egui_knob

A simple, customizable knob widget for egui.

Knob Widget Screenshot

Features

Adjustable size, font size, and stroke width
Customizable colors for the knob, indicator, and text
Label positions (Top, Bottom, Left, Right)
Custom label formatting
Two visual styles: Wiper and Dot
Configurable sweep range
Background arc with filled segments
Adjustable drag sensitivity

Installation

To use the Knob widget in your project, add the following to your Cargo.toml:

[dependencies]

egui = "0.33"

eframe = "0.33"

egui_knob = "0.3.5"

Usage

Basic Example

use egui_knob::{Knob, KnobStyle, LabelPosition};
use eframe::egui;

struct KnobApp {
    value: f32,
}

impl Default for KnobApp {
    fn default() -> Self {
        Self { value: 0.5 }
    }
}

impl eframe::App for KnobApp {
    fn update(&mut self, ctx: &egui::Context, _frame: &mut eframe::Frame) {
        egui::CentralPanel::default().show(ctx, |ui| {
            let knob = Knob::new(&mut self.value, 0.0, 1.0, KnobStyle::Wiper)
                .with_size(50.0)
                .with_font_size(14.0)
                .with_colors(egui::Color32::GRAY, egui::Color32::WHITE, egui::Color32::WHITE)
                .with_stroke_width(3.0)
                .with_label("Volume", LabelPosition::Top);

            ui.add(knob);
        });
    }
}

fn main() -> eframe::Result<()> {
    eframe::run_native(
        "Knob Example",
        eframe::NativeOptions::default(),
        Box::new(|_cc| Ok(Box::new(KnobApp::default()))),
    )
}

Advanced Examples

Custom Sweep Range

// 270° sweep starting from the left (9 o'clock position)
Knob::new(&mut value, 0.0, 100.0, KnobStyle::Wiper)
    .with_sweep_range(0.25, 0.75)
    .with_label("Gain", LabelPosition::Bottom);

Multi-Turn Knob

// 2.5 full rotations
Knob::new(&mut value, 0.0, 1.0, KnobStyle::Dot)
    .with_sweep_range(0.0, 2.5);

Stepped Values

// Snap to 0.1 increments
Knob::new(&mut value, 0.0, 1.0, KnobStyle::Wiper)
    .with_step(Some(0.1))
    .with_label_format(|v| format!("{:.1}", v));

Custom Formatting

// Display as percentage
Knob::new(&mut value, 0.0, 1.0, KnobStyle::Wiper)
    .with_label_format(|v| format!("{:.0}%", v * 100.0));

Running demo app

cargo run --example example_knob

Demo app is available at examples/example_knob.rs.

Contributing

Contributions are welcome. Feel free to open an issue or submit a PR.

egui_knob 0.3.5