Hello World
Demonstrates a basic hello world app.
git clone https://github.com/ratatui-org/ratatui.git --branch latestcd ratatuicargo run --example=hello_world --features=crossterm
//! # [Ratatui] Hello World example//!//! The latest version of this example is available in the [examples] folder in the repository.//!//! Please note that the examples are designed to be run against the `main` branch of the Github//! repository. This means that you may not be able to compile with the latest release version on//! crates.io, or the one that you have installed locally.//!//! See the [examples readme] for more information on finding examples that match the version of the//! library you are using.//!//! [Ratatui]: https://github.com/ratatui-org/ratatui//! [examples]: https://github.com/ratatui-org/ratatui/blob/main/examples//! [examples readme]: https://github.com/ratatui-org/ratatui/blob/main/examples/README.md
use std::{ io::{self, Stdout}, time::Duration,};
use anyhow::{Context, Result};use ratatui::{ crossterm::{ event::{self, Event, KeyCode}, execute, terminal::{disable_raw_mode, enable_raw_mode, EnterAlternateScreen, LeaveAlternateScreen}, }, prelude::*, widgets::Paragraph,};
/// This is a bare minimum example. There are many approaches to running an application loop, so/// this is not meant to be prescriptive. It is only meant to demonstrate the basic setup and/// teardown of a terminal application.////// A more robust application would probably want to handle errors and ensure that the terminal is/// restored to a sane state before exiting. This example does not do that. It also does not handle/// events or update the application state. It just draws a greeting and exits when the user/// presses 'q'.fn main() -> Result<()> { let mut terminal = setup_terminal().context("setup failed")?; run(&mut terminal).context("app loop failed")?; restore_terminal(&mut terminal).context("restore terminal failed")?; Ok(())}
/// Setup the terminal. This is where you would enable raw mode, enter the alternate screen, and/// hide the cursor. This example does not handle errors. A more robust application would probably/// want to handle errors and ensure that the terminal is restored to a sane state before exiting.fn setup_terminal() -> Result<Terminal<CrosstermBackend<Stdout>>> { let mut stdout = io::stdout(); enable_raw_mode().context("failed to enable raw mode")?; execute!(stdout, EnterAlternateScreen).context("unable to enter alternate screen")?; Terminal::new(CrosstermBackend::new(stdout)).context("creating terminal failed")}
/// Restore the terminal. This is where you disable raw mode, leave the alternate screen, and show/// the cursor.fn restore_terminal(terminal: &mut Terminal<CrosstermBackend<Stdout>>) -> Result<()> { disable_raw_mode().context("failed to disable raw mode")?; execute!(terminal.backend_mut(), LeaveAlternateScreen) .context("unable to switch to main screen")?; terminal.show_cursor().context("unable to show cursor")}
/// Run the application loop. This is where you would handle events and update the application/// state. This example exits when the user presses 'q'. Other styles of application loops are/// possible, for example, you could have multiple application states and switch between them based/// on events, or you could have a single application state and update it based on events.fn run(terminal: &mut Terminal<CrosstermBackend<Stdout>>) -> Result<()> { loop { terminal.draw(crate::render_app)?; if should_quit()? { break; } } Ok(())}
/// Render the application. This is where you would draw the application UI. This example just/// draws a greeting.fn render_app(frame: &mut Frame) { let greeting = Paragraph::new("Hello World! (press 'q' to quit)"); frame.render_widget(greeting, frame.size());}
/// Check if the user has pressed 'q'. This is where you would handle events. This example just/// checks if the user has pressed 'q' and returns true if they have. It does not handle any other/// events. There is a 250ms timeout on the event poll so that the application can exit in a timely/// manner, and to ensure that the terminal is rendered at least once every 250ms.fn should_quit() -> Result<bool> { if event::poll(Duration::from_millis(250)).context("event poll failed")? { if let Event::Key(key) = event::read().context("event read failed")? { return Ok(KeyCode::Char('q') == key.code); } } Ok(false)}