alphainate method

ColorValue alphainate(
  1. double amount
)

cascades this amount alpha on the existing alpha ignores any space info Should throw Exception for any value (1.0 < amount) or (amount < 0.0)

Implementation

ColorValue alphainate(double amount) {
  final newA = ((a / 255) * (amount * 255)).round();
  return ColorValue._(r, g, b, newA);
}