Merge pull request #1591 from switch87/fix/1590-offset-path-message

Offset Path: an empty result says the offset leaves nothing

crates/engine/src/cmd/pathops.rs

@@ -503,6 +503,7 @@ fn offset_path(s: &mut Session, p: &Value) -> Result<Value> {
     let roots = selected_roots(s)?;
     let ids = s.edit("Offset Path", |d, sel| {
         let (mut out, mut above) = (vec![], vec![]);
+        let mut paths = false;
         for id in &roots {
             let Some(n) = d.node(*id).cloned() else { continue };
             let mut lv = vec![];
@@ -510,6 +511,7 @@ fn offset_path(s: &mut Session, p: &Value) -> Result<Value> {
             let mut made = vec![];
             for l in lv.iter().filter(|l| !matches!(l.kind, NodeKind::Text(_))) {
                 let Some((path, rule)) = node_path(l) else { continue };
+                paths = true;
                 let base = if matches!(l.kind, NodeKind::Compound { .. }) && path.is_closed() { po::normalize(&path, rule) } else { path };
                 let off = po::offset_path(&base, delta, join, miter);
                 if off.is_empty() {
@@ -532,6 +534,9 @@ fn offset_path(s: &mut Session, p: &Value) -> Result<Value> {
             out.push(new.id);
             above.push((*id, vec![new]));
         }
+        if out.is_empty() && paths {
+            return Err(EngineError::Other("Offset Path: the offset leaves nothing of the selected paths (an inset larger than the shapes)".into()));
+        }
         if out.is_empty() {
             return Err(EngineError::Other("Offset Path: select paths".into()));
         }

crates/engine/src/tests_pathops.rs

@@ -919,3 +919,14 @@ fn trim_merge_and_crop_remove_strokes() {
         }
     }
 }
+
+/// #1590: an inset larger than the shape leaves nothing, and the error says so rather than asking
+/// for paths that are selected.
+#[test]
+fn offset_path_that_leaves_nothing_says_so() {
+    let mut s = session();
+    let a = rect(&mut s, 0.0, 0.0, 10.0, 10.0);
+    s.execute("select.set", &json!({"ids": [a.0]})).unwrap();
+    let e = s.execute("object.path.offsetPath", &json!({"offset": -20})).unwrap_err().to_string();
+    assert!(e.contains("leaves nothing") && !e.contains("select paths"), "{e}");
+}