Struct Knob 

pub struct Knob<'a, T: Numeric> { /* private fields */ }

Rotary knob bound to a numeric value.

let mut gain = -12.0_f32;
ui.add(
    Knob::new(&mut gain, -60.0..=12.0)
        .label("Gain")
        .size(KnobSize::Small)
        .default(0.0_f32)
        .value_fmt(|v| format!("{v:.0} dB")),
);

let mut dc = -1.4_f32;
ui.add(
    Knob::new(&mut dc, -5.0..=5.0)
        .label("DC offset")
        .bipolar()
        .accent(Accent::Purple)
        .show_value(true),
);

Implementations

impl<'a, T: Numeric> Knob<'a, T>

pub fn new(value: &'a mut T, range: RangeInclusive<T>) -> Self

Create a knob bound to value, constrained to range.

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

Show a label above the knob.

pub fn size(self, size: KnobSize) -> Self

Pick a visual size. Default: KnobSize::Medium.

pub fn accent(self, accent: Accent) -> Self

Pick the fill colour from one of the theme accents. Default: Accent::Sky.

pub fn bipolar(self) -> Self

Render as a bipolar knob: the active arc fills from the centre of the range toward the current value, suited to signed values (DC offset, pan, balance).

pub fn detents<I, S>(self, detents: I) -> Self

where I: IntoIterator<Item = (T, S)>, S: Into<String>,

Snap to a fixed list of (value, label) detents and render a labeled tick at each. Drag, scroll, and arrow keys step between detents. Existing step is overridden.

pub fn step(self, step: f64) -> Self

Snap continuous values to multiples of step (in the knob’s value units). Integer-typed knobs snap to 1.0 automatically. Ignored if detents is set.

pub fn log_scale(self) -> Self

Use a logarithmic value mapping. Falls back to linear if the range minimum is non-positive.

pub fn value_fmt(self, fmt: impl Fn(f64) -> String + 'a) -> Self

Provide a value formatter for the optional inline display.

pub fn show_value(self, show: bool) -> Self

Render the formatted value below the knob. Default: hidden.

pub fn default(self, default: T) -> Self

Value to reset to on Alt+click or double-click. If unset, the reset gesture is a no-op.

pub fn enabled(self, enabled: bool) -> Self

Disable the knob — no pointer, scroll, or keyboard input. Default: enabled.

Trait Implementations

impl<'a, T: Numeric> Debug for Knob<'a, T>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'a, T: Numeric> Widget for Knob<'a, T>

fn ui(self, ui: &mut Ui) -> Response

Allocate space, interact, paint, and return a Response.