MapXtreme多边形有关的方法

一、获取图元的外部曲线(多边形节点集)

        /// <summary>
        /// 获取图元的外部曲线(多边形节点集)
        /// </summary>
        /// <param name="ftr">面或矩形</param>
        /// <returns></returns>
        internal static FeatureGeometry GetGeometryCurve(FeatureGeometry ftr)
        {
            if (ftr is MultiPolygon)
            {
                var mulPolygon = ftr as MultiPolygon;
                if (mulPolygon.PolygonCount > 0)
                {
                    var pts = mulPolygon[0].Exterior[0].SamplePoints();
                    return new MultiCurve(ftr.CoordSys, CurveSegmentType.Linear, pts);
                }
            }
            else if (ftr is MapInfo.Geometry.Rectangle)
            {
                var rc = ftr as MapInfo.Geometry.Rectangle;
                var pts = new List<DPoint>();
                pts.AddRange(rc.Data.Corners());
                pts.Add(pts[0]);
                return new MultiCurve(ftr.CoordSys, CurveSegmentType.Linear, pts.ToArray());
            }
            else if (ftr is MultiCurve)
            {
                return (MultiCurve)ftr;
            }
            return null;
        }

二、取图元的拐点

        /// <summary>
        /// 取图元的拐点
        /// </summary>
        /// <param name="ftr">图元</param>
        /// <returns></returns>
        internal static List<DPoint> GetBorderNode(FeatureGeometry ftr)
        {
            var list = new List<DPoint>();
            if (ftr is MultiPolygon)
            {
                var polygon = ((MultiPolygon)ftr)[0];
                var pts = polygon.Exterior[0].SamplePoints();
                list.AddRange(pts);
            }
            else if (ftr is MultiCurve)
            {
                var multiCurve = (MultiCurve)ftr;
                foreach (Curve cv in multiCurve)
                {
                    list.AddRange(cv.SamplePoints());
                }
            }
            return list;
        }