static Color withAlpha(Color c, double alpha) {
  ret colorWithAlpha(c, alpha);
}



static Color withAlpha(double alpha, Color c) {
  ret colorWithAlpha(alpha, c);
}

static int withAlpha(double alpha, int rgb) {
  ret rgb & 0xFFFFFF | (iround(clampToZeroOne(alpha)*255) << 24);
}