AO求图层内所有线的交点

注意的问题 ：

直线的相交的部分有可能是Multipoint，也有可能是的Polyline，下面的例子中只判断了前一种情况，后一种情况尽管比较少见，但仍然需要判断。

使用IConstructPoint接口的ConstructIntersection方法可以直接构造交点

//获取IGeometryCollection集合，因为存在两条线存在多个交点的情况， //所以必须返回geometryCollection而非PointCollection private IGeometryCollection GetGeometries(IFeatureLayer pFL) { IFeatureClass pFeatureClass = pFL.FeatureClass; //求线条的总数 int intCount = pFeatureClass.FeatureCount(null); //AddGeometry的参数 object Missing = Type.Missing; //交点置于此变量中，必须用此对象初始化，因为两条线，可能存在多个交点， //即多点构成一个geometry,而GeometryBagClass对象的包容性强 IGeometryCollection pGeometryCollection = new GeometryBagClass(); IFeature pFeature1; ITopologicalOperator pTopologicalOperator; for (int i = 0; i < intCount; i++) { pFeature1 = pFeatureClass.GetFeature(i); pTopologicalOperator = (ITopologicalOperator)pFeature1.Shape; IFeature pFeature2; IGeometry pGeometry; for (int j = i + 1; j < intCount; j++) { pFeature2 = pFeatureClass.GetFeature(j); pGeometry = pTopologicalOperator.Intersect(pFeature2.Shape, esriGeometryDimension.esriGeometry0Dimension); if (pGeometry != null) { pGeometryCollection.AddGeometry(pGeometry,ref Missing,ref Missing); } } } return pGeometryCollection; } //用于拆分GeometryCollection里的multipoint这种情况，最终将所有点填入PointCollection中 private IPointCollection AddPoint() { //调用此方法，获得所有Geometry IGeometryCollection pGC = this.GetGeometries((IFeatureLayer)this.axMapControl1.get_Layer(0)); //定义一个pPointCollection接口变量，用MultipointClass对象实例化 IPointCollection pPointCollection = new MultipointClass(); object Missing = Type.Missing; //循环geometrycollection里的每一个geometry，判断它是否是IPointCollection类型 for (int i = 0; i < pGC.GeometryCount; i++) { IGeometry pGeometry = pGC.get_Geometry(i); //将每个geometry转换成IPointCollection类型，转换失败，pPC就会等于null，并以此作为判断是否是多点的依据 IPointCollection pPC = pGeometry as IPointCollection; if (pPC != null)//转换成功，是个多点的geometry，则将里面的点分别提取出来 { for (int j = 0; j < pPC.PointCount; j++) { pPointCollection.AddPoint(pPC.get_Point(j), ref Missing, ref Missing); } } else//转换失败，是只有一个点的geometry，则直接添加到pPointCollection里面 { pPointCollection.AddPoint((IPoint)pGeometry, ref Missing, ref Missing); } } return pPointCollection;//返回最终结果 }