Trait Widget

Source

pub trait Widget {
    type Response;

    // Required method
    fn ui(&mut self, ctx: &mut Context) -> Self::Response;
}

Expand description

Trait for creating custom widgets.

Implement this trait to build reusable, composable widgets with full access to the Context API — focus, events, theming, layout, and mouse interaction.

§Examples

A simple rating widget:

use slt::{Context, Widget, Color};

struct Rating {
    value: u8,
    max: u8,
}

impl Rating {
    fn new(value: u8, max: u8) -> Self {
        Self { value, max }
    }
}

impl Widget for Rating {
    type Response = bool;

    fn ui(&mut self, ui: &mut Context) -> bool {
        let focused = ui.register_focusable();
        let mut changed = false;

        if focused {
            if ui.key('+') && self.value < self.max {
                self.value += 1;
                changed = true;
            }
            if ui.key('-') && self.value > 0 {
                self.value -= 1;
                changed = true;
            }
        }

        let stars: String = (0..self.max).map(|i| {
            if i < self.value { '★' } else { '☆' }
        }).collect();

        let color = if focused { Color::Yellow } else { Color::White };
        ui.styled(stars, slt::Style::new().fg(color));

        changed
    }
}

fn main() -> std::io::Result<()> {
    let mut rating = Rating::new(3, 5);
    slt::run(|ui| {
        if ui.key('q') { ui.quit(); }
        ui.text("Rate this:");
        ui.widget(&mut rating);
    })
}