Struct WorkbenchButton 

pub struct WorkbenchButton {
    pub id: &'static str,
    pub glyph: &'static str,
    pub tooltip: &'static str,
    pub when: Option<fn(&ButtonState<'_>) -> bool>,
    pub pressed: Option<fn(&ButtonState<'_>) -> bool>,
    pub disabled: Option<fn(&ButtonState<'_>) -> Option<&'static str>>,
    pub caption: Option<fn(&ButtonState<'_>) -> String>,
    pub menu: &'static [WorkbenchButton],
}

A workbench-specific toolbar button, DATA ONLY (no egui, no behavior): the shared toolbar-button helper renders it and a click surfaces id out of the toolbar to the shell, which dispatches on id.

A button may be CONDITIONAL on document state (Self::when) and may read as PRESSED from it (Self::pressed). Both are predicates over the document (ButtonState) rather than flags the toolbar sets, so the declaration still owns the whole answer and the row stays a renderer: Drawing’s sheet buttons are offered only while a sheet is OPEN, and the armed sketch draw tool is the lit button. A None predicate is the plain case — always offered, never pressed — which is most buttons.

Three more readings came with the eCAD editors, whose actions carry them: an offered button can be DISABLED with a reason (Self::disabled), its label can be LIVE (Self::caption), and it can be a MENU of other buttons (Self::menu).

Fields

id: &'static str

Stable id the shell matches on when the button is clicked.

glyph: &'static str

The single unicode glyph shown on the square button.

tooltip: &'static str

Hover tooltip / human label.

when: Option<fn(&ButtonState<'_>) -> bool>

When this button is OFFERED at all. None = always.

pressed: Option<fn(&ButtonState<'_>) -> bool>

When this button draws PRESSED (a toggle reflecting live state, the way the toolbar’s wireframe and projection buttons do). None = a plain momentary button.

disabled: Option<fn(&ButtonState<'_>) -> Option<&'static str>>

Why an OFFERED button cannot act right now, or None when it can. A disabled button is drawn greyed with the reason on hover, and the workbench_button command refuses it with the same reason — never a silent no-op. None = never disabled.

This is eCAD’s enabled, kept apart from offered the way eCAD keeps it: Finish wire is on the row whenever the wire tool is, and greyed until there is a wire to finish, rather than blinking in and out.

caption: Option<fn(&ButtonState<'_>) -> String>

A LIVE label that replaces Self::tooltip where one is drawn, for a button whose words describe state (Bend: vertical first) or depend on the document (a copper layer’s name). None = the tooltip.

menu: &'static [WorkbenchButton]

A MENU button’s entries: clicking it opens a menu of these, each with its live caption and pressed state, instead of surfacing its own id. The entries are buttons in every other respect — ids the lookup finds and the workbench_button command presses. A menu is offered while any entry is. Empty = an ordinary button.

Implementations

impl WorkbenchButton

pub fn offered(&self, state: &ButtonState<'_>) -> bool

Whether state offers this button. The ONE reading of Self::when — the toolbar row, the workbench_button command and describe_workbenches all route through it, so a button an agent can call is exactly a button the user can see.

pub fn is_pressed(&self, state: &ButtonState<'_>) -> bool

Whether this button draws pressed in state.

pub fn disabled_reason(&self, state: &ButtonState<'_>) -> Option<&'static str>

Why this button cannot act in state, or None when it can.

pub fn label(&self, state: &ButtonState<'_>) -> String

The words this button shows in state: its live caption, or its tooltip.