Font menu: a Thai script filter

The font menu's script filter offered Japanese and Latin only, so Thai
fonts had to be found by name among every installed family. It now has
Thai too: the families whose character map has Thai. Latin lists the
families with neither Japanese nor Thai.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/text/src/fontdb.rs

@@ -574,10 +574,12 @@ impl FontClass {
         [FontClass::Serif, FontClass::Sans, FontClass::Rounded, FontClass::Script, FontClass::Monospaced, FontClass::Decorative];
 }
 
-/// What a font menu filters on: whether a family sets Japanese, and its kind.
+/// What a font menu filters on: whether a family sets Japanese or Thai, and its kind.
 #[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
 pub struct FontTraits {
     pub japanese: bool,
+    /// Its character map has Thai (ก and า).
+    pub thai: bool,
     pub class: FontClass,
 }
 
@@ -595,6 +597,7 @@ impl FontTraits {
         };
         // Hiragana (bit 49) or Katakana (bit 50) in the Unicode ranges, or the JIS code page.
         let japanese = ranges2 & (0b11 << 17) != 0 || codepages & (1 << 17) != 0 || has_japanese_name;
+        let thai = ['\u{0E01}', '\u{0E32}'].iter().all(|c| font.charmap().map(*c).is_some());
         let family_type = panose.first().copied().unwrap_or(0);
         let serif_style = panose.get(1).copied().unwrap_or(0);
         let proportion = panose.get(3).copied().unwrap_or(0);
@@ -692,7 +695,7 @@ impl FontTraits {
         } else {
             FontClass::Other
         };
-        FontTraits { japanese, class }
+        FontTraits { japanese, thai, class }
     }
 }
 

crates/ui-egui/src/font_menu.rs

@@ -84,17 +84,29 @@ const SAMPLES_PER_FRAME: usize = 4;
 const MAX_PENDING: usize = 8;
 /// What a sample shows when the font lacks the selected text's characters (or there is none).
 const FALLBACK_SAMPLE: &str = "Sample";
-/// The script filter's choices: all, Japanese, Latin.
-const SCRIPTS: usize = 3;
+/// The script filter's choices: all, Japanese, Latin, Thai.
+const SCRIPTS: usize = 4;
 
 fn script_label(i: usize) -> &'static str {
     match i {
         1 => tl!("Japanese"),
         2 => tl!("Latin"),
+        3 => tl!("Thai"),
         _ => tl!("All Scripts"),
     }
 }
 
+/// Does a family of `traits` pass script filter `script` ([`SCRIPTS`])? Latin: neither Japanese
+/// nor Thai.
+fn script_matches(script: usize, traits: vectorcraft_text::FontTraits) -> bool {
+    match script {
+        1 => traits.japanese,
+        2 => !traits.japanese && !traits.thai,
+        3 => traits.thai,
+        _ => true,
+    }
+}
+
 fn class_label(c: FontClass) -> &'static str {
     match c {
         FontClass::Serif => tl!("Serif / Mincho"),
@@ -283,7 +295,7 @@ fn list(ui: &mut Ui, state_id: egui::Id, st: &mut MenuState, current: &str, samp
                 return true;
             }
             let traits = db.family_traits(f);
-            (st.script == 0 || (st.script == 1) == traits.japanese) && st.class.is_none_or(|c| c == traits.class)
+            script_matches(st.script, traits) && st.class.is_none_or(|c| c == traits.class)
         };
         let mut rows: Vec<Row> = vec![];
         for f in db.menu_family_list().iter().filter(|f| wanted(f)) {
@@ -748,6 +760,21 @@ pub(crate) fn sample_text(app: &VectorcraftApp) -> Option<String> {
 
 #[cfg(test)]
 mod tests {
+
+    /// The script filter: Thai lists families with Thai; Latin, those with neither Thai nor
+    /// Japanese.
+    #[test]
+    fn the_thai_filter_lists_fonts_with_thai() {
+        use vectorcraft_text::FontTraits;
+        let (thai, japanese, latin) =
+            (FontTraits { thai: true, ..Default::default() }, FontTraits { japanese: true, ..Default::default() }, FontTraits::default());
+        let passing = |t: FontTraits| (0..super::SCRIPTS).filter(|s| super::script_matches(*s, t)).collect::<Vec<_>>();
+        assert_eq!(passing(thai), [0, 3]);
+        assert_eq!(passing(japanese), [0, 1]);
+        assert_eq!(passing(latin), [0, 2]);
+        assert_eq!(super::script_label(3), "Thai");
+    }
+
     use super::{Row, remap_highlight};
 
     fn family(name: &str) -> Row {

crates/ui-egui/src/i18n/de.tsv

@@ -1323,6 +1323,7 @@
 	Last Effect…	Letzter Effekt…
 	Last Page	Letzte Seite
 	Latin	Lateinisch
+	Thai	Thai
 	Latin Extended	Lateinisch, erweitert
 	Latin-1 Supplement	Lateinisch-1, Ergänzung
 	Layer	Ebene

crates/ui-egui/src/i18n/es.tsv

@@ -1341,6 +1341,7 @@
 	Last Effect…	Último efecto…
 	Last Page	Última página
 	Latin	Latín
+	Thai	Tailandés
 	Latin Extended	Latín extendido
 	Latin-1 Supplement	Suplemento Latín-1
 	Layer	Capa

crates/ui-egui/src/i18n/fr.tsv

@@ -1340,6 +1340,7 @@
 	Last Effect…	Dernier effet…
 	Last Page	Dernière page
 	Latin	Latin
+	Thai	Thaï
 	Latin Extended	Latin étendu
 	Latin-1 Supplement	Supplément Latin-1
 	Layer	Calque

crates/ui-egui/src/i18n/it.tsv

@@ -1341,6 +1341,7 @@
 	Last Effect…	Ultimo effetto…
 	Last Page	Ultima pagina
 	Latin	Latino
+	Thai	Thailandese
 	Latin Extended	Latino esteso
 	Latin-1 Supplement	Supplemento Latino-1
 	Layer	Livello

crates/ui-egui/src/i18n/ja.tsv

@@ -48,6 +48,7 @@
 	Hard	強い禁則
 	Soft	弱い禁則
 	Latin	欧文
+	Thai	タイ文字
 	Monospaced	等幅
 	Roman Baseline	欧文ベースライン
 	Rounded	丸ゴシック

crates/ui-egui/src/i18n/ru.tsv

@@ -1339,6 +1339,7 @@
 	Last Effect…	Последний эффект…
 	Last Page	Последняя страница
 	Latin	Латиница
+	Thai	Тайская
 	Latin Extended	Расширенная латиница
 	Latin-1 Supplement	Дополнение Latin-1
 	Layer	Слой

crates/ui-egui/src/i18n/uk.tsv

@@ -1335,6 +1335,7 @@
 	Last Effect…	Останній ефект…
 	Last Page	Остання сторінка
 	Latin	Латиниця
+	Thai	Тайська
 	Latin Extended	Розширена латиниця
 	Latin-1 Supplement	Додаток Latin-1
 	Layer	Шар

crates/ui-egui/src/i18n/zh-hans.tsv

@@ -3417,6 +3417,7 @@
 	Graphics: {adapter}	显卡：{adapter}
 	Japanese	日文
 	Latin	拉丁文
+	Thai	泰文
 	Layer Options	图层选项
 	Layers Panel Options	图层面板选项
 	Monospaced	等宽

crates/ui-egui/src/i18n/zh-hant.tsv

@@ -1316,6 +1316,7 @@
 	Last Effect…	最後一次效果…
 	Last Page	最後一頁
 	Latin	拉丁文
+	Thai	泰文
 	Latin Extended	拉丁文擴充
 	Latin-1 Supplement	拉丁文-1 補充
 	Layer	圖層

docs/type-parity.md

@@ -1,6 +1,6 @@
 # Type parity
 
-> **Last reviewed:** 2026-10-10 · **Last updated:** 2026-10-11 · **Change:** minor (Thai, Lao, Khmer and Myanmar lines break between words; the caret steps over whole clusters such as Thai consonants with their marks; Thai typed in a font without Thai falls back to a font made for Thai; earlier: Proportional Metrics in vertical type, `vpal`, #966) · **Target:** Adobe Illustrator 2026 (30.x)
+> **Last reviewed:** 2026-10-10 · **Last updated:** 2026-10-11 · **Change:** minor (the font menu's script filter lists Thai fonts; Thai, Lao, Khmer and Myanmar lines break between words; the caret steps over whole clusters such as Thai consonants with their marks; Thai typed in a font without Thai falls back to a font made for Thai; earlier: Proportional Metrics in vertical type, `vpal`, #966) · **Target:** Adobe Illustrator 2026 (30.x)
 
 Type is Illustrator's largest single area by use (weight 13 of 105 across "Type core" and "Type advanced" in
 [target-app-parity.md](target-app-parity.md)). This checklist lists the features one by one. Status is from the
@@ -26,6 +26,7 @@ against Illustrator's public documentation; **estimated** unless noted.
 | Character size and horizontal scale after object/group scaling | done | #1034: fields and setters compensate the stored affine; point size follows the transformed em-height axis, not the glyph ink bounds. Range edits, keyboard increments, leading and baseline shift use document points; rotation, reflection and shear remain editable. |
 | Preserve font sizes while scaling a group | missing | Separate enhancement; scaling still scales text with the other artwork. |
 | OpenType panel, Glyphs panel, alternates | done | Highlight Alternate Glyphs preference unused (#394) |
+| Font menu: samples, live preview, filters, favourites; font matching by any name; Find Font | done | #339; script filter: Japanese, Latin, Thai |
 | Font menu: samples, live preview, filters, favourites; font matching by any name; Find Font | done | #339 |
 | Missing glyphs set in an installed font made for their script (Thai, Lao, Khmer, Myanmar first; then any font that has them) | done | Thai: Leelawadee UI, Tahoma, Thonburi, Sukhumvit Set, Noto Sans Thai, TLWG |
 | Variable fonts | partial | named instances as styles; axis sliders missing |
@@ -54,6 +55,7 @@ against Illustrator's public documentation; **estimated** unless noted.
 
 | Date | Change | Summary |
 |---|---|---|
+| 2026-10-11 | minor | Font menu: a Thai script filter beside Japanese and Latin; score unchanged (estimated) |
 | 2026-10-11 | minor | Thai, Lao, Khmer and Myanmar text breaks its lines between words (ICU4X line segmenter) instead of only at spaces; score unchanged (estimated) |
 | 2026-10-11 | minor | The Type tool's arrows and Delete move by grapheme cluster, never between a Thai consonant and its vowel or tone marks; score unchanged (estimated) |
 | 2026-10-11 | minor | Thai (Lao, Khmer, Myanmar) missing from the font in use falls back to an installed font made for the script instead of whichever face covering it loaded first; score unchanged (estimated) |