学步园

if(x <= -width || y <= -height)
   return;
  if(y < 0){
   offset -= y*scanlength;
   y = 0;
  }
  height = Math.min(height, Math.min(HEIGHT - y, (((int[])rgbData).length - offset) / scanlength));
  if(x<0){
   offset -= x;
   x = 0;
  }
  width = Math.min(WIDTH, Math.min(width, scanlength - (offset % scanlength)));
   g.drawRGB((int[]) rgbData, offset, scanlength, x, y, width, height, processAlpha);