AI import: non-native art stays upright unless its placement mirrors it

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

crates/eps/src/import/ai/read.rs

@@ -1283,12 +1283,15 @@ impl<'a> Reader<'a> {
         if bbox.width() <= 0.0 || bbox.height() <= 0.0 {
             return Ok(());
         }
-        // The art's own box onto the object's box (its measure of the same art), upside down:
-        // the object's space has y down, and the PDF's content is kept in its own y-up
-        // coordinates, so the PDF's bottom is the top of the box.
-        let fit = Affine::translate((target.x0, target.y1))
-            * Affine::scale_non_uniform(target.width() / bbox.width(), -target.height() / bbox.height())
-            * Affine::translate((-bbox.x0, -bbox.y0));
+        // The art's own box onto the object's box (its measure of the same art). The PDF importer
+        // hands the art back as the page shows it, and it keeps that orientation unless its
+        // placement mirrors it (a negative determinant): the usual `/RTransform` `1 0 0 -1 …` with
+        // the origin's flip doesn't, and the art then shows as the file's own PDF part draws it.
+        let fit = if place.determinant() < 0.0 {
+            Affine::translate((target.x0, target.y1)) * Affine::scale_non_uniform(target.width() / bbox.width(), -target.height() / bbox.height())
+        } else {
+            Affine::translate((target.x0, target.y0)) * Affine::scale_non_uniform(target.width() / bbox.width(), target.height() / bbox.height())
+        } * Affine::translate((-bbox.x0, -bbox.y0));
         for n in &mut art {
             n.transform(fit, true);
             // The PDF's swatches stay with it: its colours keep their values, unlinked.

crates/eps/src/import/ai/tests.rs

@@ -718,8 +718,8 @@ fn ascii85_comment_lines(bytes: &[u8]) -> String {
 /// `/Bounds` in a space measured from `/Origin` with y down, then `/RTransform`. Two squares at
 /// 1..5 × 2..8 of a 10-point page, blue below red: bounds (1, 2)–(5, 8) → from the origin
 /// (10, 20), y down, (11, 18)–(15, 12) → twice that plus (100, 50): x 122..130, y 74..86 in art
-/// space, which is y 14..26 in the document (crop marks 100 high). The space has y down, so the
-/// PDF's bottom (blue) is the top of the box.
+/// space, which is y 14..26 in the document (crop marks 100 high). That placement mirrors (`2 0 0 2`
+/// with the origin's flip), so the PDF's bottom (blue) is the top of the box.
 #[test]
 fn non_native_art_is_drawn_from_its_pdf_fitted_to_its_bounds() {
     let pdf = tiny_pdf(10.0, "0 0 1 rg 1 2 4 3 re f 1 0 0 rg 1 5 4 3 re f");
@@ -756,6 +756,34 @@ fn non_native_art_is_drawn_from_its_pdf_fitted_to_its_bounds() {
     assert_ne!(paths[0].id, paths[1].id);
 }
 
+/// The usual placement, `/RTransform` `1 0 0 -1 …`, doesn't mirror (with the origin's flip its
+/// determinant is positive), so the art shows upright, as the file's own PDF part draws it: the
+/// PDF's top (red) at the top. Bounds
+/// (1, 2)–(5, 8) from the origin (10, 20), y down, → (11, 18)–(15, 12) → x 111..115, y 32..38 in
+/// art space, y 62..68 in the document (crop marks 100 high).
+#[test]
+fn non_native_art_placed_without_a_mirror_stays_upright() {
+    let pdf = tiny_pdf(10.0, "0 0 1 rg 1 2 4 3 re f 1 0 0 rg 1 5 4 3 re f");
+    let foreign = format!(
+        "q\n/ForeignObject :\n1 /Version ,\n1 0 0 -1 100 50  /RTransform ,\n10 20  /Origin ,\n1 2 5 8  /Bounds ,\n/Data ,\n{};\n0 0 Xd\n6 () XW\n0 Ae\n{}h\nW\nn\nQ\n",
+        ascii85_comment_lines(&pdf),
+        rect_path(110.0, 30.0, 116.0, 40.0)
+    );
+    let s = read_ok(&layer(&foreign));
+    assert!(s.warnings.is_empty(), "{:?}", s.warnings);
+    let objects = art(&s.doc);
+    let NodeKind::Group { children, clip: true } = &objects[0].kind else { panic!("{:?}", objects[0].kind) };
+    let group = &children[1];
+    let bounds = group.geometric_bounds().unwrap();
+    for (got, want) in [(bounds.x0, 111.0), (bounds.y0, 62.0), (bounds.x1, 115.0), (bounds.y1, 68.0)] {
+        assert!((got - want).abs() < 1e-6, "{bounds:?}");
+    }
+    let paths = group.children().unwrap();
+    let (blue, red) = (paths[0].geometric_bounds().unwrap(), paths[1].geometric_bounds().unwrap());
+    assert!((red.y0 - 62.0).abs() < 1e-6 && (red.y1 - 65.0).abs() < 1e-6, "red {red:?}");
+    assert!((blue.y0 - 65.0).abs() < 1e-6 && (blue.y1 - 68.0).abs() < 1e-6, "blue {blue:?}");
+}
+
 #[test]
 fn cmyk_documents() {
     let doc = read_ok(&format!("%AI9_ColorModel: 2\n{}", layer(""))).doc;