Modifiers

Demonstrates the style Modifiers

run

git clone https://github.com/ratatui/ratatui.git --branch latest
cd ratatui
cargo run --example=modifiers --features=crossterm

modifiers.rs

//! # [Ratatui] Modifiers 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/ratatui
//! [examples]: https://github.com/ratatui/ratatui/blob/main/examples
//! [examples readme]: https://github.com/ratatui/ratatui/blob/main/examples/README.md

// This example is useful for testing how your terminal emulator handles different modifiers.
// It will render a grid of combinations of foreground and background colors with all
// modifiers applied to them.

use std::{error::Error, iter::once, result};

use itertools::Itertools;
use ratatui::{
    crossterm::event::{self, Event, KeyCode, KeyEventKind},
    layout::{Constraint, Layout},
    style::{Color, Modifier, Style, Stylize},
    text::Line,
    widgets::Paragraph,
    DefaultTerminal, Frame,
};

type Result<T> = result::Result<T, Box<dyn Error>>;

fn main() -> Result<()> {
    color_eyre::install()?;
    let terminal = ratatui::init();
    let app_result = run(terminal);
    ratatui::restore();
    app_result
}

fn run(mut terminal: DefaultTerminal) -> Result<()> {
    loop {
        terminal.draw(draw)?;
        if let Event::Key(key) = event::read()? {
            if key.kind == KeyEventKind::Press && key.code == KeyCode::Char('q') {
                return Ok(());
            }
        }
    }
}

fn draw(frame: &mut Frame) {
    let vertical = Layout::vertical([Constraint::Length(1), Constraint::Min(0)]);
    let [text_area, main_area] = vertical.areas(frame.area());
    frame.render_widget(
        Paragraph::new("Note: not all terminals support all modifiers")
            .style(Style::default().fg(Color::Red).add_modifier(Modifier::BOLD)),
        text_area,
    );
    let layout = Layout::vertical([Constraint::Length(1); 50])
        .split(main_area)
        .iter()
        .flat_map(|area| {
            Layout::horizontal([Constraint::Percentage(20); 5])
                .split(*area)
                .to_vec()
        })
        .collect_vec();

    let colors = [
        Color::Black,
        Color::DarkGray,
        Color::Gray,
        Color::White,
        Color::Red,
    ];
    let all_modifiers = once(Modifier::empty())
        .chain(Modifier::all().iter())
        .collect_vec();
    let mut index = 0;
    for bg in &colors {
        for fg in &colors {
            for modifier in &all_modifiers {
                let modifier_name = format!("{modifier:11?}");
                let padding = (" ").repeat(12 - modifier_name.len());
                let paragraph = Paragraph::new(Line::from(vec![
                    modifier_name.fg(*fg).bg(*bg).add_modifier(*modifier),
                    padding.fg(*fg).bg(*bg).add_modifier(*modifier),
                    // This is a hack to work around a bug in VHS which is used for rendering the
                    // examples to gifs. The bug is that the background color of a paragraph seems
                    // to bleed into the next character.
                    ".".black().on_black(),
                ]));
                frame.render_widget(paragraph, layout[index]);
                index += 1;
            }
        }
    }
}