Merge PR #685 from NikitkaRa: PPTX: keep the notes master's own placeholders and colour map on save

# Conflicts:
#	crates/pptx/src/write/mod.rs
#	crates/pptx/tests/roundtrip.rs

crates/pptx/src/write/mod.rs

@@ -385,23 +385,27 @@ struct NotesMasterWrite {
 }
 
 fn notes_master_write(p: &Presentation) -> Option<NotesMasterWrite> {
-    let kept = p.notes_master.as_ref().filter(|m| !m.shapes.is_empty());
+    let nm = p.notes_master.as_deref();
+    let kept = nm.filter(|m| !m.shapes.is_empty());
     let has_notes = p.slides.iter().any(|s| !s.notes.is_empty());
-    if !has_notes && kept.is_none() {
+    if !has_notes && nm.is_none() {
         return None;
     }
+    let default_bg = || Background::Ref { idx: 1001, color: deckcraft_model::ColorRef::scheme(deckcraft_color::SchemeSlot::Bg1) };
     Some(match kept {
         Some(m) => NotesMasterWrite {
             shapes: m.shapes.clone(),
-            background: m.background.clone(),
+            background: Some(m.background.clone().unwrap_or_else(default_bg)),
             color_map: m.color_map.clone(),
             style: if m.body_style.is_empty() { notes_style() } else { m.body_style.clone() },
             theme: Some(m.theme.clone()),
         },
+        // A master without placeholders of its own gets PowerPoint's defaults, keeping its
+        // background and colour map.
         None => NotesMasterWrite {
             shapes: notes_master_shapes(p.notes_size),
-            background: Some(Background::Ref { idx: 1001, color: deckcraft_model::ColorRef::scheme(deckcraft_color::SchemeSlot::Bg1) }),
-            color_map: vec![],
+            background: Some(nm.and_then(|m| m.background.clone()).unwrap_or_else(default_bg)),
+            color_map: nm.map(|m| m.color_map.clone()).unwrap_or_default(),
             style: notes_style(),
             theme: None,
         },

crates/pptx/tests/roundtrip.rs

@@ -1376,3 +1376,37 @@ fn color_pulse_keeps_its_effect_colour_and_duration() {
     assert_eq!(a.amount, None, "no grow/shrink scale is invented");
     assert_eq!(a.duration_ms, 1000);
 }
+
+#[test]
+fn notes_master_placeholders_and_colour_map_survive_save() {
+    let mut p = defaults::new_presentation(None);
+    let mut box1 = shape(&mut p, "Confidential", 100000.0, 200000.0, 3000000.0, 400000.0);
+    box1.text = Some(TextBody::from_text("Company confidential"));
+    let map: Vec<(String, String)> = [("bg1", "dk1"), ("tx1", "lt1"), ("bg2", "dk2"), ("tx2", "lt2")]
+        .iter()
+        .chain(
+            [
+                ("accent1", "accent1"),
+                ("accent2", "accent2"),
+                ("accent3", "accent3"),
+                ("accent4", "accent4"),
+                ("accent5", "accent5"),
+                ("accent6", "accent6"),
+                ("hlink", "hlink"),
+                ("folHlink", "folHlink"),
+            ]
+            .iter(),
+        )
+        .map(|(a, b)| (a.to_string(), b.to_string()))
+        .collect();
+    let m = deckcraft_model::Master { name: "Notes Master".into(), shapes: vec![box1], color_map: map.clone(), ..Default::default() };
+    p.notes_master = Some(Arc::new(m));
+    // No slide has notes: the notes master must still be written.
+    let q = round(&p);
+    let nm = q.notes_master.as_deref().expect("notes master kept");
+    assert_eq!(nm.shapes.len(), 1, "own shapes, not the defaults");
+    let sh = &nm.shapes[0];
+    assert_eq!(sh.name, "Confidential");
+    assert_eq!(sh.text.as_ref().map(|t| t.text()), Some("Company confidential".to_string()));
+    assert_eq!(nm.color_map, map);
+}