I have written an application with a panel and three buttons. I want to

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Asked: May 21, 20262026-05-21T12:48:12+00:00 2026-05-21T12:48:12+00:00

I have written an application with a panel and three buttons. I want to

0

I have written an application with a panel and three buttons. I want to add selection this buttons using the mouse. I mean like we have in Windows on the Desktop. I press the left mouse button and with the movement of the mouse the area selection is growing.

Is there a specific interface in this or do I have it manually call the appropriate methods for event listeners and there draw transparent rectangle? Here is a picture:

Example Screenshot

So I have a problem when I paint rectangle using event mouse-dragged, button is repainting so user see blinking button. I want to this button don’t disapear when I paint rectangle. I think that I need to use glassPane. This is my conception. I have a frame. In frame I add panel with button and I need another panel where I will paint transparent rectangle. I am thinking then my button will not be still repainting. What do you think about this conception. Or maybe someone have another idea. This is code:

        @Override
        public void mousePressed(MouseEvent e) {
            startPoint=e.getPoint();
            setOpaque(true);

            Graphics2D g2 = (Graphics2D)getGraphics();

            Rectangle2D prostokat = new Rectangle2D.Double();
            prostokat.setFrameFromDiagonal(e.getPoint().x, e.getPoint().y,startPoint.x, startPoint.y);
            g2.setComposite(AlphaComposite.getInstance(rule, alpha));
            g2.draw(prostokat);
            g2.setColor(Color.BLUE);
            g2.fill(prostokat);


        }



        @Override
        public void mouseDragged(MouseEvent e) {
            setOpaque(true);

            Graphics2D g2 = (Graphics2D)getGraphics();
            Rectangle2D prostokat = new Rectangle2D.Double();

            prostokat.setFrameFromDiagonal(e.getPoint().x, e.getPoint().y,startPoint.x, startPoint.y);
            g2.setComposite(AlphaComposite.getInstance(rule, alpha));
            g2.draw(prostokat);
            g2.setColor(Color.BLUE);
            g2.fill(prostokat);
            paintComponent(g2);


        }

        int rule = AlphaComposite.SRC_OVER;
        float alpha = 0.85F;




    public static void main(String[] args) {

        EventQueue.invokeLater(new Runnable()
        {
public void run()
            {
                zaznacz rys = new zaznacz();
                JFrame frame = new JFrame();
                JButton Button = new JButton("1");
                JPanel panel = new JPanel();



                panel.add(Button);
                rys.add(panel);
                frame.setSize(400,300);
                frame.setVisible(true);
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                panel.setOpaque(false);

                frame.add(rys);


            }
        });
    }

}

I know that code is no perfect but almost work. I have a little problem. When I press the mousebutton and dragging my button disapear.
enter image description here

I don’t need advise like “your code is wrong”. I know that and I want to somebody help me what I must correct. I know that I shouldn’t use paintComponent() in mouseEvents but only that way I can paint transparent rectangle. Or maybe you can othet idea how I can draw transparent rectangle. I try and try and I think that i must change mouseDragged method. because when I delete code from this method and only draw rectangle over a button all is ok. But problem is when I need draw rectangle by dragging mouse. I should change paint but I don’t have idea how. Anyone can help me or try help me?