Screen tearing JPanel game and double buffering

Question

I am currently using a JPanel to draw the elements from my game, however, there is occasional stuttering with the graphics, after some research I learnt about screen tearing and double buffering, which I believe is the solution to my problem, however, currently with my code I am finding it extremely difficult to implement without tearing out a lot of code.

I am wondering if anyone could possibly provide either a simpler way to fix my screen tearing on a small 2D tile based game, or how to do double buffering with my current code, thank you very much!

Frame.java

public class Frame extends JPanel implements KeyListener {

public static Game game;
public static boolean[] mouseDown = new boolean[4];
public static int width, height;
public static Font font = new Font("Arial", Font.BOLD, 16);
public static JFrame frame;
public Frame()
{
    setFocusable(true);
    requestFocus();
    setOpaque(true);
    addKeyListener((KeyListener) this);
    addMouseListener(new MouseAdapter() {
        @Override
        public void mousePressed(MouseEvent e) {
        }
        @Override
        public void mouseReleased(MouseEvent e) {

        }
    });
    addMouseMotionListener(new MouseMotionListener() {
        @Override
        public void mouseMoved(MouseEvent e) {
        }
        @Override
        public void mouseDragged(MouseEvent e) {
        }
    });
}

@Override
public void paint(Graphics g) {
    Graphics2D g2d = (Graphics2D) g;
    g2d.setBackground(Color.BLACK);
    g2d.setFont(font);
    super.setBackground(Color.BLACK);
    super.paintComponent(g2d);
    //This is where I use g2d to draw onto the JPanel
}

public static void main(String[] args) {
    java.awt.EventQueue.invokeLater(new Runnable() {
        public void run() {
            frame = new JFrame("Game");
            frame.add(new Frame());
            frame.setSize(1000, 750);
            frame.setExtendedState(frame.getExtendedState() | JFrame.MAXIMIZED_BOTH);
            frame.setVisible(true);
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        }});
}

Game.java

    public void gameStart() { 

    Thread gameThread =  new Thread() {
        // Override run() to provide the running behavior of this thread.
        @Override
        public void run() {
            gameLoop();
        }
    };
    // Start the thread. start() calls run(), which in turn calls gameLoop().
    gameThread.start();
}

public void gameLoop() {
    while (!isGameFinished) {
        beginTime = System.nanoTime();
        gameUpdate();
        frame.repaint();
        // Delay timer to provide the necessary delay to meet the target rate
        timeTaken = System.nanoTime() - beginTime;
        timeLeft = (UPDATE_PERIOD_NSEC - timeTaken) / 1000000L;  // in milliseconds
        if (timeLeft < 10) timeLeft = 10;   // set a minimum
        try { // Provides the necessary delay and also yields control so that other thread can do work.
            Thread.sleep(timeLeft);
        } catch (InterruptedException ex) { }
    }
}

public void gameStart() { 

    Thread gameThread =  new Thread() {
        // Override run() to provide the running behavior of this thread.
        @Override
        public void run() {
            gameLoop();
        }
    };
    // Start the thread. start() calls run(), which in turn calls gameLoop().
    gameThread.start();
}

public void gameLoop() {
    while (!isGameFinished) {
        beginTime = System.nanoTime();
        gameUpdate();
        frame.repaint();
        timeTaken = System.nanoTime() - beginTime;
        timeLeft = (UPDATE_PERIOD_NSEC - timeTaken) / 1000000L;
        if (timeLeft < 10) timeLeft = 10;   // set a minimum
        try { 
            Thread.sleep(timeLeft);
        } catch (InterruptedException ex) { }
    }
}

As shown in the code, the Game class contains the Game loop, which will constantly repaint the Frame class. How can I tweak this code to allow for double buffering to remove screen tearing? Thanks!

Don't modify the sate of the panel from within the paint method, this will setup additional paint cycles — MadProgrammer, Aug 17 '14 at 11:21
Consider providing a [runnable example](https://stackoverflow.com/help/mcve) which demonstrates your problem. This will result in less confusion and better responses — MadProgrammer, Aug 17 '14 at 11:22
A complete example is examined [here](http://stackoverflow.com/a/3256941/230513). — trashgod, Aug 17 '14 at 13:05

score 0 · Answer 1 · answered Aug 20 '15 at 09:44

Double buffering is the best way to fix it. Try calling Toolkit#sync (Toolkit.getDefaultToolkit().sync()) , which sometimes removes the issue. You won't be tearing down much code if you switch to double buffering, just move the code in paint to a separate method.

Screen tearing JPanel game and double buffering

1 Answers1