question: public void union ( double x , double y , double w , double h ) { if ( status == INVALID ) return ; if ( status == EMPTY ) { setClip ( x , y , w , h ) ; status = INUSE ; return ; } clip [ 0 ] = Math . min ( clip [ 0 ] , x ) ; clip [ 1 ] = Math . min ( clip [ 1 ] , y ) ; clip [ 6 ] = Math . max ( clip [ 6 ] , x + w ) ; clip [ 7 ] = Math . max ( clip [ 7 ] , y + h ) ; }
target:  Union this clip with another region. As a result, this clip will become a bounding box around the two original regions.