Function contrast

docs/app/js/sanddance-app.js:142920–142923

(color1, color2)

    return 0.2126 * r + 0.7152 * g + 0.0722 * b;
} // https://www.w3.org/TR/2008/REC-WCAG20-20081211/#contrast-ratiodef
function contrast(color1, color2) {
    const lum1 = luminance(color1), lum2 = luminance(color2), lumL = Math.max(lum1, lum2), lumD = Math.min(lum1, lum2);
    return (lumL + 0.05) / (lumD + 0.05);
}
function merge() {
    const args = [].slice.call(arguments);
    args.unshift({});