arcgis 线转面

/// <summary>
/// 由线转为面
/// </summary>
/// <param name="pPolyline"></param>
/// <returns></returns>
private IPolygon PolyLineToPolygon(IPolyline pPolyline)
{
    object obj = Type.Missing;

    IClone pClonepPolyline = pPolyline as IClone;

    try
    {
        // 闭合线
        if (pPolyline.IsClosed)
        {
            ISegmentCollection pPolylineSegment = pClonepPolyline.Clone()
                as ISegmentCollection;
            ISegmentCollection pPolygonSegment = new PolygonClass();

            for (int i = 0; i < pPolylineSegment.SegmentCount; i++)
            {
                pPolygonSegment.AddSegment(
                    pPolylineSegment.get_Segment(i), ref obj, ref obj);
            }

            return pPolygonSegment as IPolygon;
        }
        // 非闭合线
        else
        {
            IPointCollection pPolylinePoint = pClonepPolyline.Clone()
                as IPointCollection;
            IPointCollection pPolygonPoint = new PolygonClass();

            for (int i = 0; i < pPolylinePoint.PointCount; i++)
            {
                pPolygonPoint.AddPoint(
                    pPolylinePoint.get_Point(i), ref obj, ref obj);
            }

            IPolygon pPolygon = pPolygonPoint as IPolygon;
            //pPolygon.Close();

            return pPolygonPoint as IPolygon;
        }
    }
    catch (Exception exc)
    {
        Console.WriteLine(exc.Message);
        return null;
    }
}