Swing/RatingLabel のバックアップ(No.20)

private final ImageProducer ip = orgIcon.getImage().getSource();

private static ImageIcon makeStarImageIcon(
    ImageProducer ip, float rf, float gf, float bf) {
  return new ImageIcon(Toolkit.getDefaultToolkit().createImage(
    new FilteredImageSource(ip, new SelectedImageFilter(rf, gf, bf))));
}

class SelectedImageFilter extends RGBImageFilter {
  private final float rf;
  private final float gf;
  private final float bf;

  protected SelectedImageFilter(float rf, float gf, float bf) {
    super();
    this.rf = Math.min(1f, rf);
    this.gf = Math.min(1f, gf);
    this.bf = Math.min(1f, bf);
    canFilterIndexColorModel = false;
  }

  @Override public int filterRGB(int x, int y, int argb) {
    int r = (int) (((argb >> 16) & 0xFF) * rf);
    int g = (int) (((argb >>  8) & 0xFF) * gf);
    int b = (int) (((argb)       & 0xFF) * bf);
    return (argb & 0xFF_00_00_00) | (r << 16) | (g << 8) | (b);
  }
}