/// <summary>         /// 求直线外一点到该直线的投影点         /// </summary>         /// <param name="pLine">线上任一点</param>         /// <param name="k">直线斜率</param>         /// <param name="pOut">线外指定点</param>         /// <param name="pProject">投影点</param>         protected void GetProjectivePoint(PointF pLine, double k, PointF pOut, ref PointF pProject)         {             if (k == 0) //垂线斜率不存在情况             {                 pProject.X = pOut.X;                 pProject.Y = pLine.Y;             }             else             {                 pProject.X = (float)((k * pLine.X + pOut.X / k + pOut.Y - pLine.Y) / (1 / k + k));                 pProject.Y = (float)(-1 / k * (pProject.X - pOut.X) + pOut.Y);             }         }