.has_family(fam)) {
+        // Make sure a face with the marks is loaded, then the cluster must take one.
+        for fam in ["DejaVu Sans", "Segoe UI"] {
+            if db.has_family(fam) {
+                let _ = db.face(fam, "Regular");
+            }
+        }
+        let f = db.cascade(&cluster, std::slice::from_ref(&run_face), "Regular");
+        assert!(deckcraft_fonts::covers_cluster(&f, &cluster), "{} lacks the marks", f.family);
+    }
+    let _ = f;
+}

crates/ui-egui/src/ribbon.rs

@@ -1382,7 +1382,7 @@ fn transitions(app: &mut SlideApp, ui: &mut Ui) {
         let r = big_button(ui, Icon::EffectOptions, "Effect\nOptions", !opts.is_empty());
         egui::Popup::menu(&r).show(|ui| {
             for o in opts {
-                if ui.button(option_label(o)).clicked() {
+                if ui.button(deckcraft_model::anim::transition_option_label(&kind, o)).clicked() {
                     run(app, "transition.options", json!({"option": o}));
                 }
             }

crates/ui-egui/src/show.rs

@@ -61,6 +61,10 @@ struct Transition {
     /// The slide left behind (Morph matches its shapes) and the Morph frame texture.
     from: Option<usize>,
     morph: Option<TextureHandle>,
+    /// Backgrounds and contents of the old and new slides, rendered once when the transition
+    /// moves contents over backgrounds (Pan, Ferris Wheel, Reveal…): old back, old content, new
+    /// back, new content.
+    parts: Option<[Option<TextureHandle>; 4]>,
     start: f64,
     kind: String,
     option: String,
@@ -138,7 +142,7 @@ impl Show {
                     self.last_viewed = from;
                 }
                 self.trans = if kind != "none" && dur > 0.0 && !doc.show.without_animation {
-                    Some(Transition { old, from, morph: None, start: now, kind, option, dur })
+                    Some(Transition { old, from, morph: None, parts: None, start: now, kind, option, dur })
                 } else {
                     None
                 };
@@ -202,24 +206,43 @@ fn fit(avail: Rect, doc: &Presentation) -> Rect {
     Rect::from_center_size(avail.center(), vec2(sw * s, sh * s))
 }
 
+/// A transition layer as an egui mesh: [`deckcraft_anim::layer_mesh`]'s triangles (perspective
+/// cards subdivided so their pictures stay straight) with per-vertex opacity.
 fn quad_mesh(tex: Option<egui::TextureId>, rect: Rect, l: &Layer, color: Color32) -> Mesh {
     let mut m = match tex {
         Some(id) => Mesh::with_texture(id),
         None => Mesh::default(),
     };
-    let a = (l.alpha.clamp(0.0, 1.0) * 255.0) as u8;
-    let col = if tex.is_some() { Color32::from_white_alpha(a) } else { color.gamma_multiply(l.alpha.clamp(0.0, 1.0) as f32) };
-    for k in 0..4 {
-        let q = l.quad.get(k).copied().unwrap_or([0.0, 0.0]);
-        let uv = l.uv.get(k).copied().unwrap_or([0.0, 0.0]);
-        let p = pos2(rect.min.x + q[0] as f32 * rect.width(), rect.min.y + q[1] as f32 * rect.height());
-        m.vertices.push(egui::epaint::Vertex { pos: p, uv: pos2(uv[0] as f32, uv[1] as f32), color: col });
+    let (verts, tris) = deckcraft_anim::layer_mesh(l);
+    for v in &verts {
+        let a = if v.a.is_finite() { v.a.clamp(0.0, 1.0) } else { 0.0 };
+        let col = if tex.is_some() { Color32::from_white_alpha((a * 255.0).round() as u8) } else { color.gamma_multiply(a as f32) };
+        let p = pos2(rect.min.x + v.pos[0] as f32 * rect.width(), rect.min.y + v.pos[1] as f32 * rect.height());
+        m.vertices.push(egui::epaint::Vertex { pos: p, uv: pos2(v.uv[0] as f32, v.uv[1] as f32), color: col });
+    }
+    for t in tris {
+        m.add_triangle(t[0], t[1], t[2]);
     }
-    m.add_triangle(0, 1, 2);
-    m.add_triangle(0, 2, 3);
     m
 }
 
+/// Render the backgrounds and contents of a transition's two slides into textures, once.
+fn part_textures(ctx: &egui::Context, doc: &Presentation, from: Option<usize>, to: usize, size: (u32, u32)) -> [Option<TextureHandle>; 4] {
+    use deckcraft_render::SlidePart;
+    let threads = if cfg!(target_arch = "wasm32") { 0 } else { std::thread::available_parallelism().map(|n| n.get().min(8) as u16).unwrap_or(0) };
+    let opts = RenderOpts { scale: size.0 as f64 / doc.slide_size.width.max(1.0), size: Some(size), threads, ..Default::default() };
+    let tex = |i: usize, part: SlidePart, name: &str| {
+        let img = deckcraft_render::render_slide_part(doc, i, part, &opts);
+        ctx.load_texture(name, crate::textures::to_color_image(&img, false), egui::TextureOptions::LINEAR)
+    };
+    [
+        from.map(|i| tex(i, SlidePart::Backdrop, "trans-old-back")),
+        from.map(|i| tex(i, SlidePart::Content, "trans-old-content")),
+        Some(tex(to, SlidePart::Backdrop, "trans-new-back")),
+        Some(tex(to, SlidePart::Content, "trans-new-content")),
+    ]
+}
+
 pub fn ui(app: &mut SlideApp, ui: &mut Ui) {
     let ctx = ui.ctx().clone();
     let Some(doc) = app.session.active().map(|d| d.doc.clone()) else {
@@ -470,18 +493,37 @@ pub fn ui(app: &mut SlideApp, ui: &mut Ui) {
             tr.morph = Some(frame);
             drew = true;
             ctx.request_repaint();
-        } else if let (Some(tr), Some(new)) = (&show.trans, &tex) {
+        } else if let (Some(tr), Some(new)) = (show.trans.as_mut(), &tex) {
             let p = ((now - tr.start) / tr.dur.max(0.01)).clamp(0.0, 1.0);
             if p < 1.0 {
-                for l in deckcraft_anim::transition_layers(&tr.kind, &tr.option, p) {
+                // Slides split into background and content are rendered once per transition;
+                // every frame only composites cached textures.
+                if tr.parts.is_none() && deckcraft_anim::uses_slide_parts(&tr.kind, &tr.option) {
+                    tr.parts = Some(part_textures(&ctx, &doc, tr.from, idx, size));
+                }
+                let aspect = doc.slide_size.width / doc.slide_size.height.max(1.0);
+                let part = |k: usize| tr.parts.as_ref().and_then(|p| p.get(k).cloned().flatten());
+                let parts = [part(0), part(1), part(2), part(3)];
+                for l in deckcraft_anim::transition_frame(&tr.kind, &tr.option, p, aspect) {
+                    let old_or_black = |t: Option<&TextureHandle>| match t {
+                        Some(o) => quad_mesh(Some(o.id()), srect, &l, Color32::WHITE),
+                        None => quad_mesh(None, srect, &l, Color32::BLACK),
+                    };
                     let mesh = match l.source {
-                        Source::Old => match &tr.old {
-                            Some(o) => quad_mesh(Some(o.id()), srect, &l, Color32::WHITE),
-                            None => quad_mesh(None, srect, &l, Color32::BLACK),
-                        },
+                        Source::Old => old_or_black(tr.old.as_ref()),
                         Source::New => quad_mesh(Some(new.id()), srect, &l, Color32::WHITE),
                         Source::Black => quad_mesh(None, srect, &l, Color32::BLACK),
                         Source::White => quad_mesh(None, srect, &l, Color32::WHITE),
+                        Source::OldBack => old_or_black(parts[0].as_ref().or(tr.old.as_ref())),
+                        Source::NewBack => quad_mesh(Some(parts[2].as_ref().unwrap_or(new).id()), srect, &l, Color32::WHITE),
+                        Source::OldContent => match &parts[1] {
+                            Some(t) => quad_mesh(Some(t.id()), srect, &l, Color32::WHITE),
+                            None => continue,
+                        },
+                        Source::NewContent => match &parts[3] {
+                            Some(t) => quad_mesh(Some(t.id()), srect, &l, Color32::WHITE),
+                            None => continue,
+                        },
                     };
                     painter.add(egui::Shape::mesh(mesh));
                 }

docs/animation-parity.md

@@ -1,6 +1,6 @@
 # Transitions and animations: parity with PowerPoint
 
-> **Last reviewed:** 2026-10-10 · **Last updated:** 2026-10-10 · **Change:** major (created; effect lists counted from `crates/model/src/anim.rs` against PowerPoint 16.113's galleries) · **Target:** Microsoft PowerPoint for Mac 16.113 (Microsoft 365)
+> **Last reviewed:** 2026-10-13 · **Last updated:** 2026-10-13 · **Change:** major (transitions measured frame by frame against PowerPoint for Windows' video export and retuned; previous: created) · **Target:** Microsoft PowerPoint for Mac 16.113 (Microsoft 365)
 
 Transitions and animations are what make a deck a presentation, and the part of PowerPoint people
 notice first when it's missing. Scores roll up into [target-app-parity.md](target-app-parity.md)
@@ -9,14 +9,31 @@ notice first when it's missing. Scores roll up into [target-app-parity.md](targe
 ## Transitions: 48 of 48
 
 `crates/model/src/anim.rs` `TRANSITIONS` lists every transition in PowerPoint's gallery, in its
-three groups, with its Effect Options. All 48 round-trip through PPTX
-(`every_transition_kind_round_trips`), including the PowerPoint 2010+ `p14`/`p15` ones.
+three groups, with its Effect Options (now also Page Curl Single, Glitter Hexagons, Shred In/Out
+and Zoom and Rotate). All 48 round-trip through PPTX with the elements, attributes and defaults
+PowerPoint itself writes (`every_transition_kind_round_trips`,
+`transition_xml_matches_powerpoints_elements`, `transition_defaults_read_like_powerpoint`): 145 of
+145 PowerPoint-built test slides reopen in PowerPoint with the same effect after a DeckCraft
+save.
+
+**Measured against PowerPoint (2026-10-13).** Synthetic two-colour decks with asymmetric markers
+were built in PowerPoint for Windows over COM with every transition and option (150 variants,
+2 s each), exported with `CreateVideo` at 30 fps, and compared frame by frame with
+`deckcraft-cli render-transition` at the same progress (`plan/powerpoint/tools/synth_transitions.ps1`,
+`trans_compare.py`). Mean absolute difference over all variants at t = 0.1…0.9 (0–255): **35.7
+before, 15.0 after**. Curves (fades are a smoothstep, moves ease in-out; Cover, Uncover and Pan
+have their own measured curves), directions and option meanings (e.g. Glitter starts on the
+option's side, Ripple's corner is where the wave heads, Wind/Airplane/Origami "Left" is `invX`),
+soft edges (Wipe, Split, Shape, Clock, Ripple) and the Dynamic Content transitions moving the
+slides' contents over cross-fading backgrounds now follow PowerPoint. 3-D transitions are
+perspective-projected cards (`crates/anim/src/transition_geom.rs`) drawn with
+perspective-correct subdivided meshes.
 
 | Group | PowerPoint | DeckCraft | Fidelity |
 |---|---|---|---|
-| Subtle (Morph, Fade, Push, Wipe, Split, Reveal, Cut, Random Bars, Shape, Uncover, Cover, Flash) | 12 | 12 | 2-D, close to PowerPoint |
-| Exciting (Fall Over, Drape, Curtains, Wind, Prestige, Fracture, Crush, Peel Off, Page Curl, Airplane, Origami, Dissolve, Checkerboard, Blinds, Clock, Ripple, Honeycomb, Glitter, Vortex, Shred, Switch, Flip, Gallery, Cube, Doors, Box, Comb, Zoom, Random) | 29 | 29 | 3-D ones are fake 3-D (trapezoid quads, `crates/anim/src/transition.rs`); particle effects (Vortex, Shred, Fracture, Crush) approximate |
-| Dynamic Content (Pan, Ferris Wheel, Conveyor, Rotate, Window, Orbit, Fly Through) | 7 | 7 | Same approach |
+| Subtle (Morph, Fade, Push, Wipe, Split, Reveal, Cut, Random Bars, Shape, Uncover, Cover, Flash) | 12 | 12 | Matches PowerPoint's frames (mean diff 1–8; Random Bars and Reveal Through Black ~15) |
+| Exciting (Fall Over, Drape, Curtains, Wind, Prestige, Fracture, Crush, Peel Off, Page Curl, Airplane, Origami, Dissolve, Checkerboard, Blinds, Clock, Ripple, Honeycomb, Glitter, Vortex, Shred, Switch, Flip, Gallery, Cube, Doors, Box, Comb, Zoom, Random) | 29 | 29 | Perspective 3-D cards with measured motion; cloth, paper and particle effects (Curtains, Peel Off, Page Curl, Airplane, Origami, Fracture, Crush, Honeycomb, Vortex, Shred) are flat approximations of PowerPoint's meshes |
+| Dynamic Content (Pan, Ferris Wheel, Conveyor, Rotate, Window, Orbit, Fly Through) | 7 | 7 | Contents move over cross-fading backgrounds, as in PowerPoint (mean diff 5–17) |
 
 | Transition feature | PowerPoint | DeckCraft |
 |---|---|---|
@@ -28,7 +45,7 @@ three groups, with its Effect Options. All 48 round-trip through PPTX
 | Morph: Words and Characters | yes | yes (#5) |
 | Morph: geometry (circle to star) | yes | yes (#27) |
 | Morph: `!!` name forcing, pictures, 3-D models, ink | yes | names partly; no 3-D or ink |
-| Frame-by-frame comparison with PowerPoint | | **not done** |
+| Frame-by-frame comparison with PowerPoint | | done (Windows, 2026-10-13); headless frames: `deckcraft-cli render-transition` |
 
 ## Animations: 64 of ~190 effects
 
@@ -69,11 +86,12 @@ In, Wipe, Zoom, Float In, Grow/Shrink, Pulse, Spin, motion lines): weighted, ~85
 | Rewind and other effect options on round trip (#77) | 1–2 |
 | Transition sounds | 1–2 |
 | Morph across pictures, `!!` names, align once per transition (#67) | 2–4 |
-| Reference captures from PowerPoint for the 3-D transitions, then tuning | 2–4 |
-| **Total** | **~14–26** (the Transitions and Animations rows of the feature table; part of the Features dimension's 140–240 h) |
+| Cloth, paper and particle transitions as real meshes (Curtains, Peel Off, Page Curl, Airplane, Origami, Vortex, Shred, Honeycomb) | 4–8 |
+| **Total** | **~16–30** (the Transitions and Animations rows of the feature table; part of the Features dimension's 140–240 h) |
 
 ## Revision history
 
 | Date | Change | Summary |
 |---|---|---|
+| 2026-10-13 | major | Transitions measured frame by frame against PowerPoint's video export and retuned (mean diff 35.7 → 15.0); PowerPoint's XML defaults and option meanings; new options |
 | 2026-10-10 | major | Created: 48/48 transitions, 64 of ~190 animation effects, pane and option depth, estimates |

docs/architecture.md

@@ -1,6 +1,6 @@
 # DeckCraft architecture
 
-> **Last reviewed:** 2026-10-10 · **Last updated:** 2026-10-10 · **Change:** major (created from the code on main at d556ff9; AGENTS.md §4 keeps the rules) · **Target:** Microsoft PowerPoint for Mac 16.113 (Microsoft 365)
+> **Last reviewed:** 2026-10-13 · **Last updated:** 2026-10-13 · **Change:** minor (transition frames: perspective meshes, slide parts, headless compositor; previous: created from the code on main at d556ff9) · **Target:** Microsoft PowerPoint for Mac 16.113 (Microsoft 365)
 
 How DeckCraft is built today. The binding rules (layering, everything is a command, thin UI, never
 break wasm, never crash) are in [AGENTS.md](../AGENTS.md) §3–§5; this document describes what
@@ -49,8 +49,12 @@ Programmatic calls never open dialogs. Pointer gestures go through `Session::poi
 ## Rendering and the show
 
 The renderer draws a slide to an RGBA pixmap on the CPU; the UI uploads it as an egui texture.
-Transitions are layers of textured quads over the old and new slide images (fake 3-D from
-trapezoids). The show window and the presenter view are egui viewports; animation state per shape
+Transitions are layers of textured quads over the old and new slide images, or over their
+backgrounds and contents rendered apart (Dynamic Content), from `anim::transition_frame`: 3-D
+effects project cards through a perspective camera and `anim::layer_mesh` subdivides them so
+textures stay straight; soft edges are per-corner opacities. The show renders the slides once per
+transition and only composites cached textures each frame; `render::composite_transition` is the
+CPU twin used by `deckcraft-cli render-transition` and the tests. The show window and the presenter view are egui viewports; animation state per shape
 comes from `anim::timeline` each frame. PDF export renders each slide at print resolution and
 overlays an invisible real-text layer with embedded font subsets.
 
@@ -74,4 +78,5 @@ macOS, Windows, Linux, FreeBSD and web artifacts.
 
 | Date | Change | Summary |
 |---|---|---|
+| 2026-10-13 | minor | Transitions: perspective meshes, background/content parts, CPU compositor |
 | 2026-10-10 | major | Created from the code on main (d556ff9) and AGENTS.md §4 |