static Color colorWithAlpha(Color c, double alpha) {
  ret new Color(clampZeroToOne(c.getRed()/255f),
    clampZeroToOne(c.getGreen()/255f),
    clampZeroToOne(c.getBlue()/255f),
    (float) alpha);
}

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