Listing 8. Fill the quadrants with yellow and violet color.
  //Fill two of the quadrants with yellow.
  floodfill(screen,100,100,makecol(255,255,0));
  floodfill(screen,300,300,makecol(255,255,0));
  
  //Fill the other two quadrants with violet. //Must be
  // careful to avoid the lines of pixels when specifying
  // the point around which to fill.
  floodfill(screen,90,300,makecol(255,0,255));
  floodfill(screen,300,90,makecol(255,0,255));