Export for Screens: <filename> takes the saved document's file name

In a file name pattern, <filename> is documented as the document's name
without its extension, but it expanded to the File Info title whenever the
document had one, so a saved my-logo.vectorcraft titled "Logo: final
version" exported as Logo--final-version__Artboard 1.png. The Full
Document file and the .zip took the same title.

Export for Screens and the dialog's Example line now take <filename> from
the document's file, as Save names it (save.rs), and fall back to the
title only for a document that has not been saved.

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

@@ -382,7 +382,7 @@ struct Naming {
 }
 
 impl Naming {
-    /// The naming of params `o` for a document titled `title`.
+    /// The naming of params `o` for a document named `title`: its file's path, or its title before it is saved.
     fn of(o: &ScreenParams, title: &str) -> Result<Self> {
         let folders = Folders::of(o)?;
         // A prefix names files, not folders.
@@ -669,7 +669,9 @@ pub(crate) fn export(s: &mut Session, p: &Value) -> Result<Value> {
     let o = ScreenParams::of(p)?;
     let rows = rows_of(s, p, o.preset.as_deref())?;
     o.one_source()?;
-    let naming = Naming::of(&o, &s.doc()?.doc.title)?;
+    // `<filename>`: the document's file, as Save names it, or its title before it is saved.
+    let st = s.doc()?;
+    let naming = Naming::of(&o, st.path.as_deref().unwrap_or(&st.doc.title))?;
     let selection = o.selection_mode()?;
     let selected = if selection.is_some() { selected_artwork(s)? } else { vec![] };
     let doc = s.doc()?.doc.clone();
@@ -846,13 +848,14 @@ pub fn first_file(s: &Session, p: &Value) -> Result<String> {
     let rows = rows_of(s, &p, o.preset.as_deref())?;
     o.one_source()?;
     let selection = o.selection_mode()?;
-    let doc = &s.doc()?.doc;
+    let st = s.doc()?;
+    let doc = &st.doc;
     let mut selected = if selection.is_some() { selected_artwork(s)? } else { vec![] };
     // A file per object: objects that draw nothing write no file.
     if selection == Some(true) {
         selected = selected.into_iter().find(|id| export_crop(doc, &[*id]).is_some()).into_iter().collect();
     }
-    let naming = Naming::of(&o, &doc.title)?;
+    let naming = Naming::of(&o, st.path.as_deref().unwrap_or(&doc.title))?;
     let items = items(doc, &o, selection, &selected, &naming.filename, false, false)?;
     let (Some(item), Some(r)) = (items.first(), rows.first()) else { return Err(bad(C, "nothing to export")) };
     let (sub, file) = naming.file(item, 0, 0, r);

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

@@ -205,6 +205,39 @@ fn the_first_file_is_the_file_the_export_writes_first() {
     }
 }
 
+/// A saved document's `<filename>`, Full Document file and ZIP are named after its file without the
+/// extension, as Save names it, whatever its File Info title says.
+#[cfg(not(target_arch = "wasm32"))]
+#[test]
+fn a_saved_document_exports_under_its_file_name() {
+    let mut s = session(1);
+    s.execute("file.info", &json!({"title": "Logo: final version"})).unwrap();
+    let dir = std::env::temp_dir().join(format!("vc-screens-filename-{}", std::process::id()));
+    std::fs::create_dir_all(&dir).unwrap();
+    s.execute("document.save", &json!({"path": dir.join("my-logo.vectorcraft").to_string_lossy()})).unwrap();
+    for (p, name) in [
+        (json!({"name": "<filename>__<name>", "formats": [{"format": "png"}]}), "my-logo__Artboard 1.png"),
+        (json!({"fullDocument": true, "formats": [{"format": "png"}]}), "my-logo.png"),
+    ] {
+        assert_eq!(names(&export(&mut s, p.clone())), [name], "{p}");
+        assert_eq!(super::screens::first_file(&s, &p).unwrap(), name, "{p}");
+    }
+    assert_eq!(export(&mut s, json!({"zip": true, "formats": [{"format": "svg"}]}))["name"], "my-logo.zip");
+    let _ = std::fs::remove_dir_all(dir);
+}
+
+/// A document that has not been saved has no file: `<filename>` is its title.
+#[test]
+fn an_unsaved_document_exports_under_its_title() {
+    let mut s = Session::new();
+    s.execute("file.new", &json!({"width": 40, "height": 30, "name": "Poster"})).unwrap();
+    s.execute("shape.rectangle", &json!({"x": 5, "y": 5, "width": 20, "height": 20})).unwrap();
+    s.execute("file.info", &json!({"title": "Spring poster"})).unwrap();
+    let p = json!({"name": "<filename>", "formats": [{"format": "png"}]});
+    assert_eq!(names(&export(&mut s, p.clone())), ["Spring-poster.png"]);
+    assert_eq!(super::screens::first_file(&s, &p).unwrap(), "Spring-poster.png");
+}
+
 #[cfg(not(target_arch = "wasm32"))]
 #[test]
 fn sub_folders_are_made_in_the_export_folder() {