Design: Variants gallery with four colour variations of the theme

PowerPoint's Design tab shows the current theme in four variants. The
Variants group had only the Colors and Fonts menus. theme_variants builds
four colour schemes from the theme's built-in colours (as designed, two
accent rotations, and a dark variant with light and dark swapped), so
switching between variants doesn't drift. design.variant applies one to
the master; design.variants reports them and which is applied. The
Design tab shows them as a gallery before Colors and Fonts.

Co-authored-by: Cursor <cursoragent@cursor.com>

crates/engine/src/cmd/design.rs

@@ -17,6 +17,8 @@ pub fn specs() -> Vec<CommandSpec> {
         cmd!("design.theme", "Themes", ["Design", "Themes"], None, "{name} (see design.themes)", has_doc, theme),
         cmd!(query "design.themes", "Theme Gallery", [], None, "{} → themes, colour schemes and font schemes", always, themes),
         cmd!("design.colors", "Colors", ["Design", "Variants"], None, "{name} | {colors: {accent1: #RRGGBB, …}}", has_doc, colors),
+        cmd!("design.variant", "Variants", ["Design", "Variants"], None, "{index: 0..3} (see design.variants)", has_doc, variant),
+        cmd!(query "design.variants", "Variant Gallery", [], None, "{} → the current theme's four colour variants and which is applied", has_doc, variants),
         cmd!("design.fonts", "Fonts", ["Design", "Variants"], None, "{name} | {major, minor}", has_doc, fonts),
         cmd!(
             "design.background",
@@ -125,6 +127,32 @@ fn colors(s: &mut Session, p: &Value) -> Result<Value> {
     ok()
 }
 
+fn variant(s: &mut Session, p: &Value) -> Result<Value> {
+    let index = p.get("index").and_then(Value::as_u64).ok_or_else(|| bad("design.variant", "missing `index` (0..3)"))? as usize;
+    s.edit(|doc, sel| {
+        let mi = master_index(doc, sel);
+        let m = Arc::make_mut(doc.masters.get_mut(mi).ok_or_else(|| bad("design.variant", "no master"))?);
+        let v = deckcraft_model::theme::theme_variants(&m.theme);
+        m.theme.colors =
+            v.get(index).cloned().ok_or_else(|| bad("design.variant", format!("no variant {index}; 0..{}", v.len().saturating_sub(1))))?;
+        Ok(())
+    })?;
+    Ok(json!({"variant": index}))
+}
+
+fn variants(s: &mut Session, _p: &Value) -> Result<Value> {
+    let st = s.doc()?;
+    let mi = master_index(&st.doc, &st.selection);
+    let th = st.doc.masters.get(mi).map(|m| m.theme.clone()).unwrap_or_default();
+    let v = deckcraft_model::theme::theme_variants(&th);
+    let current = v.iter().position(|c| c.colors == th.colors.colors);
+    Ok(json!({
+        "theme": th.name,
+        "current": current,
+        "variants": v.iter().map(|c| json!({"name": c.name, "colors": c.colors.iter().map(|x| format!("#{}", x.hex())).collect::<Vec<_>>()})).collect::<Vec<_>>(),
+    }))
+}
+
 fn fonts(s: &mut Session, p: &Value) -> Result<Value> {
     let scheme = if let Some(name) = str_param(p, "name") {
         builtin_font_schemes()

crates/engine/src/tests.rs

@@ -835,3 +835,31 @@ fn slide_ranges_parse_like_powerpoints_print_box() {
     let opts = cmd::file::pdf_options(&json!({"slides": [0, 7, 1]}), 2).unwrap();
     assert_eq!(opts.slides, Some(vec![0, 1]), "indices past the end are dropped");
 }
+
+#[test]
+fn theme_variants_apply_and_report_the_current_one() {
+    let mut s = session();
+    let name = deckcraft_model::theme::builtin_themes()[1].name.clone();
+    s.execute("design.theme", &json!({"name": name})).unwrap();
+    let v = s.execute("design.variants", &json!({})).unwrap();
+    assert_eq!(v["variants"].as_array().unwrap().len(), 4);
+    assert_eq!(v["current"], json!(0));
+    let base = s.doc().unwrap().doc.masters[0].theme.colors.clone();
+    s.execute("design.variant", &json!({"index": 1})).unwrap();
+    let c = s.doc().unwrap().doc.masters[0].theme.colors.clone();
+    assert_eq!(c.colors[4], base.colors[5], "accents rotate");
+    assert_eq!(c.colors[0], base.colors[0]);
+    assert_eq!(s.execute("design.variants", &json!({})).unwrap()["current"], json!(1));
+    // From a variant, another variant is built from the theme's own colours, not the variant's.
+    s.execute("design.variant", &json!({"index": 3})).unwrap();
+    let d = s.doc().unwrap().doc.masters[0].theme.colors.clone();
+    assert_eq!((d.colors[0], d.colors[1], d.colors[4]), (base.colors[1], base.colors[0], base.colors[4]));
+    s.execute("design.variant", &json!({"index": 0})).unwrap();
+    assert_eq!(s.doc().unwrap().doc.masters[0].theme.colors.colors, base.colors);
+    assert!(s.execute("design.variant", &json!({"index": 9})).is_err());
+    // It survives PPTX.
+    s.execute("design.variant", &json!({"index": 2})).unwrap();
+    let p = s.doc().unwrap().doc.as_ref().clone();
+    let back = deckcraft_pptx::import(&deckcraft_pptx::export(&p).unwrap()).unwrap();
+    assert_eq!(back.masters[0].theme.colors.colors, p.masters[0].theme.colors.colors);
+}

crates/model/src/theme.rs

@@ -150,6 +150,31 @@ pub fn default_format() -> FormatScheme {
 }
 
 /// Our original built-in themes (shown in Design ▸ Themes). Colours and names are our own.
+/// Design ▸ Variants: four colour variations of `t`, built from its built-in colours when it is
+/// a built-in theme (so picking one variant after another doesn't drift), else from its own.
+/// 1: as designed; 2 and 3: the accents rotated; 4: dark (light and dark colours swapped).
+pub fn theme_variants(t: &Theme) -> Vec<ColorScheme> {
+    let base = builtin_themes().into_iter().find(|b| b.name == t.name).map_or_else(|| t.colors.clone(), |b| b.colors);
+    let rotate = |by: usize| {
+        let mut c = base.clone();
+        let accents: Vec<_> = base.colors.get(4..10).map(<[_]>::to_vec).unwrap_or_default();
+        for (i, slot) in c.colors.iter_mut().skip(4).take(6).enumerate() {
+            if let Some(a) = accents.get((i + by) % accents.len().max(1)) {
+                *slot = *a;
+            }
+        }
+        c
+    };
+    let mut dark = base.clone();
+    dark.colors.swap(0, 1);
+    dark.colors.swap(2, 3);
+    let mut out = vec![base.clone(), rotate(1), rotate(3), dark];
+    for (i, c) in out.iter_mut().enumerate().skip(1) {
+        c.name = format!("{} {}", base.name, i + 1);
+    }
+    out
+}
+
 pub fn builtin_themes() -> Vec<Theme> {
     let t = |name: &str, colors: ColorScheme, major: &str, minor: &str| Theme {
         name: name.into(),

crates/ui-egui/src/ribbon.rs

@@ -1233,6 +1233,29 @@ fn design(app: &mut SlideApp, ui: &mut Ui) {
             run(app, "design.theme", json!({"name": n}));
         }
     });
+    // Variants: the current theme in its four colour variations.
+    if let Some(th) = app.session.active().and_then(|d| d.doc.masters.first().map(|m| m.theme.clone())) {
+        let variants = deckcraft_model::theme::theme_variants(&th);
+        let tiles: Vec<deckcraft_model::Theme> = variants.iter().map(|c| deckcraft_model::Theme { colors: c.clone(), ..th.clone() }).collect();
+        let names: Vec<String> = variants.iter().map(|c| c.name.clone()).collect();
+        let sel = variants.iter().position(|c| c.colors == th.colors.colors);
+        group(ui, |ui| {
+            if let Some(i) = widgets::gallery(
+                ui,
+                tiles.len(),
+                vec2(84.0, 56.0),
+                sel,
+                |p, r, i| {
+                    if let Some(t) = tiles.get(i) {
+                        paint_theme_tile(p, r, t);
+                    }
+                },
+                |i| names.get(i).cloned().unwrap_or_default(),
+            ) {
+                run(app, "design.variant", json!({"index": i}));
+            }
+        });
+    }
     group(ui, |ui| {
         let r = big_button(ui, Icon::Colors, "Colors", true);
         egui::Popup::menu(&r).width(240.0).show(|ui| {

docs/parity-checklist.md

@@ -3,12 +3,12 @@
 > **Generated:** 2026-10-10 (summary by `cargo xtask parity`; rows re-scored 2026-10-10 against PowerPoint for Mac 16.113.4) · **Target:** Microsoft PowerPoint for Mac 16.113 (Microsoft 365)
 
 The summary between `<!-- SUMMARY -->
-**Weighted breadth parity: 79%** over 191 features.
+**Weighted breadth parity: 80%** over 191 features.
 
 | Priority | Features | Done | Partial | Missing | Parity |
 |---|---|---|---|---|---|
 | P0 | 72 | 61 | 11 | 0 | 92% |
-| P1 | 65 | 38 | 21 | 6 | 75% |
+| P1 | 65 | 39 | 20 | 6 | 75% |
 | P2 | 54 | 13 | 15 | 26 | 38% |
 
 | Area | Parity |
@@ -17,7 +17,7 @@ The summary between `<!-- SUMMARY -->
 | Files | 71% |
 | Slides | 90% |
 | Views | 90% |
-| Masters & themes | 85% |
+| Masters & themes | 88% |
 | Shapes | 88% |
 | Format | 83% |
 | Arrange | 100% |
@@ -94,7 +94,7 @@ Open P0 items: Contextual tabs (Shape Format, Picture Format, Table Design/Layou
 | Masters & themes | Insert/rename/delete layouts, insert placeholders | P1 | D |
 | Masters & themes | Handout and Notes masters | P2 | M |
 | Masters & themes | Built-in themes (original designs) | P0 | D |
-| Masters & themes | Theme variants | P1 | P |
+| Masters & themes | Theme variants | P1 | D |
 | Masters & themes | Colour schemes (built-in and custom) | P0 | D |
 | Masters & themes | Font schemes (built-in and custom) | P0 | D |
 | Masters & themes | Effect schemes / background styles | P2 | P |