Merge PR #1946: XLSX: keep cell fonts' charset (Arabic 178) and family on save

crates/xlsx/src/styles.rs: family/charset block ported into the dxf.is_none() branch of font_xml (PR #1225 made it take Option<&DxfStated>)
docs/file-format-parity.md: header Change line keeps both sides' clauses

crates/engine/src/cmd/format.rs

@@ -296,7 +296,11 @@ fn underline(s: &mut Session, p: &Json) -> Result<Json> {
 
 fn font_name(s: &mut Session, p: &Json) -> Result<Json> {
     let Some(name) = str_param(p, "name").map(str::to_string) else { return Err(bad("home.fontName", "missing `name`")) };
-    apply_style(s, p, |st| st.font.name = name.clone())
+    apply_style(s, p, |st| {
+        st.font.name = name.clone();
+        st.font.charset = None;
+        st.font.family = None;
+    })
 }
 
 fn font_size(s: &mut Session, p: &Json) -> Result<Json> {

crates/engine/src/tests.rs

@@ -1207,6 +1207,24 @@ fn structured_refs_to_columns_with_edge_spaces() {
     assert_eq!([v(&s, "F1"), v(&s, "F2"), v(&s, "F3")], [n(5.0), n(5.0), n(5.0)]);
 }
 
+#[test]
+fn changing_the_font_name_drops_the_old_fonts_charset_and_family() {
+    let mut s = s();
+    {
+        let wb = std::sync::Arc::make_mut(&mut s.doc_mut().unwrap().wb);
+        let arabic = wb.styles.derive(gridcraft_model::StyleId::DEFAULT, |st| {
+            st.font.name = "Traditional Arabic".into();
+            st.font.charset = Some(178);
+            st.font.family = Some(1);
+        });
+        wb.sheet_mut(0).unwrap().set_style(CellRef::parse("A1").unwrap(), arabic);
+    }
+    s.execute("home.fontName", json!({"range": "A1", "name": "Arial"})).unwrap();
+    let d = s.doc().unwrap();
+    let font = &d.wb.styles.get(d.wb.active().unwrap().style_id(CellRef::parse("A1").unwrap())).font;
+    assert_eq!((font.name.as_str(), font.charset, font.family), ("Arial", None, None));
+}
+
 #[test]
 fn table_rename_keeps_a_defined_name_with_the_same_name() {
     let mut s = s();

crates/model/src/style.rs

@@ -161,6 +161,12 @@ pub struct Font {
     pub strike: bool,
     pub color: Color,
     pub vert: VertAlign,
+    /// Windows character set the font was chosen for (178 = Arabic); kept so Excel substitutes a font for the same script.
+    #[serde(default)]
+    pub charset: Option<u8>,
+    /// Font family class (1 roman, 2 swiss, 3 modern…); `None` is swiss, the default.
+    #[serde(default)]
+    pub family: Option<u8>,
 }
 
 impl Eq for Font {}
@@ -168,7 +174,7 @@ impl Hash for Font {
     fn hash<H: Hasher>(&self, h: &mut H) {
         self.name.hash(h);
         self.size.to_bits().hash(h);
-        (self.bold, self.italic, self.underline, self.strike, self.color, self.vert).hash(h);
+        (self.bold, self.italic, self.underline, self.strike, self.color, self.vert, self.charset, self.family).hash(h);
     }
 }
 
@@ -183,6 +189,8 @@ impl Default for Font {
             strike: false,
             color: Color::Auto,
             vert: VertAlign::Baseline,
+            charset: None,
+            family: None,
         }
     }
 }

crates/xlsx/src/styles.rs

@@ -57,6 +57,9 @@ fn bool_prop(e: &El, name: &str) -> bool {
     e.child(name).is_some_and(|c| c.flag("val", true))
 }
 
+const DEFAULT_FONT_FAMILY: u8 = 2;
+const MAX_FONT_FAMILY: u8 = 14;
+
 pub fn read_font(e: &El, palette: &[u32]) -> Font {
     let mut f = Font::default();
     if let Some(n) = e.child("name").or_else(|| e.child("rFont")).and_then(|n| n.attr("val")) {
@@ -84,6 +87,12 @@ pub fn read_font(e: &El, palette: &[u32]) -> Font {
             _ => VertAlign::Baseline,
         };
     }
+    f.charset = e.child("charset").and_then(|c| c.attr_u32("val")).and_then(|v| u8::try_from(v).ok());
+    f.family = e
+        .child("family")
+        .and_then(|c| c.attr_u32("val"))
+        .and_then(|v| u8::try_from(v).ok())
+        .filter(|v| *v <= MAX_FONT_FAMILY && *v != DEFAULT_FONT_FAMILY);
     f.color = opt_color(e.child("color"), palette);
     // Text 1 (dk1) is what "automatic" font colour means in practice.
     if f.color == Color::Theme(1, 0) {
@@ -445,7 +454,11 @@ fn font_xml(f: &Font, dxf: Option<&DxfStated>, minor: bool) -> String {
         s.push_str("<color theme=\"1\"/>");
     }
     if dxf.is_none() {
-        let _ = write!(s, "<name val=\"{}\"/><family val=\"2\"/>", esc_attr(&f.name));
+        let family = f.family.filter(|v| *v <= MAX_FONT_FAMILY).unwrap_or(DEFAULT_FONT_FAMILY);
+        let _ = write!(s, "<name val=\"{}\"/><family val=\"{family}\"/>", esc_attr(&f.name));
+        if let Some(charset) = f.charset {
+            let _ = write!(s, "<charset val=\"{charset}\"/>");
+        }
         if minor {
             s.push_str("<scheme val=\"minor\"/>");
         }

crates/xlsx/src/tests/roundtrip.rs

@@ -1128,6 +1128,64 @@ fn default_font_survives_a_round_trip() {
     assert_eq!(font0(&saved), (Some("12".into()), Some("Calibri".into()), Some("2".into()), Some("minor".into())));
 }
 
+fn one_font_workbook(font: &str) -> Vec<u8> {
+    let styles = format!(
+        r#"<styleSheet xmlns="http://schemas.openxmlformats.org/spreadsheetml/2006/main"><fonts count="1"><font>{font}</font></fonts><fills count="1"><fill><patternFill patternType="none"/></fill></fills><borders count="1"><border><left/><right/><top/><bottom/><diagonal/></border></borders><cellStyleXfs count="1"><xf numFmtId="0" fontId="0" fillId="0" borderId="0"/></cellStyleXfs><cellXfs count="1"><xf numFmtId="0" fontId="0" fillId="0" borderId="0" xfId="0"/></cellXfs><cellStyles count="1"><cellStyle name="Normal" xfId="0" builtinId="0"/></cellStyles></styleSheet>"#
+    );
+    let rels = r#"<Relationship Id="rId2" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/styles" Target="styles.xml"/>"#;
+    super::minimal("<sheetData/>", &[("xl/styles.xml", &styles)], rels, "")
+}
+
+#[test]
+fn font_charset_and_family_roundtrip() {
+    let file = one_font_workbook(r#"<name val="Traditional Arabic"/><family val="1"/><charset val="178"/>"#);
+    let (wb, _) = read_xlsx(&file).unwrap();
+    let saved = write_xlsx(&wb).unwrap();
+    let mut pkg = Package::open(&saved).unwrap();
+    let xml = String::from_utf8(pkg.read("xl/styles.xml").unwrap().unwrap()).unwrap();
+    assert!(xml.contains("<name val=\"Traditional Arabic\"/><family val=\"1\"/><charset val=\"178\"/>"), "{xml}");
+
+    let (back, _) = read_xlsx(&saved).unwrap();
+    let font = &back.styles.get(StyleId::DEFAULT).font;
+    let back_saved = write_xlsx(&back).unwrap();
+    let mut pkg = Package::open(&back_saved).unwrap();
+    let xml = String::from_utf8(pkg.read("xl/styles.xml").unwrap().unwrap()).unwrap();
+    assert!(xml.contains("<name val=\"Traditional Arabic\"/><family val=\"1\"/><charset val=\"178\"/>"), "{xml}");
+    assert_eq!(font.name, "Traditional Arabic");
+    assert_eq!(font.family, Some(1));
+    assert_eq!(font.charset, Some(178));
+}
+
+#[test]
+fn fonts_without_charset_write_unchanged() {
+    let file = one_font_workbook(r#"<name val="Arial"/>"#);
+    let saved = write_xlsx(&read_xlsx(&file).unwrap().0).unwrap();
+    let mut pkg = Package::open(&saved).unwrap();
+    let xml = String::from_utf8(pkg.read("xl/styles.xml").unwrap().unwrap()).unwrap();
+    assert!(xml.contains("<name val=\"Arial\"/><family val=\"2\"/>"), "{xml}");
+    assert!(!xml.contains("<charset"), "{xml}");
+}
+
+#[test]
+fn out_of_range_family_is_ignored() {
+    let file = one_font_workbook(r#"<name val="Arial"/><family val="15"/>"#);
+    let (wb, _) = read_xlsx(&file).unwrap();
+    assert_eq!(wb.styles.get(StyleId::DEFAULT).font.family, None);
+    let saved = write_xlsx(&wb).unwrap();
+    let mut pkg = Package::open(&saved).unwrap();
+    let xml = String::from_utf8(pkg.read("xl/styles.xml").unwrap().unwrap()).unwrap();
+    assert!(xml.contains("<name val=\"Arial\"/><family val=\"2\"/>"), "{xml}");
+
+    let mut set_directly = wb.clone();
+    let wide = set_directly.styles.derive(StyleId::DEFAULT, |st| st.font.family = Some(200));
+    set_directly.sheet_mut(0).unwrap().set_value(CellRef::new(0, 0), Value::text("x"));
+    set_directly.sheet_mut(0).unwrap().set_style(CellRef::new(0, 0), wide);
+    let saved = write_xlsx(&set_directly).unwrap();
+    let mut pkg = Package::open(&saved).unwrap();
+    let xml = String::from_utf8(pkg.read("xl/styles.xml").unwrap().unwrap()).unwrap();
+    assert!(!xml.contains("<family val=\"200\"/>"), "{xml}");
+}
+
 #[test]
 fn solid_data_bar_survives_with_sparklines_and_gradient_neighbours() {
     let mut wb = Workbook::new();