Merge pull request #1586 from p0lyg0n/fix/pdf-type-on-a-path-tracking

PDF/.ai import: evenly tracked type on a path keeps its length

crates/pdf/src/import_text.rs

@@ -350,6 +350,20 @@ impl TextLine {
             t.runs = tracked_each(std::mem::take(&mut t.runs), own, self.at.size);
         }
         if let Some(path) = path {
+            // Evenly spaced type keeps its length along the path: the path runs through the
+            // glyphs' origins, one curve each, to the end of the last glyph, and tracking makes up
+            // the difference from the advances.
+            if own.is_none() {
+                let length: f64 = path.segments().take(self.baseline.len()).map(|seg| kurbo::ParamCurveArclen::arclen(&seg, 1e-3)).sum();
+                let laid = vectorcraft_text::layout(db, &t);
+                let natural: f64 = laid.glyphs.iter().map(|g| g.advance).sum();
+                let chars: usize = t.runs.iter().map(|r| r.text.chars().count()).sum();
+                let size = self.at.size;
+                if chars > 1 && length.is_finite() && (length - natural).abs() > size * 0.01 {
+                    let (tracking, spaces) = spacing(&laid, &[], length - natural, chars, size);
+                    t.runs = tracked(std::mem::take(&mut t.runs), tracking, &spaces);
+                }
+            }
             t.kind = TextKind::OnPath { path: vectorcraft_geom::PathData::from_bezpath(&path), start: 0.0, end: None };
             t.xf = Affine::IDENTITY;
             t.cached_bounds = Some(vectorcraft_text::layout(db, &t).bounds);

crates/pdf/src/tests_realtext.rs

@@ -424,3 +424,22 @@ fn glyphs_spaced_each_their_own_way_keep_their_place() {
         }
     });
 }
+
+/// Evenly tracked type on a path comes back with its tracking: each glyph where it was along the
+/// curve, not closed up to the font's advances.
+#[test]
+fn evenly_tracked_type_on_a_path_keeps_its_length() {
+    let mut arc = BezPath::new();
+    arc.move_to((40.0, 200.0));
+    arc.curve_to((100.0, 80.0), (260.0, 80.0), (320.0, 200.0));
+    let mut t = TextObject::point(Point::ORIGIN, "ARCHING TYPE", CharStyle { tracking: 80.0, ..style(24.0) });
+    t.kind = TextKind::OnPath { path: PathData::from_bezpath(&arc), start: 0.0, end: None };
+    let d = doc(vec![t]);
+    let want = origins(&d);
+    let back = import_as(&pdf(&d, false).bytes, TextAs::default());
+    let got = origins(&back);
+    assert_eq!(got.len(), want.len(), "{:?}", texts(&back));
+    for (g, w) in got.iter().zip(&want) {
+        assert!(g.distance(*w) < 0.3, "{got:?}\nvs {want:?}");
+    }
+}