Place: PDF pages and SVGs keep their exact size (#511)

file.place sized a placed PDF page (and SVG) from its size rounded to
whole points, while the export draws the page into that size: a page of
91.774 x 613.276 pt became 92 x 613 and was drawn 0.25 % wider and
0.3 % shorter, so pieces laid edge to edge left gaps of up to 1.9 pt.
A 100.4 x 50.4 pt page placed 100.4 pt wide came out 50.2 pt tall:
`Rect { x0: 0.0, y0: 0.0, x1: 100.4, y1: 50.2 }`.

The graphic's natural size is now the exact page (crop box) or SVG size;
the rounded pixel size stays for display and preflight. place.load (the
place cursor) gets the same exact size.

Co-authored-by: Claude Opus 5.5 <[email protected]>

crates/engine/src/cmd/file.rs

@@ -313,8 +313,9 @@ fn file_place(s: &mut Session, p: &Value) -> Result<Value> {
             .map(|(w, h)| (w.round().max(1.0) as u32, h.round().max(1.0) as u32))
             .ok_or_else(|| bad("file.place", "can't read that PDF page"))?,
     };
-    // 72 ppi by default unless the file says otherwise; scale so it fits the page when huge.
-    let (nw, nh) = eps_size.unwrap_or((pw as f64, ph as f64));
+    // 72 ppi by default unless the file says otherwise; scale so it fits the page when huge. PDF pages
+    // and SVGs keep their exact size: rounding it to whole points would stretch them unevenly.
+    let (nw, nh) = eps_size.or_else(|| designcraft_render::natural_size(&bytes, pdf_page as usize)).unwrap_or((pw as f64, ph as f64));
     // Image Import Options › Crop to: the frame shows that box of the PDF page.
     let crop_box = match str_param(p, "pdfCrop") {
         Some(k) if designcraft_render::is_pdf(&bytes) => {
@@ -440,6 +441,7 @@ pub(crate) fn read_source(p: &Value) -> Result<(Vec<u8>, String, Option<String>)
 fn place_load(s: &mut Session, p: &Value) -> Result<Value> {
     let (bytes, name, link) = read_source(p)?;
     let (pw, ph) = designcraft_render::image_size(&bytes).ok_or_else(|| bad("place.load", "unsupported or corrupt image"))?;
+    let natural = designcraft_render::natural_size(&bytes, 0).unwrap_or((pw as f64, ph as f64));
     let aid = s.edit(|d, _| {
         let aid = AssetId(d.alloc());
         let mime = designcraft_render::image_mime(&bytes).to_string();
@@ -449,7 +451,7 @@ fn place_load(s: &mut Session, p: &Value) -> Result<Value> {
         );
         Ok(aid)
     })?;
-    s.loaded = Some((aid, (pw as f64, ph as f64)));
+    s.loaded = Some((aid, natural));
     s.set_tool("placeGun");
     Ok(json!({"asset": aid.0, "name": name, "width": pw, "height": ph}))
 }
@@ -689,6 +691,24 @@ mod pdf_crop_tests {
         assert!((trim.width() - 612.0).abs() < 1e-3 && (trim.height() - 792.0).abs() < 1e-3, "{trim:?}");
         assert!(t.execute("file.place", &json!({"base64": b64, "name": "a.pdf", "pdfCrop": "nope"})).is_err());
     }
+
+    #[test]
+    fn placed_pdf_keeps_its_exact_page_size() {
+        // A 100.4 x 50.4 pt page placed 100.4 pt wide is 50.4 pt tall, not stretched to whole points.
+        let mut s = Session::new();
+        s.execute("file.new", &json!({"width": 100.4, "height": 50.4, "pages": 1})).unwrap();
+        let b64 = s.execute("file.exportPdf", &json!({})).unwrap()["base64"].as_str().unwrap().to_string();
+        let mut t = Session::new();
+        t.execute("file.new", &json!({})).unwrap();
+        let r = t.execute("file.place", &json!({"base64": b64, "name": "a.pdf", "width": 100.4, "x": 0, "y": 0})).unwrap();
+        let id = designcraft_doc::ItemId(r["id"].as_u64().unwrap());
+        let d = &t.doc().unwrap().doc;
+        let it = d.item(id).unwrap();
+        let b = it.bounds();
+        assert!((b.width() - 100.4).abs() < 1e-3 && (b.height() - 50.4).abs() < 1e-3, "{b:?}");
+        let designcraft_doc::Content::Graphic(g) = &it.content else { panic!("not a graphic") };
+        assert!((g.size.0 - 100.4).abs() < 1e-3 && (g.size.1 - 50.4).abs() < 1e-3, "{:?}", g.size);
+    }
 }
 
 #[cfg(test)]

crates/render/src/lib.rs

@@ -1022,6 +1022,15 @@ pub fn image_size(bytes: &[u8]) -> Option<(u32, u32)> {
     designcraft_images::pixel_size(bytes)
 }
 
+/// Natural size of a placed graphic, unrounded: a PDF page (crop box) and an SVG in points, a raster
+/// in pixels. Placed graphics are drawn at this size; `image_size` rounds it to whole pixels for display.
+pub fn natural_size(bytes: &[u8], page: usize) -> Option<(f64, f64)> {
+    if is_pdf(bytes) {
+        return pdf_page_size(bytes, page).map(|(w, h)| (w.max(1e-3), h.max(1e-3)));
+    }
+    designcraft_images::natural_size(bytes)
+}
+
 /// MIME type guess for encoded image bytes.
 /// Is this a PDF file (placed PDFs are graphics)?
 pub fn is_pdf(bytes: &[u8]) -> bool {