Merge PR #505 from NikitkaRa: Transitions: choose a transition sound and play it in the show

# Conflicts:
#	crates/pptx/tests/roundtrip.rs

crates/engine/src/cmd/transition.rs

@@ -30,6 +30,15 @@ pub fn specs() -> Vec<CommandSpec> {
             has_slide,
             timing
         ),
+        cmd!(
+            "transition.sound",
+            "Sound",
+            ["Transitions", "Timing"],
+            None,
+            "{path? | data: base64, name?; none?: true (No Sound); index?} — the sound plays as the slide comes in",
+            has_slide,
+            sound
+        ),
         cmd!("transition.applyAll", "Apply To All", ["Transitions", "Timing"], None, "{}", has_slide, apply_all),
         cmd!(query "transition.list", "Transition Gallery", [], None, "{} → [{id, label, category, duration, options}]", always, list),
     ]
@@ -108,6 +117,42 @@ fn timing(s: &mut Session, p: &Value) -> Result<Value> {
     ok()
 }
 
+/// Transitions › Sound: embed an audio file as the slides' transition sound, or `none` to remove it.
+fn sound(s: &mut Session, p: &Value) -> Result<Value> {
+    let list = slide_indices(s, p)?;
+    if bool_param(p, "none") == Some(true) {
+        s.edit(|doc, _| {
+            for i in list {
+                if let Some(sl) = doc.slides.get_mut(i)
+                    && let Some(t) = Arc::make_mut(sl).transition.as_mut()
+                {
+                    t.sound = None;
+                }
+            }
+            Ok(())
+        })?;
+        return Ok(json!({"sound": null}));
+    }
+    let (name, bytes) = super::insert::media_bytes(p, "transition.sound")?;
+    let ct = super::insert::content_type(&name, &bytes);
+    let bytes = Arc::new(bytes);
+    let audible = deckcraft_media::probe(&bytes).is_ok_and(|i| i.audio.is_some());
+    let bytes = Arc::try_unwrap(bytes).unwrap_or_else(|a| (*a).clone());
+    if !audible && !ct.starts_with("audio/") {
+        return Err(bad("transition.sound", format!("{name} is not a sound file ({ct})")));
+    }
+    let media = s.edit(|doc, _| {
+        let media = doc.add_media(&name, ct, bytes);
+        for i in list {
+            if let Some(sl) = doc.slides.get_mut(i) {
+                Arc::make_mut(sl).transition.get_or_insert_with(Transition::default).sound = Some(media);
+            }
+        }
+        Ok(media)
+    })?;
+    Ok(json!({"sound": name, "media": media.0, "playable": audible}))
+}
+
 fn apply_all(s: &mut Session, _p: &Value) -> Result<Value> {
     s.edit(|doc, sel| {
         let t = doc.slides.get(sel.slide).and_then(|x| x.transition.clone());

crates/pptx/tests/roundtrip.rs

@@ -1214,3 +1214,48 @@ fn text_transparency_round_trips() {
     let Some(deckcraft_model::Fill::Solid { color }) = &sh.text.as_ref().unwrap().paragraphs[0].runs[0].props.fill else { panic!() };
     assert!((color.alpha() - 0.6).abs() < 1e-9, "{color:?}");
 }
+
+/// A tiny 8 kHz mono 16-bit WAV of `n` silent samples.
+fn wav(n: u32) -> Vec<u8> {
+    let mut v = Vec::new();
+    v.extend_from_slice(b"RIFF");
+    v.extend_from_slice(&(36 + n * 2).to_le_bytes());
+    v.extend_from_slice(b"WAVEfmt ");
+    v.extend_from_slice(&16u32.to_le_bytes());
+    v.extend_from_slice(&1u16.to_le_bytes());
+    v.extend_from_slice(&1u16.to_le_bytes());
+    v.extend_from_slice(&8000u32.to_le_bytes());
+    v.extend_from_slice(&16000u32.to_le_bytes());
+    v.extend_from_slice(&2u16.to_le_bytes());
+    v.extend_from_slice(&16u16.to_le_bytes());
+    v.extend_from_slice(b"data");
+    v.extend_from_slice(&(n * 2).to_le_bytes());
+    v.resize(v.len() + n as usize * 2, 0);
+    v
+}
+
+/// Transitions › Sound: a chosen sound is embedded, saved as `p:sndAc`, read back, and No Sound
+/// removes it; a file that isn't audio is refused.
+#[test]
+fn transition_sound_is_set_saved_and_removed() {
+    use deckcraft_engine::Session;
+    use serde_json::json;
+    let b64 = deckcraft_engine::cmd::base64_encode(&wav(800));
+    let mut s = Session::with_new();
+    s.execute("transition.set", &json!({"kind": "fade"})).unwrap();
+    let r = s.execute("transition.sound", &json!({"data": b64, "name": "chime.wav"})).unwrap();
+    assert_eq!(r["playable"], true, "{r}");
+    let doc = s.doc().unwrap().doc.clone();
+    let m = doc.slides[0].transition.as_ref().and_then(|t| t.sound).expect("sound set");
+    assert_eq!(doc.media(m).map(|i| i.name.as_str()), Some("chime.wav"));
+    let bytes = deckcraft_pptx::export(&doc).unwrap();
+    let back = deckcraft_pptx::import(&bytes).unwrap();
+    let t = back.slides[0].transition.as_ref().expect("transition");
+    assert_eq!(t.kind, "fade");
+    let m = t.sound.expect("sound survives the save");
+    assert_eq!(back.media(m).map(|i| i.data.len()), Some(wav(800).len()));
+    s.execute("transition.sound", &json!({"none": true})).unwrap();
+    assert!(s.doc().unwrap().doc.slides[0].transition.as_ref().is_some_and(|t| t.sound.is_none()));
+    let not_audio = deckcraft_engine::cmd::base64_encode(b"hello, not a sound");
+    assert!(s.execute("transition.sound", &json!({"data": not_audio, "name": "notes.txt"})).is_err());
+}

crates/ui-egui/src/lib.rs

@@ -619,6 +619,13 @@ impl SlideApp {
         Ok(())
     }
 
+    /// Transitions › Sound › Other Sound…: pick an audio file for the selected slides.
+    pub(crate) fn pick_transition_sound(&mut self) {
+        if self.services.pick_open.is_some() {
+            self.pick_and_insert("audio", "transition.sound");
+        }
+    }
+
     fn pick_and_insert(&mut self, purpose: &str, cmd: &str) {
         if let Some(pick) = self.services.pick_open.as_mut() {
             if let Some(path) = pick(purpose) {

crates/ui-egui/src/ribbon.rs

@@ -1400,6 +1400,28 @@ fn transitions(app: &mut SlideApp, ui: &mut Ui) {
         });
     });
     group(ui, |ui| {
+        // Sound in its own column, so the timing column keeps its three rows.
+        rows(ui, |ui| {
+            ui.horizontal(|ui| {
+                ui.label("Sound:");
+                let name = cur
+                    .as_ref()
+                    .and_then(|t| t.sound)
+                    .and_then(|m| app.session.active().and_then(|d| d.doc.media(m).map(|i| i.name.clone())))
+                    .unwrap_or_else(|| "[No Sound]".into());
+                egui::ComboBox::from_id_salt("transition_sound").width(120.0).selected_text(name).show_ui(ui, |ui| {
+                    if ui.selectable_label(cur.as_ref().is_none_or(|t| t.sound.is_none()), "[No Sound]").clicked() {
+                        run(app, "transition.sound", json!({"none": true}));
+                    }
+                    let can_pick = app.services.pick_open.is_some();
+                    let r = ui.add_enabled(can_pick, egui::Button::new("Other Sound…"));
+                    if r.clicked() {
+                        app.pick_transition_sound();
+                    }
+                    r.on_disabled_hover_text("Choosing a sound file needs the desktop app");
+                });
+            });
+        });
         rows(ui, |ui| {
             ui.horizontal(|ui| {
                 ui.label("Duration:");

crates/ui-egui/src/show.rs

@@ -721,6 +721,9 @@ pub fn ui(app: &mut SlideApp, ui: &mut Ui) {
     }
 }
 
+/// The media-host voice for slide transition sounds (no shape has this id).
+pub(crate) const TRANSITION_SOUND: ShapeId = ShapeId(u32::MAX);
+
 /// Start the media of a newly shown slide: media from the previous slide stops unless it plays
 /// across slides; media set to start automatically plays. Everything stops at the end.
 fn show_media(app: &mut SlideApp, show: &mut Show, doc: &Presentation) {
@@ -729,8 +732,16 @@ fn show_media(app: &mut SlideApp, show: &mut Show, doc: &Presentation) {
         return;
     }
     show.media_slide = cur;
+    let sound = cur.and_then(|i| doc.slides.get(i)).and_then(|s| s.transition.as_ref()).and_then(|t| t.sound);
     let keep: Vec<ShapeId> = match cur {
-        Some(_) => app.media.ids().into_iter().filter(|id| crate::media::find_clip(doc, *id).is_some_and(|c| c.play_across_slides)).collect(),
+        Some(_) => app
+            .media
+            .ids()
+            .into_iter()
+            .filter(|id| crate::media::find_clip(doc, *id).is_some_and(|c| c.play_across_slides))
+            // A transition sound plays to its end, as in PowerPoint, unless the new slide has its own.
+            .chain(sound.is_none().then_some(TRANSITION_SOUND).filter(|id| app.media.is_playing(*id)))
+            .collect(),
         None => vec![],
     };
     for id in app.media.ids() {
@@ -738,6 +749,10 @@ fn show_media(app: &mut SlideApp, show: &mut Show, doc: &Presentation) {
             app.media.stop(id);
         }
     }
+    if let Some(media) = sound {
+        let clip = deckcraft_model::MediaClip { media, volume: 1.0, ..Default::default() };
+        app.media.play(doc, TRANSITION_SOUND, &clip, None, crate::media::Owner::Show);
+    }
     if let Some(i) = cur {
         for (id, _, clip) in crate::media::slide_media(doc, i) {
             if clip.autoplay && !keep.contains(&id) {

docs/animation-parity.md

@@ -39,7 +39,7 @@ perspective-correct subdivided meshes.
 |---|---|---|
 | Effect Options per transition | yes | yes |
 | Duration, advance on click / after time, Apply To All | yes | yes |
-| Transition sounds | yes | **no** (the model has the field; no picker, no playback) |
+| Transition sounds | yes | partly: Transitions › Sound › Other Sound… embeds a file, it plays as the slide comes in and round-trips; no built-in sounds, Stop Previous Sound or Loop Until Next Sound |
 | Preview in the editor | yes | yes |
 | Morph: objects move, resize, recolour | yes | yes |
 | Morph: Words and Characters | yes | yes (#5) |
@@ -84,7 +84,7 @@ In, Wipe, Zoom, Float In, Grow/Shrink, Pulse, Spin, motion lines): weighted, ~85
 | Animation Pane timeline, preview from selected, effect dialog depth | 5–8 |
 | The remaining ~126 effects (most are parameter variations of existing ones) | 3–6 |
 | Rewind and other effect options on round trip (#77) | 1–2 |
-| Transition sounds | 1–2 |
+| Transition sounds: built-in sounds, Stop Previous Sound, Loop Until Next Sound | 1–2 |
 | Morph across pictures, `!!` names, align once per transition (#67) | 2–4 |
 | 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) |

docs/parity-checklist.md

@@ -199,7 +199,7 @@ Open P0 items: Contextual tabs (Shape Format, Picture Format, Table Design/Layou
 | Transitions | Transition gallery (fade, push, wipe, split, cover, uncover, zoom, morph…) | P0 | D |
 | Transitions | Effect options and duration | P0 | D |
 | Transitions | Advance on click / after time, apply to all | P0 | D |
-| Transitions | Transition sounds | P2 | M |
+| Transitions | Transition sounds | P2 | P |
 | Transitions | Morph | P1 | D |
 | Animations | Entrance, emphasis, exit effects | P0 | D |
 | Animations | Motion paths | P1 | P |