Trait Backend

Source

pub trait Backend {
    // Required methods
    fn size(&self) -> (u32, u32);
    fn buffer_mut(&mut self) -> &mut Buffer;
    fn flush(&mut self) -> Result<()>;
}

Expand description

Rendering backend for SLT.

Implement this trait to render SLT UIs to custom targets — alternative terminals, GUI embeds, test harnesses, WASM canvas, etc.

The built-in terminal backend (run(), run_with()) handles setup, teardown, and event polling automatically. For custom backends, pair this trait with AppState and frame() to drive the render loop yourself.

§Example

use slt::{Backend, AppState, Buffer, Rect, RunConfig, Context, Event};

struct MyBackend {
    buffer: Buffer,
}

impl Backend for MyBackend {
    fn size(&self) -> (u32, u32) {
        (self.buffer.area.width, self.buffer.area.height)
    }
    fn buffer_mut(&mut self) -> &mut Buffer {
        &mut self.buffer
    }
    fn flush(&mut self) -> std::io::Result<()> {
        // Render self.buffer to your target
        Ok(())
    }
}

fn main() -> std::io::Result<()> {
    let mut backend = MyBackend {
        buffer: Buffer::empty(Rect::new(0, 0, 80, 24)),
    };
    let mut state = AppState::new();
    let config = RunConfig::default();

    loop {
        let events: Vec<Event> = vec![]; // Collect your own events
        if !slt::frame(&mut backend, &mut state, &config, &events, &mut |ui| {
            ui.text("Hello from custom backend!");
        })? {
            break;
        }
    }
    Ok(())
}

Required Methods§

Source

fn size(&self) -> (u32, u32)

Returns the current display size as (width, height) in cells.

Source

fn buffer_mut(&mut self) -> &mut Buffer

Returns a mutable reference to the display buffer.

SLT writes the UI into this buffer each frame. After frame() returns, call flush() to present the result.

Source

fn flush(&mut self) -> Result<()>

Flush the buffer contents to the display.

Called automatically at the end of each frame() call. Implementations should present the current buffer to the user — by writing ANSI escapes, drawing to a canvas, updating a texture, etc.