Double buffering seems choppy

Question

I am trying to implement double buffering for a game, but I am not sure if I am doing it correctly.

I am calling this.repaint() in my main game loop, which then should do this:

@Override
public void paint(Graphics g){
    // this.getWidth() / this.getHeight() is the window size
    this.dbImage = createImage(this.getWidth(), this.getHeight());
    this.dbg = dbImage.getGraphics();
    this.paintComponent(dbg);
    g.drawImage(this.dbImage, 0, 0, this);
}

@Override
public void paintComponent(Graphics g){
    try{
        g.drawImage(bg, 0, 0, this);
        // gameObjects is an ArrayList with an object in it that represents 
        // an item on the screen, such as an enemy or a bullet
        for(int i = 0; i < gameObjects.size(); i++){
            GameObject go = gameObjects.get(i);
            g.drawImage(go.getSprite(), go.getX(), go.getY(), this);
        }
    }catch(Exception e){
    }
}

I basically did what this guy does here: YouTube Video The issue I am having, is that it seems to be running worse that before I had the double buffering. At times items freeze for half a second then catches back up and it runs normal, then it happens again within a few minutes (or less).

Can be garbage collection kicking in. There must be a property opt,on to make it continuous. — huseyin tugrul buyukisik, May 11 '13 at 21:46
g.drawImage(bg, 0, 0, this); Should be done on go.getsprite to get rid of double-drawing. You must do it on a back-image where is not seen. — huseyin tugrul buyukisik, May 11 '13 at 21:49
Multiple drawing on sprite but single drawing on screen by that sprite. Does go.getSprite().drawImage(a,x,y,this) work? — huseyin tugrul buyukisik, May 11 '13 at 21:50
Have you considered using Active painting instead? Similar to what huseyin suggested below. Basically disable repaint and manually draw everything on each game tick. — Nikki, May 11 '13 at 22:07

score 0 · Answer 1 · answered May 11 '13 at 21:54

Create an image, create a buffer for that image, then do all drawing on the buffer so it doesnt get painted to screen for every single drawing operation. When all done for a whole frame, you draw that image really on screen now.

In init:

offscreen = createImage(dim.width,dim.height); 
bufferGraphics = offscreen.getGraphics();

In drawing part(whatever you want on buffer):

 bufferGraphics.fillRect(20, 20+m,0,20);

In drawing screen when all done:

  g.drawImage(offscreen,0,0,this);

If these doesnt satisfy, there is triple buffering too.

Double buffering seems choppy

1 Answers1