Swing/ZoomLevelsSlider のバックアップ(No.2)

@Override protected TrackListener createTrackListener(JSlider slider) {
  return new TrackListener() {
    @Override public void mouseClicked(MouseEvent e) {
      boolean doubleClick = SwingUtilities.isLeftMouseButton(e) && e.getClickCount() >= 2;
      if (doubleClick && thumbRect.contains(e.getPoint())) {
        slider.setValue(0);
      } else {
        super.mouseClicked(e);
      }
    }

    @Override public void mouseDragged(MouseEvent e) {
      // case HORIZONTAL:
      int halfThumbWidth = thumbRect.width / 2;
      int trackLength = trackRect.width;
      int pos = e.getX() + halfThumbWidth;
      int possibleTickPos = slider.getMaximum() - slider.getMinimum();
      int tickSp = Math.max(slider.getMajorTickSpacing(), 10);
      int tickPixels = trackLength * tickSp / possibleTickPos;
      int tickPixels2 = tickPixels / 2;
      int trackCenter = (int) trackRect.getCenterX();
      if (trackCenter - tickPixels2 < pos && pos < trackCenter + tickPixels2) {
        e.translatePoint(trackCenter - halfThumbWidth - e.getX(), 0);
        offset = 0;
      }
      super.mouseDragged(e);
    }
  };
}