Repainting specific areas of the canvas

Question

Hello, ive been trying all day to search for good examples on how to repaint specific areas of the screen. I know there are som atributes to the repaint() method, but im trying to repaint an area of 20x20 px on the left corner of the screen with a thread. Can someone pleeeeeeez guide me maybe to how to accomplish this. Thanks in advance.

Answer 1

Well you would call repaint(0,0,20,20), instead of just repaint().
But more importantly is that you set up your paint() method so that it can recognize that you're only repainting part of the screen. Something like:
public void paint(Graphics g) {
  // you use the Graphics.getClip????() methods to find out the clipping region for this paint request:
  int clipX = g.getClipX();
  int clipY = g.getClipY();
  int clipW = g.getClipWidth();
  int clipH = g.getClipHeight();
  // now, if you called repaint(0,0,20,20) then clipX=0, clipY=0, clipW=20 and clipH=20
  // so you can now use these variables to set up code that only repaints the appropiate part of the screen
}Even if you don't set up the paint() method this way, it will still work, because anything you paint outside the clipping region won't show up on screen. But I imagine that you want to repaint just part of the screen because you need the painting to be faster, so unless you take the clipping region into account, all the paint code will be executed and you won't gain too much speed by only repainting part of the screen.
shmoove