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ArcGIS Pro SDK （九）几何 13 多部件

环境：Visual Studio 2022 + .NET6 + ArcGIS Pro SDK 3.0

1 获取多部分要素的各个部分

public IEnumerable<Geometry> MultipartToSinglePart(Geometry inputGeometry)
{// 保存输入几何的部分的列表List<Geometry> singleParts = new List<Geometry>();// 检查输入是否为空指针或几何是否为空if (inputGeometry == null || inputGeometry.IsEmpty)return singleParts;// 根据几何类型，将各个部分/点单独添加到列表中switch (inputGeometry.GeometryType){case GeometryType.Envelope:singleParts.Add(inputGeometry.Clone() as Envelope);break;case GeometryType.Multipatch:singleParts.Add(inputGeometry.Clone() as Multipatch);break;case GeometryType.Multipoint:var multiPoint = inputGeometry as Multipoint;foreach (var point in multiPoint.Points){// 将集合中的每个点作为独立的点添加到列表中singleParts.Add(point);}break;case GeometryType.Point:singleParts.Add(inputGeometry.Clone() as MapPoint);break;case GeometryType.Polygon:var polygon = inputGeometry as Polygon;foreach (var polygonPart in polygon.Parts){// 使用PolygonBuilderEx将线段转换为独立的多边形实例singleParts.Add(PolygonBuilderEx.CreatePolygon(polygonPart));}break;case GeometryType.Polyline:var polyline = inputGeometry as Polyline;foreach (var polylinePart in polyline.Parts){// 使用PolylineBuilderEx将线段转换为独立的折线实例singleParts.Add(PolylineBuilderEx.CreatePolyline(polylinePart));}break;case GeometryType.Unknown:break;default:break;}return singleParts;
}

2 获取多边形的最外层环

public Polygon GetOutermostRings(Polygon inputPolygon)
{if (inputPolygon == null || inputPolygon.IsEmpty)return null;List<Polygon> internalRings = new List<Polygon>();// 将多边形的各个部分分解成单独的几何列表// 请参阅 "获取多部分要素的各个部分" 代码段中的 MultipartToSinglePartvar parts = MultipartToSinglePart(inputPolygon);// 获取按面积排序的顺时针几何（面积 > 0）的枚举var clockwiseParts = parts.Where(geom => ((Polygon)geom).Area > 0).OrderByDescending(geom => ((Polygon)geom).Area);// 对于每个外环foreach (var part in clockwiseParts){// 将第一个（最大的）环添加到内部集合中if (internalRings.Count == 0)internalRings.Add(part as Polygon);// 使用标志指示当前部分是否在已经选择的多边形内bool isWithin = false;foreach (var item in internalRings){if (GeometryEngine.Instance.Within(part, item))isWithin = true;}// 如果当前多边形不在内部集合的任何多边形内// 则它是分离的，需要被添加if (isWithin == false)internalRings.Add(part as Polygon);}PolygonBuilderEx outerRings = new PolygonBuilderEx();// 现在基于内部多边形集合组装一个新的多边形几何foreach (var ring in internalRings){outerRings.AddParts(ring.Parts);}// 返回最终的外环几何return outerRings.ToGeometry();
}