Struct Toggle

pub struct Toggle<Msg: Clone> {
    pub value: bool,
    pub on_toggle: Option<Msg>,
    pub label: Option<String>,
    pub id: Option<WidgetId>,
}

A two-state on / off switch.

Renders as a horizontal pill with a circular thumb that slides between the off (left, divider colour) and on (right, accent colour) positions. The widget is stateless: the application owns value and rebuilds the toggle from its current state on every frame. Tapping or pressing Enter / Space while focused emits the message configured with Self::on_toggle — the app’s update is then expected to flip the bool and re-render.

// In view():
toggle( self.wifi_enabled )
    .label( "Wi-Fi" )
    .on_toggle( Msg::ToggleWifi )

See also Checkbox for binary opt-in controls (terms acceptance, multi-select form fields) where the pill-style affordance is too prominent.

Fields

value: bool

Current on / off state. Drawn from this field every frame; the runtime never mutates it.

on_toggle: Option<Msg>

Message emitted on activation. None leaves the toggle inert (it still renders and takes focus, but does nothing on press).

label: Option<String>

Optional label drawn to the left of the track.

id: Option<WidgetId>

Optional stable identifier for focus management.

Implementations

impl<Msg: Clone> Toggle<Msg>

pub fn new(value: bool) -> Self

Create a toggle in the given state, with no label and no callback.

Wire activation through Self::on_toggle before adding it to a widget tree, otherwise the toggle is decorative.

pub fn on_toggle(self, msg: Msg) -> Self

Set the message emitted when the toggle is activated (tap, Enter or Space while focused). The application’s update is responsible for flipping value in response.

pub fn label(self, label: impl Into<String>) -> Self

Set a text label rendered to the left of the track. The toggle’s preferred width grows to fit label_width + gap + track_width, capped at the parent-supplied max_width.

pub fn id(self, id: WidgetId) -> Self

Assign a stable identifier so the application can target this toggle through crate::App::take_focus_request.

pub fn preferred_size(&self, max_width: f32, canvas: &Canvas) -> (f32, f32)

Return the preferred (width, height) given available max_width.

Width is track_width for an unlabelled toggle, or label_width + gap + track_width (clamped to max_width) when a label is set. Height is the theme-defined row height.

pub fn paint_bounds(&self, rect: Rect) -> Rect

Bounding box of everything painted at rect across all states. The focus ring is drawn as track_rect.expand( FOCUS_W + 2 ) with a stroke of width FOCUS_W, so it extends FOCUS_W + 2 + FOCUS_W/2 ≈ 6.5 px beyond the track. Since the track sits at the right edge of rect, the ring can extend that far outside the widget’s layout rect.

pub fn draw(&self, canvas: &mut Canvas, rect: Rect, focused: bool)

Trait Implementations

impl<Msg: Clone + 'static> From<Toggle<Msg>> for Element<Msg>

fn from(t: Toggle<Msg>) -> Self

Converts to this type from the input type.