Themes

A theme is a self-contained class that owns the entire visual representation - the palette (per-role ANSI style codes), the glyphs (marker, caret, scroll indicators, separators - each a Unicode/ASCII pair) and how every row is composed. AbstractTheme implements all of it with a neutral base, and a concrete theme overrides only what it colours. The ThemeManager turns a theme name into an instance; two themes are built in:

use DrevOps\Tui\Theme\ThemeManager;

ThemeManager::create('dark');   // bright foregrounds for a dark terminal
ThemeManager::create('light');  // higher-contrast foregrounds for a light terminal

When a form sets no theme (or the explicit 'auto' sentinel), the interactive TUI picks dark or light from the actual terminal background: it queries the background colour over OSC 11, falls back to the COLORFGBG environment variable, and settles on dark when neither answers. An explicit ->theme('dark') or ->theme('light') opts out of detection.

A custom theme subclasses a built-in theme (e.g. DarkTheme) or AbstractTheme, overrides the styles or glyphs it changes and merges the rest from the parent - roles it does not mention keep working:

use DrevOps\Tui\Theme\DarkTheme;

class OceanTheme extends DarkTheme {
  protected function defineStyles(): array {
    return ['title' => '1;96', 'value' => '96', 'marker' => '1;96'] + parent::defineStyles();
  }
}

Override any render* method to change how an element is laid out. Lowest friction: a form names the class directly, with no registration:

$form = Form::create('My form')->theme('\App\OceanTheme')/* ... */;

Or register a short alias with ThemeManager::register('ocean', OceanTheme::class), then ->theme('ocean') - an unknown theme name fails loudly instead of silently falling back. Here is the playground's ocean theme with a start banner: