question: public void limit ( double x1 , double y1 , double x2 , double y2 ) { clip [ 0 ] = Math . max ( clip [ 0 ] , x1 ) ; clip [ 1 ] = Math . max ( clip [ 1 ] , y1 ) ; clip [ 6 ] = Math . min ( clip [ 6 ] , x2 ) ; clip [ 7 ] = Math . min ( clip [ 7 ] , y2 ) ; }
target:  Limit the clip such that it fits within the specified region.