Merge pull request #2859 from ham9zah/fix/ai-rtl-paragraph-alignment

G9: .ai right-to-left paragraphs keep their alignment

crates/eps/src/import/ate.rs

@@ -14,9 +14,11 @@
 //!
 //! Where type sits: a story lays its lines out round a point `F` (the anchor: the start of a line of
 //! left-aligned type, the middle of a centred one, the end of a right-aligned one), each line with an
-//! offset from it. The frame of the story gives a matrix that carries that layout onto the canvas of
-//! the app, which is 16383 points a side; the canvas's centre, 8191.5, is the centre of the file's
-//! `%AI3_TemplateBox`. See [`Story::place`].
+//! offset from it. A right-to-left paragraph (key `33` of its attributes) swaps the two: its
+//! "left"-aligned lines end at the anchor and its "right"-aligned ones start there. The frame of the
+//! story gives a matrix that carries that layout onto the canvas of the app, which is 16383 points a
+//! side; the canvas's centre, 8191.5, is the centre of the file's `%AI3_TemplateBox`. See
+//! [`Story::place`].
 
 use std::collections::BTreeMap;
 
@@ -253,6 +255,9 @@ enum FrameKind {
 #[derive(Clone, Debug, Default, PartialEq)]
 struct Para {
     justify: u8,
+    /// A right-to-left paragraph: its left and right alignments are each other's (the line of
+    /// "left"-aligned type ends at its anchor).
+    rtl: bool,
     first_indent: f64,
     left_indent: f64,
     right_indent: f64,
@@ -429,6 +434,7 @@ impl Texts {
         let num = |k: &str| pick(k).and_then(Val::num).filter(|v| v.abs() < 1e5).unwrap_or(0.0);
         Para {
             justify: pick("0").and_then(Val::num).map_or(0, |v| v.clamp(0.0, 6.0) as u8),
+            rtl: pick("33").and_then(Val::num) == Some(1.0),
             first_indent: num("1"),
             left_indent: num("2"),
             right_indent: num("3"),
@@ -747,6 +753,8 @@ impl Story {
 fn para_style(p: &Para, scale: f64) -> ParaStyle {
     ParaStyle {
         justify: match p.justify {
+            0 if p.rtl => Justify::Right,
+            1 if p.rtl => Justify::Left,
             1 => Justify::Right,
             2 => Justify::Center,
             3 => Justify::JustifyLeft,
@@ -795,6 +803,20 @@ fn art_scale(to_doc: Affine) -> f64 {
 mod tests {
     use super::*;
 
+    #[test]
+    fn right_to_left_paragraphs_swap_left_and_right_alignment() {
+        let texts =
+            Texts { stories: vec![], fonts: vec![], defaults: Val::Dict(BTreeMap::new()), para_defaults: read(b"/33 1").unwrap(), frames: vec![] };
+        let justify = |own: &[u8]| para_style(&texts.para(Some(&read(own).unwrap())), 1.0).justify;
+        // Right to left from the document's defaults, or the paragraph's own.
+        assert_eq!(justify(b"/0 0"), Justify::Right);
+        assert_eq!(justify(b"/0 1 /33 1"), Justify::Left);
+        assert_eq!(justify(b"/0 2"), Justify::Center);
+        // Left to right keeps them.
+        assert_eq!(justify(b"/0 0 /33 0"), Justify::Left);
+        assert_eq!(justify(b"/0 1 /33 0"), Justify::Right);
+    }
+
     #[test]
     fn values_read_nested_dictionaries_lists_and_utf16_strings() {
         let v = read(b" /1 << /0 [ 1 2.5 -3 ] /2 (\xfe\xff\x00h\x00i) /3 true /99 /Name >> /0 (a\\)b\\n)").unwrap();