rnfa-rb42/src/utils/color.js

Original project: https://github.com/santomegonzalo/react-native-floating-action

export function shadeColor(color, percent) {
  let R;
  let G;
  let B;

  if (color.indexOf('rgb') === 0) {
    [R, G, B] = color.replace(/^(rgb|rgba)\(/, '').replace(/\)$/, '').replace(/\s/g, '').split(',');
  } else {
    R = parseInt(color.substring(1, 3), 16);
    G = parseInt(color.substring(3, 5), 16);
    B = parseInt(color.substring(5, 7), 16);
  }

  R = parseInt((R * (100 + percent)) / 100, 0); // eslint-disable-line
  G = parseInt((G * (100 + percent)) / 100, 0); // eslint-disable-line
  B = parseInt((B * (100 + percent)) / 100, 0); // eslint-disable-line

  R = R < 255 ? R : 255;
  G = G < 255 ? G : 255;
  B = B < 255 ? B : 255;

  const RR =
    R.toString(16).length === 1 ? `0${R.toString(16)}` : R.toString(16);
  const GG =
    G.toString(16).length === 1 ? `0${G.toString(16)}` : G.toString(16);
  const BB =
    B.toString(16).length === 1 ? `0${B.toString(16)}` : B.toString(16);

  return `#${RR}${GG}${BB}`;
}