ArcEngine利用ITopologicalOperator实现裁剪功能

       本博客发表过一篇ArcEngine通过调用GP工具实现裁剪的文章，但是GP工具对输入输出的参数要求高，而且用于裁剪的图层为shp文件，如果在系统中需要通过鼠标绘制图形实现裁剪，那么GP工具就不是那么方便。博主通过参考其他文章，实现了利用ITopologicalOperator完成裁剪功能，该方法同样适用于文件类型的裁剪图层，也适用于鼠标绘制实现裁剪。       

               IGeometry outputGeometry = null;    //裁剪后的图形
            ITopologicalOperator2 topo = null;
            if (sourceGeometry.SpatialReference != clipGeometry.SpatialReference)  //sourceGeometry为被裁剪的图形
            {
                clipGeometry.Project(sourceGeometry.SpatialReference);
            }   //此处应保持裁剪与被裁剪图层的空间参考一致，否则容易发生异常

            switch (sourceGeometry.GeometryType)
            {
                case esriGeometryType.esriGeometryPolyline:
                    topo = sourceGeometry as ITopologicalOperator2;
                    topo.IsKnownSimple_2 = true;
                    topo.Simplify();
                    outputGeometry = topo.Intersect(topo.Intersect(clipGeometry, esriGeometryDimension.esriGeometry1Dimension), esriGeometryDimension.esriGeometry1Dimension);
                    break;

                case esriGeometryType.esriGeometryPolygon:
                    topo = sourceGeometry as ITopologicalOperator2;
                    topo.IsKnownSimple_2 = true;
                    topo.Simplify();
                    outputGeometry = topo.Difference(topo.Difference(clipGeometry));
                    break;

                default:
                    outputGeometry = sourceGeometry;
                    break;
            }
            return outputGeometry;