From 81f0aa53ffe5b67fb9aa5cc921f3f3577e2a5d77 Mon Sep 17 00:00:00 2001
From: MarekSpodBiedry <73122968+MarekSpodBiedry@users.noreply.github.com>
Date: Mon, 19 Oct 2026 22:27:04 +0200
Subject: [PATCH] Keep a layout's plot window corners when saving DXF (#1667)

---
 crates/doc/src/tables.rs              |  3 +++
 crates/io/src/dxf_read.rs             |  1 +
 crates/io/src/dxf_write.rs            |  8 ++++----
 crates/io/tests/layout_plot_window.rs | 25 +++++++++++++++++++++++++
 4 files changed, 33 insertions(+), 4 deletions(-)
 create mode 100644 crates/io/tests/layout_plot_window.rs

diff --git a/crates/doc/src/tables.rs b/crates/doc/src/tables.rs
index 498296237..45e7a469b 100644
--- a/crates/doc/src/tables.rs
+++ b/crates/doc/src/tables.rs
@@ -752,6 +752,8 @@ pub struct PageSetup {
     pub landscape: bool,
     /// "layout" | "extents" | "display" | "window" | "limits".
     pub plot_area: String,
+    /// Plot window corners `[x1, y1, x2, y2]` (DXF plot layout groups 48, 49, 140, 141); used when `plot_area` is "window".
+    pub plot_window: [f64; 4],
     pub scale_to_fit: bool,
     /// Paper units per drawing unit.
     pub scale: f64,
@@ -779,6 +781,7 @@ impl Default for PageSetup {
             margins_mm: [6.35, 6.35, 6.35, 6.35],
             landscape: true,
             plot_area: "layout".into(),
+            plot_window: [0.0; 4],
             scale_to_fit: false,
             scale: 1.0,
             plot_style_table: String::new(),
diff --git a/crates/io/src/dxf_read.rs b/crates/io/src/dxf_read.rs
index 92d803e17..2bd7e8d8d 100644
--- a/crates/io/src/dxf_read.rs
+++ b/crates/io/src/dxf_read.rs
@@ -2248,6 +2248,7 @@ fn page_setup(t: &T) -> PageSetup {
         _ => "layout",
     }
     .into();
+    p.plot_window = [t.fd(48, 0.0), t.fd(49, 0.0), t.fd(140, 0.0), t.fd(141, 0.0)].map(|v| if v.is_finite() { v } else { 0.0 });
     p.plot_style_table = t.s(7).unwrap_or_default();
     p
 }
diff --git a/crates/io/src/dxf_write.rs b/crates/io/src/dxf_write.rs
index 521654e3d..7991d013b 100644
--- a/crates/io/src/dxf_write.rs
+++ b/crates/io/src/dxf_write.rs
@@ -2565,10 +2565,10 @@ fn tags_for(d: &Drawing, version: Version, target: Version) -> Vec<Tag> {
             (45, page.height_mm),
             (46, 0.0),
             (47, 0.0),
-            (48, 0.0),
-            (49, 0.0),
-            (140, 0.0),
-            (141, 0.0),
+            (48, page.plot_window[0]),
+            (49, page.plot_window[1]),
+            (140, page.plot_window[2]),
+            (141, page.plot_window[3]),
             (142, scale),
             (143, 1.0),
         ] {
diff --git a/crates/io/tests/layout_plot_window.rs b/crates/io/tests/layout_plot_window.rs
new file mode 100644
index 000000000..448fa83e5
--- /dev/null
+++ b/crates/io/tests/layout_plot_window.rs
@@ -0,0 +1,25 @@
+//! #1667: a layout whose page setup plots a window (DXF plot type 4) lost the window corners
+//! (groups 48, 49, 140, 141) on save: they were written as zero.
+
+use cadcraft_doc::{Drawing, Layout, PageSetup};
+use cadcraft_io::{read, write_dxf};
+
+#[test]
+fn plot_window_corners_round_trip_through_dxf() {
+    let mut d = Drawing::new_metric();
+    let mut l = Layout::new("WIN", 3);
+    l.page = PageSetup {
+        width_mm: 297.0,
+        height_mm: 420.0,
+        margins_mm: [0.0; 4],
+        plot_area: "window".into(),
+        plot_window: [0.0, -297.0, 420.0, 0.0],
+        ..PageSetup::default()
+    };
+    d.layouts.push(l);
+
+    let back = read(write_dxf(&d).as_bytes(), "win.dxf").unwrap();
+    let page = &back.layouts.iter().find(|l| l.name == "WIN").unwrap().page;
+    assert_eq!(page.plot_area, "window");
+    assert_eq!(page.plot_window, [0.0, -297.0, 420.0, 0.0]);
+}