Merge pull request #3288 from dotCooCoo/feat/kashida

Paragraph: Insert Kashidas justifies Arabic lines with kashidas

crates/doc/src/text.rs

@@ -598,6 +598,35 @@ impl Default for JustificationOptions {
     }
 }
 
+/// Insert Kashidas (Paragraph panel): how long the kashidas are that lengthen the Arabic words of
+/// a justified paragraph's lines. A kashida is a tatweel (U+0640) drawn between a word's last pair
+/// of joined letters, at most one in each word. Short, Medium and Long kashidas are at most a quarter
+/// of an em, half an em and an em long; a Stylistic kashida is a row of whole tatweels as the font
+/// draws them, at most an em long.
+#[derive(Clone, Copy, Debug, Default, PartialEq, Eq, Hash, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub enum Kashida {
+    /// No kashidas: justified lines widen their word spaces.
+    #[default]
+    None,
+    Short,
+    Medium,
+    Long,
+    Stylistic,
+}
+
+impl Kashida {
+    /// The longest kashida, in ems of the letter that follows it in the text; 0 for None.
+    pub fn max_em(self) -> f64 {
+        match self {
+            Kashida::None => 0.0,
+            Kashida::Short => 0.25,
+            Kashida::Medium => 0.5,
+            Kashida::Long | Kashida::Stylistic => 1.0,
+        }
+    }
+}
+
 /// Paragraph attributes (the Paragraph panel).
 ///
 /// Saved through [`ParaStyleFile`], which keeps files with text openable by builds from before
@@ -645,6 +674,9 @@ pub struct ParaStyle {
     /// commas starting or ending a line hang outside the margin, and asterisks, tildes, ellipses,
     /// dashes, colons and semicolons hang by half. East Asian punctuation hangs by burasagari.
     pub roman_hanging: bool,
+    /// Insert Kashidas (Paragraph panel): justified lines lengthen their Arabic words with
+    /// kashidas before they widen their word spaces.
+    pub kashida: Kashida,
 }
 
 impl ParaStyle {
@@ -706,6 +738,8 @@ struct ParaStyleFile {
     kinsoku: Kinsoku,
     #[serde(default, skip_serializing_if = "crate::skip::is_default")]
     roman_hanging: bool,
+    #[serde(default, skip_serializing_if = "crate::skip::is_default")]
+    kashida: Kashida,
 }
 
 impl From<ParaStyle> for ParaStyleFile {
@@ -734,6 +768,7 @@ impl From<ParaStyle> for ParaStyleFile {
             burasagari,
             kinsoku,
             roman_hanging,
+            kashida,
             ..
         } = p;
         Self {
@@ -756,6 +791,7 @@ impl From<ParaStyle> for ParaStyleFile {
             burasagari,
             kinsoku,
             roman_hanging,
+            kashida,
         }
     }
 }
@@ -782,6 +818,7 @@ impl From<ParaStyleFile> for ParaStyle {
             burasagari,
             kinsoku,
             roman_hanging,
+            kashida,
             ..
         } = f;
         Self {
@@ -803,6 +840,7 @@ impl From<ParaStyleFile> for ParaStyle {
             burasagari,
             kinsoku,
             roman_hanging,
+            kashida,
         }
     }
 }

crates/engine/src/cmd/panelcmds.rs

@@ -43,7 +43,7 @@ pub fn specs() -> Vec<CommandSpec> {
             "Character / Paragraph",
             [],
             None,
-            "{ids?|id?, kerning?: 1/1000 em|\"auto\", baselineShift?: pt, hScale?: %, vScale?: %, rotation?: deg, underline?, strikethrough?, allCaps?, smallCaps?: bool, position?: \"normal\"|\"superscript\"|\"subscript\" (sizes from Document Setup), leftIndent?, rightIndent?, firstLineIndent?, spaceBefore?, spaceAfter?: pt (±1296), hyphenate?: bool, wordsLongerThan?: letters 1..25 (5), afterFirst?, beforeLast?: letters 1..15 (3), hyphenLimit?: lines 0..25 (0: no limit), hyphenationZone?: pt 0..1296 (0; Single-line Composer only), hyphenateCapitalized?: bool (true) (Paragraph panel menu › Hyphenation…: only words longer than wordsLongerThan break, keeping afterFirst letters before the hyphen and beforeLast after it; at most hyphenLimit lines in a row end with a hyphen; a line whose text already ends within hyphenationZone of its right edge breaks before the next word instead of hyphenating it; the counts are rounded, and every value is clamped to its range), wordSpacing?: % 0..1000 (80, 100, 133), letterSpacing?: % of a word space -100..500 (0, 0, 0), glyphScaling?: % 50..200 (100, 100, 100): each [min, desired, max] or {min?, desired?, max?} (Paragraph panel menu › Justification…: Desired applies to every line, Minimum and Maximum bound what justified lines may use; values are clamped to their range, and Minimum ≤ Desired ≤ Maximum must hold afterwards or nothing changes), autoLeading?: % of the size 0..500 (120; the leading of characters whose leading is Auto), singleWordJustification?: \"fullJustify\"|\"alignLeft\"|\"alignCenter\"|\"alignRight\" (a justified line holding one word), mojikumi?: \"none\"|\"lineEndHalf\" (Japanese punctuation spacing), kinsoku?: \"none\"|\"hard\"|\"soft\" (Kinsoku Set: Soft lets 々, ー and small kana start a line), direction?: \"auto\"|\"leftToRight\"|\"rightToLeft\" (paragraph direction; auto: from each paragraph's first strong character), leadingModel?: \"romanBaseline\"|\"emBoxTop\" (leading measured baseline to baseline, or em box top to top), charAlign?: \"romanBaseline\"|\"emBoxTop\"|\"emBoxCenter\"|\"emBoxBottom\"|\"icfTop\"|\"icfBottom\" (where characters smaller than the largest on their line line up with it), proportionalMetrics?: bool (full-width glyphs on the font's proportional widths: `palt` in horizontal type, `vpal` in vertical type), digits?: \"default\"|\"arabic\"|\"hindi\"|\"farsi\" (Character panel menu › Digits: the numeral system every digit is drawn in, whatever was typed), fontAxes?: {\"wght\": 650, …} (Character panel › Variable Font, as text.setRangeStyle: each axis named set in its units and clamped to its range, null back to the style's own setting), burasagari?: \"none\"|\"standard\"|\"forced\" (Paragraph panel menu › Burasagari None/Regular/Force: an East Asian comma or full stop ending an area type line hangs outside it: when it doesn't fit, or always; new type: \"standard\"), romanHangingPunctuation?: bool (Paragraph panel menu › Roman Hanging Punctuation: quotation marks, hyphens, full stops and commas starting or ending a line hang outside the margin, asterisks, tildes, ellipses, dashes, colons and semicolons by half; off by default), composer?: \"singleLine\"|\"everyLine\" (line breaking, Every-line by default), start?: byte, end?: byte} (baselineShift is in document points and hScale includes the object transform; groups include their text descendants; with a range: the character attributes style that range and the paragraph attributes apply to the paragraphs it touches; without: all the text)",
+            "{ids?|id?, kerning?: 1/1000 em|\"auto\", baselineShift?: pt, hScale?: %, vScale?: %, rotation?: deg, underline?, strikethrough?, allCaps?, smallCaps?: bool, position?: \"normal\"|\"superscript\"|\"subscript\" (sizes from Document Setup), leftIndent?, rightIndent?, firstLineIndent?, spaceBefore?, spaceAfter?: pt (±1296), hyphenate?: bool, wordsLongerThan?: letters 1..25 (5), afterFirst?, beforeLast?: letters 1..15 (3), hyphenLimit?: lines 0..25 (0: no limit), hyphenationZone?: pt 0..1296 (0; Single-line Composer only), hyphenateCapitalized?: bool (true) (Paragraph panel menu › Hyphenation…: only words longer than wordsLongerThan break, keeping afterFirst letters before the hyphen and beforeLast after it; at most hyphenLimit lines in a row end with a hyphen; a line whose text already ends within hyphenationZone of its right edge breaks before the next word instead of hyphenating it; the counts are rounded, and every value is clamped to its range), wordSpacing?: % 0..1000 (80, 100, 133), letterSpacing?: % of a word space -100..500 (0, 0, 0), glyphScaling?: % 50..200 (100, 100, 100): each [min, desired, max] or {min?, desired?, max?} (Paragraph panel menu › Justification…: Desired applies to every line, Minimum and Maximum bound what justified lines may use; values are clamped to their range, and Minimum ≤ Desired ≤ Maximum must hold afterwards or nothing changes), autoLeading?: % of the size 0..500 (120; the leading of characters whose leading is Auto), singleWordJustification?: \"fullJustify\"|\"alignLeft\"|\"alignCenter\"|\"alignRight\" (a justified line holding one word), mojikumi?: \"none\"|\"lineEndHalf\" (Japanese punctuation spacing), kinsoku?: \"none\"|\"hard\"|\"soft\" (Kinsoku Set: Soft lets 々, ー and small kana start a line), direction?: \"auto\"|\"leftToRight\"|\"rightToLeft\" (paragraph direction; auto: from each paragraph's first strong character), leadingModel?: \"romanBaseline\"|\"emBoxTop\" (leading measured baseline to baseline, or em box top to top), charAlign?: \"romanBaseline\"|\"emBoxTop\"|\"emBoxCenter\"|\"emBoxBottom\"|\"icfTop\"|\"icfBottom\" (where characters smaller than the largest on their line line up with it), proportionalMetrics?: bool (full-width glyphs on the font's proportional widths: `palt` in horizontal type, `vpal` in vertical type), digits?: \"default\"|\"arabic\"|\"hindi\"|\"farsi\" (Character panel menu › Digits: the numeral system every digit is drawn in, whatever was typed), fontAxes?: {\"wght\": 650, …} (Character panel › Variable Font, as text.setRangeStyle: each axis named set in its units and clamped to its range, null back to the style's own setting), burasagari?: \"none\"|\"standard\"|\"forced\" (Paragraph panel menu › Burasagari None/Regular/Force: an East Asian comma or full stop ending an area type line hangs outside it: when it doesn't fit, or always; new type: \"standard\"), romanHangingPunctuation?: bool (Paragraph panel menu › Roman Hanging Punctuation: quotation marks, hyphens, full stops and commas starting or ending a line hang outside the margin, asterisks, tildes, ellipses, dashes, colons and semicolons by half; off by default), kashida?: \"none\"|\"short\"|\"medium\"|\"long\"|\"stylistic\" (Paragraph panel › Insert Kashidas: justified lines of horizontal area type lengthen each Arabic word with a kashida between its last pair of joined letters, at most a quarter, half or whole em long, or whole tatweels up to an em for stylistic, before they widen their word spaces; none by default), composer?: \"singleLine\"|\"everyLine\" (line breaking, Every-line by default), start?: byte, end?: byte} (baselineShift is in document points and hScale includes the object transform; groups include their text descendants; with a range: the character attributes style that range and the paragraph attributes apply to the paragraphs it touches; without: all the text)",
             has_doc,
             set_format
         ),
@@ -312,6 +312,7 @@ fn set_format(s: &mut Session, p: &Value) -> Result<Value> {
         "fontAxes",
         "burasagari",
         "romanHangingPunctuation",
+        "kashida",
         "composer",
     ];
     if !keys.iter().any(|k| p.get(*k).is_some()) {
@@ -372,6 +373,17 @@ fn set_format(s: &mut Session, p: &Value) -> Result<Value> {
             _ => return Err(bad(C, "`burasagari` must be \"none\", \"standard\" or \"forced\"")),
         }),
     };
+    let kashida = match p.get("kashida") {
+        None => None,
+        Some(v) => Some(match v.as_str() {
+            Some("none") => vectorcraft_doc::text::Kashida::None,
+            Some("short") => vectorcraft_doc::text::Kashida::Short,
+            Some("medium") => vectorcraft_doc::text::Kashida::Medium,
+            Some("long") => vectorcraft_doc::text::Kashida::Long,
+            Some("stylistic") => vectorcraft_doc::text::Kashida::Stylistic,
+            _ => return Err(bad(C, "`kashida` must be \"none\", \"short\", \"medium\", \"long\" or \"stylistic\"")),
+        }),
+    };
     let spacing = |k: &str| spacing_param(p, k, C);
     let (word_spacing, letter_spacing, glyph_scaling) = (spacing("wordSpacing")?, spacing("letterSpacing")?, spacing("glyphScaling")?);
     let single_word = match p.get("singleWordJustification") {
@@ -521,6 +533,9 @@ fn set_format(s: &mut Session, p: &Value) -> Result<Value> {
                 if let Some(v) = flag("romanHangingPunctuation") {
                     para.roman_hanging = v;
                 }
+                if let Some(v) = kashida {
+                    para.kashida = v;
+                }
                 if let Some(v) = composer {
                     para.composer = v;
                 }

crates/engine/src/cmd/textstyles.rs

@@ -179,6 +179,7 @@ pub fn para_attrs(v: &ParaStyle) -> Map<String, Value> {
         ("burasagari", json!(v.burasagari)),
         ("kinsoku", json!(v.kinsoku)),
         ("roman_hanging", json!(v.roman_hanging)),
+        ("kashida", json!(v.kashida)),
     ] {
         m.insert(k.into(), x);
     }

crates/engine/src/cmd/typecmd.rs

@@ -1098,6 +1098,43 @@ mod area_tests {
         assert!(text(&s).para_at(1).roman_hanging);
     }
 
+    /// Paragraph panel › Insert Kashidas: `text.setFormat {kashida}` sets it per paragraph in one
+    /// undo step, the paragraph is saved with it only when it is not None and opens with it, an
+    /// unknown value changes nothing, and paragraph styles carry it.
+    #[test]
+    fn insert_kashidas_is_set_per_paragraph_and_saved_only_when_set() {
+        use vectorcraft_doc::text::Kashida;
+        let mut s = Session::new();
+        s.execute("file.new", &json!({"width": 400, "height": 400})).unwrap();
+        let id = s
+            .execute("text.create", &json!({"x": 10, "y": 10, "size": 20, "text": "كتب محمد\nعلي", "area": {"width": 300, "height": 200}}))
+            .unwrap()["id"]
+            .as_u64()
+            .unwrap();
+        let text = |s: &Session| match &s.doc().unwrap().doc.node(NodeId(id)).unwrap().kind {
+            NodeKind::Text(t) => (**t).clone(),
+            _ => panic!("text"),
+        };
+        assert_eq!(text(&s).para_at(0).kashida, Kashida::None);
+        assert!(serde_json::to_value(text(&s).para_at(0)).unwrap().get("kashida").is_none());
+        s.execute("select.set", &json!({"ids": [id]})).unwrap();
+        // Only the first paragraph (the caret's range).
+        s.execute("text.setFormat", &json!({"kashida": "medium", "start": 0, "end": 0})).unwrap();
+        assert_eq!((text(&s).para_at(0).kashida, text(&s).para_at(1).kashida), (Kashida::Medium, Kashida::None));
+        assert_eq!(serde_json::to_value(text(&s).para_at(0)).unwrap()["kashida"], "medium");
+        let reopened = vectorcraft_format::load(&vectorcraft_format::save(&s.doc().unwrap().doc, false)).unwrap();
+        let Some(NodeKind::Text(back)) = reopened.node(NodeId(id)).map(|n| &n.kind) else { panic!("text") };
+        assert_eq!((back.para_at(0).kashida, back.para_at(1).kashida), (Kashida::Medium, Kashida::None));
+        assert!(s.execute("text.setFormat", &json!({"kashida": "wide"})).is_err());
+        assert_eq!(text(&s).para_at(0).kashida, Kashida::Medium, "an unknown value changes nothing");
+        s.execute("edit.undo", &json!({})).unwrap();
+        assert_eq!(text(&s).para_at(0).kashida, Kashida::None);
+        // A paragraph style carries it.
+        s.execute("paraStyle.new", &json!({"name": "Stretched", "attrs": {"kashida": "stylistic"}})).unwrap();
+        s.execute("paraStyle.apply", &json!({"name": "Stretched", "id": id})).unwrap();
+        assert_eq!(text(&s).para_at(1).kashida, Kashida::Stylistic);
+    }
+
     /// Paragraph panel menu › Justification…: `text.setFormat` sets each paragraph's word and
     /// letter spacing, glyph scaling, Auto Leading and Single Word Justification, clamped to their
     /// ranges, in one undo step; Minimum ≤ Desired ≤ Maximum must hold or nothing changes. They

crates/text/src/kashida.rs

@@ -0,0 +1,185 @@
+//! Paragraph panel › Insert Kashidas: justified lines lengthen their Arabic words with kashidas.
+//!
+//! [`plan`] picks, in each Arabic word of a justified line, the place between its last pair of
+//! joined letters, and shares the line's room among those places, each kashida up to its
+//! [`Kashida::max_em`]. The layout draws each kashida as tatweels (U+0640) in the face of the
+//! letter after it, and the word spaces take the room the kashidas leave.
+//!
+//! Behavior reference (public documentation):
+//! <https://web.archive.org/web/20260906105741/https://helpx.adobe.com/illustrator/desktop/design-with-text/fonts-and-scripts/justify-text-using-kashida-and-hyphenation.html>
+//! and <https://web.archive.org/web/20250816144754/https://helpx.adobe.com/illustrator/using/arabic-hebrew.html>.
+
+use std::ops::Range;
+
+use vectorcraft_doc::text::Kashida;
+
+use crate::shape::SGlyph;
+
+/// The tatweel (kashida) character.
+pub(crate) const TATWEEL: char = '\u{0640}';
+
+/// How a character joins its neighbors in cursive Arabic, from the Unicode Character Database's
+/// `ArabicShaping.txt` for the Arabic block (U+0600 to U+06FF). Other characters do not join,
+/// except the zero width joiner, and the nonspacing and enclosing marks and format characters
+/// that the file does not list, which joining goes across.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+enum Joining {
+    /// Joins the letters on both sides.
+    Dual,
+    /// Joins the letter before it only.
+    Right,
+    /// Joins both sides without changing its own form (the tatweel, the zero width joiner).
+    Causing,
+    /// Skipped over: joining goes on across it (nonspacing and enclosing marks, format
+    /// characters).
+    Transparent,
+    None,
+}
+
+fn joining(c: char) -> Joining {
+    use unicode_general_category::{GeneralCategory, get_general_category};
+    match c {
+        '\u{0620}'
+        | '\u{0626}'
+        | '\u{0628}'
+        | '\u{062A}'..='\u{062E}'
+        | '\u{0633}'..='\u{063F}'
+        | '\u{0641}'..='\u{0647}'
+        | '\u{0649}'
+        | '\u{064A}' => Joining::Dual,
+        '\u{066E}' | '\u{066F}' | '\u{0678}'..='\u{0687}' | '\u{069A}'..='\u{06BF}' | '\u{06C1}' | '\u{06C2}' | '\u{06CC}' | '\u{06CE}' => {
+            Joining::Dual
+        }
+        '\u{06D0}' | '\u{06D1}' | '\u{06FA}'..='\u{06FC}' | '\u{06FF}' => Joining::Dual,
+        '\u{0622}'..='\u{0625}'
+        | '\u{0627}'
+        | '\u{0629}'
+        | '\u{062F}'..='\u{0632}'
+        | '\u{0648}'
+        | '\u{0671}'..='\u{0673}'
+        | '\u{0675}'..='\u{0677}' => Joining::Right,
+        '\u{0688}'..='\u{0699}'
+        | '\u{06C0}'
+        | '\u{06C3}'..='\u{06CB}'
+        | '\u{06CD}'
+        | '\u{06CF}'
+        | '\u{06D2}'
+        | '\u{06D3}'
+        | '\u{06D5}'
+        | '\u{06EE}'
+        | '\u{06EF}' => Joining::Right,
+        TATWEEL | '\u{200D}' => Joining::Causing,
+        '\u{0600}'..='\u{0605}' | '\u{06DD}' | '\u{200C}' => Joining::None,
+        _ if matches!(get_general_category(c), GeneralCategory::NonspacingMark | GeneralCategory::EnclosingMark | GeneralCategory::Format) => {
+            Joining::Transparent
+        }
+        _ => Joining::None,
+    }
+}
+
+/// Is the cluster of glyph `a` joined to the cluster of glyph `b` that follows it in `text`: both
+/// right to left in one face, `a`'s last character other than a mark joining the letter after it,
+/// and `b` starting with a letter that joins the one before it?
+fn joined(text: &str, a: &SGlyph, b: &SGlyph) -> bool {
+    if a.face.id() != b.face.id() || a.level != b.level || !a.level.is_rtl() || a.byte + a.len != b.byte {
+        return false;
+    }
+    let last = text.get(a.byte..a.byte + a.len).and_then(|s| s.chars().rev().find(|&c| joining(c) != Joining::Transparent));
+    let first = text.get(b.byte..b.byte + b.len).and_then(|s| s.chars().next());
+    matches!(last.map(joining), Some(Joining::Dual | Joining::Causing))
+        && matches!(first.map(joining), Some(Joining::Dual | Joining::Right | Joining::Causing))
+}
+
+/// The tatweel of `g`'s face and its advance in points at `g`'s scale; None when the face has
+/// no tatweel.
+pub(crate) fn tatweel(g: &SGlyph) -> Option<(u32, f64)> {
+    let gid = g.face.glyph_for(TATWEEL);
+    let advance = g.face.advance(gid) * g.sx;
+    (gid != 0 && advance.is_finite() && advance > 0.0).then_some((gid, advance))
+}
+
+/// The most tatweels one Stylistic kashida is drawn with.
+pub(crate) const MAX_TATWEELS: f64 = 64.0;
+
+/// The kashidas of the glyphs `line` (indices into `sg`, a paragraph's glyphs in logical order;
+/// `text` is the plain text) of a justified line with `room` points to fill: for each Arabic
+/// word with joined letters, at its last pair of them, the byte offset of the cluster after the kashida and
+/// the kashida's length, in text order. Words end at spaces, inline graphics, and characters other than letters
+/// and marks (punctuation, digits, symbols). Every kashida takes an equal share of `room`, up to
+/// `kind`'s longest in ems of the letter after it (as wide as its horizontal scale draws it); a
+/// Stylistic kashida is a whole number of tatweels, at most [`MAX_TATWEELS`], and a word whose
+/// share is shorter than one tatweel gets none. A line of words without joined letters, or whose
+/// font has no tatweel, gets none.
+pub(crate) fn plan(text: &str, sg: &[SGlyph], line: Range<usize>, kind: Kashida, room: f64) -> Vec<(usize, f64)> {
+    if kind == Kashida::None || !room.is_finite() || room <= 0.0 {
+        return vec![];
+    }
+    // The first glyph of the cluster after each word's last joint.
+    let mut picks: Vec<usize> = Vec::new();
+    let mut word: Option<usize> = None;
+    let mut prev: Option<usize> = None;
+    let mut j = line.start;
+    while j < line.end {
+        let Some(g) = sg.get(j) else { break };
+        let end = (j + 1..line.end).find(|&e| sg.get(e).is_none_or(|n| n.byte != g.byte)).unwrap_or(line.end);
+        let first = text.get(g.byte..g.byte + g.len).and_then(|s| s.chars().next());
+        let not_a_letter = first.is_some_and(|c| !c.is_alphabetic() && joining(c) != Joining::Transparent);
+        if g.is_space() || g.inline.is_some() || not_a_letter {
+            picks.extend(word.take());
+            prev = None;
+        } else {
+            if prev.and_then(|p| sg.get(p)).is_some_and(|a| joined(text, a, g)) && tatweel(g).is_some() {
+                word = Some(j);
+            }
+            prev = Some(j);
+        }
+        j = end;
+    }
+    picks.extend(word);
+    if picks.is_empty() {
+        return vec![];
+    }
+    let share = room / picks.len() as f64;
+    let mut out = Vec::with_capacity(picks.len());
+    for g in picks.iter().filter_map(|&k| sg.get(k)) {
+        let Some((_, t)) = tatweel(g) else { continue };
+        let longest = kind.max_em() * g.face.units_per_em() * g.sx;
+        let mut len = share.min(longest);
+        if kind == Kashida::Stylistic {
+            len = (len / t).floor().min(MAX_TATWEELS) * t;
+        }
+        if len.is_finite() && len > 1e-6 {
+            out.push((g.byte, len));
+        }
+    }
+    out
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    /// Beh joins on both sides, alef and waw only to the letter before them, hamza to neither;
+    /// marks and the format characters the file does not list are skipped, the number signs and
+    /// the end of ayah it lists join neither side, and the tatweel and the zero width joiner join
+    /// both sides.
+    #[test]
+    fn arabic_letters_join_as_arabic_shaping_lists_them() {
+        assert_eq!(joining('ب'), Joining::Dual);
+        assert_eq!(joining('ي'), Joining::Dual);
+        assert_eq!(joining('ک'), Joining::Dual);
+        assert_eq!(joining('ا'), Joining::Right);
+        assert_eq!(joining('و'), Joining::Right);
+        assert_eq!(joining('ة'), Joining::Right);
+        assert_eq!(joining('ء'), Joining::None);
+        assert_eq!(joining('\u{064E}'), Joining::Transparent);
+        assert_eq!(joining('\u{061C}'), Joining::Transparent);
+        assert_eq!(joining('\u{0600}'), Joining::None);
+        assert_eq!(joining('\u{0605}'), Joining::None);
+        assert_eq!(joining('\u{06DD}'), Joining::None);
+        assert_eq!(joining(TATWEEL), Joining::Causing);
+        assert_eq!(joining('\u{200D}'), Joining::Causing);
+        assert_eq!(joining('\u{200C}'), Joining::None);
+        assert_eq!(joining('a'), Joining::None);
+    }
+}

crates/text/src/layout.rs

@@ -4,6 +4,7 @@ use std::ops::Range;
 
 use kurbo::{Affine, BezPath, PathEl, Point, Rect, Shape, Vec2};
 use unicode_bidi::{BidiInfo, Level};
+use vectorcraft_doc::text::Kashida;
 use vectorcraft_doc::{
     Burasagari, CharStyle, HyphenationOptions, InlineArt, Justify, Kinsoku, LeadingModel, Mojikumi, ParaDirection, ParaStyle, PathAlign, PathEffect,
     SingleWordJustify, TextKind, TextObject,
@@ -14,6 +15,7 @@ use crate::composer::{Breakpoint, Params, compose};
 use crate::fontdb::FontDb;
 use crate::hyphen::hyphen_points_with;
 use crate::justify::{Flex, LineFit, apply_desired, fit_line, is_word_space};
+use crate::kashida;
 use crate::shape::{
     Punct, SGlyph, Tcy, cap_x_heights, hyphen_glyph, is_cjk, mark_word_ends, no_line_end, no_line_start, punct, shape_range, soft_line_start,
     style_metrics,
@@ -140,6 +142,34 @@ impl Ctx<'_> {
             scale: 1.0,
         });
     }
+
+    /// Draw a kashida `len` points long from `at` (the pen on the baseline) on line `line`, as
+    /// tatweels in the face, size and style of glyph `g`. Short, Medium and Long kashidas are one
+    /// tatweel stretched along the baseline; a Stylistic one is tatweels side by side. Each tatweel
+    /// is a glyph at `g`'s byte offset that stands for no character (length 0) and does not
+    /// advance: `g`'s advance takes the kashida in.
+    fn emit_kashida(&mut self, g: &SGlyph, kind: Kashida, len: f64, at: Point, line: usize) {
+        let Some((gid, t)) = kashida::tatweel(g) else { return };
+        let mut k = g.clone();
+        k.gid = gid;
+        k.adv = t;
+        k.dx = 0.0;
+        k.dy = 0.0;
+        k.len = 0;
+        k.lead = 0.0;
+        k.ch = kashida::TATWEEL;
+        k.inline = None;
+        k.tcy = None;
+        if kind == Kashida::Stylistic {
+            let n = (len / t).round().clamp(1.0, kashida::MAX_TATWEELS) as usize;
+            for m in 0..n {
+                let x = at.x + m as f64 * t;
+                self.emit(&k, Affine::translate((x, at.y)), Point::new(x, at.y), 0.0, 0.0, line);
+            }
+            return;
+        }
+        self.emit(&k, Affine::translate((at.x, at.y)) * Affine::scale_non_uniform(len / t, 1.0), at, 0.0, 0.0, line);
+    }
 }
 
 /// Lay out a text object into text-space glyph outlines (default [`LayoutOptions`]).
@@ -1934,6 +1964,11 @@ fn flow(cx: &mut Ctx<'_>, paras: &[Range<usize>], t: &TextObject, regions: Optio
                 (true, SingleWordJustify::AlignCenter) => (1, false),
                 (true, SingleWordJustify::AlignRight) => (2, false),
             };
+            // Insert Kashidas: the Arabic words of a horizontal line take its room on kashidas,
+            // and the word spaces and gaps take what is left.
+            let kashidas =
+                if justify && !cx.vertical && room > w + EPS { kashida::plan(cx.text, &sg, i..body, para.kashida, room - w) } else { vec![] };
+            let w = w + kashidas.iter().map(|k| k.1).sum::<f64>();
             if justify && (room - w).abs() > EPS {
                 let line_flex = |j: usize| if held.contains(&j) { Flex::default() } else { flex.get(j).copied().unwrap_or_default() };
                 if cjk_gaps > 0 && room > w {
@@ -1989,7 +2024,7 @@ fn flow(cx: &mut Ctx<'_>, paras: &[Range<usize>], t: &TextObject, regions: Optio
             let leading_space_width: f64 =
                 order.iter().take_while(|&&offset| i + offset >= trimmed).filter_map(|&offset| sg.get(i + offset)).map(|g| g.adv).sum();
             let mut x = start_x - leading_space_width;
-            for offset in order {
+            for (oi, &offset) in order.iter().enumerate() {
                 let j = i + offset;
                 let Some(g) = sg.get(j) else { continue };
                 let mut adv = g.adv;
@@ -2020,6 +2055,16 @@ fn flow(cx: &mut Ctx<'_>, paras: &[Range<usize>], t: &TextObject, regions: Optio
                         adv += per_gap;
                     }
                 }
+                // The kashida before a cluster in the text is drawn at the cluster's right, between
+                // it and the letter before it, and the cluster's last glyph advances over it: the
+                // caret, selection and hit testing take it as part of the cluster.
+                let kashida = kashidas
+                    .binary_search_by_key(&g.byte, |k| k.0)
+                    .ok()
+                    .and_then(|at| kashidas.get(at))
+                    .filter(|_| order.get(oi + 1).and_then(|&o| sg.get(i + o)).is_none_or(|next| next.byte != g.byte))
+                    .map(|k| k.1);
+                adv += kashida.unwrap_or(0.0);
                 let y = baseline - align_shift(g, cx.style_at(g.byte).char_align, line_em, cx.vertical);
                 let place = if scale != 1.0 { Affine::translate((x, y)) * Affine::scale_non_uniform(scale, 1.0) } else { Affine::translate((x, y)) };
                 cx.emit(g, place, Point::new(x, y), 0.0, adv, li);
@@ -2034,6 +2079,9 @@ fn flow(cx: &mut Ctx<'_>, paras: &[Range<usize>], t: &TextObject, regions: Optio
                         tab.outline.extend(dots);
                     }
                 }
+                if let Some(len) = kashida {
+                    cx.emit_kashida(g, para.kashida, len, Point::new(x + adv - len, y), li);
+                }
                 x += adv;
                 if j < trimmed {
                     x_end = x;

crates/text/src/lib.rs

@@ -19,6 +19,7 @@ mod fontconfig;
 mod fontdb;
 pub mod hyphen;
 mod justify;
+mod kashida;
 mod layout;
 mod shape;
 #[cfg(not(target_arch = "wasm32"))]
@@ -286,15 +287,36 @@ fn dir(angle: f64) -> Vec2 {
     Vec2::new(angle.cos(), angle.sin())
 }
 
-/// Caret for byte offset `byte`, as a (top, bottom) segment in text space.
+/// The left and right x of the cluster of `glyphs[i]` (glyphs of one line of horizontal type
+/// that is not on a path): the glyphs next to it with its byte offset and length, and the
+/// tatweels of a kashida after it (length 0, the same byte offset). None for vertical type and
+/// type on a path.
+fn cluster_extent(layout: &TextLayout, glyphs: &[PositionedGlyph], i: usize) -> Option<(f64, f64)> {
+    let g = glyphs.get(i).filter(|_| !layout.vertical && !layout.on_path)?;
+    let same = |o: &PositionedGlyph| o.byte == g.byte && (o.len == g.len || o.len == 0);
+    let start = glyphs.get(..i)?.iter().rposition(|o| !same(o)).map_or(0, |p| p + 1);
+    let end = glyphs.get(i..)?.iter().position(|o| !same(o)).map_or(glyphs.len(), |p| i + p);
+    let span = glyphs.get(start..end)?;
+    let left = span.iter().map(|o| o.origin.x).fold(f64::INFINITY, f64::min);
+    let right = span.iter().map(|o| o.origin.x + o.advance).fold(f64::NEG_INFINITY, f64::max);
+    (left.is_finite() && right.is_finite()).then_some((left, right))
+}
+
+/// Caret for byte offset `byte`, as a (top, bottom) segment in text space. In horizontal type, a
+/// cluster drawn with several glyphs is measured whole ([`cluster_extent`]).
 pub fn caret_position(layout: &TextLayout, byte: usize) -> (Point, Point) {
     let Some(line) = layout.lines.get(layout.line_of(byte)) else {
         return (Point::ZERO, Point::ZERO);
     };
     let glyphs = &layout.glyphs[line.glyph_start..line.glyph_end];
-    let (pos, angle) = if let Some(g) = glyphs.iter().find(|g| g.byte <= byte && g.byte + g.len > byte) {
+    let (pos, angle) = if let Some(i) = glyphs.iter().position(|g| g.byte <= byte && g.byte + g.len > byte) {
+        let g = &glyphs[i];
         let frac = if byte <= g.byte { 0.0 } else { (byte - g.byte) as f64 / g.len.max(1) as f64 };
-        (g.origin + dir(g.angle) * (g.advance * if g.rtl { 1.0 - frac } else { frac }), g.angle)
+        let (origin, advance) = match cluster_extent(layout, glyphs, i) {
+            Some((left, right)) => (Point::new(left, g.origin.y), right - left),
+            None => (g.origin, g.advance),
+        };
+        (origin + dir(g.angle) * (advance * if g.rtl { 1.0 - frac } else { frac }), g.angle)
     } else if let Some(g) = glyphs.iter().max_by_key(|g| g.byte + g.len) {
         (g.origin + dir(g.angle) * if g.rtl { 0.0 } else { g.advance }, g.angle)
     } else {
@@ -359,13 +381,15 @@ pub fn byte_in_line(layout: &TextLayout, li: usize, x: f64) -> usize {
     let Some(line) = layout.lines.get(li) else { return 0 };
     let glyphs = &layout.glyphs[line.glyph_start..line.glyph_end];
     // A cluster drawn with several adjacent glyphs (a Devanagari pre-base matra and its consonant,
-    // a consonant and its reph) has one caret stop at each end of its glyphs taken together.
+    // a consonant and its reph) has one caret stop at each end of its glyphs taken together. The
+    // tatweels of a kashida have no source length and come after the glyphs of the letter after
+    // the kashida in the text; they belong to that letter's cluster.
     let mut clusters: Vec<(f64, f64, &PositionedGlyph)> = Vec::with_capacity(glyphs.len());
     for g in glyphs {
         let left = layout.logical_point(g.origin).x;
         let right = left + g.advance;
         match clusters.last_mut() {
-            Some((l, r, c)) if c.byte == g.byte && c.len == g.len => (*l, *r) = (l.min(left), r.max(right)),
+            Some((l, r, c)) if c.byte == g.byte && (c.len == g.len || g.len == 0) => (*l, *r) = (l.min(left), r.max(right)),
             _ => clusters.push((left, right, g)),
         }
     }
@@ -402,9 +426,11 @@ pub fn line_end_of(layout: &TextLayout, byte: usize) -> usize {
 fn x_in_line(layout: &TextLayout, li: usize, byte: usize) -> f64 {
     let line = &layout.lines[li];
     let glyphs = &layout.glyphs[line.glyph_start..line.glyph_end];
-    if let Some(g) = glyphs.iter().find(|g| g.byte <= byte && g.byte + g.len > byte) {
+    if let Some(i) = glyphs.iter().position(|g| g.byte <= byte && g.byte + g.len > byte) {
+        let g = &glyphs[i];
         let frac = if byte <= g.byte { 0.0 } else { (byte - g.byte) as f64 / g.len.max(1) as f64 };
-        return layout.logical_point(g.origin).x + g.advance * if g.rtl { 1.0 - frac } else { frac };
+        let (left, advance) = cluster_extent(layout, glyphs, i).map_or((layout.logical_point(g.origin).x, g.advance), |(l, r)| (l, r - l));
+        return left + advance * if g.rtl { 1.0 - frac } else { frac };
     }
     glyphs.iter().max_by_key(|g| g.byte + g.len).map_or(line.x0, |g| layout.logical_point(g.origin).x + if g.rtl { 0.0 } else { g.advance })
 }

crates/text/src/tests_justify.rs

@@ -3,6 +3,7 @@
 
 use super::*;
 use kurbo::{Affine, Shape};
+use vectorcraft_doc::text::Kashida;
 use vectorcraft_doc::{CharStyle, JustificationOptions, Justify, SingleWordJustify, TextKind};
 use vectorcraft_geom::PathData;
 
@@ -136,6 +137,173 @@ fn single_word_lines_follow_single_word_justification() {
     assert!((c0 - 15.0).abs() < 1e-3 && (c1 - (w - 15.0)).abs() < 1e-3, "centred: {c0}..{c1}");
 }
 
+/// An OpenType (GSUB) Arabic face with a tatweel: craft-fonts' Noto Sans Arabic when the build has
+/// craft-fonts (`CRAFT_FONTS_DIR`), else an installed one. None skips the test.
+fn arabic_face(test: &str) -> Option<std::sync::Arc<FontFace>> {
+    let opentype = |face: &FontFace| {
+        use skrifa::raw::TableProvider;
+        face.skrifa().is_some_and(|f| f.gsub().is_ok())
+    };
+    let face = ["Noto Sans Arabic", "Arial", "Geeza Pro"]
+        .into_iter()
+        .filter_map(|name| db().face(name, "Regular"))
+        .find(|face| face.covers('ب') && face.covers('د') && face.covers('\u{0640}') && opentype(face));
+    match &face {
+        Some(face) => eprintln!("ASSERTIONS RUN: {test}; Arabic font {} {}", face.family, face.style),
+        None => eprintln!("SKIPPED: {test}; no font covers Arabic and the tatweel"),
+    }
+    face
+}
+
+/// Arabic type at 20 pt in `face`, in a frame 300 pt wide, aligned as `justify` with `kashida`.
+fn arabic_area(face: &FontFace, text: &str, justify: Justify, kashida: Kashida) -> TextObject {
+    let st = CharStyle { font_family: face.family.clone(), font_style: face.style.clone(), size: 20.0, ..CharStyle::default() };
+    let mut t = TextObject::point(Point::ZERO, text, st);
+    t.kind = TextKind::Area { frame: PathData::from_bezpath(&Rect::new(0.0, 0.0, 300.0, 1000.0).to_path(0.1)) };
+    t.xf = Affine::IDENTITY;
+    t.para.justify = justify;
+    t.para.kashida = kashida;
+    t
+}
+
+/// The kashida glyphs of a layout: tatweels that stand for no character.
+fn kashidas<'a>(l: &'a TextLayout, face: &FontFace) -> Vec<&'a PositionedGlyph> {
+    let tatweel = face.glyph_for('\u{0640}');
+    l.glyphs.iter().filter(|g| g.len == 0 && g.gid == tatweel).collect()
+}
+
+/// Insert Kashidas: a justified Arabic line lengthens each word with one kashida between its last
+/// two joined letters, up to a quarter, half or whole em (Stylistic: whole tatweels up to an em),
+/// before it widens the word space. The line keeps its width, the kashida fills the gap between
+/// the letters it joins, and None leaves the line as it was.
+#[test]
+fn justified_arabic_lines_take_their_room_on_kashidas() {
+    let Some(face) = arabic_face("justified_arabic_lines_take_their_room_on_kashidas") else { return };
+    // Two words whose last letters join (teh and beh, meem and dal) and one whose letters (waw, reh,
+    // dal) join none after them.
+    let text = "كتب ورد محمد";
+    let spaces: Vec<usize> = text.match_indices(' ').map(|(b, _)| b).collect();
+    let off = layout(db(), &arabic_area(&face, text, Justify::JustifyAll, Kashida::None));
+    assert!(off.glyphs.iter().all(|g| g.len > 0), "no kashidas without Insert Kashidas");
+    let measure = |l: &TextLayout| l.lines[0].x1 - l.lines[0].x0;
+    assert!((measure(&off) - 300.0).abs() < 1e-6, "the line fills the frame: {}", measure(&off));
+    let space = at(&off, spaces[0]).advance;
+    let tatweel = face.advance(face.glyph_for('\u{0640}')) * 20.0 / face.units_per_em();
+    for (kind, longest) in [(Kashida::Short, 5.0), (Kashida::Medium, 10.0), (Kashida::Long, 20.0), (Kashida::Stylistic, 20.0)] {
+        let on = layout(db(), &arabic_area(&face, text, Justify::JustifyAll, kind));
+        let k = kashidas(&on, &face);
+        let mut bytes: Vec<usize> = k.iter().map(|g| g.byte).collect();
+        bytes.sort_unstable();
+        bytes.dedup();
+        assert_eq!(bytes, ["كتب".len() - 'ب'.len_utf8(), text.len() - 'د'.len_utf8()], "{kind:?}: before the last letter of each word");
+        let each = if kind == Kashida::Stylistic { (longest / tatweel).floor() * tatweel } else { longest };
+        let mut total = 0.0;
+        for &b in &bytes {
+            let (start, end, count) = kashida_span(&on, &face, b);
+            assert!((end - start - each).abs() < 1e-6, "{kind:?}: {start}..{end}");
+            total += end - start;
+            if kind == Kashida::Stylistic {
+                assert!((count as f64 * tatweel - each).abs() < 1e-6, "{kind:?}: whole tatweels");
+            }
+            // The letter after the kashida in the text advances over it to the letter before it,
+            // so the caret before that letter and a selection of it reach the letter before it.
+            let after = on.glyphs.iter().filter(|o| o.byte == b && o.len > 0);
+            let len = after.clone().map(|o| o.len).max().unwrap();
+            let ink = after.clone().map(|o| o.origin.x).fold(f64::MAX, f64::min);
+            assert!(ink < start && (after.map(|o| o.origin.x + o.advance).fold(f64::MIN, f64::max) - end).abs() < 1e-6, "{kind:?}");
+            let caret = caret_position(&on, b).0.x;
+            assert!((caret - end).abs() < 1e-6, "{kind:?}: the caret before the letter: {caret} {end}");
+            let x_max = selection_quads(&on, b, b + len).iter().flatten().map(|p| p.x).fold(f64::MIN, f64::max);
+            assert!((x_max - end).abs() < 1e-6, "{kind:?}: the selection takes the kashida in: {x_max} {end}");
+        }
+        assert!((measure(&on) - measure(&off)).abs() < 1e-6, "{kind:?}: same width");
+        for &b in &spaces {
+            assert!((at(&on, b).advance - (space - total / 2.0)).abs() < 1e-6, "{kind:?}: the spaces give up the kashidas' length");
+        }
+    }
+    // A click on a letter and its kashida goes to the nearer edge of the two taken together: dal is
+    // narrower than a Long kashida.
+    let on = layout(db(), &arabic_area(&face, text, Justify::JustifyAll, Kashida::Long));
+    let dal = text.len() - 'د'.len_utf8();
+    let (start, end, _) = kashida_span(&on, &face, dal);
+    let ink = on.glyphs.iter().filter(|o| o.byte == dal && o.len > 0).map(|o| o.origin.x).fold(f64::MAX, f64::min);
+    let middle = (ink + end) / 2.0;
+    assert!(start < middle, "the kashida is longer than the letter: {ink} {start} {end}");
+    assert_eq!(byte_in_line(&on, 0, (start + middle) / 2.0), text.len(), "left of the middle: the letter's left edge");
+    assert_eq!(byte_in_line(&on, 0, (middle + end) / 2.0), dal, "right of the middle: its right edge");
+    // A letter with a vowel mark is a cluster of two glyphs: the caret before it and a selection of
+    // it still reach the letter before the kashida.
+    let marked = "كتبَ ورد";
+    let on = layout(db(), &arabic_area(&face, marked, Justify::JustifyAll, Kashida::Medium));
+    let beh = "كت".len();
+    let (_, end, _) = kashida_span(&on, &face, beh);
+    assert!(on.glyphs.iter().filter(|o| o.byte == beh && o.len > 0).count() >= 2, "beh and fatha");
+    assert!((caret_position(&on, beh).0.x - end).abs() < 1e-6, "{} {end}", caret_position(&on, beh).0.x);
+    let x_max = selection_quads(&on, beh, "كتبَ".len()).iter().flatten().map(|p| p.x).fold(f64::MIN, f64::max);
+    assert!((x_max - end).abs() < 1e-6, "{x_max} {end}");
+    // Punctuation ends a word as a space does.
+    let text = "كتب/محمد";
+    let on = layout(db(), &arabic_area(&face, text, Justify::JustifyAll, Kashida::Medium));
+    let mut bytes: Vec<usize> = kashidas(&on, &face).iter().map(|g| g.byte).collect();
+    bytes.sort_unstable();
+    assert_eq!(bytes, ["كتب".len() - 'ب'.len_utf8(), text.len() - 'د'.len_utf8()]);
+    // At 50% horizontal scale an em is half as wide; the line still fills the frame.
+    for kind in [Kashida::Long, Kashida::Stylistic] {
+        let text = "كتب ورد محمد";
+        let mut t = arabic_area(&face, text, Justify::JustifyAll, kind);
+        for r in &mut t.runs {
+            r.style.h_scale = 50.0;
+        }
+        let half = layout(db(), &t);
+        let each = if kind == Kashida::Stylistic { (10.0 / (tatweel * 0.5)).floor() * tatweel * 0.5 } else { 10.0 };
+        for b in ["كتب".len() - 'ب'.len_utf8(), text.len() - 'د'.len_utf8()] {
+            let (start, end, _) = kashida_span(&half, &face, b);
+            assert!((end - start - each).abs() < 1e-6, "{kind:?} at 50%: {start}..{end}");
+        }
+        assert!((measure(&half) - 300.0).abs() < 1e-6, "{kind:?} at 50%: {}", measure(&half));
+    }
+}
+
+/// Where the kashida before the cluster at byte `b` starts, where the letter before it in the text
+/// starts (the kashida's end), and how many tatweels draw it.
+fn kashida_span(l: &TextLayout, face: &FontFace, b: usize) -> (f64, f64, usize) {
+    let k: Vec<_> = kashidas(l, face).into_iter().filter(|g| g.byte == b).collect();
+    let start = k.iter().map(|g| g.origin.x).fold(f64::MAX, f64::min);
+    let end = l.glyphs.iter().filter(|o| o.byte + o.len == b && o.len > 0).map(|o| o.origin.x).fold(f64::MAX, f64::min);
+    (start, end, k.len())
+}
+
+/// Insert Kashidas changes only justified horizontal lines of Arabic: right-aligned and Auto
+/// Arabic paragraphs, a justified Latin one and justified vertical Arabic type are set as with
+/// None.
+#[test]
+fn kashidas_leave_unjustified_and_latin_lines_as_they_were() {
+    let same = |a: &TextLayout, b: &TextLayout| {
+        assert_eq!(a.glyphs.len(), b.glyphs.len());
+        for (x, y) in a.glyphs.iter().zip(&b.glyphs) {
+            assert_eq!((x.gid, x.byte, x.len, x.origin, x.advance), (y.gid, y.byte, y.len, y.origin, y.advance));
+        }
+    };
+    let latin = |k: Kashida| {
+        let mut t = area("ab cd", 300.0, Justify::JustifyAll, JustificationOptions::default());
+        t.para.kashida = k;
+        layout(db(), &t)
+    };
+    same(&latin(Kashida::Long), &latin(Kashida::None));
+    let Some(face) = arabic_face("kashidas_leave_unjustified_and_latin_lines_as_they_were") else { return };
+    let arabic = |j: Justify, k: Kashida| layout(db(), &arabic_area(&face, "كتب محمد", j, k));
+    same(&arabic(Justify::Right, Kashida::Long), &arabic(Justify::Right, Kashida::None));
+    same(&arabic(Justify::Auto, Kashida::Medium), &arabic(Justify::Auto, Kashida::None));
+    assert!(!kashidas(&arabic(Justify::JustifyAll, Kashida::Medium), &face).is_empty());
+    // Vertical type is set as with None too.
+    let vertical = |k: Kashida| {
+        let mut t = arabic_area(&face, "كتب محمد", Justify::JustifyAll, k);
+        t.vertical = true;
+        layout(db(), &t)
+    };
+    same(&vertical(Kashida::Medium), &vertical(Kashida::None));
+}
+
 /// Auto Leading: characters whose leading is Auto are set at the paragraph's share of their size;
 /// an explicit leading is kept.
 #[test]

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

@@ -1789,6 +1789,9 @@
 	Modified:	Модифицирано:
 	Modify	Модифициране
 	Mojikumi	Моджикуми
+	Insert Kashidas	Вмъкване на кашиди
+	Long	Дълго
+	Stylistic	Стилистично
 	Mojikumi Set	Набор Mojikumi
 	Kinsoku Set	Набор Kinsoku
 	Hard	Твърдо

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

@@ -1756,6 +1756,9 @@ lighting	Light	Světlo
 	Left Indent	Odsazení zleva
 	Left-to-Right Paragraph Direction	Směr odstavce zleva doprava
 	Line-end Punctuation Half Width	Interpunkce na konci řádku poloviční šířky
+	Insert Kashidas	Vložit kašídy
+	Long	Dlouhý
+	Stylistic	Stylistický
 	Mojikumi Set	Sada Mojikumi
 	Kinsoku Set	Sada Kinsoku
 	Hard	Pevné

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

@@ -1573,6 +1573,9 @@ lighting	Light	Lys
 	Left Indent	Venstre indrykning
 	Left-to-Right Paragraph Direction	Afsnitsretning fra venstre mod højre
 	Line-end Punctuation Half Width	Skilletegn i halv bredde ved linjeslut
+	Insert Kashidas	Indsæt kashidaer
+	Long	Lang
+	Stylistic	Stilistisk
 	Mojikumi Set	Mojikumi-sæt
 	Kinsoku Set	Kinsoku-sæt
 	Hard	Hård

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

@@ -1838,6 +1838,9 @@ file-filter	Templates	Vorlagen
 	Modified:	Geändert:
 	Modify	Ändern
 	Mojikumi	Mojikumi
+	Insert Kashidas	Kashidas einfügen
+	Long	Lang
+	Stylistic	Stilistisch
 	Mojikumi Set	Mojikumi-Satz
 	Kinsoku Set	Kinsoku-Satz
 	Hard	Hart

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

@@ -2549,6 +2549,9 @@ theme	Appearance	Εμφάνιση
 	Modified since it was read: {path}	Τροποποιήθηκε μετά την ανάγνωση: {path}
 	Modified:	Τροποποιήθηκε:
 	Mojikumi	Mojikumi
+	Insert Kashidas	Εισαγωγή κασίντα
+	Long	Μακρύ
+	Stylistic	Στιλιστικό
 	Mojikumi Set	Σύνολο Mojikumi
 	Kinsoku Set	Σύνολο Kinsoku
 	Mono	Μονοφωνικό

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

@@ -1830,6 +1830,9 @@
 	Modified:	Modificado:
 	Modify	Modificar
 	Mojikumi	Mojikumi
+	Insert Kashidas	Insertar kashidas
+	Long	Larga
+	Stylistic	Estilística
 	Mojikumi Set	Conjunto de mojikumi
 	Kinsoku Set	Conjunto de kinsoku
 	Hard	Fuerte

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

@@ -1719,6 +1719,9 @@ lighting	Light	Valo
 	Left Indent	Vasen sisennys
 	Left-to-Right Paragraph Direction	Kappaleen suunta vasemmalta oikealle
 	Line-end Punctuation Half Width	Rivinlopun välimerkit puolileveinä
+	Insert Kashidas	Lisää kashidat
+	Long	Pitkä
+	Stylistic	Tyylitelty
 	Mojikumi Set	Mojikumi-joukko
 	Kinsoku Set	Kinsoku-joukko
 	Hard	Tiukka

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

@@ -1829,6 +1829,9 @@
 	Modified:	Modifié :
 	Modify	Modifier
 	Mojikumi	Mojikumi
+	Insert Kashidas	Insérer des kashidas
+	Long	Longue
+	Stylistic	Stylistique
 	Mojikumi Set	Jeu de mojikumi
 	Kinsoku Set	Jeu de kinsoku
 	Hard	Fort

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

@@ -2316,6 +2316,9 @@ file-filter	Templates	Sablonok
 	Modified:	Módosítva:
 	Modify	Módosítás
 	Mojikumi	Mojikumi
+	Insert Kashidas	Kasidák beszúrása
+	Long	Hosszú
+	Stylistic	Stilisztikai
 	Mojikumi Set	Mojikumi-készlet
 	Monitor RGB	Monitor-RGB
 	Mono	Egyszínű

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

@@ -1573,6 +1573,9 @@ lighting	Light	Cahaya
 	Left Indent	Indentasi kiri
 	Left-to-Right Paragraph Direction	Arah paragraf kiri ke kanan
 	Line-end Punctuation Half Width	Tanda baca akhir baris lebar setengah
+	Insert Kashidas	Sisipkan kashida
+	Long	Panjang
+	Stylistic	Stilistik
 	Mojikumi Set	Set Mojikumi
 	Kinsoku Set	Set Kinsoku
 	Hard	Keras

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

@@ -1856,6 +1856,9 @@ file-filter	Templates	Modelli
 	Modified:	Modificato:
 	Modify	Modifica
 	Mojikumi	Mojikumi
+	Insert Kashidas	Inserisci kashida
+	Long	Lunga
+	Stylistic	Stilistica
 	Mojikumi Set	Set mojikumi
 	Kinsoku Set	Set kinsoku
 	Hard	Forte

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

@@ -48,6 +48,9 @@
 	Japanese	日本語
 	Join Our Discord	Discord に参加
 	Line-end Punctuation Half Width	行末約物半角
+	Insert Kashidas	カシーダを挿入
+	Long	長い
+	Stylistic	スタイリスティック
 	Mojikumi Set	文字組み
 	Kinsoku Set	禁則処理
 	Hard	強い禁則

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

@@ -1475,6 +1475,9 @@ lighting	Light	სინათლე
 	Left Indent	მარცხენა შეწევა
 	Left-to-Right Paragraph Direction	აბზაცის მიმართულება მარცხნიდან მარჯვნივ
 	Line-end Punctuation Half Width	სტრიქონის ბოლოს პუნქტუაცია ნახევარი სიგანით
+	Insert Kashidas	ქაშიდების ჩასმა
+	Long	გრძელი
+	Stylistic	სტილისტური
 	Mojikumi Set	Mojikumi-ის ნაკრები
 	Kinsoku Set	Kinsoku-ის ნაკრები
 	Hard	მკაცრი

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

@@ -44,6 +44,9 @@
 	Japanese	일본어
 	Join Our Discord	Discord 참여하기
 	Line-end Punctuation Half Width	줄 끝 문장 부호 반각
+	Insert Kashidas	카시다 삽입
+	Long	길게
+	Stylistic	스타일
 	Mojikumi Set	모지쿠미 세트
 	Kinsoku Set	긴소쿠 세트
 	Hard	강하게

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

@@ -1587,6 +1587,9 @@ lighting	Light	Licht
 	Left Indent	Links inspringen
 	Left-to-Right Paragraph Direction	Alinearichting van links naar rechts
 	Line-end Punctuation Half Width	Leestekens op regeleinde op halve breedte
+	Insert Kashidas	Kashida's invoegen
+	Long	Lang
+	Stylistic	Stilistisch
 	Mojikumi Set	Mojikumi-set
 	Kinsoku Set	Kinsoku-set
 	Hard	Hard

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

@@ -1676,6 +1676,9 @@ lighting	Light	Światło
 	Left Indent	Wcięcie z lewej
 	Left-to-Right Paragraph Direction	Kierunek akapitu od lewej do prawej
 	Line-end Punctuation Half Width	Interpunkcja na końcu wiersza o połowie szerokości
+	Insert Kashidas	Wstaw kaszidy
+	Long	Długi
+	Stylistic	Stylistyczny
 	Mojikumi Set	Zestaw mojikumi
 	Kinsoku Set	Zestaw kinsoku
 	Hard	Ścisły

crates/ui-egui/src/i18n/pt-br.tsv

@@ -3136,6 +3136,9 @@ lighting	Light	Luz
 	Lock Others	Bloquear outros
 	Merge Selected	Mesclar selecionados
 	Model	Modelo
+	Insert Kashidas	Inserir Kashidas
+	Long	Longo
+	Stylistic	Estilístico
 	Mojikumi Set	Conjunto Mojikumi
 	Kinsoku Set	Conjunto Kinsoku
 	Hard	Duro

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

@@ -1854,6 +1854,9 @@ file-filter	Templates	Шаблоны
 	Modified:	Изменено:
 	Modify	Изменить
 	Mojikumi	Mojikumi
+	Insert Kashidas	Вставлять кашиды
+	Long	Длинные
+	Stylistic	Стилистические
 	Mojikumi Set	Набор mojikumi
 	Kinsoku Set	Набор kinsoku
 	Hard	Строгий

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

@@ -1789,6 +1789,9 @@
 	Modified:	Ändrad:
 	Modify	Ändra
 	Mojikumi	Mojikumi
+	Insert Kashidas	Infoga kashidor
+	Long	Lång
+	Stylistic	Stilistisk
 	Mojikumi Set	Mojikumi-uppsättning
 	Kinsoku Set	Kinsoku-uppsättning
 	Hard	Hård

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

@@ -1850,6 +1850,9 @@ file-filter	Templates	Шаблони
 	Modified:	Змінено:
 	Modify	Змінити
 	Mojikumi	Mojikumi
+	Insert Kashidas	Вставляти кашиди
+	Long	Довгі
+	Stylistic	Стилістичні
 	Mojikumi Set	Набір mojikumi
 	Kinsoku Set	Набір kinsoku
 	Hard	Суворий

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

@@ -2127,6 +2127,9 @@ file-filter	Templates	Mẫu
 	Modified:	Đã sửa đổi:
 	Modify	Sửa đổi
 	Mojikumi	Mojikumi
+	Insert Kashidas	Chèn kashida
+	Long	Dài
+	Stylistic	Kiểu cách
 	Mojikumi Set	Bộ Mojikumi
 	Monitor RGB	RGB màn hình
 	Mono	Đơn sắc

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

@@ -4599,6 +4599,9 @@ imageTrace	Outline	轮廓
 	Left-to-Right Paragraph Direction	从左到右段落方向
 	Right-to-Left Paragraph Direction	从右到左段落方向
 	Line-end Punctuation Half Width	行尾标点半角
+	Insert Kashidas	插入卡希达
+	Long	长
+	Stylistic	风格化
 	Mojikumi Set	标点挤压集
 	Kinsoku Set	Kinsoku 集
 	Hard	强

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

@@ -2583,6 +2583,9 @@ file-filter	Templates	範本
 	Modified since it was read: {path}	讀取後已被修改：{path}
 	Modified:	修改時間：
 	Modify	修改
+	Insert Kashidas	插入卡希達
+	Long	長
+	Stylistic	風格化
 	Mojikumi Set	標點間距
 	Kinsoku Set	Kinsoku 集
 	Hard	強

crates/ui-egui/src/panels/paragraph.rs

@@ -1,7 +1,7 @@
 //! Paragraph panel: seven alignment buttons, Paragraph Direction (with the Indic options), indents,
-//! space before/after, Hyphenate, Mojikumi Set and Kinsoku Set (with the East Asian options); the panel menu
-//! turns Roman Hanging Punctuation on and off, opens Justification… and Hyphenation… and picks the
-//! Single-line or Every-line Composer.
+//! space before/after, Hyphenate, Insert Kashidas (with the Indic options), Mojikumi Set and Kinsoku
+//! Set (with the East Asian options); the panel menu turns Roman Hanging Punctuation on and off,
+//! opens Justification… and Hyphenation… and picks the Single-line or Every-line Composer.
 
 use egui::{Ui, vec2};
 use serde_json::{Value, json};
@@ -247,6 +247,28 @@ pub fn show(app: &mut VectorcraftApp, ui: &mut Ui) {
         return;
     }
     hyphenate_check(app, ui, &para);
+    // How long the kashidas are that justify Arabic lines, with the Middle Eastern (Indic) options.
+    if app.session.prefs.show_indic_options {
+        ui.horizontal(|ui| {
+            use vectorcraft_doc::text::Kashida;
+            widgets::dim_label(ui, tl!("Insert Kashidas"));
+            let kinds = [
+                (tl!("None"), Kashida::None, "none"),
+                (tl!("Short"), Kashida::Short, "short"),
+                (tl!("Medium"), Kashida::Medium, "medium"),
+                (tl!("Long"), Kashida::Long, "long"),
+                (tl!("Stylistic"), Kashida::Stylistic, "stylistic"),
+            ];
+            let names = kinds.map(|k| k.0);
+            let current = kinds.iter().find(|k| k.1 == para.kashida).map_or(names[0], |k| k.0);
+            // Already translated: shown as they are.
+            if let Some(i) = widgets::dropdown_names(ui, "pa-kashida", current, &names, ui.available_width() - 4.0)
+                && let Some((_, _, key)) = kinds.get(i)
+            {
+                format(app, json!({"kashida": key}));
+            }
+        });
+    }
     // Japanese composition: how punctuation is spaced (JLREQ 3.1), with the East Asian options.
     if app.session.prefs.show_east_asian_options {
         ui.horizontal(|ui| {
@@ -345,7 +367,7 @@ pub fn menu(app: &mut VectorcraftApp, ui: &mut Ui) {
 /// Reset Panel: the paragraphs the panel acts on ([`format`]) take Auto alignment, no indents or
 /// paragraph spacing, Hyphenate off with the default Hyphenation and Justification options, Auto
 /// direction, Bottom-to-Bottom Leading, Regular burasagari, the Hard kinsoku set, the Every-line
-/// Composer and Roman Hanging Punctuation off.
+/// Composer, Roman Hanging Punctuation off and no kashidas.
 fn reset_panel(app: &mut VectorcraftApp) {
     let h = HyphenationOptions::default();
     let j = vectorcraft_doc::JustificationOptions::default();
@@ -355,7 +377,7 @@ fn reset_panel(app: &mut VectorcraftApp) {
         json!({
             "leftIndent": 0, "rightIndent": 0, "firstLineIndent": 0, "spaceBefore": 0, "spaceAfter": 0, "hyphenate": false,
             "wordsLongerThan": h.words_longer_than, "afterFirst": h.after_first, "beforeLast": h.before_last,
-            "hyphenLimit": h.hyphen_limit, "hyphenationZone": h.zone, "hyphenateCapitalized": h.capitalized,
+            "hyphenLimit": h.hyphen_limit, "hyphenationZone": h.zone, "hyphenateCapitalized": h.capitalized, "kashida": "none",
             "wordSpacing": j.word_spacing, "letterSpacing": j.letter_spacing, "glyphScaling": j.glyph_scaling,
             "autoLeading": j.auto_leading, "singleWordJustification": "fullJustify",
             "direction": "auto", "leadingModel": "romanBaseline", "burasagari": "standard", "kinsoku": "hard", "composer": "everyLine",
@@ -587,6 +609,32 @@ mod tests {
         assert!(tips(&mut app) > without, "two more buttons");
     }
 
+    /// Insert Kashidas is in the panel with the Middle Eastern (Indic) options only, shows the
+    /// paragraph's setting, and Reset Panel sets it back to None.
+    #[test]
+    fn insert_kashidas_shows_with_the_indic_options_and_reset_panel_turns_it_off() {
+        let mut app = VectorcraftApp::new(Session::new(), Default::default());
+        app.run("file.new", json!({"width": 400, "height": 200})).unwrap();
+        let id = app.run("text.create", json!({"x": 20, "y": 50, "text": "كتب محمد"})).unwrap()["id"].clone();
+        app.run("select.set", json!({"ids": [id]})).unwrap();
+        crate::i18n::set_current(crate::i18n::Lang::EN);
+        let painted = |app: &mut VectorcraftApp| crate::tests_labels::painted_text(app, show);
+        assert!(!painted(&mut app).contains("Insert Kashidas"));
+        app.session.prefs.show_indic_options = true;
+        let text = painted(&mut app);
+        assert!(text.contains("Insert Kashidas") && text.contains("None"), "{text}");
+        app.run("text.setFormat", json!({"kashida": "medium"})).unwrap();
+        assert!(painted(&mut app).contains("Medium"));
+        let kashida = |app: &VectorcraftApp| {
+            let node = app.session.active().unwrap().doc.node(vectorcraft_doc::NodeId(id.as_u64().unwrap())).unwrap();
+            let NodeKind::Text(text) = &node.kind else { panic!("text") };
+            text.para_at(0).kashida
+        };
+        assert_eq!(kashida(&app), vectorcraft_doc::text::Kashida::Medium);
+        reset_panel(&mut app);
+        assert_eq!(kashida(&app), vectorcraft_doc::text::Kashida::None);
+    }
+
     /// Reset Panel turns Hyphenate and Roman Hanging Punctuation off and sets the Hyphenation and
     /// Justification options back to their defaults in every paragraph it acts on, so the paragraphs
     /// save neither.

docs/mcp.md

@@ -3792,6 +3792,27 @@ values the Paragraph panel shows, with Preview; OK sends the values that changed
 ```json
 {"name":"run_command","arguments":{"command":"text.setFormat","params":{"wordSpacing":[80,100,150],"letterSpacing":{"max":5},"singleWordJustification":"alignLeft"}}}
 ```
+
+## Insert Kashidas
+
+`text.setFormat {kashida}` (Paragraph panel › Insert Kashidas, shown with the Indic options) sets how the justified
+lines of the paragraphs of the selected type (or `ids`, or the paragraphs a `start` / `end` range touches) lengthen
+their Arabic words: `"none"` (the default), `"short"`, `"medium"`, `"long"` or `"stylistic"`. On a justified line of
+horizontal area type that is shorter than its measure, each Arabic word with joined letters gets one kashida between its
+last pair of them: a tatweel (U+0640) in the font of the letter after it. Words end at spaces, inline graphics and
+characters other than letters and marks, such as punctuation, digits and symbols. The kashidas share the line's room
+equally, each at most a quarter of an em (short), half an em (medium) or an em (long) of that letter's size at its
+horizontal scale; a stylistic kashida is a row of the font's own tatweels, as many whole ones as fit in its share and in
+an em. The word spaces and the rest of justification take the room the kashidas leave, so the line keeps its width.
+Line breaks are the same as with none. Lines that are not justified, words without joined letters and fonts without a
+tatweel get no kashidas. Each tatweel is a glyph of the layout that stands for no character and does not advance; the
+letter after the kashida advances over it, so the caret before that letter, a selection of it and a click on it take
+the kashida in. The setting is saved with the paragraph (`kashida` in `para`) only when it is not none, paragraph
+styles carry it, and Reset Panel sets it back to none. The change is one undo step.
+
+```json
+{"name":"run_command","arguments":{"command":"text.setFormat","params":{"kashida":"medium"}}}
+```
 ## Kinsoku Set
 
 `text.setFormat {kinsoku: "hard"|"soft"|"none"}` sets the Paragraph panel's Kinsoku Set of the selected type (or `ids`):

docs/target-app-parity.md

@@ -657,6 +657,7 @@ Moved from the ROADMAP's "Shipped so far" on 2026-10-10. Update it when a featur
   The frames of threaded text share one Optical Margin Alignment setting: turning it on or off in one frame sets it in every frame, threading frames gives the thread its first frame's setting, and frames taken out of a thread keep it.
   Type › Optical Margin Alignment (`type.opticalMarginAlignment`) hangs the punctuation and letter edges at the ends of a type object's lines outside its margins: at the left of left-aligned lines, at the right of right-aligned lines, and at both ends of centered and justified lines, in point and area type of left-to-right paragraphs. Quotation marks, hyphens, full stops and commas hang wholly; asterisks, tildes, ellipses, en and em dashes, colons and semicolons hang by half; and A, V, W, Y, v, w and y hang by a tenth of their width. It is off by default and saved with the type object.
   The Paragraph panel menu's Hyphenation… (`ui.hyphenation`, `text.setFormat {wordsLongerThan, afterFirst, beforeLast, hyphenLimit, hyphenationZone, hyphenateCapitalized}`) sets each paragraph's hyphenation limits: the shortest word that breaks, the fewest letters on each side of the hyphen, the most hyphenated lines in a row, a zone at the right edge where the Single-line Composer breaks before a word instead of hyphenating it, and whether capitalized words break. The defaults are words longer than 5 letters, 3 letters on each side, no limit or zone, and capitalized words hyphenated; paragraph styles and the native file keep the options.
+  The Paragraph panel's Insert Kashidas (with the Indic options; `text.setFormat {kashida}`) lengthens each Arabic word of a justified horizontal area type line with a kashida, a tatweel between its last pair of joined letters, before the word spaces widen: Short, Medium and Long kashidas are at most a quarter, half and a whole em long, Stylistic ones are whole tatweels up to an em, and None (the default) leaves the line as before; paragraph styles and the native file keep the setting.
   In vertical type, the Tabs panel names its alignment buttons Top-Justified Tab, Center-Justified Tab, Bottom-Justified Tab and Decimal-Justified Tab, in their tool tips and for screen readers, and labels the position field Y. In horizontal type the buttons keep the names Left-Justified Tab and Right-Justified Tab, and the field keeps the label X.
   The Tabs panel's ruler is numbered in the General unit with the canvas rulers' label steps and a tick every tenth of a step. With the panel menu's Snap to Unit on, or Shift held, a tab stop placed by a click on the ruler or dragged on it lands on the nearest tick (`text.tabs.set`).
   When a drag on the Tabs panel's ruler or a value typed in its X field moves a tab stop past another stop, the moved stop stays selected.