mirror of
https://github.com/ratatui-org/ratatui
synced 2024-11-22 12:43:16 +00:00
80 lines
3.6 KiB
Rust
80 lines
3.6 KiB
Rust
use std::{
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io::{self, Stdout},
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time::Duration,
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};
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use anyhow::{Context, Result};
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use crossterm::{
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event::{self, Event, KeyCode},
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execute,
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terminal::{disable_raw_mode, enable_raw_mode, EnterAlternateScreen, LeaveAlternateScreen},
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};
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use ratatui::prelude::*;
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/// This is a bare minimum example. There are many approaches to running an application loop, so
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/// this is not meant to be prescriptive. It is only meant to demonstrate the basic setup and
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/// teardown of a terminal application.
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///
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/// A more robust application would probably want to handle errors and ensure that the terminal is
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/// restored to a sane state before exiting. This example does not do that. It also does not handle
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/// events or update the application state. It just draws a greeting and exits when the user
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/// presses 'q'.
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fn main() -> Result<()> {
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let mut terminal = setup_terminal().context("setup failed")?;
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run(&mut terminal).context("app loop failed")?;
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restore_terminal(&mut terminal).context("restore terminal failed")?;
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Ok(())
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}
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/// Setup the terminal. This is where you would enable raw mode, enter the alternate screen, and
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/// hide the cursor. This example does not handle errors. A more robust application would probably
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/// want to handle errors and ensure that the terminal is restored to a sane state before exiting.
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fn setup_terminal() -> Result<Terminal<CrosstermBackend<Stdout>>> {
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let mut stdout = io::stdout();
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enable_raw_mode().context("failed to enable raw mode")?;
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execute!(stdout, EnterAlternateScreen).context("unable to enter alternate screen")?;
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Terminal::new(CrosstermBackend::new(stdout)).context("creating terminal failed")
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}
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/// Restore the terminal. This is where you disable raw mode, leave the alternate screen, and show
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/// the cursor.
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fn restore_terminal(terminal: &mut Terminal<CrosstermBackend<Stdout>>) -> Result<()> {
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disable_raw_mode().context("failed to disable raw mode")?;
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execute!(terminal.backend_mut(), LeaveAlternateScreen)
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.context("unable to switch to main screen")?;
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terminal.show_cursor().context("unable to show cursor")
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}
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/// Run the application loop. This is where you would handle events and update the application
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/// state. This example exits when the user presses 'q'. Other styles of application loops are
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/// possible, for example, you could have multiple application states and switch between them based
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/// on events, or you could have a single application state and update it based on events.
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fn run(terminal: &mut Terminal<CrosstermBackend<Stdout>>) -> Result<()> {
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loop {
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terminal.draw(crate::render_app)?;
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if should_quit()? {
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break;
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}
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}
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Ok(())
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}
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/// Render the application. This is where you would draw the application UI. This example just
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/// draws a greeting.
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fn render_app(frame: &mut ratatui::Frame<CrosstermBackend<Stdout>>) {
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let greeting = Paragraph::new("Hello World! (press 'q' to quit)");
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frame.render_widget(greeting, frame.size());
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}
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/// Check if the user has pressed 'q'. This is where you would handle events. This example just
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/// checks if the user has pressed 'q' and returns true if they have. It does not handle any other
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/// events. There is a 250ms timeout on the event poll so that the application can exit in a timely
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/// manner, and to ensure that the terminal is rendered at least once every 250ms.
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fn should_quit() -> Result<bool> {
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if event::poll(Duration::from_millis(250)).context("event poll failed")? {
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if let Event::Key(key) = event::read().context("event read failed")? {
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return Ok(KeyCode::Char('q') == key.code);
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}
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}
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Ok(false)
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}
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