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How do you double the buffer in java for a game?

So, in the game I'm working on, I have marble following the mouse, but when this happens, the screen flickers.

The background includes two jpegs and 9 rectangles. How can I do this with double buffering? Here is the code for the main window.

/**
 * Write a description of class Window here.
 * 
 * @author (your name) 
 * @version (a version number or a date)
 */
public class Window extends JApplet implements MouseMotionListener
{
    private BufferedImage image; 
    private BufferedImage side;
    private int mouseX;
    private int mouseY;

    public Window(){
        try {
            image = ImageIO.read(new File("Backgrounds/violet.jpg"));
            side = ImageIO.read(new File("Backgrounds/side margin.jpg"));
        } catch (IOException ex) { }    
    }   

    private void delay(int delay)
    {
        try {
            Thread.sleep(delay);
        } catch (InterruptedException e) {}
    }

    public void init()
    {
        this.addMouseMotionListener(this);
    }

    public void paint (Graphics page)
    {
        page.drawImage(image, 0, 0, null);
        page.setColor(Color.blue);
        page.fillRect(0, 0, 160, 160);
        page.setColor(Color.black);
        page.fillRect(15, 15, 130, 130);
        page.setColor(Color.green);
        page.fillRect(340, 0, 160, 160);
        page.setColor(Color.black);
        page.fillRect(355, 15, 130, 130);
        page.setColor(Color.yellow);
        page.fillRect(0, 340, 160, 160);
        page.setColor(Color.black);
        page.fillRect(15, 355, 130, 130);
        page.setColor(Color.red);
        page.fillRect(340, 340, 160, 160);
        page.setColor(Color.black);
        page.fillRect(355, 355, 130, 130);
        page.drawImage(side, 500, 0, null);
        page.drawString(Score.getScore(), 560, 110);
        //conveyors
        page.setColor(Color.gray);
        page.fillRect(235, 0, 30, 160);

        //marble
        delay(100);

        page.fillOval(mouseX, mouseY , 40, 40);          
    }

    public void mouseMoved(MouseEvent e)
    {
        mouseX = e.getX();
        mouseY = e.getY();
        repaint();
    }

    public void mouseDragged(MouseEvent e)
    {

    }
}
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4 answers

Double buffering is conceptually quite simple, instead of drawing objects one at a time, you draw them on the image and then tell the renderer to draw the whole image. This eliminates flicker.

Here is an example of how you can do this ( source )

class DoubleBufferedCanvas extends Canvas {

    public void update(Graphics g) {
    Graphics offgc;
    Image offscreen = null;
    Dimension d = size();

    // create the offscreen buffer and associated Graphics
    offscreen = createImage(d.width, d.height);
    offgc = offscreen.getGraphics();
    // clear the exposed area
    offgc.setColor(getBackground());
    offgc.fillRect(0, 0, d.width, d.height);
    offgc.setColor(getForeground());
    // do normal redraw
    paint(offgc);
    // transfer offscreen to window
    g.drawImage(offscreen, 0, 0, this);
    }
}

, BufferStrategy . . lakam99 .

+16

Swing , .

setDoubleBuffered(true) ( JPanel), .

: setDoubleBuffered

+2

, . Java2D, , . , Slick2D 2d, . Java2D, OpenGL. Java, , Slick2D - . , , , Id , Java-. , http://slick.cokeandcode.com/

+2

I think your problem is not double buffering. You should add super.paint(page);to the first line of your drawing method.

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