ratatui/examples/histogram.rs

use crossterm::{
    event::{self, DisableMouseCapture, EnableMouseCapture, Event, KeyCode},
    execute,
    terminal::{disable_raw_mode, enable_raw_mode, EnterAlternateScreen, LeaveAlternateScreen},
};
use ratatui::{
    backend::{Backend, CrosstermBackend},
    layout::{Constraint, Direction, Layout},
    style::{Color, Style},
    widgets::{Block, Borders, Histogram},
    Frame, Terminal,
};
use std::{
    error::Error,
    io,
    time::{Duration, Instant},
};

use rand::{rngs::ThreadRng, thread_rng, Rng};

struct App {
    data: Vec<u64>,
    size: usize,
    rng: ThreadRng,
}

impl App {
    fn new(size: usize) -> App {
        let data = vec![0; size];
        App {
            data,
            rng: thread_rng(),
            size,
        }
    }

    fn on_tick(&mut self) {
        for i in 0..self.size {
            self.data[i] = self.rng.gen_range(0..100);
        }
    }
}

fn main() -> Result<(), Box<dyn Error>> {
    // setup terminal
    enable_raw_mode()?;
    let mut stdout = io::stdout();
    execute!(stdout, EnterAlternateScreen, EnableMouseCapture)?;
    let backend = CrosstermBackend::new(stdout);
    let mut terminal = Terminal::new(backend)?;

    // create app and run it
    let tick_rate = Duration::from_millis(250);
    let app = App::new(100);
    let res = run_app(&mut terminal, app, tick_rate);

    // restore terminal
    disable_raw_mode()?;
    execute!(
        terminal.backend_mut(),
        LeaveAlternateScreen,
        DisableMouseCapture
    )?;
    terminal.show_cursor()?;

    if let Err(err) = res {
        println!("{:?}", err)
    }

    Ok(())
}

fn run_app<B: Backend>(
    terminal: &mut Terminal<B>,
    mut app: App,
    tick_rate: Duration,
) -> io::Result<()> {
    let mut last_tick = Instant::now();
    loop {
        terminal.draw(|f| ui(f, &app))?;

        let timeout = tick_rate
            .checked_sub(last_tick.elapsed())
            .unwrap_or_else(|| Duration::from_secs(0));
        if crossterm::event::poll(timeout)? {
            if let Event::Key(key) = event::read()? {
                if let KeyCode::Char('q') = key.code {
                    return Ok(());
                }
            }
        }
        if last_tick.elapsed() >= tick_rate {
            app.on_tick();
            last_tick = Instant::now();
        }
    }
}

fn ui<B: Backend>(f: &mut Frame<B>, app: &App) {
    let chunks = Layout::default()
        .direction(Direction::Vertical)
        .margin(2)
        .constraints([Constraint::Percentage(100)].as_ref())
        .split(f.size());
    let histogram = Histogram::default()
        .block(Block::default().title("Data1").borders(Borders::ALL))
        .data(&app.data, 10)
        .bar_style(Style::default().fg(Color::Yellow))
        .value_style(Style::default().fg(Color::Black).bg(Color::Yellow));
    f.render_widget(histogram, chunks[0]);
}