pure-color/convert/hwb2rgb.js

Pure functions for color conversion and parsing

// http://dev.w3.org/csswg/css-color/#hwb-to-rgb
function hwb2rgb(hwb) {
  var h = hwb[0] / 360,
      wh = hwb[1] / 100,
      bl = hwb[2] / 100,
      ratio = wh + bl,
      i, v, f, n;

  // wh + bl cant be > 1
  if (ratio > 1) {
    wh /= ratio;
    bl /= ratio;
  }

  i = Math.floor(6 * h);
  v = 1 - bl;
  f = 6 * h - i;
  if ((i & 0x01) != 0) {
    f = 1 - f;
  }
  n = wh + f * (v - wh);  // linear interpolation

  switch (i) {
    default:
    case 6:
    case 0: r = v; g = n; b = wh; break;
    case 1: r = n; g = v; b = wh; break;
    case 2: r = wh; g = v; b = n; break;
    case 3: r = wh; g = n; b = v; break;
    case 4: r = n; g = wh; b = v; break;
    case 5: r = v; g = wh; b = n; break;
  }

  return [r * 255, g * 255, b * 255];
}

module.exports = hwb2rgb;