DXF export: dashed polylines continue their linetype around vertices

A polyline with a linetype now sets group 70 bit 128, so the dash pattern runs on through its vertices instead of restarting at each corner. This applies to LWPOLYLINE and the R12 POLYLINE.

crates/cad/src/scene.rs

@@ -872,7 +872,8 @@ impl<'a> Scene<'a> {
         let pts: Vec<Point> = pts.iter().map(|p| self.pt(*p)).collect();
         let layer = self.layer.clone();
         let h = self.handle();
-        let flags = i64::from(closed);
+        // Bit 128: a linetype runs on through the vertices instead of restarting at each one.
+        let flags = i64::from(closed) | if style.linetype.is_some() { 128 } else { 0 };
         if self.o.version.lwpolyline() {
             self.e.entity("LWPOLYLINE", h, fixed::MODEL_RECORD, &layer, style, "AcDbPolyline");
             self.e.int(90, pts.len() as i64);

crates/cad/src/tests.rs

@@ -696,6 +696,30 @@ fn dashes_that_start_part_way_into_their_pattern_are_outlined() {
     assert_eq!(get(&entities(&editable)[0], 6), Some("DASHED1"));
 }
 
+#[test]
+fn dashed_polylines_continue_their_pattern_around_corners() {
+    let rect = |dash: Option<Dash>| {
+        doc_with(|d| {
+            let mut n = path(d, shapes::rectangle(Rect::new(10.0, 10.0, 110.0, 60.0)), Paint::None, Paint::solid(Color::BLACK), 1.0);
+            if let Some(st) = n.appearance.stroke_mut() {
+                st.dash = dash.clone();
+            }
+            vec![n]
+        })
+    };
+    let flags = |out: &DxfOutput| entities(out).first().and_then(|e| get(e, 70).map(str::to_string));
+    // Group 70 bit 128 makes the linetype run on through the vertices instead of restarting
+    // at each one; a solid polyline keeps only its closed bit.
+    let dashed = rect(Some(Dash { pattern: vec![6.0, 3.0], offset: 0.0, align_corners: false }));
+    for o in [opts(&dashed), DxfOptions { alter_paths: true, ..opts(&dashed) }, DxfOptions { preserve: Preserve::Editability, ..opts(&dashed) }] {
+        assert_eq!(flags(&export(&dashed, &o).unwrap()).as_deref(), Some("129"));
+    }
+    let r12 = export(&dashed, &DxfOptions { version: DxfVersion::R12, ..opts(&dashed) }).unwrap();
+    assert_eq!((kinds(&r12).first().map(String::as_str), flags(&r12).as_deref()), (Some("POLYLINE"), Some("129")));
+    let solid = rect(None);
+    assert_eq!(flags(&export(&solid, &opts(&solid)).unwrap()).as_deref(), Some("1"));
+}
+
 fn text_doc(text: &str, size: f64) -> Document {
     doc_with(|d| {
         let style = CharStyle { size, fill: Paint::solid(Color::rgb(0.0, 0.5, 0.0)), ..CharStyle::default() };