One way is to use translate(x, y) before you start drawing the circles.  Store x and y as global variables and use the keyPressed() callback to increment/decrement them as appropriate when keys are pressed.

1. // Press a key repeatedly to reveal an offscreen ellipse
2. 
   
3. int x = 0;
4. 
   
5. void setup() {
6. }
7. 
   
8. void draw() {
9.   background(0);
10.   translate(x, 0);
11.   ellipse(-30, 50, 20, 20);
12. }
13. 
    
14. void keyPressed() {
15.   x++;
16. }

Please just copy and paste code on to your forum post rather than using external text upload services unless there's a good reason not to.

Cheers. I'll Look at that. When i cut and paste the code a warning popped up saying the post was too long.

I have no issue with external sites for text (as long as it is accessed directly), although perhaps something like PasteBin would have respected the indentation...

You already draw in buf, you just have to use the same technique for any drawing function:
buf.translate( ... );
buf.rect( ... );
buf.fill( ... );
buf.ellipse( ... );
and so on. Still between begin/endDraw().