ArcEngine中合并断开的线要素（根据几何判断）

在上一篇ArcEngine环境下合并断开的线要素（根据属性）随笔中介绍了如何通过shp文件属性表中相同的属性字段进行线要素的合并。今天刚把通过几何条件判断的方式连接断开的线要素的ArcGIS 插件完成，在这里把思路和代码和大家分享下：

一，程序思路和实现过程

1.首先读取shp线文件，将各条线要素遍历，存储在List<IFeature>,这里之所以不存在List<IPolyline>和List<IGeometry>中的原因是后两者会丢失要素的属性信息；

2.为了简化合并算法的逻辑和复杂性，采用分治思想。将线要素分为需要进行合并和不需要进行合并（独立的线，ToPoint或FromPoint是“节点”的线和ToPoint,FromPoint均是“节点”线）的两大类，分别存储在两个集合中；

3.现在只需对需要进行合并的的线要素集合进行合并操作。首先从集合中选取一条Polyline,然后在集合剩下的元素中寻找与其ToPoint或FromPoint相同的线要素，然后使用ITopologicalOperator2.Union（）方法进行合并，然后寻找和合并后新的Polyline的ToPoint或FromPoint相同的线要素继续合并，没合并一次，就将合并入的Polyline从集合中移除，直到剩下的Polyline不可和当前合并的Polyline合并为止，这样就得到了第一条合并好的Polyline。接着从集合剩下的线要素再找一条Polyline开始新一轮合并操作，直到List<IFeature>为空，整个合并操作结束；

4.得到合并好的List<IFeature> mergeResultLineList后，需要为其添加属性（NAME等字段），通过IFeatureBuffer接口写入shape和Fields，然后Flush到文件中，结束。

二，程序实例和结果

图1  程序执行结果

图2  合并前的属性表

图3  合并后的属性表

三，程序详细代码

 public class MergeDisconnectLine : ESRI.ArcGIS.Desktop.AddIns.Button
     {

         public int CountPercent { get; set; }
         IMap map = null;
         private List<IFeature> DisconnPolylineList = new List<IFeature>();
         private List<IFeature> firstRowFeatureList = new List<IFeature>();

         public MergeDisconnectLine()
         {
             IMxDocument mxDoc = ArcMap.Application.Document as IMxDocument;
             map = mxDoc.FocusMap;
         }
         protected override void OnClick()
         {
             //
             //  TODO: Sample code showing how to access button host
             //
             ArcMap.Application.CurrentTool = null;

             //计算程序耗时
             DateTime beforDT = System.DateTime.Now;
             //Application.EnableVisualStyles();
             //Application.SetCompatibleTextRenderingDefault(false);
             ////ProgressBar pBar = new ProgressBar();
             //Application.Run(new ProgressBar());
             List<IFeature> allPolylineList = getAllPolyline();
             List<IFeature> noNeedUnionLineList = getWithoutNeedUnionLineList(allPolylineList);
             List<IFeature> toUnionLineList = GetToUnionLineList(allPolylineList, noNeedUnionLineList);
             List<IFeature> unionLineList = MergeLineListOperate(toUnionLineList);
             AddField();
             WriteNoNeedUnionLineToFile(noNeedUnionLineList);
             WriteUnionLineToFile(unionLineList, firstRowFeatureList);
             DateTime afterDT = System.DateTime.Now;
             TimeSpan ts = afterDT.Subtract(beforDT);
             int minutes = ts.Minutes;
             int seconds = ts.Seconds%;
             //pBar.Hide();
             MessageBox.Show("线要素合并结束，运行程序共耗时约：" + minutes + "分"+ seconds + "秒");
         }
         //获取shp文件中所有的Polyline(IFeature)对象
         public List<IFeature> getAllPolyline()
         {
             IFeatureLayer featureLayer = map.get_Layer() as IFeatureLayer;
             IFeatureClass featureClass = featureLayer.FeatureClass;
             IQueryFilter queryFilter = new QueryFilter();
             queryFilter.WhereClause = "";
             IFeatureCursor pFeatCursor = featureClass.Search(queryFilter, false);
             IFeature pFeature = pFeatCursor.NextFeature();

             while (pFeature != null)
             {
                 if (featureClass.ShapeType == esriGeometryType.esriGeometryPolyline)
                 {
                     DisconnPolylineList.Add(pFeature);
                 }
                 pFeature = pFeatCursor.NextFeature();
             }
             return DisconnPolylineList;
         }

         //获取需要进行合并的线（是noNeedUnionLineList的补集）
         public List<IFeature> GetToUnionLineList(List<IFeature> allPolylineList, List<IFeature> noNeedUnionLineList)
         {
             List<IFeature> toUnionLineList = allPolylineList;
             foreach (IFeature featureLine in noNeedUnionLineList)
             {
                 toUnionLineList.Remove(featureLine);
             }
             return toUnionLineList;
         }

         //获取不需要进行合并的线（独立线，一端是节点的线，和两端都是节点的线）
         public List<IFeature> getWithoutNeedUnionLineList(List<IFeature> allPolylineList)
         {
             List<IFeature> noNeedUnionLineList = new List<IFeature>();
             foreach (IFeature featureLine in allPolylineList)
             {
                 int count = featureLine.Fields.FieldCount;
                 List<IFeature> allPolylineListCopy = allPolylineList;
                 IGeometry geoLine = featureLine.Shape;
                 IPolyline lineFirst = geoLine as IPolyline;
                 IPoint startPt1 = lineFirst.FromPoint;
                 IPoint endPt1 = lineFirst.ToPoint;
                 int fromFlag = ;
                 int toFlag = ;
                 for (int i = ; i < allPolylineListCopy.Count; i++)
                 {
                     IFeature line2 = allPolylineListCopy[i];
                     IGeometry geoLine2 = line2.Shape;
                     IPolyline lineSecond = geoLine2 as IPolyline;
                     IPoint startPt2 = lineSecond.FromPoint;
                     IPoint endPt2 = lineSecond.ToPoint;
                     //FromPoint相同的点
                     if ((startPt1.X == startPt2.X && startPt1.Y == startPt2.Y) ||
                         (startPt1.X == endPt2.X && startPt1.Y == endPt2.Y))
                     {
                         fromFlag++;
                     }
                     //ToPoint相同的点
                     if ((endPt1.X == endPt2.X && endPt1.Y == endPt2.Y) ||
                     (endPt1.X == startPt2.X && endPt1.Y == startPt2.Y))
                     {
                         toFlag++;
                     }
                 }
                 if (fromFlag >  || toFlag >  || (fromFlag ==  && toFlag == ))
                 {
                     noNeedUnionLineList.Add(featureLine);
                     //noNeedUnionLineFileds.Add(featureLine.Fields);
                 }
             }
             return noNeedUnionLineList;
         }

         //将需要进行合并的线要素（没有节点）集合进行合并，结果为多条线
         public List<IFeature> MergeLineListOperate(List<IFeature> toUnionLineList)
         {
             List<IFeature> mergeResultLineList = new List<IFeature>();
             int CountPercent = ;
             while (toUnionLineList.Count > )
             {
                 CountPercent++;
                 //初始化当前合并的线要素
                 IFeature unionCurrentLine = toUnionLineList[];
                 //将第一个要素的属性字段值作为最终合并线要素的值
                 firstRowFeatureList.Add(unionCurrentLine);
                 List<IFeature> currentMergeLineList = new List<IFeature>();
                 int count2 = ;
                 do
                 {
                     count2++;
                     IFeature featureFirst = unionCurrentLine;
                     IGeometry geoLineFirst = featureFirst.Shape;
                     IPolyline lineFirst = geoLineFirst as IPolyline;
                     IPoint startPt1 = lineFirst.FromPoint;
                     IPoint endPt1 = lineFirst.ToPoint;
                     toUnionLineList.Remove(featureFirst);
                     currentMergeLineList.Clear();
                     currentMergeLineList.Add(featureFirst); 

                     List<IFeature> allPolylineListTemp1 = new List<IFeature>();
                     List<IFeature> allPolylineListTemp2 = new List<IFeature>();
                     int bStart1 = ;
                     int bStart2 = ;
                     for (int j = ; j < toUnionLineList.Count; j++)
                     {
                         IFeature featureSecond = toUnionLineList[j];
                         IGeometry geoLineSecond = featureSecond.Shape;
                         IPolyline lineSecond = geoLineSecond as IPolyline;
                         IPoint startPt2 = lineSecond.FromPoint;
                         IPoint endPt2 = lineSecond.ToPoint;

                         if ((startPt1.X == startPt2.X && startPt1.Y == startPt2.Y) ||
                             (startPt1.X == endPt2.X && startPt1.Y == endPt2.Y))
                         {
                             bStart1++;
                             if (bStart1 > )
                             {
                                 allPolylineListTemp1.Add(featureSecond);
                                 currentMergeLineList.AddRange(allPolylineListTemp1);
                                 toUnionLineList.Remove(featureSecond);
                             }
                         }
                         if ((endPt1.X == endPt2.X && endPt1.Y == endPt2.Y) ||
                             (endPt1.X == startPt2.X && endPt1.Y == startPt2.Y))
                         {
                             bStart2++;
                             if (bStart2 > )
                             {
                                 allPolylineListTemp2.Add(featureSecond);
                                 currentMergeLineList.AddRange(allPolylineListTemp2);
                                 toUnionLineList.Remove(featureSecond);
                             }

                         }

                     }
                     if (currentMergeLineList.Count > )
                     {
                         unionCurrentLine = UnionCurrentLineList(currentMergeLineList);
                     }
                     else
                     {
                         int ii = ;
                     }
                 } while (currentMergeLineList.Count > );

                 mergeResultLineList.Add(unionCurrentLine);
             }
             return mergeResultLineList;
         }

         //为待写入图层添加Name和GB字段
         public void AddField()
         {
             IFeatureLayer featureLayer2 = map.get_Layer() as IFeatureLayer;
             IFeatureClass featureClass2 = featureLayer2.FeatureClass;
             IClass pClass = featureClass2 as IClass;
             IField fld1 = new Field();
             IField fld2 = new Field();
             IFieldEdit2 fld_NAME = fld1 as IFieldEdit2;
             IFieldEdit2 fld_GB = fld2 as IFieldEdit2;
             fld_NAME.Type_2 = esriFieldType.esriFieldTypeString;
             fld_NAME.Name_2 = "NAME";
             fld_GB.Type_2 = esriFieldType.esriFieldTypeString;
             fld_GB.Name_2 = "GB";
             pClass.AddField(fld_GB);
             pClass.AddField(fld_NAME);

         }

         public void WriteNoNeedUnionLineToFile(List<IFeature> pLineList)
         {
             foreach (IFeature featureLine in pLineList)
             {
                 IFeatureLayer featureLayer2 = map.get_Layer() as IFeatureLayer;
                 IFeatureClass featureClass2 = featureLayer2.FeatureClass;
                 IFeatureBuffer featureBuffer = featureClass2.CreateFeatureBuffer();
                 IFeatureCursor featureCursor;
                 featureCursor = featureClass2.Insert(true);
                 IGeometry pGeometry = featureLine.Shape;
                 featureBuffer.Shape = pGeometry;
                 int NAME_Index = featureLine.Fields.FindField("NAME");
                 int GB_Index = featureLine.Fields.FindField("GB");
                 string name = featureLine.get_Value(NAME_Index).ToString();
                 string gb = featureLine.get_Value(GB_Index).ToString();
                 int fieldindex1 = featureBuffer.Fields.FindField("NAME");
                 int fieldindex2 = featureBuffer.Fields.FindField("GB");
                 if (fieldindex1 >= )
                 {
                     featureBuffer.set_Value(fieldindex1, name);
                 }
                 if (fieldindex2 >= )
                 {
                     featureBuffer.set_Value(fieldindex2, gb);
                 }
                 featureCursor.InsertFeature(featureBuffer);
                 featureCursor.Flush();
                 System.Runtime.InteropServices.Marshal.ReleaseComObject(featureCursor);
             }
         }
         public void WriteUnionLineToFile(List<IFeature> mergeResultLineList, List<IFeature> firstFeatureList)
         {
             int index = ;
             foreach (IFeature featureLine in mergeResultLineList)
             {
                 IFeatureLayer featureLayer2 = map.get_Layer() as IFeatureLayer;
                 IFeatureClass featureClass2 = featureLayer2.FeatureClass;
                 IFeatureBuffer featureBuffer = featureClass2.CreateFeatureBuffer();
                 IFeatureCursor featureCursor;
                 featureCursor = featureClass2.Insert(true);
                 IGeometry pGeometry = featureLine.Shape;
                 featureBuffer.Shape = pGeometry;
                 int NAME_Index = firstFeatureList[index].Fields.FindField("NAME");
                 int GB_Index = firstFeatureList[index].Fields.FindField("GB");
                 string name = firstFeatureList[index].get_Value(NAME_Index).ToString();
                 string gb = firstFeatureList[index].get_Value(GB_Index).ToString();
                 int fieldindex1 = featureBuffer.Fields.FindField("NAME");
                 int fieldindex2 = featureBuffer.Fields.FindField("GB");
                 if (fieldindex1 >= )
                 {
                     featureBuffer.set_Value(fieldindex1, name);
                 }
                 if (fieldindex2 >= )
                 {
                     featureBuffer.set_Value(fieldindex2, gb);
                 }

                 featureCursor.InsertFeature(featureBuffer);
                 featureCursor.Flush();
                 System.Runtime.InteropServices.Marshal.ReleaseComObject(featureCursor);
                 index++;
             }
         }

         //将传入的List<IPolylne>中的多条线要素进行合并为一条线要素
         public IFeature UnionCurrentLineList(List<IFeature> currentMergeLineList)
         {
             IFeatureLayer featureLayer = map.get_Layer() as IFeatureLayer;
             IFeatureClass featureClass = featureLayer.FeatureClass;

             ITopologicalOperator2 pTopologicalOperator;
             IFeature pFeatureTemp = currentMergeLineList[];
             IGeometry pGeometry = pFeatureTemp.Shape;
             int i = ;
             while (i < currentMergeLineList.Count)
             {
                 pTopologicalOperator = pGeometry as ITopologicalOperator2;
                 //ITopologicalOperator的操作是bug很多的，先强制的检查下面三个步骤，再进行操作
                 //modifiy in 2016/03/20 12:47
                 pTopologicalOperator.IsKnownSimple_2 = false;
                 pTopologicalOperator.Simplify();
                 pGeometry.SnapToSpatialReference();

                 pGeometry = currentMergeLineList[i].Shape;
                 pGeometry = pTopologicalOperator.Union(pGeometry);
                 i++;
             }
             IFeature unionLine = featureClass.CreateFeature();
             unionLine.Shape = pGeometry;
             IDataset pDataset = featureClass as IDataset;
             pDataset.Workspace.ExecuteSQL("delete from " + featureClass.AliasName + " where SHAPE_Length = 0" );
             return unionLine;
         }

         protected override void OnUpdate()
         {
             Enabled = ArcMap.Application != null;
         }
     }

-------------------------------------------------------------------------------------------------------------------------

本文系作者GISQZC原创文章，欢迎转载，但必须注明出处，否则将追究相关法律责任！