背景：

如果Polyline不为简单的几何图形，则求出其自相交的点。如果FromPoint和ToPoint重合也一并返回。

实现逻辑：

一、创建IMulitPointpTargetPoint

二、判断Polyline是否首尾相接，如果首尾相接，将点加入到pTargetPoint;

三、判断Polyline是否为简单的几何图形，如果不是则进行以下步骤：

1）得出Polyline中所有Path的起点和终点，List<IPoint>lstOrigin;

2）将Polyline简单化，得出所有Path在LstOrigin中找不到的起点和终点，添加到pTargetPoint中

第三步的代码：

private IMultipoint getInersectPoint(IPolyline pPolyline){IGeometryCollection pGeoColl = pPolyline as IGeometryCollection;List<IPoint> lstPoint = new List<IPoint>();for (int i = 0; i < pGeoColl.GeometryCount; i++){IPath pPath = pGeoColl.get_Geometry(i) as IPath;IPoint pTemp = lstPoint.Find(p => (p.X == pPath.FromPoint.X && p.Y == pPath.FromPoint.Y));if (pTemp == null) lstPoint.Add(pPath.FromPoint);pTemp = lstPoint.Find(p => (p.X == pPath.ToPoint.X && p.Y == pPath.ToPoint.Y));if (pTemp == null) lstPoint.Add(pPath.ToPoint);}ITopologicalOperator2 ptopo = pPolyline as ITopologicalOperator2;ptopo.IsKnownSimple_2 = false;ptopo.Simplify();IMultipoint pMultipoint = new MultipointClass();IPointCollection pPointColl = pMultipoint as IPointCollection;for (int i = 0; i < pGeoColl.GeometryCount; i++){IPath pPath = pGeoColl.get_Geometry(i) as IPath;IPoint pTemp = lstPoint.Find(p => (p.X == pPath.FromPoint.X && p.Y == pPath.FromPoint.Y));if (pTemp == null) pPointColl.AddPoint(pPath.FromPoint);pTemp = lstPoint.Find(p => (p.X == pPath.ToPoint.X && p.Y == pPath.ToPoint.Y));if (pTemp == null) pPointColl.AddPoint(pPath.ToPoint);}return pMultipoint;}