MARKUS

        /// move control point has same location of given pt along given delta

        /// </summary>

        /// <author>humkyung</author>

        /// <date>2019.06.20</date>

        /// <param name="pt"></param>

        /// <param name="dx"></param>

        /// <param name="dy"></param>

        public override void OnMoveCtrlPoint(Point pt, double dx, double dy)

        {

            IPath path = (this as IPath);

            Point selected = MathSet.getNearPoint(path.PointSet, pt);

            selected.X += dx;

            selected.Y += dy;

            int i = 0;

            for (i = 0; i < (this as IPath).PointSet.Count; i++)

            {

                if (pt.Equals((this as IPath).PointSet[i])) break;

            }

            List<Point> pts = path.PointSet;

            if ((pts[0].X > pts[1].X && dx > 0) || (pts[0].X < pts[1].X && dx < 0))

            {

                pts[1] = new Point(pts[1].X + dx, pts[1].Y);

            }

            if ((pts[0].Y > pts[1].Y && dy > 0) || (pts[0].Y < pts[1].Y && dy < 0))

            {

                pts[1] = new Point(pts[1].X, pts[1].Y + dy);

            }

            path.PointSet[1] = pts[1];

            path.PointSet[i] = selected;

            this.updateControl();

        }

        /// <summary>