How to find if a Panel has anything in it?

Question

Hi guys
I have a panel that has been painted(just like a paintbrush). say my panel is 300X500 in size, Now, I wanna go through all those 300X500 little rectangles to find out if each of them is painted or not. So, In my double forloop, each time how do I get that particular area and after I get it, how do I check if it is painted or not?
for(int a=0; a<300; a++)
   for(int b=0; b<500; b++)
      // 1. get each small rectangle
      // 2. check if it is painted(black) or white(by default)
}Any suggestions please...
Cheers
-Uday

Answer 1

When I drag the mouse on my panel, for each mousedrag event, i draw a square that is 3 pixels each side centered around that point (sothat the line appears thicker). After I am done with this, I wanna scan the whole panel to see what part of it is painted.
        public Graphics drawG = null;
        public Point oldpoint = null;
        public void mouseDragged(MouseEvent e)
          if(drawG==null)
               drawG = CenterPanel.getGraphics();
               drawG.setColor(Color.blue);
          int x = e.getX();
          int y = e.getY();
          Color temp = drawG.getColor();                    
          if(oldpoint==null)
               oldpoint = new Point(x,y);
          else
               oldpoint.x = x;
               oldpoint.y = y;
          drawG.fillRect(x-1,y-1,3,3);
        }Infact, I figured out a roundabout way to achieve this, But I was wondering if anyone know any straight forward solution.
Cheers
-Uday