How to paint an image over the JPanel and add components in it

Question

My application is a simple game of Brick Breaker. In order to paint the visuals of the application I\'m using the paintComponent method. The application also has several buttons

Answer 1

Use below code snippet for your reference:

import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.Toolkit;

import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.plaf.basic.BasicPanelUI;

class MyPanelUI extends BasicPanelUI {
    public void paint(Graphics g, JComponent c) {
        Toolkit toolkit = Toolkit.getDefaultToolkit();
        Graphics2D g2d = (Graphics2D) g;

        Image img = toolkit.getImage("/usr/share/backgrounds/warty-final-ubuntu.png");
        g2d.drawImage(img, 0, 0, null);
    }

    public Dimension getPreferredSize(JComponent c) {
        return super.getPreferredSize(c);
    }
}

public class PanelBGTest {

    public static void main(String[] args) {
        JFrame frame = new JFrame();

        JPanel panel = new JPanel();
        panel.setUI(new MyPanelUI());
        panel.setLayout(new FlowLayout());
        panel.add(new JButton("This is button"));

        SwingUtilities.updateComponentTreeUI(frame);

        frame.add(panel);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(400, 400);
        frame.setVisible(true);
    }
}

using paint component is not good practice so its always better to extent your component UI class from basic component UI class and override the paint() method. This way swing will take care of all the rendering / re-rendering part and your component(s) added to panel will be visible too.

Now, I strongly recommend that you stop and go have a read through:

• Performing Custom Painting
• Painting in AWT and Swing
• BufferStrategy and BufferCapabilities
• How to Use Layered Panes