JSliderのスタイルを変更する

UIManager.put("Slider.horizontalThumbIcon", new Icon() {
  @Override public void paintIcon(Component c, Graphics g, int x, int y) {}
  @Override public int getIconWidth()  { return 15; }
  @Override public int getIconHeight() { return 64; }
});
UIManager.put("Slider.trackWidth", 64);
UIManager.put("Slider.majorTickLength", 6);

JSlider slider = makeSlider();
slider.setUI(new MetalSliderUI() {
  int[] pallet = makeGradientPallet();
  @Override public void paintTrack(Graphics g) {
    // Color trackColor = !slider.isEnabled()
    //   ? MetalLookAndFeel.getControlShadow() : slider.getForeground();
    boolean leftToRight = true; //MetalUtils.isLeftToRight(slider);
    Color controlDarkShadow = Color.GRAY;
    Color controlHighlight = new Color(200, 255, 200);
    Color controlShadow = new Color(0, 100, 0);

    g.translate(trackRect.x, trackRect.y);

    int trackLeft = 0;
    int trackTop = 0;
    int trackRight = 0;
    int trackBottom = 0;

    // Draw the track
    if (slider.getOrientation() == SwingConstants.HORIZONTAL) {
      trackBottom = (trackRect.height - 1) - getThumbOverhang();
      trackTop = trackBottom - (getTrackWidth() - 1);
      trackRight = trackRect.width - 1;
    } else {
      if (leftToRight) {
        trackLeft = (trackRect.width - getThumbOverhang()) - getTrackWidth();
        trackRight = (trackRect.width - getThumbOverhang()) - 1;
      } else {
        trackLeft = getThumbOverhang();
        trackRight = getThumbOverhang() + getTrackWidth() - 1;
      }
      trackBottom = trackRect.height - 1;
    }

    if (slider.isEnabled()) {
      g.setColor(controlDarkShadow);
      g.drawRect(trackLeft, trackTop,
                (trackRight - trackLeft) - 1, (trackBottom - trackTop) - 1);

      g.setColor(controlHighlight);
      g.drawLine(trackLeft + 1, trackBottom, trackRight, trackBottom);
      g.drawLine(trackRight, trackTop + 1, trackRight, trackBottom);

      g.setColor(controlShadow);
      g.drawLine(trackLeft + 1, trackTop + 1, trackRight - 2, trackTop + 1);
      g.drawLine(trackLeft + 1, trackTop + 1, trackLeft + 1, trackBottom - 2);
    } else {
      g.setColor(controlShadow);
      g.drawRect(trackLeft, trackTop,
                 (trackRight - trackLeft) - 1, (trackBottom - trackTop) - 1);
    }

    // Draw the fill
    int middleOfThumb = 0;
    int fillTop = 0;
    int fillLeft = 0;
    int fillBottom = 0;
    int fillRight = 0;

    if (slider.getOrientation() == SwingConstants.HORIZONTAL) {
      middleOfThumb = thumbRect.x + (thumbRect.width / 2);
      middleOfThumb -= trackRect.x; // To compensate for the g.translate()
      fillTop = !slider.isEnabled() ? trackTop : trackTop + 1;
      fillBottom = !slider.isEnabled() ? trackBottom - 1 : trackBottom - 2;

      if (!drawInverted()) {
        fillLeft = !slider.isEnabled() ? trackLeft : trackLeft + 1;
        fillRight = middleOfThumb;
      } else {
        fillLeft = middleOfThumb;
        fillRight = !slider.isEnabled() ? trackRight - 1 : trackRight - 2;
      }
    } else {
      middleOfThumb = thumbRect.y + (thumbRect.height / 2);
      middleOfThumb -= trackRect.y; // To compensate for the g.translate()
      fillLeft = !slider.isEnabled() ? trackLeft : trackLeft + 1;
      fillRight = !slider.isEnabled() ? trackRight - 1 : trackRight - 2;

      if (!drawInverted()) {
        fillTop = middleOfThumb;
        fillBottom = !slider.isEnabled() ? trackBottom - 1 : trackBottom - 2;
      } else {
        fillTop = !slider.isEnabled() ? trackTop : trackTop + 1;
        fillBottom = middleOfThumb;
      }
    }

    if (slider.isEnabled()) {
      g.setColor(slider.getBackground());
      g.drawLine(fillLeft, fillTop, fillRight, fillTop );
      g.drawLine(fillLeft, fillTop, fillLeft, fillBottom );

      double x = (fillRight - fillLeft) / (double) (trackRight - trackLeft);
      g.setColor(getColorFromPallet(pallet, x));
      g.fillRect(fillLeft + 1, fillTop + 1,
                 fillRight - fillLeft, fillBottom - fillTop);
    } else {
      g.setColor(controlShadow);
      g.fillRect(fillLeft, fillTop, fillRight - fillLeft, trackBottom - trackTop);
    }

    int yy = trackTop + (trackBottom - trackTop) / 2;
    for (int i = 10; i >= 0; i--) {
      g.setColor(new Color(1f, 1f, 1f, i * .07f));
      g.drawLine(trackLeft + 2, yy, (trackRight - trackLeft), yy);
      yy--;
    }
    g.translate(-trackRect.x, -trackRect.y);
  }
});