Swing/ZoomAndPanPanel のバックアップ(No.2)

class ZoomAndPanePanel extends JPanel {
  private final AffineTransform coordTransform = new AffineTransform();
  private final transient Image img;
  private final Rectangle imgrect;
  private transient ZoomHandler handler;
  private transient DragScrollListener listener;

  public ZoomAndPanePanel(Image img) {
    super();
    this.img = img;
    this.imgrect = new Rectangle(img.getWidth(null), img.getHeight(null));
  }
  @Override public void paintComponent(Graphics g) {
    super.paintComponent(g);
    Graphics2D g2 = (Graphics2D) g.create();
    g2.setPaint(new Color(0x55FF0000, true));
    Rectangle r = new Rectangle(500, 140, 150, 150);

    //AffineTransform at = g2.getTransform();
    //at.concatenate(coordTransform);
    //g2.setTransform(at);
    //g2.drawImage(img, 0, 0, this);
    //g2.fill(r);

    //g2.drawRenderedImage((java.awt.image.RenderedImage) img, coordTransform);
    g2.drawImage(img, coordTransform, this);
    g2.fill(coordTransform.createTransformedShape(r));

    //XXX
    //g2.setTransform(coordTransform);
    //g2.drawImage(img, 0, 0, this);

    g2.dispose();
  }
  @Override public Dimension getPreferredSize() {
    Rectangle r = coordTransform.createTransformedShape(imgrect).getBounds();
    return new Dimension(r.width, r.height);
  }
  @Override public void updateUI() {
    removeMouseListener(listener);
    removeMouseMotionListener(listener);
    removeMouseWheelListener(handler);
    super.updateUI();
    listener = new DragScrollListener();
    addMouseListener(listener);
    addMouseMotionListener(listener);
    handler = new ZoomHandler();
    addMouseWheelListener(handler);
  }

  protected class ZoomHandler extends MouseAdapter {
    private static final int MIN_ZOOM = -9;
    private static final int MAX_ZOOM = 16;
    private static final int EXTENT = 1;
    private final BoundedRangeModel zoomRange = new DefaultBoundedRangeModel(
        0, EXTENT, MIN_ZOOM, MAX_ZOOM + EXTENT);
    @Override public void mouseWheelMoved(MouseWheelEvent e) {
      int dir = e.getWheelRotation();
      int z = zoomRange.getValue();
      zoomRange.setValue(z + EXTENT * (dir > 0 ? -1 : 1));
      if (z != zoomRange.getValue()) {
        Component c = e.getComponent();
        Container p = SwingUtilities.getAncestorOfClass(JViewport.class, c);
        if (p instanceof JViewport) {
          JViewport vport = (JViewport) p;
          Rectangle ovr = vport.getViewRect();
          double s = dir > 0 ? 1d / 1.2 : 1.2;
          coordTransform.scale(s, s);
          //double s = 1d + zoomRange.getValue() * .1;
          //coordTransform.setToScale(s, s);
          AffineTransform at = AffineTransform.getScaleInstance(s, s);
          Rectangle nvr = at.createTransformedShape(ovr).getBounds();
          Point vp = nvr.getLocation();
          vp.translate((nvr.width - ovr.width) / 2,
                       (nvr.height - ovr.height) / 2);
          vport.setViewPosition(vp);
          c.revalidate();
          c.repaint();
        }
      }
    }
  }
}