From ab6bff5e4e9a67d7a2e63ed65e0ad82179549c37 Mon Sep 17 00:00:00 2001
From: Marco Arnulfo <103679419+marcoarnulfo@users.noreply.github.com>
Date: Sat, 24 Oct 2026 07:52:00 +0200
Subject: [PATCH] SETVAR CECOLOR takes the colour names and indexes the color
 command takes (fixes #1999) (#2014)

---
 crates/engine/src/cmd/mod.rs             |  1 +
 crates/engine/src/cmd/props.rs           | 21 +++++++++-
 crates/engine/src/sysvars.rs             |  2 +
 crates/engine/tests/it/main.rs           |  1 +
 crates/engine/tests/it/setvar_cecolor.rs | 51 ++++++++++++++++++++++++
 5 files changed, 74 insertions(+), 2 deletions(-)
 create mode 100644 crates/engine/tests/it/setvar_cecolor.rs

diff --git a/crates/engine/src/cmd/mod.rs b/crates/engine/src/cmd/mod.rs
index e1185c14..74bc7f69 100644
--- a/crates/engine/src/cmd/mod.rs
+++ b/crates/engine/src/cmd/mod.rs
@@ -33,6 +33,7 @@ pub mod plotters;
 mod props;
 pub use draw2::breakline::BreaklineOptions;
 pub use props::MatchProps;
+pub(crate) use props::set_current_color_value;
 mod qselect;
 mod selecttools;
 mod settings;
diff --git a/crates/engine/src/cmd/props.rs b/crates/engine/src/cmd/props.rs
index 2d408b00..7ef3aa68 100644
--- a/crates/engine/src/cmd/props.rs
+++ b/crates/engine/src/cmd/props.rs
@@ -418,7 +418,25 @@ fn run_set(s: &mut Session, p: &Value) -> Result<Value> {
 
 fn run_color(s: &mut Session, p: &Value) -> Result<Value> {
     let c = p.get("color").and_then(parse_color).ok_or_else(|| bad("color", "`color` is required"))?;
-    let d = s.doc_mut()?;
+    set_current_color(s.doc_mut()?, c);
+    ok()
+}
+
+/// `setvar CECOLOR`: the same input as the `color` command, stored the same way.
+pub(crate) fn set_current_color_value(s: &mut Session, v: &Value) -> Option<()> {
+    // An out-of-range index is refused here, where `color` folds it to ByLayer.
+    let c = match v {
+        Value::String(t) => Color::parse(t),
+        Value::Number(n) => n.as_i64().and_then(|i| Color::parse(&i.to_string())),
+        _ => None,
+    }?;
+    set_current_color(s.doc_mut().ok()?, c);
+    Some(())
+}
+
+/// A true colour keeps its RGB in CECOLOR_RGB (which wins for new objects); any other colour must
+/// clear a stale one.
+fn set_current_color(d: &mut cadcraft_doc::Drawing, c: Color) {
     match c {
         Color::True(rgb) => {
             d.header.set_i64("CECOLOR", i64::from(cadcraft_color::nearest_aci(rgb)));
@@ -429,7 +447,6 @@ fn run_color(s: &mut Session, p: &Value) -> Result<Value> {
             d.header.vars.remove("CECOLOR_RGB");
         }
     }
-    ok()
 }
 
 mod linfile;
diff --git a/crates/engine/src/sysvars.rs b/crates/engine/src/sysvars.rs
index b77f0465..89bde769 100644
--- a/crates/engine/src/sysvars.rs
+++ b/crates/engine/src/sysvars.rs
@@ -276,6 +276,8 @@ pub fn set(s: &mut Session, name: &str, v: &Value) -> Result<()> {
     let st = &mut s.settings;
     match n.as_str() {
         "OSMODE" => st.osmode = v.as_u64().or_else(|| v.as_str().and_then(|s| s.trim().parse().ok())).ok_or_else(bad)? as u32 & 0x7fff,
+        // The `color` command's input: ByLayer, ByBlock, a name, an index or a true colour.
+        "CECOLOR" => crate::cmd::set_current_color_value(s, v).ok_or_else(bad)?,
         "OSNAPHATCH" => st.osnaphatch = as_bool(v).ok_or_else(bad)?,
         "ANNOAUTOSCALE" => st.annoautoscale = as_i(v).filter(|i| (-4..=4).contains(i)).ok_or_else(bad)? > 0,
         // A scale of the drawing's list; ANNOAUTOSCALE adds it to the annotative objects.
diff --git a/crates/engine/tests/it/main.rs b/crates/engine/tests/it/main.rs
index b6e088a1..3edc0db9 100644
--- a/crates/engine/tests/it/main.rs
+++ b/crates/engine/tests/it/main.rs
@@ -108,6 +108,7 @@ mod select_similar;
 mod select_underscore_keywords;
 mod selection_cycling;
 mod selection_modes;
+mod setvar_cecolor;
 mod setvar_coverage;
 mod shapes;
 mod snap_annotations;
diff --git a/crates/engine/tests/it/setvar_cecolor.rs b/crates/engine/tests/it/setvar_cecolor.rs
new file mode 100644
index 00000000..a8347ddc
--- /dev/null
+++ b/crates/engine/tests/it/setvar_cecolor.rs
@@ -0,0 +1,51 @@
+//! `setvar CECOLOR` takes what the `color` command takes: "ByLayer", "ByBlock", a colour name or an
+//! index (#1999).
+
+use cadcraft_engine::Session;
+use cadcraft_engine::doc::color::{Color, Rgb};
+use serde_json::{Value, json};
+
+fn cecolor(s: &mut Session) -> Value {
+    s.execute("getvar", &json!({ "name": "CECOLOR" })).unwrap()["value"].clone()
+}
+
+fn new_line_color(s: &mut Session) -> Color {
+    s.execute("line", &json!({ "points": [[0, 0], [10, 0]] })).unwrap();
+    s.doc().unwrap().model.last().unwrap().common.color
+}
+
+#[test]
+fn setvar_cecolor_accepts_names() {
+    for (value, aci) in [("BYLAYER", 256), ("ByLayer", 256), ("BYBLOCK", 0), ("red", 1), ("250", 250)] {
+        let mut s = Session::new();
+        s.execute("setvar", &json!({ "name": "CECOLOR", "value": value })).unwrap_or_else(|e| panic!("{value}: {e}"));
+        assert_eq!(cecolor(&mut s), json!(aci), "{value}");
+    }
+}
+
+#[test]
+fn setvar_cecolor_name_replaces_a_true_colour() {
+    let mut s = Session::new();
+    s.execute("color", &json!({ "color": "10,20,30" })).unwrap();
+    assert_eq!(new_line_color(&mut s), Color::True(Rgb(10, 20, 30)));
+    s.execute("setvar", &json!({ "name": "CECOLOR", "value": "ByLayer" })).unwrap();
+    assert_eq!(cecolor(&mut s), json!(256));
+    assert_eq!(new_line_color(&mut s), Color::ByLayer);
+}
+
+#[test]
+fn setvar_cecolor_number_replaces_a_true_colour() {
+    let mut s = Session::new();
+    s.execute("color", &json!({ "color": "10,20,30" })).unwrap();
+    s.execute("setvar", &json!({ "name": "CECOLOR", "value": 250 })).unwrap();
+    assert_eq!(new_line_color(&mut s), Color::Index(250));
+}
+
+#[test]
+fn setvar_cecolor_refuses_what_is_not_a_colour() {
+    let mut s = Session::new();
+    for bad in [json!("chartreuse"), json!(257), json!(-1), json!(true)] {
+        assert!(s.execute("setvar", &json!({ "name": "CECOLOR", "value": bad })).is_err(), "{bad}");
+    }
+    assert_eq!(cecolor(&mut s), json!(256));
+}