colorRotate function

Color colorRotate(Color color, double degrees)

Implementation

Color colorRotate(Color color, double degrees) {
  Map<String, double> hsl = colorToHSL(color);
  double hue = hsl["h"] ?? 0;
  hue = (hue + degrees) % 360;
  hue = hue < 0 ? 360 + hue : hue;
  hsl["h"] = hue;
  double h = hsl["h"] ?? 0;
  double s = hsl["s"] ?? 0;
  double l = hsl["l"] ?? 0;

  s /= 100;
  l /= 100;

  double c = (1 - (2 * l - 1).abs()) * s,
      x = c * (1 - ((h / 60) % 2 - 1).abs()),
      m = l - c / 2,
      r = 0,
      g = 0,
      b = 0;

  if (0 <= h && h < 60) {
    r = c;
    g = x;
    b = 0;
  } else if (60 <= h && h < 120) {
    r = x;
    g = c;
    b = 0;
  } else if (120 <= h && h < 180) {
    r = 0;
    g = c;
    b = x;
  } else if (180 <= h && h < 240) {
    r = 0;
    g = x;
    b = c;
  } else if (240 <= h && h < 300) {
    r = x;
    g = 0;
    b = c;
  } else if (300 <= h && h < 360) {
    r = c;
    g = 0;
    b = x;
  }
  // Having obtained RGB, convert channels to hex
  int _r = ((r + m) * 255).round();
  int _g = ((g + m) * 255).round();
  int _b = ((b + m) * 255).round();
  return Color.fromARGB(0xff, _r, _g, _b);
}