Write Wipeout entities to DXF so saving keeps them (#79) (#147)

* Write Wipeout entities to DXF so saving keeps them (#79)

* Wipeout: clip vertices are in image pixel space (origin top-left, y down)

Write and read the boundary with y flipped, so other programs show the same
shape and wipeouts from other programs are no longer mirrored vertically.
Tested with an asymmetric boundary.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

* Wipeout: collapse nested if (clippy)

Co-Authored-By: Claude Opus 5.5 <[email protected]>

---------

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

crates/io/src/dxf_read.rs

@@ -313,7 +313,8 @@ fn entity(kind: &str, tags: &[Tag]) -> Option<(Common, EntityKind)> {
             let o = t.p(10);
             let u = t.p(11);
             let v = t.p(12);
-            let pts: Vec<Vec2> = t.pts(14).into_iter().map(|q| o.xy() + u.xy() * (q.x + 0.5) + v.xy() * (q.y + 0.5)).collect();
+            // Clip vertices are in pixel space: origin at the image's top-left corner, y pointing down.
+            let pts: Vec<Vec2> = t.pts(14).into_iter().map(|q| o.xy() + u.xy() * (q.x + 0.5) + v.xy() * (0.5 - q.y)).collect();
             EntityKind::Wipeout(Wipeout { boundary: pts })
         }
         "IMAGE" => {

crates/io/src/dxf_write.rs

@@ -5,7 +5,7 @@ use std::collections::HashMap;
 use cadcraft_color::Color;
 use cadcraft_doc::*;
 use cadcraft_dxf::Tag;
-use cadcraft_geom::{Vec2, Vec3};
+use cadcraft_geom::{Bounds2, Vec2, Vec3};
 
 use crate::dxf_ext::{self, DimVal, K};
 
@@ -797,7 +797,40 @@ fn entity(w: &mut W, d: &Drawing, e: &Entity, owner: &str, paper: bool, cx: &Ctx
                 w.xdata(dxf_ext::frozen_xdata(&v.frozen_layers));
             }
         }
-        // Not yet written: images, wipeouts, tables, multileaders, unknown objects.
+        EntityKind::Wipeout(wo) => {
+            // A 1x1 image spanning the boundary's extents. Clip vertices are in pixel space, whose origin is
+            // the image's top-left corner with y pointing down: the reader maps each vertex back through
+            // insert + u * (x + 0.5) + v * (0.5 - y).
+            // Polygonal clip boundaries are closed, so the first vertex is repeated when needed.
+            let b = Bounds2::from_points(wo.boundary.iter().copied());
+            let o = if b.is_empty() { Vec2::ZERO } else { b.min };
+            let (sx, sy) = (if b.width() > 0.0 { b.width() } else { 1.0 }, if b.height() > 0.0 { b.height() } else { 1.0 });
+            w.s(0, "WIPEOUT");
+            common(w, e, owner, paper, "AcDbWipeout");
+            w.i(90, 0);
+            w.p(10, Vec3::new(o.x, o.y, 0.0));
+            w.p(11, Vec3::new(sx, 0.0, 0.0));
+            w.p(12, Vec3::new(0.0, sy, 0.0));
+            w.p2(13, Vec2::new(1.0, 1.0));
+            // Display flags 7 = show image, show unaligned, use clipping boundary; clipping on; default brightness/contrast/fade.
+            w.i(70, 7);
+            w.i(280, 1);
+            w.i(281, 50);
+            w.i(282, 50);
+            w.i(283, 0);
+            w.i(71, 2);
+            let mut pts = wo.boundary.clone();
+            if let (Some(first), Some(last)) = (pts.first().copied(), pts.last().copied())
+                && first != last
+            {
+                pts.push(first);
+            }
+            w.i(91, pts.len() as i64);
+            for q in pts {
+                w.p2(14, Vec2::new((q.x - o.x) / sx - 0.5, 0.5 - (q.y - o.y) / sy));
+            }
+        }
+        // Not yet written: images, tables, multileaders, unknown objects.
         _ => {}
     }
 }
@@ -1177,6 +1210,9 @@ pub fn write(d: &Drawing) -> String {
     if !cx.assoc.is_empty() {
         classes.push(("DIMASSOC", "AcDbDimAssoc", 0, false));
     }
+    if every.iter().any(|e| matches!(e.kind, EntityKind::Wipeout(_))) {
+        classes.push(("WIPEOUT", "AcDbWipeout", 127, true));
+    }
     for (dxf_name, cpp, proxy, is_entity) in classes {
         w.s(0, "CLASS");
         w.s(1, dxf_name);

crates/io/src/tests.rs

@@ -1285,6 +1285,32 @@ fn dimension_text_rotation_roundtrips() {
     assert!(rot.is_some_and(|r| (r - dm.text_rotation).abs() < 1e-9), "block text rotation {rot:?}");
 }
 
+/// Wipeout clip vertices are in image pixel space (origin top-left, y down): an asymmetric
+/// boundary must keep its orientation, both through our reader and in the file itself.
+#[test]
+fn wipeout_boundary_keeps_its_orientation() {
+    let mut d = Drawing::new_imperial();
+    // A triangle with its apex at the top.
+    let boundary = vec![Vec2::new(0.0, 0.0), Vec2::new(10.0, 0.0), Vec2::new(0.0, 4.0)];
+    d.add(&Space::Model, Common::default(), EntityKind::Wipeout(Wipeout { boundary: boundary.clone() })).unwrap();
+    let text = write_dxf(&d);
+    // The apex (0, 4) is at the top-left corner of the image: pixel (-0.5, -0.5).
+    let pts: Vec<(f64, f64)> = {
+        let lines: Vec<&str> = text.lines().map(str::trim).collect();
+        let mut v = Vec::new();
+        for i in 0..lines.len().saturating_sub(3) {
+            if lines[i] == "14" && lines[i + 2] == "24" {
+                v.push((lines[i + 1].parse().unwrap(), lines[i + 3].parse().unwrap()));
+            }
+        }
+        v
+    };
+    assert!(pts.iter().any(|&(x, y)| (x + 0.5).abs() < 1e-9 && (y + 0.5).abs() < 1e-9), "{pts:?}");
+    let back = roundtrip(&d);
+    let got = first(&back, |k| if let EntityKind::Wipeout(w) = k { Some(w.boundary.clone()) } else { None });
+    assert_eq!(&got[..3], &boundary[..]);
+}
+
 #[test]
 fn arc_length_dimension_keeps_its_kind_and_centre_on_roundtrip() {
     let mut d = Drawing::new_metric();
@@ -1475,3 +1501,16 @@ fn long_gradient_name_is_cut_only_in_xdata() {
     let back = read_dxf(text.as_bytes()).unwrap();
     assert_eq!(hatches(&back).into_iter().next().and_then(|h| h.gradient).unwrap().name, name);
 }
+
+#[test]
+fn wipeout_survives_dxf_roundtrip() {
+    let mut d = Drawing::new_imperial();
+    let boundary = vec![Vec2::new(2.0, 3.0), Vec2::new(12.0, 3.0), Vec2::new(12.0, 13.0), Vec2::new(2.0, 13.0)];
+    d.add(&Space::Model, Common::default(), EntityKind::Wipeout(Wipeout { boundary: boundary.clone() })).unwrap();
+    let back = roundtrip(&d);
+    let got = first(&back, |k| if let EntityKind::Wipeout(w) = k { Some(w.boundary.clone()) } else { None });
+    // The DXF polygon is closed, so the first vertex is repeated at the end.
+    assert_eq!(got.len(), 5);
+    assert_eq!(&got[..4], &boundary[..]);
+    assert_eq!(got[4], boundary[0]);
+}