JProgressBarの不確定モードアニメーションを一方向に変更する

class OneDirectionIndeterminateProgressBarUI extends BasicProgressBarUI {
  // @see com/sun/java/swing/plaf/windows/WindowsProgressBarUI.java
  @Override protected Rectangle getBox(Rectangle r) {
    Rectangle rect = super.getBox(r);
    int framecount = getFrameCount() / 2;
    int currentFrame = getAnimationIndex() % framecount;

    if (progressBar.getOrientation() == JProgressBar.VERTICAL) {
      int len = progressBar.getHeight();
      len += rect.height * 2; // add 2x for the trails
      double delta = len / (double) framecount;
      rect.y = (int) (delta * currentFrame);
    } else {
      int len = progressBar.getWidth();
      len += rect.width * 2; // add 2x for the trails
      double delta = len / (double) framecount;
      rect.x = (int) (delta * currentFrame);
    }
    return rect;
  }
}