TUIs with ratatui

use crossterm::event::{self, Event, KeyCode};
use ratatui::{prelude::*, widgets::Paragraph};
 
fn main() -> anyhow::Result<()> {
    let mut terminal = Terminal::new(CrosstermBackend::new(std::io::stderr()))?;
    terminal.clear()?;
    loop {
        terminal.draw(|f| {
            let area = f.area();
            f.render_widget(Paragraph::new("Press q to quit"), area);
        })?;
        if let Event::Key(key) = event::read()? {
            if key.code == KeyCode::Char('q') { break; }
        }
    }
    terminal.show_cursor()?;
    Ok(())
}

use crossterm::event::{self, Event, KeyCode};
use ratatui::{
    layout::{Constraint, Direction, Layout},
    prelude::*,
    widgets::{Block, Borders, List, ListItem},
};
 
struct App {
    items: Vec<String>,
    selected: usize,
}
 
impl App {
    fn next(&mut self) {
        self.selected = (self.selected + 1) % self.items.len();
    }
}
 
fn main() -> anyhow::Result<()> {
    let mut app = App {
        items: vec!["alpha".into(), "beta".into(), "gamma".into()],
        selected: 0,
    };
    let mut terminal = Terminal::new(CrosstermBackend::new(std::io::stderr()))?;
    loop {
        terminal.draw(|f| {
            let chunks = Layout::default()
                .direction(Direction::Vertical)
                .constraints([Constraint::Min(3), Constraint::Length(1)])
                .split(f.area());
            let items: Vec<ListItem> = app.items.iter()
                .enumerate()
                .map(|(i, s)| {
                    let style = if i == app.selected {
                        Style::default().bg(Color::Blue)
                    } else {
                        Style::default()
                    };
                    ListItem::new(s.as_str()).style(style)
                })
                .collect();
            f.render_widget(
                List::new(items).block(Block::default().borders(Borders::ALL).title("Items")),
                chunks[0],
            );
        })?;
        if let Event::Key(key) = event::read()? {
            match key.code {
                KeyCode::Char('q') => break,
                KeyCode::Down | KeyCode::Char('j') => app.next(),
                _ => {}
            }
        }
    }
    Ok(())
}