可以将一个Polygon类型的数据或者Polyline的数据赋值给该接口的变量，如：

Set pUnionedPolylines =NewPolyline Set pTopOp = pUnionedPolylines

ITopologicalOperator接口的第一个方法ConstructUnion(geometries ) （方法，合并图形的工具，输入的参数是一个IEnumGeometry类型的参数，此方法效率甚高）

ITopologicalOperator接口的第二个方法Cut(cutter, leftGeom, rightGeom) （方法，剪切图形，第一个参数为剪切的线要素，为IPloyline类型，第二个第三个参数均为剪切后的图形，为输出参数）

ITopologicalOperator接口的第三个方法Boundary（方法，获取一个图形的边框，一个Polygon的boundary是一个Polyline类型的要素，一个Polyline的boundary是一个nultipoint类型的要素，一个Point的boundary是为空的） ITopologicalOperator接口的第四个方法Buffer(distance) （方法，创造一个Polygon的要素来显示缓冲区域，参数为缓冲距离）

例子代码：

'This example demonstrateshowtouseITopologicalOperator::Buffer Sub exampleITopologicalOperator_Buffer()

Dim ptc AsIPointCollection,iAsLong,paAsIArea,ptopoAsITopologicalOperator Dim pt(4) AsIPoint,poutPolyAsIPolygon Set ptc = NewPolygon

'The spatial referenceshouldbesethereusingIGeometry::SpatialReference(Codeskippedhere) For i = 0To4

Set pt(i) =NewPoint

Next

pt(0).PutCoords0,0 pt(1).PutCoords0,10 pt(2).PutCoords10,10 pt(3).PutCoords10,0 pt(4).PutCoords0,0 ptc.AddPoints5,pt(0) Set pa = ptc

Debug.Print \ originalpolygon: \ pa.Area Set ptopo = ptc

Set poutPoly = ptopo.Buffer(1)'Outsidebuffer Set pa = poutPoly

Debug.Print \ polygonpositivedistance: \ pa.Area Set poutPoly = ptopo.Buffer(-1)'Insidebuffer

Set pa = poutPoly

Debug.Print \ polygonnegativedistance: \ pa.Area End Sub

ITopologicalOperator接口的第五个方法Clip (clipperEnvelope ) （方法，输入一个IEnvelope类型的变量，来获取被这个边框剪切的要素，并将切割后的变量返回给调用方法的变量）

ITopologicalOperator接口的第六个方法QueryClipped (clipperEnvelope, clippedGeometry ) （方法，与Clip类似，但是第二个参数为剪切后返回输出的参数，本身不会改变）

ITopologicalOperator接口的第七个方法ConvexHull（方法，构造一个Geometry，大部分为Polygon类型的几何要素，该要素为调用此方法的ITopologicalOperator类型的变量最小的外边框）

ITopologicalOperator接口的第八个方法SymmetricDifference (other ) （方法，并集减去交集的部分，调用次方法的变量为第一个参数，other为第二个参数，最后返回变量到一个Geometry类型的变量，该变量的范围均在两个参数范围内，但不在两个参数相交的部分）

25. 创建Buffer并选择里面的要素 ===============================

怎样创建buffer：（来源于管网线处理删除冗余节点） ===============================

Dim pTopOper As ITopologicalOperator Set pTopOper = pfeature.Shape Dim pGeometry As IGeometry Set pGeometry = pTopOper.Buffer(1)

(注意，这个pfeature是在前面定义的pfeature=pFeatureCursor.NextFeature,不用重新定义一个)

=============================== 怎样在buffer里面选择要素： ===============================

Dim pSpFilter AsISpatialFilter Set pSpFilter = NewSpatialFilter

Dim pTopOper AsITopologicalOperator Set pTopOper = pfeature.Shape Dim pGeometry AsIGeometry Set pGeometry = pTopOper.Buffer(1)

Set pSpFilter.Geometry =pGeometry pSpFilter.SpatialRel= esriSpatialRelContains

'（esriSpatialRelContains是ISpatialFilter里面SpatialRel的一种参数esriSpatialRelEnum，值为8，代表在这个区域内包含的要素）

Set m_pSelGW_D = pLyr_D

m_pSelGW_D.SelectFeaturespSpFilter, esriSelectionResultNew, False '（m_pSelGW_D是IfeatureSelection类型的变量） pSpFilter.SpatialRel= esriSpatialRelIntersects

Set m_pSelGW_X = pLyr

m_pSelGW_X.SelectFeaturespSpFilter,esriSelectionResultNew,False

26. Merge要素Union要素

Vb语言： Private Sub UnionSelected() Dim pMxDoc AsIMxDocument Dim pFtrLyr AsIFeatureLayer Dim pFtrCls AsIFeatureClass Dim pFtrSel AsIFeatureSelection Dim pFtr AsIFeature Dim pEnumGeom AsIEnumGeometry Dim pEnumGeomBind AsIEnumGeometryBind Dim pTopOp AsITopologicalOperator Dim pUnionedPolylinesAsIPolyline

' Getareftotheselectedpolylinesinthe1stlayer Set pMxDoc =ThisDocument

Set pFtrLyr =pMxDoc.FocusMap.Layer(0) Set pFtrSel =pFtrLyr

Set pFtrCls =pFtrLyr.FeatureClass

' Createanenumerationoftheselectedpolyines Set pEnumGeom =NewEnumFeatureGeometry Set pEnumGeomBind =pEnumGeom

pEnumGeomBind.BindGeometrySource Nothing,pFtrSel.SelectionSet

pEnumGeom.Reset

' Unionthepolylines

Set pUnionedPolylines= New Polyline Set pTopOp =pUnionedPolylines pTopOp.ConstructUnion pEnumGeom

' Addthisnewunionedpolylinetothefeatureclass Set pFtr =pFtrCls.CreateFeature Set pFtr.Shape =pUnionedPolylines pFtr.Store

End Sub

C#语言：

if(pFC.ShapeType== ESRI.ArcGIS.Geometry.esriGeometryType.esriGeometryPolygon) {

IEnumGeometry pEnumGeom;

IEnumGeometryBindpEnumGeomBind= new EnumFeatureGeometryClass(); IFeatureLayer pLyr =newFeatureLayerClass(); pLyr.FeatureClass = pFC;

IFeatureSelectionpFeatSel =(IFeatureSelection)pLyr;

IQueryFilter pQfliter =newQueryFilterClass(); pQfliter.WhereClause = this.SQLText.Text;

pFeatSel.SelectFeatures(pQfliter, esriSelectionResultEnum.esriSelectionResultNew,false);

pEnumGeomBind.BindGeometrySource(null,pFeatSel.SelectionSet); pEnumGeom = (IEnumGeometry)pEnumGeomBind; ITopologicalOperatorpTopo =newPolygonClass(); pTopo.ConstructUnion(pEnumGeom); pGeom = (IGeometry)pTopo;

} returnpGeom;

=============================== 怎样从Table中获取具体需求值的Row： ===============================

ITable pTable = (ITable)pFC;

intindex =pTable.Fields.FindField(\ IQueryFilter pQFilter = newQueryFilterClass(); ICursor pCur;

pCur =pTable.Search(pQFilter,false); IRow pRow = new Row();

IRow pAnswerRow = new Row(); pRow =pCur.NextRow(); while (pRow != null) {

stringValue = pRow.get_Value(index).ToString();

if (Value == \ {

pAnswerRow = pRow; break; }

pRow = pCur.NextRow(); } =============================== 怎样ZoomInCenter：

===============================

Public Sub ZoomInCenter() Dim pMxDocumentAsIMxDocument Dim pActiveViewAsIActiveView

Dim pDisplayTransformAsIDisplayTransformation Dim pEnvelopeAsIEnvelope Dim pCenterPointAsIPoint

Set pMxDocument = Application.Document

Set pActiveView = pMxDocument.FocusMap

Set pDisplayTransform =pActiveView.ScreenDisplay.DisplayTransformation Set pEnvelope = pDisplayTransform.VisibleBounds