private void CalculateDestinationSize( )
{
if ( sourceQuadrilateral == null )
throw new NullReferenceException( "Source quadrilateral was not set." );
newWidth = (int) Math.Max( sourceQuadrilateral[0].DistanceTo( sourceQuadrilateral[1] ),
sourceQuadrilateral[2].DistanceTo( sourceQuadrilateral[3] ) );
newHeight = (int) Math.Max( sourceQuadrilateral[1].DistanceTo( sourceQuadrilateral[2] ),
sourceQuadrilateral[3].DistanceTo( sourceQuadrilateral[0] ) );
}