TanSanC

class DraggableComponent extends JComponent

{

    /** If sets <b>TRUE</b> this component is draggable */

    private boolean draggable = true;

    /**

     * 2D Point representing the coordinate where mouse is, relative parent

     * container

     */

    protected Point anchorPoint;

    /** Default mouse cursor for dragging action */

    protected Cursor draggingCursor = Cursor

           .getPredefinedCursor(Cursor.HAND_CURSOR);

    /**

     * If sets <b>TRUE</b> when dragging component, it will be painted over each

     * other (z-Buffer change)

     */

    protected boolean overbearing = false;

    public DraggableComponent()

    {

        addDragListeners();

        setOpaque(true);

        setBackground(new Color(240, 240, 240));

    }

    /**

     * Add Mouse Motion Listener with drag function

     */

    private void addDragListeners()

    {

        /**

         * This handle is a reference to THIS because in next Mouse Adapter

         * "this" is not allowed

         */

        final DraggableComponent handle = this;

        addMouseMotionListener(new MouseAdapter()

        {

           @Override

           public void mouseMoved(MouseEvent e)

           {

               anchorPoint = e.getPoint();

           setCursor(Cursor.getPredefinedCursor(Cursor.HAND_CURSOR));

           }

           @Override

           public void mouseDragged(MouseEvent e)

           {

               int anchorX = anchorPoint.x;

               int anchorY = anchorPoint.y;

               Point parentOnScreen = getParent().getLocationOnScreen();

               Point mouseOnScreen = e.getLocationOnScreen();

               Point position = new Point(mouseOnScreen.x - parentOnScreen.x

                       - anchorX, mouseOnScreen.y - parentOnScreen.y - anchorY);

               setLocation(position);

               // Change Z-Buffer if it is "overbearing"

               if (overbearing)

               {

                   getParent().setComponentZOrder(handle, 0);

                   repaint();

               }

           }

        });

    }

    @Override

    protected void paintComponent(Graphics g)

    {

        super.paintComponent(g);

        if (isOpaque())

        {

           g.setColor(getBackground());

           g.fillRect(0, 0, getWidth(), getHeight());

        }

    }

    private void removeDragListeners()

    {

        for (MouseMotionListener listener : this.getMouseMotionListeners())

        {

           removeMouseMotionListener(listener);

        }

        setCursor(Cursor.getDefaultCursor());

    }

}