C# +AO获取线段中点

 public static IPoint getLineCenterPoint(IPolyline pPolyline)
    {
        double d = pPolyline.Length;
        IPoint pPoint = new PointClass();
        try
        {
            pPolyline.QueryPoint(esriSegmentExtension.esriNoExtension, d / 2, false, pPoint);


            return pPoint;

        }
        catch (Exception ex)
        {
            return null;

        }

    }