MARKUS

        /// call when mouse is moving while drawing control

        /// </summary>

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

        /// <param name="bAxisLocked"></param>

        public override void OnCreatingMouseMove(Point pt, bool bAxisLocked, bool bShiftKeyPressed)

        {

            this.EndPoint = pt;

            if (bAxisLocked)

            {

                Point tmp = this.EndPoint;

                string angle = MathSet.returnAngleString(this.StartPoint, ref tmp, true);

                this.EndPoint = tmp;

            }

            if (bShiftKeyPressed)

            {

                List<Point> Points = this.GetRegularTrianglePoints(this.StartPoint, this.EndPoint);

                if (2 == Points.Count())

                {

                    this.MidPoint = Points[0];

                    this.EndPoint = Points[1];

                }

            }

            this.PointSet = new List<Point>

            {

                this.StartPoint,

                this.MidPoint,

                this.EndPoint,

            };

        }

        /// <summary>

        /// <summary>

        /// 정삼각형을 그리기위한 두 포인트를 계산하여 넘겨줌

        /// </summary>

        /// <author>humkyung</author>

        /// <date>2018.04.26</date>

        /// <param name="StartP"></param>

        /// <param name="EndP"></param>

        /// <returns></returns>

        /// <history>humkyung 2018.05.11 apply axis lock</history>

        private List<Point> GetRegularTrianglePoints(Point StartP, Point EndP, bool bCheckAxis = false)

        {

            List<Point> res = new List<Point>();

            double dx = EndP.X - StartP.X;

            double dy = EndP.Y - StartP.Y;

            double length = Math.Sqrt(dx * dx + dy * dy);

            double baseLength = length * Math.Tan(30.0 * Math.PI / 180.0);

            dx /= length;

            dy /= length;

            double tmp = dx;

            dx = -dy; dy = tmp; /// rotate by 90 degree

            res.Add(new Point(EndP.X + dx * baseLength, EndP.Y + dy * baseLength));

            res.Add(new Point(EndP.X - dx * baseLength, EndP.Y - dy * baseLength));

            return res;

        }