paragraph/
paragraph.rs

1//! # [Ratatui] Paragraph example
2//!
3//! The latest version of this example is available in the [examples] folder in the repository.
4//!
5//! Please note that the examples are designed to be run against the `main` branch of the Github
6//! repository. This means that you may not be able to compile with the latest release version on
7//! crates.io, or the one that you have installed locally.
8//!
9//! See the [examples readme] for more information on finding examples that match the version of the
10//! library you are using.
11//!
12//! [Ratatui]: https://github.com/ratatui/ratatui
13//! [examples]: https://github.com/ratatui/ratatui/blob/main/examples
14//! [examples readme]: https://github.com/ratatui/ratatui/blob/main/examples/README.md
15
16use std::{
17    io::{self},
18    time::{Duration, Instant},
19};
20
21use color_eyre::Result;
22use ratatui::{
23    buffer::Buffer,
24    crossterm::event::{self, Event, KeyCode, KeyEventKind},
25    layout::{Constraint, Layout, Rect},
26    style::{Color, Stylize},
27    text::{Line, Masked, Span},
28    widgets::{Block, Paragraph, Widget, Wrap},
29    DefaultTerminal,
30};
31
32fn main() -> Result<()> {
33    color_eyre::install()?;
34    let terminal = ratatui::init();
35    let app_result = App::new().run(terminal);
36    ratatui::restore();
37    app_result
38}
39
40#[derive(Debug)]
41struct App {
42    should_exit: bool,
43    scroll: u16,
44    last_tick: Instant,
45}
46
47impl App {
48    /// The duration between each tick.
49    const TICK_RATE: Duration = Duration::from_millis(250);
50
51    /// Create a new instance of the app.
52    fn new() -> Self {
53        Self {
54            should_exit: false,
55            scroll: 0,
56            last_tick: Instant::now(),
57        }
58    }
59
60    /// Run the app until the user exits.
61    fn run(mut self, mut terminal: DefaultTerminal) -> Result<()> {
62        while !self.should_exit {
63            terminal.draw(|frame| frame.render_widget(&self, frame.area()))?;
64            self.handle_events()?;
65            if self.last_tick.elapsed() >= Self::TICK_RATE {
66                self.on_tick();
67                self.last_tick = Instant::now();
68            }
69        }
70        Ok(())
71    }
72
73    /// Handle events from the terminal.
74    fn handle_events(&mut self) -> io::Result<()> {
75        let timeout = Self::TICK_RATE.saturating_sub(self.last_tick.elapsed());
76        while event::poll(timeout)? {
77            if let Event::Key(key) = event::read()? {
78                if key.kind == KeyEventKind::Press && key.code == KeyCode::Char('q') {
79                    self.should_exit = true;
80                }
81            }
82        }
83        Ok(())
84    }
85
86    /// Update the app state on each tick.
87    fn on_tick(&mut self) {
88        self.scroll = (self.scroll + 1) % 10;
89    }
90}
91
92impl Widget for &App {
93    fn render(self, area: Rect, buf: &mut Buffer) {
94        let areas = Layout::vertical([Constraint::Max(9); 4]).split(area);
95        Paragraph::new(create_lines(area))
96            .block(title_block("Default alignment (Left), no wrap"))
97            .gray()
98            .render(areas[0], buf);
99        Paragraph::new(create_lines(area))
100            .block(title_block("Default alignment (Left), with wrap"))
101            .gray()
102            .wrap(Wrap { trim: true })
103            .render(areas[1], buf);
104        Paragraph::new(create_lines(area))
105            .block(title_block("Right alignment, with wrap"))
106            .gray()
107            .right_aligned()
108            .wrap(Wrap { trim: true })
109            .render(areas[2], buf);
110        Paragraph::new(create_lines(area))
111            .block(title_block("Center alignment, with wrap, with scroll"))
112            .gray()
113            .centered()
114            .wrap(Wrap { trim: true })
115            .scroll((self.scroll, 0))
116            .render(areas[3], buf);
117    }
118}
119
120/// Create a bordered block with a title.
121fn title_block(title: &str) -> Block {
122    Block::bordered()
123        .gray()
124        .title(title.bold().into_centered_line())
125}
126
127/// Create some lines to display in the paragraph.
128fn create_lines(area: Rect) -> Vec<Line<'static>> {
129    let short_line = "A long line to demonstrate line wrapping. ";
130    let long_line = short_line.repeat(usize::from(area.width) / short_line.len() + 4);
131    let mut styled_spans = vec![];
132    for span in [
133        "Styled".blue(),
134        "Spans".red().on_white(),
135        "Bold".bold(),
136        "Italic".italic(),
137        "Underlined".underlined(),
138        "Strikethrough".crossed_out(),
139    ] {
140        styled_spans.push(span);
141        styled_spans.push(" ".into());
142    }
143    vec![
144        Line::raw("Unstyled Line"),
145        Line::raw("Styled Line").black().on_red().bold().italic(),
146        Line::from(styled_spans),
147        Line::from(long_line.green().italic()),
148        Line::from_iter([
149            "Masked text: ".into(),
150            Span::styled(Masked::new("my secret password", '*'), Color::Red),
151        ]),
152    ]
153}
paragraph/paragraph.rs

paragraph/
paragraph.rs
