Swing/PaintPanel のバックアップの現在との差分(No.2)

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class PaintPanel extends JPanel {
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  private static final Stroke STROKE = new BasicStroke(
      3f, BasicStroke.CAP_ROUND, BasicStroke.JOIN_ROUND);
  private transient List<Shape> list;
  private transient Path2D path;
  private transient MouseAdapter handler;

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#screenshot
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  @Override public void updateUI() {
    removeMouseMotionListener(handler);
    removeMouseListener(handler);
    super.updateUI();
    handler = new MouseAdapter() {
      @Override public void mousePressed(MouseEvent e) {
        path = new Path2D.Double();
        list.add(path);
        Point p = e.getPoint();
        path.moveTo(p.x, p.y);
        repaint();
      }

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**サンプルコード [#jb2b9b9e]
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#code{{
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 class PaintPanel extends JPanel implements MouseMotionListener, MouseListener {
   private Point startPoint = new Point(-1,-1);
   private Point endPoint   = new Point(-1,-1);
   public PaintPanel() {
     super();
     addMouseMotionListener(this);
     addMouseListener(this);
   }
   public void paintComponent(Graphics g) {
     //super.paintComponent(g);
     Graphics2D g2d = (Graphics2D)g;
     g2d.setStroke(new BasicStroke(3.0F));
     g2d.setPaint(Color.black);
     g2d.drawLine(startPoint.x, startPoint.y,
                  endPoint.x,   endPoint.y);
     startPoint = endPoint;
   }
   public void mouseDragged(MouseEvent e) {
     endPoint = e.getPoint();
     repaint();
   }
   public void mousePressed(MouseEvent e) {
     startPoint = e.getPoint();
   }
   public void mouseMoved(MouseEvent e) {}
   public void mouseExited(MouseEvent e) {}
   public void mouseEntered(MouseEvent e) {}
   public void mouseReleased(MouseEvent e) {}
   public void mouseClicked(MouseEvent e) {}
 }
      @Override public void mouseDragged(MouseEvent e) {
        Point p = e.getPoint();
        path.lineTo(p.x, p.y);
        repaint();
      }
    };
    addMouseMotionListener(handler);
    addMouseListener(handler);
    list = new ArrayList<Shape>();
  }
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  @Override protected void paintComponent(Graphics g) {
    super.paintComponent(g);
    if (list != null) {
      Graphics2D g2 = (Graphics2D) g.create();
      g2.setPaint(Color.BLACK);
      g2.setStroke(STROKE);
      for (Shape s : list) {
        g2.draw(s);
      }
      g2.dispose();
    }
  }
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}
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