Import PDF: linked pages on their trim boxes keep the bleed between artboards

Linked pages on their trim boxes were spaced by the 36 pt gap alone, so
with a large bleed one page's bleed box reached into the next artboard
and a page export could show part of its neighbor. The artboards are
now laid out once the document's bleed is known, 36 pt apart plus the
bleed on both sides: the document's bleed, or a page's own bleed box
where it reaches farther.

crates/engine/src/cmd/fileio/pdfimport.rs

@@ -221,7 +221,7 @@ fn page_options(page: usize, o: &LoadOptions) -> ImportOptions {
 /// a PDF-compatible `.ai` asked for its crop box gets its trim box, as it opens), in a row from the
 /// left with the gap a PDF's artboards open with, and a layer named after the page. On its trim box,
 /// a page shows its bleed box round the artboard, and the document's bleed is the pages' bleed (the
-/// widest on each side). The document opens
+/// widest on each side); the artboards are then the gap apart plus the bleed on both sides. The document opens
 /// in CMYK when most of the pages read in CMYK, unless `o.color_mode` names a mode. Refused without a
 /// path, for any other file, with a password (a linked page is read again without one), with
 /// `textAs: outlines` (a linked page shows the file's own type) and for a file over
@@ -262,8 +262,11 @@ pub(super) fn linked_pages(name: &str, bytes: &[u8], path: Option<&str>, o: &Loa
     let shared = Arc::new(bytes.to_vec());
     // The file is hashed once for all its pages.
     let hash = link.hash.clone().unwrap_or_else(|| vectorcraft_doc::links::hash_bytes(bytes));
-    let (mut x, mut warnings, mut cmyk_pages) = (0.0, Vec::<String>::new(), 0);
-    for (i, &index) in picked.iter().enumerate() {
+    let (mut warnings, mut cmyk_pages) = (Vec::<String>::new(), 0);
+    // Each page as read, with its bleed (top, bottom, left, right). The pages are laid out once
+    // the document's bleed is known.
+    let mut read_pages = Vec::with_capacity(picked.len());
+    for &index in &picked {
         let page = index as u32 + 1;
         let file_once = document::SharedFile { bytes: &shared, hash: &hash, opened: &opened };
         // On its trim box, a page shows its bleed box, the artboard on the trim box inside it, so
@@ -272,7 +275,7 @@ pub(super) fn linked_pages(name: &str, bytes: &[u8], path: Option<&str>, o: &Loa
         let page_box = if bleed.is_some() { vectorcraft_doc::PageBox::Bleed } else { document::page_box(crop) };
         let read = |bounding| document::shared_source(name, file_once, Some(path), page, bounding, page_box, C);
         // A blank page has no art's bounds: it keeps its crop box, as opening it as art does.
-        let (s, bounding) = match read(bounding) {
+        let (mut s, bounding) = match read(bounding) {
             Err(e) if bounding && e.to_string().contains("has no art to place") => (read(false)?, false),
             s => (s?, bounding),
         };
@@ -283,10 +286,26 @@ pub(super) fn linked_pages(name: &str, bytes: &[u8], path: Option<&str>, o: &Loa
         }
         cmyk_pages += usize::from(s.color_mode == ColorMode::Cmyk);
         // The document's bleed is the widest of the pages' on each side.
-        let [top, bottom, left, right] = bleed.unwrap_or_default();
-        for (side, b) in doc.setup.bleed.iter_mut().zip([top, bottom, left, right]) {
+        let sides = bleed.unwrap_or_default();
+        for (side, b) in doc.setup.bleed.iter_mut().zip(sides) {
             *side = side.max(b.min(vectorcraft_doc::setup::MAX_BLEED));
         }
+        for w in std::mem::take(&mut s.warnings) {
+            if !warnings.contains(&w) {
+                warnings.push(w);
+            }
+        }
+        read_pages.push((page, s, bounding, sides));
+    }
+    // Each artboard is the gap from the one before plus the bleed on both sides of it: the
+    // document's bleed, which export adds round every artboard, or a page's own bleed box where it
+    // reaches farther. Neither page then shows or exports the other's art.
+    let [_, _, doc_left, doc_right] = doc.setup.bleed;
+    let mut x = 0.0;
+    for (i, (page, s, bounding, [top, bottom, left, right])) in read_pages.into_iter().enumerate() {
+        if i > 0 {
+            x += doc_left.max(left);
+        }
         let mut node = document::node(&mut doc, &s, LinkInfo { page: Some(page), ..link.clone() }, bounding);
         if let NodeKind::PlacedDocument(p) = &mut node.kind {
             p.xf = Affine::translate((x - left, -top));
@@ -299,12 +318,7 @@ pub(super) fn linked_pages(name: &str, bytes: &[u8], path: Option<&str>, o: &Loa
         doc.layers.push(Arc::new(layer));
         let rect = Rect::new(x, 0.0, x + s.frame.width() - left - right, s.frame.height() - top - bottom);
         doc.artboards.push(Artboard { id: i as u32 + 1, name: format!("Artboard {}", i + 1), rect, ..board.clone() });
-        x = rect.x1 + gap;
-        for w in s.warnings {
-            if !warnings.contains(&w) {
-                warnings.push(w);
-            }
-        }
+        x = rect.x1 + doc_right.max(right) + gap;
     }
     // Pages painted mostly in CMYK read as CMYK documents, as opening them as art does: the
     // document opens in CMYK (with the CMYK default swatches) when most of its pages do.

crates/engine/src/cmd/fileio/tests_aiimport.rs

@@ -1205,6 +1205,46 @@ fn link_pages_open_an_ai_file_on_its_trim_box_with_its_bleed() {
     let _ = std::fs::remove_dir_all(&d);
 }
 
+#[test]
+fn link_pages_on_their_trim_boxes_keep_the_bleed_between_the_artboards() {
+    // Two 100 pt trim boxes: the first with 60 pt of bleed on each side, the second with 80 pt on
+    // its left, more than the largest document bleed (72 pt).
+    let entries = format!("/PieceInfo << /Illustrator << /Private << /AIPrivateData1 {} 0 R /NumBlock 1 >> >> >>", first_extra(2));
+    let first = PdfPage {
+        bleed: Some([0.0, 0.0, 220.0, 220.0]),
+        trim: Some([60.0, 60.0, 160.0, 160.0]),
+        entries,
+        ..PdfPage::new(220.0, 220.0, "0 g 0 0 220 220 re f")
+    };
+    let second = PdfPage {
+        bleed: Some([0.0, 0.0, 240.0, 220.0]),
+        trim: Some([80.0, 60.0, 180.0, 160.0]),
+        ..PdfPage::new(240.0, 220.0, "0 g 0 0 240 220 re f")
+    };
+    let d = std::env::temp_dir().join(format!("vc-ailinkpagesgap-{}", std::process::id()));
+    std::fs::create_dir_all(&d).unwrap();
+    let path = d.join("pages.ai");
+    std::fs::write(&path, pdf_with(&[first, second], &["<< /Length 4 >>\nstream\ndata\nendstream"], None)).unwrap();
+    let path = path.to_string_lossy().to_string();
+    let mut s = Session::new();
+    s.execute("document.open", &json!({"path": path, "linkPages": true})).unwrap();
+    let doc = &s.doc().unwrap().doc;
+    assert_eq!(doc.setup.bleed, [60.0, 60.0, 72.0, 60.0], "top, bottom, left, right");
+    // The first page's bleed ends at 160; the second's starts 36 pt later, 80 pt left of its trim box.
+    let boards: Vec<(f64, f64)> = doc.artboards.iter().map(|a| (a.rect.x0, a.rect.x1)).collect();
+    assert_eq!(boards, [(0.0, 100.0), (276.0, 376.0)]);
+    let shown: Vec<f64> = doc
+        .layers
+        .iter()
+        .map(|l| match &l.children().unwrap()[0].kind {
+            NodeKind::PlacedDocument(p) => p.xf.translation().x,
+            k => panic!("{k:?}"),
+        })
+        .collect();
+    assert_eq!(shown, [-60.0, 196.0], "each page's bleed box round its artboard");
+    let _ = std::fs::remove_dir_all(&d);
+}
+
 /// A page of text alone, as text-only art has in its PDF part: no path is painted.
 const TEXT_ART: &str = "BT /F1 36 Tf 10 40 Td (Text only) Tj ET";
 

docs/mcp.md

@@ -1282,7 +1282,7 @@ placed document linked to that page of the file, as `file.place` with `link` pla
 Each page gets an artboard of its `cropTo` box (`bounding`: its art's bounds; a blank page gets its crop box), in a row from the left 36 pt apart, and
 a layer named after the page (`Page 2`). A PDF-compatible `.ai` with `cropTo: "crop"` gets its trim boxes, as it does
 when it opens as art. A page on its trim box shows its bleed box round the artboard, and the pages give the document
-their bleed. The document opens in CMYK when most of those pages are painted mostly in
+their bleed; the artboards are then 36 pt apart plus the bleed on both sides. The document opens in CMYK when most of those pages are painted mostly in
 CMYK, unless `colorMode` names a mode. All the pages' objects share one copy of the file. The Links panel lists each
 page, and `links.embed` makes a page editable art.
 `document.open` refuses `linkPages` for a file that is not a PDF or a PDF-compatible `.ai`, for a file given as