Show key hints that fit the width

Each screen declares its hints as a const array. A Hint is a key, a label and a rank:

use pito_footer::Hint;

const HINTS: [Hint; 8] = [
    Hint::new("↑↓", "move"),
    Hint::new("enter", "open").rank(1),
    Hint::new("/", "search").rank(2),
    Hint::new("f", "filter").rank(3),
    Hint::new("s", "sort").rank(4),
    Hint::new("y", "copy").rank(5),
    Hint::new("?", "help").rank(6),
    Hint::new("ctrl+c", "twice quit").pinned(),
];

Footer::new(&HINTS) draws them as key label · key label under a rule, keys in the accent style made bold and labels in the muted one. When the width runs out:

• the highest rank drops first, the later one on a tie;
• the order of the hints that stay is kept;
• a pinned hint goes last of all;
• the app’s version, set with version("app", "1.4.2") and drawn as app v1.4.2 at the right end, goes before any hint. It never pushes a hint out and is never clipped.

The picture above is the gallery’s fit scene: cargo run --example gallery --features crossterm -- fit.

Wrap instead of drop

wrap(true) flows every hint over as many rows as it needs. Ask the footer how many rows to give it, and place it at the bottom:

use pito_footer::Footer;
use ratatui::{Frame, layout::Rect};

fn draw(frame: &mut Frame) {
    let footer = Footer::new(&HINTS).wrap(true).version("app", "1.4.2");
    let area = frame.area();
    let height = footer.height(area.width);
    frame.render_widget(footer, Rect { y: area.bottom().saturating_sub(height), height, ..area });
}

height(width) counts every row the footer draws, the rule above the hints included, so the same call works with or without wrapping, a notice or a confirm.

Show or hide the hints with ?

Help holds whether the hints are open, and toggles on ? unless the app names another key with toggle_on. Pinned hints and the notice stay when it closes:

use pito_footer::{Footer, Help, Key};

let mut help = Help::new(true);
let used = help.key(Key::Char('?'));
assert!(used && !help.open());
let footer = Footer::new(&HINTS).help(&help);

help.key(key) returns true when it used the key. An app whose ? opens a help page instead simply doesn’t use Help.

Accept only the keys on screen

shown(key, width) says whether a key’s hint is on screen at that width, so an app can ignore a key whose hint was dropped:

let footer = Footer::new(&HINTS);
if footer.shown("s", area.width) {
    sort();
}

Fine tuning

• separator(" · ") sets what goes between hints, and gap(n) the cells between the segments of a status row.
• indent(n) insets the hints, the notice and the confirm by n cells while the rule stays full width.
• rule(false) drops the rule row above the footer.
• Hint::lead("Press") puts a word before the key, as in “Press ctrl+c again to quit”.
• styles(Styles::new().accent(..).muted(..).rule(..)) sets the styles; every style comes from the app.