An example of using Widget with ratatui in a slimmed down manner

ratatuiwidgetexample.rs

use crossterm::{
    event::{self, Event, KeyCode},
    terminal::{disable_raw_mode, enable_raw_mode, EnterAlternateScreen, LeaveAlternateScreen},
    ExecutableCommand,
};
use ratatui::{prelude::*, widgets::*};
use std::io::{self, stdout, Error};

#[derive(Debug, Default)]
struct App {
    pub mode: Mode,
}

#[derive(Debug, Default, Clone, Copy, PartialEq, Eq)]
enum Mode {
    #[default]
    Running,
    Quit,
}

struct Banner {
    pub text: String,
}

impl Widget for &Banner {
    fn render(self, area: Rect, buf: &mut Buffer) {
        let title_block = Block::default()
            .borders(Borders::ALL)
            .style(Style::default());

        Paragraph::new(Text::styled(&self.text, Style::default()))
            .block(title_block)
            .render(area, buf);
    }
}

impl App {
    pub fn run(&mut self, terminal: &mut Terminal<impl Backend>) -> Result<(), Error> {
        while self.is_running() {
            self.draw(terminal)?;
            self.handle_keypress()?;
        }
        Ok(())
    }

    fn is_running(&self) -> bool {
        self.mode != Mode::Quit
    }

    fn draw(&self, terminal: &mut Terminal<impl Backend>) -> Result<(), Error> {
        terminal.draw(|frame| {
            frame.render_widget(self, frame.size());
        })?;
        Ok(())
    }

    pub fn handle_keypress(&mut self) -> Result<(), Error> {
        if let Event::Key(key) = event::read()? {
            match self.mode {
                Mode::Running => match key.code {
                    KeyCode::Char('q') => self.mode = Mode::Quit,
                    _ => {}
                },
                Mode::Quit => {}
            }
        }
        Ok(())
    }

    fn render_title_bar(&self, area: Rect, buf: &mut Buffer) {
        let banner = Banner {
            text: "Title 1".to_string(),
        };
        banner.render(area, buf);
    }

    fn render_middle_bar(&self, area: Rect, buf: &mut Buffer) {
        let banner = Banner {
            text: "Title 2".to_string(),
        };
        banner.render(area, buf);
    }
}

impl Widget for &App {
    fn render(self, area: Rect, buf: &mut Buffer) {
        let vertical = Layout::vertical([Constraint::Length(3), Constraint::Length(3)]);
        let [title_bar, middle_bar] = vertical.areas(area);

        self.render_title_bar(title_bar, buf);
        self.render_middle_bar(middle_bar, buf);
    }
}

fn main() -> Result<(), Error> {
    let mut terminal = Terminal::new(CrosstermBackend::new(io::stdout()))?;
    let _ = enable_raw_mode();
    stdout().execute(EnterAlternateScreen)?;

    App::default().run(&mut terminal)?;

    let _ = disable_raw_mode();
    stdout().execute(LeaveAlternateScreen)?;

    Ok(())
}