color-generator.php

<?php
/**
 * Requires ariColor: https://aristath.github.io/ariColor/
 */

add_action( 'wp', function() {
	if ( ! class_exists( 'ariColor' ) ) {
		return;
	}
	$colors = [];
	$hexes  = [];
	for ( $h = 0; $h <= 259; $h += 15 ) {
		for ( $s = 0; $s <= 100; $s += 4 ) {
			for ( $l = 0; $l <= 100; $l += 4 ) {
				$hsl = "hsl($h,$s%,$l%)";
				$color = ariColor::newColor( $hsl );
				$lum = ( 0.2126 * $color->red ) + ( 0.7152 * $color->green ) + ( 0.0722 * $color->blue );
				$color_props = [ $h, $s, $l, $lum ];
				$hex = $color->toCSS( 'hex' );
				if ( ! in_array( $hex, $hexes ) ) {
					$hexes[] = $hex;
					$colors[] = $color_props;
				}
			}
		}
	}
	usort( $colors, function( $a, $b ) {
		if ( $a[3] === $b[3] ) {
			return 0;
		}
		return $a[3] > $b[3] ? -1 : 1;
	});
	foreach ( $colors as $i => $color ) {
		$color[ 3 ] = round( $color[ 3 ] );
		$colors[ $i ] = $color;

		echo '<span style="width:20px;height:20px;margin:5px;border-radius:3px;background-color:hsl(' . $color[0] . ', ' . $color[1] . '%, ' . $color[2] . '%);display:inline-block;"></span>';
	}
	$json = json_encode( $colors );
	error_log( $json );
	var_dump( $colors );
});