feat(statusbar): drawing-units pill with INSUNITS picker

Add a Units pill that shows the drawing's current INSUNITS value and
opens a picker to change it (Unitless, mm, cm, m, km, in, ft, mi, yd).
Toggleable from the status-bar customization menu like the other pills.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/mod.rs

@@ -173,6 +173,8 @@ pub(super) struct OpenCADStudio {
     scale_popup_open: bool,
     /// True while the status-bar customization menu is open.
     statusbar_menu_open: bool,
+    /// True while the drawing-units picker is open.
+    units_popup_open: bool,
     /// Clean-screen mode: hide ribbon and side panels for a full canvas.
     clean_screen: bool,
     /// Which status-bar pills the user has chosen to show (persisted).
@@ -746,6 +748,12 @@ pub enum Message {
     ToggleStatusPill(crate::ui::statusbar_config::StatusPill),
     /// Toggle clean-screen mode (hide ribbon + side panels).
     ToggleCleanScreen,
+    /// Toggle the drawing-units picker open/closed.
+    ToggleUnitsPopup,
+    /// Close the drawing-units picker.
+    CloseUnitsPopup,
+    /// Set the drawing units (INSUNITS) for the active drawing.
+    SetDrawingUnits(i16),
     /// Toggle dynamic input overlay (F12).
     ToggleDynInput,
     /// Toggle object snap tracking (F11).
@@ -1203,6 +1211,7 @@ impl OpenCADStudio {
             snap_popup_open: false,
             scale_popup_open: false,
             statusbar_menu_open: false,
+            units_popup_open: false,
             statusbar_config: crate::ui::statusbar_config::StatusBarConfig::load(),
             clean_screen: false,
             pre_cmd_tangent: None,

src/app/update.rs

@@ -3580,6 +3580,21 @@ impl OpenCADStudio {
                 self.clean_screen ^= true;
                 Task::none()
             }
+            Message::ToggleUnitsPopup => {
+                self.units_popup_open ^= true;
+                Task::none()
+            }
+            Message::CloseUnitsPopup => {
+                self.units_popup_open = false;
+                Task::none()
+            }
+            Message::SetDrawingUnits(code) => {
+                self.units_popup_open = false;
+                let i = self.active_tab;
+                self.tabs[i].scene.document.header.insertion_units = code;
+                self.tabs[i].dirty = true;
+                Task::none()
+            }
             Message::ToggleSnap(t) => {
                 self.snapper.toggle(t);
                 Task::none()

src/app/view.rs

@@ -1157,6 +1157,8 @@ impl OpenCADStudio {
                         tab.scene.document.header.lineweight_display,
                         cursor_coord,
                         self.clean_screen,
+                        tab.scene.document.header.insertion_units,
+                        self.units_popup_open,
                         &self.statusbar_config,
                     )
                 })
@@ -1199,6 +1201,14 @@ impl OpenCADStudio {
             iced::widget::Space::new().width(0).height(0).into()
         };
 
+        let units_layer: Element<'_, Message> = if self.units_popup_open {
+            crate::ui::units_popup::units_popup_overlay(
+                tab.scene.document.header.insertion_units,
+            )
+        } else {
+            iced::widget::Space::new().width(0).height(0).into()
+        };
+
         let dropdown_layer: Element<'_, Message> = self
             .ribbon
             .dropdown_overlay(
@@ -1235,6 +1245,7 @@ impl OpenCADStudio {
             snap_layer,
             scale_layer,
             statusbar_menu_layer,
+            units_layer,
             dropdown_layer,
             layout_ctx_layer,
             qselect_layer,

src/ui/mod.rs

@@ -25,6 +25,7 @@ pub mod statusbar_config;
 pub mod statusbar_menu;
 pub mod tablestyle;
 pub mod textstyle;
+pub mod units_popup;
 
 pub use app_menu::AppMenu;
 pub use command_line::CommandLine;

src/ui/statusbar.rs

@@ -55,6 +55,10 @@ impl StatusBar {
         cursor_world: glam::Vec3,
         // True while clean-screen mode hides the ribbon and side panels.
         clean_screen: bool,
+        // Drawing units (INSUNITS) for the units pill.
+        insertion_units: i16,
+        // True while the drawing-units picker is open.
+        units_popup_open: bool,
         // Which pills the user has chosen to show on the bar.
         config: &'a StatusBarConfig,
     ) -> Element<'a, Message> {
@@ -160,6 +164,15 @@ impl StatusBar {
         if vis(StatusPill::Scale) {
             right_status = right_status.push(scale_element);
         }
+        if vis(StatusPill::Units) {
+            right_status = right_status.push(tip(
+                units_btn(
+                    crate::ui::units_popup::unit_short(insertion_units),
+                    units_popup_open,
+                ),
+                "Drawing Units (INSUNITS)\nClick to change",
+            ));
+        }
         if vis(StatusPill::Vp) && !vp_label.is_empty() {
             right_status = right_status.push(tip(
                 status_pill(vp_label).into(),
@@ -749,6 +762,34 @@ const SNAP_OFF_HOVER: Color = Color {
 
 // ── Scale popup button ────────────────────────────────────────────────────
 
+fn units_btn(label: &str, open: bool) -> Element<'static, Message> {
+    let label = label.to_string();
+    button(
+        text(label)
+            .size(10)
+            .color(if open { SNAP_BORDER_ON } else { OSNAP_OFF_TEXT }),
+    )
+    .on_press(Message::ToggleUnitsPopup)
+    .style(move |_: &Theme, status| button::Style {
+        background: Some(Background::Color(match (open, status) {
+            (true, button::Status::Hovered) => SNAP_ON_HOVER,
+            (true, _) => SNAP_ON_BG,
+            (false, button::Status::Hovered) => SNAP_OFF_HOVER,
+            (false, _) => SNAP_OFF_BG,
+        })),
+        border: Border {
+            color: if open { SNAP_BORDER_ON } else { BORDER_COLOR },
+            width: 1.0,
+            radius: 2.0.into(),
+        },
+        text_color: if open { SNAP_BORDER_ON } else { OSNAP_OFF_TEXT },
+        shadow: iced::Shadow::default(),
+        snap: false,
+    })
+    .padding([2, 6])
+    .into()
+}
+
 fn scale_popup_btn(label: &str, open: bool) -> Element<'static, Message> {
     let label = label.to_string();
     button(

src/ui/statusbar_config.rs

@@ -22,6 +22,7 @@ pub enum StatusPill {
     Osnap,
     Space,
     Scale,
+    Units,
     Vp,
     CleanScreen,
 }
@@ -41,6 +42,7 @@ impl StatusPill {
         StatusPill::Osnap,
         StatusPill::Space,
         StatusPill::Scale,
+        StatusPill::Units,
         StatusPill::Vp,
         StatusPill::CleanScreen,
     ];
@@ -59,6 +61,7 @@ impl StatusPill {
             StatusPill::Osnap => "osnap",
             StatusPill::Space => "space",
             StatusPill::Scale => "scale",
+            StatusPill::Units => "units",
             StatusPill::Vp => "vp",
             StatusPill::CleanScreen => "cleanscreen",
         }
@@ -78,6 +81,7 @@ impl StatusPill {
             StatusPill::Osnap => "Object Snap",
             StatusPill::Space => "Model/Paper Space",
             StatusPill::Scale => "Annotation Scale",
+            StatusPill::Units => "Drawing Units",
             StatusPill::Vp => "Viewport Count",
             StatusPill::CleanScreen => "Clean Screen",
         }

src/ui/units_popup.rs

@@ -0,0 +1,138 @@
+//! Drawing-units picker — sets the INSUNITS header value. Rendered as a
+//! floating overlay above the status bar, same pattern as the scale picker.
+
+use iced::widget::{button, column, container, mouse_area, row, text};
+use iced::{Background, Border, Color, Element, Fill, Length, Padding, Theme};
+
+use crate::app::Message;
+
+/// Units offered in the picker: (INSUNITS code, menu label).
+const UNITS: &[(i16, &str)] = &[
+    (0, "Unitless"),
+    (4, "Millimeters"),
+    (5, "Centimeters"),
+    (6, "Meters"),
+    (7, "Kilometers"),
+    (1, "Inches"),
+    (2, "Feet"),
+    (3, "Miles"),
+    (10, "Yards"),
+];
+
+/// Short label shown on the status-bar pill for an INSUNITS code.
+pub fn unit_short(code: i16) -> &'static str {
+    match code {
+        1 => "in",
+        2 => "ft",
+        3 => "mi",
+        4 => "mm",
+        5 => "cm",
+        6 => "m",
+        7 => "km",
+        10 => "yd",
+        0 => "Unitless",
+        _ => "Unit",
+    }
+}
+
+/// Full-screen overlay: transparent click-catcher + units list pinned
+/// bottom-right, above the status bar.
+pub fn units_popup_overlay(current: i16) -> Element<'static, Message> {
+    let rows: Vec<Element<'static, Message>> = UNITS
+        .iter()
+        .map(|&(code, label)| unit_row(label, code == current, Message::SetDrawingUnits(code)))
+        .collect();
+
+    let panel = container(column(rows))
+        .style(|_: &Theme| container::Style {
+            background: Some(Background::Color(PANEL_BG)),
+            border: Border {
+                color: PANEL_BORDER,
+                width: 1.0,
+                radius: 3.0.into(),
+            },
+            ..Default::default()
+        })
+        .width(Length::Fixed(140.0));
+
+    let positioned = container(panel)
+        .align_right(Fill)
+        .align_bottom(Fill)
+        .padding(Padding {
+            bottom: 27.0,
+            right: 4.0,
+            top: 0.0,
+            left: 0.0,
+        })
+        .width(Fill)
+        .height(Fill);
+
+    mouse_area(positioned)
+        .on_press(Message::CloseUnitsPopup)
+        .into()
+}
+
+fn unit_row(label: &'static str, active: bool, msg: Message) -> Element<'static, Message> {
+    let check = text(if active { "✓" } else { "  " })
+        .size(11)
+        .color(if active { CHECK_COLOR } else { Color::TRANSPARENT })
+        .width(Length::Fixed(14.0));
+
+    let lbl = text(label)
+        .size(11)
+        .color(if active { LABEL_ON } else { LABEL_OFF });
+
+    let content = row![check, lbl].spacing(6).align_y(iced::Center);
+
+    button(content)
+        .on_press(msg)
+        .style(|_: &Theme, status| button::Style {
+            background: Some(Background::Color(match status {
+                button::Status::Hovered => ROW_HOVER,
+                _ => Color::TRANSPARENT,
+            })),
+            ..Default::default()
+        })
+        .width(Fill)
+        .padding([4, 10])
+        .into()
+}
+
+// ── Colours ───────────────────────────────────────────────────────────────
+
+const PANEL_BG: Color = Color {
+    r: 0.15,
+    g: 0.15,
+    b: 0.15,
+    a: 1.0,
+};
+const PANEL_BORDER: Color = Color {
+    r: 0.32,
+    g: 0.32,
+    b: 0.32,
+    a: 1.0,
+};
+const ROW_HOVER: Color = Color {
+    r: 0.22,
+    g: 0.22,
+    b: 0.22,
+    a: 1.0,
+};
+const CHECK_COLOR: Color = Color {
+    r: 0.35,
+    g: 0.75,
+    b: 1.00,
+    a: 1.0,
+};
+const LABEL_ON: Color = Color {
+    r: 0.92,
+    g: 0.92,
+    b: 0.92,
+    a: 1.0,
+};
+const LABEL_OFF: Color = Color {
+    r: 0.65,
+    g: 0.65,
+    b: 0.65,
+    a: 1.0,
+};