Creating glasspane

I have a question. Can I create glasspane in body MousePressed ? If yes anyone can write me how? I mean that I press mouse button and glass pane is visible and I can painting on him.

EDIT

Ok I have now what I want. My glass pane is creating when I click mouse button and disapear when I release this button. Now I have another question. Where I should create my painting method. I want draw rectangle on this glasss pane using mouse dragged. Where I must impleme开发者_如何学Cnt paint method? In other class or in this events? I implement one my try paint function but I don't know if this is good way. This is my code:

public class Selection extends JPanel
{
    static Point startPoint;
    public static void GUI()
    {

        final JFrame frame = new JFrame();
        JPanel panel = new JPanel();
        JButton button = new JButton("Select");
        final JPanel glassPane = new JPanel();


        frame.setSize(400, 300);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        panel.add(button);
        glassPane.setOpaque(false);
        frame.add(panel);


        frame.setGlassPane(glassPane);
        glassPane.addMouseListener(new MouseAdapter()
        {

            @Override
            public void mousePressed(MouseEvent e)
            {
                super.mousePressed(e);
                System.out.println("f.getGlassPane() mousePressed");
                if(e.getButton() == MouseEvent.BUTTON1)


                frame.getGlassPane().setVisible(true);

                startPoint=e.getPoint();

                Graphics2D g = null;
                Graphics2D g2 = (Graphics2D) g;
                Rectangle2D rect = new Rectangle2D.Double();
                rect.setFrameFromDiagonal(e.getPoint().x, e.getPoint().y,startPoint.x, startPoint.y);
                g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.5F));
                g2.setColor(Color.BLUE);
                g2.fill(rect);
                g2.draw(rect);

            }

        });
        glassPane.addMouseMotionListener(new MouseMotionListener() {


            @Override
            public void mouseDragged(MouseEvent e) 
            {


            }

            @Override
            public void mouseMoved(MouseEvent e) {
                // TODO Auto-generated method stub

            }
        });

        frame.addMouseListener(new MouseAdapter()
        {
            @Override
            public void mousePressed(MouseEvent e)
            {
                super.mousePressed(e);
                if(e.getButton() == MouseEvent.BUTTON1)

                frame.getGlassPane().setVisible(true);

            }
            public void mouseReleased(MouseEvent e)
            {                     
                    frame.getGlassPane().setVisible(false);
            }
        });



        frame.setVisible(true);
    }


        int x1, x2, y1,y2;
        public void paintComponent(Graphics g)
        {
            Graphics2D g2 = (Graphics2D)g;
             g2.drawRect(x1,y1, x2, y2);
        }


    public static void main(String[] args) 
    {

        GUI();
    }

}

Hi please check out my answer to some other question where I present a way in which a glass pane can be used to simulated dialog behaviour. There you have shown how to show it and hide it on mouse click in my case right mouse click. This example should get you started nicely.

I see no problem creating a glasspane and attaching it to a RootPaneContainer from inside moussePressed() method.

However, I may wonder why create a new glass pane every time the user clicks the mouse; that wouldn't be very performant; it is probably wiser to create and attach a glass pane up front and then change its content during mouse click).

Now, regarding "painting on the glass pane", it depends on what you mean by "painting", if this means using a "Graphics" instance to directly draw on the glass pane, the answer is NO (well, actually you could but, your painting would disappear at first UI refresh...)

Such painting must occur in paintComponent() method of your glass pane (that you must override).