Themes ​

A Theme is a palette of colors named for what they are for rather than what they look like, and it is the only styling most apps ever touch. Every component picks its default look from these roles, so switching the theme restyles the whole app.

Most roles have a foreground companion chosen to contrast with the fill, so text stays readable whichever role paints behind it.

Using a preset ​

Choose one built-in preset directly:

use ratcn::Theme;

let theme = Theme::catppuccin();
let area = frame.area();
ratcn.render(frame, area, &state, &theme, |ctx| {
    // Declare components.
});

The presets are default_dark, terminal, catppuccin, gruvbox, nord, tokyo_night, and solarized. Theme::presets() returns them as a &'static [Theme] in stable picker order — iterate or index it, and take the count from the slice itself.

Solving one from two colors ​

Theme::adaptive(background, foreground, palette16) derives a whole palette from a background and a foreground someone else chose, and the pair carries the polarity: a light background yields a light theme, with wells sitting darker than the screen and text darkening from there. palette16 is the terminal's own ANSI colors, where the caller has them, and fills three roles: error, warning, and the accent. On a terminal, ratcn::terminal (feature termina) supplies the pair: it asks the terminal at startup and re-solves as the user flips their terminal theme underneath the app. See Host integration for the session that does the asking.

Writing your own ​

To author a palette, start from a preset and assign the roles you care about. Theme is #[non_exhaustive]; its fields are public and the presets are const, so a const fn builds one. The display name is a &'static str.

use ratatui::style::Color;
use ratcn::Theme;

const fn operations() -> Theme {
    let mut theme = Theme::default_dark();
    theme.name = "Operations";
    theme.accent = Color::LightCyan;
    theme.warning = Color::LightYellow;
    theme
}

const THEME: Theme = operations();

Pass the same theme to runtime rendering and paint-only widgets so both halves of the library agree. To recolor a single component, use that component's .style(|theme| ...) override — see each component page's Styling section.