如何用一个面要素去挖除(挖空)一个线图层

内容摘要

思路是利用CLIP出来的结果再求出差异Difference

过程描述

'        Dim pGeometry As IGeometry '        Dim pacGeo As IGeoFeatureLayer '        Set pacGeo = m_pActiveLayer '        If pacGeo.FeatureClass.ShapeType = esriGeometryPolygon Then             Set pGeometry = Me.MapControl1.TrackPolygon '        End If         If pGeometry Is Nothing Then Exit Sub         ''''''''''''''''''''''''''''''''''''''''''''''''         '/////////////1.求出交集,并保存_HIS/////////////////////////////////////         Dim pInputTable As ITable         Set pInputTable = m_pActiveLayer         Dim pOverlayTable As ITable                 Dim pTmpMapLyr As IFeatureLayer         Set pTmpMapLyr = New FeatureLayer                 Dim wks As IFeatureWorkspace         Dim wsf As IWorkspaceFactory         Set wsf = New ShapefileWorkspaceFactory                 'wsf.Create "c:", "tmp", Nothing, 0         Set wks = wsf.OpenFromFile("c:tmp", 0)                 Set pTmpMapLyr.SpatialReference = m_pMap.SpatialReference                         Set pTmpMapLyr.FeatureClass = wks.OpenFeatureClass("test1")         '        Dim lyfc As IFeatureClass         '        Set lyfc = pTmpMapLyr.FeatureClass                 Dim pOutBuff As IFeatureBuffer         Dim pOutFeat As IFeature '        pOutFeat.FeatureType = esriFTSimple         Dim pOutCurTmp As IFeatureCursor         Set pOutCurTmp = pTmpMapLyr.FeatureClass.Insert(True)         Set pOutBuff = pTmpMapLyr.FeatureClass.CreateFeatureBuffer         Set pOutFeat = pOutBuff         Set pOutFeat.Shape = pGeometry         pOutCurTmp.InsertFeature pOutBuff                 '        Set pOverlayTable = pGeometry         Set pOverlayTable = pTmpMapLyr         ' Error checking         If pInputTable Is Nothing Then             MsgBox "Table QI failed"             Exit Sub         End If         If pOverlayTable Is Nothing Then             MsgBox "Table QI failed"             Exit Sub         End If         Set wks = Nothing         ' Set output location and feature class name         Dim pNewWSName As IWorkspaceName         Set pNewWSName = New WorkspaceName          pNewWSName.WorkspaceFactoryProgID = "esriCore.ShapeFileWorkspaceFactory.1"         ' Define the output feature class name         Dim pFeatClassName As IFeatureClassName         Set pFeatClassName = New FeatureClassName         Dim pDatasetName As IDatasetName         Set pDatasetName = pFeatClassName         '输出Dataset的Name为Union_result         pDatasetName.Name = m_pActiveLayer.Name & "_his"         Set pDatasetName.WorkspaceName = pNewWSName         ' Set the tolerance. Passing 0.0 causes the default tolerance to be used.         ' The default tolerance is 1/10,000 of the extent of the data frame's spatial domain         Dim pTol As Double         pTol = 0#         ' Perform the union         Dim pBGP As IBasicGeoprocessor         Set pBGP = New BasicGeoprocessor         Dim pOutputFeatClass As IFeatureClass         pBGP.SpatialReference = m_pMap.SpatialReference         Set pOutputFeatClass = pBGP.Clip(pInputTable, False, pOverlayTable, False, pTol, pFeatClassName)                  '/////////////////2.做差异分析,保留差异,全落在内的部分删除.////////////////         '找出被面覆盖的要素用于更新,删除或改变         Dim pOutCur As IFeatureCursor         Set pOutCur = pOutputFeatClass.Search(Nothing, False)    '相交的要素         Dim pfeatureOut As IFeature         Dim pfeatureIn As IFeature         Set pfeatureOut = pOutCur.NextFeature         ''''''''''''''''''''''''         Dim pFInClass As IFeatureClass         Dim pInCursor As IFeatureCursor         Dim pFilter As ISpatialFilter '        Dim pFeatureLayer As IGeoFeatureLayer         Set pFeatureLayer = m_pActiveLayer         Set pFInClass = pFeatureLayer.FeatureClass                 Dim pTopo As ITopologicalOperator         Dim pGeom As IGeometry         Dim mArea As IArea                         Do While Not pfeatureOut Is Nothing                 Set pFilter = New SpatialFilter                 With pFilter                 Set .Geometry = pfeatureOut.Shape                 .GeometryField = "SHAPE"                                 .SpatialRel = esriSpatialRelIntersects                 Set .OutputSpatialReference(.GeometryField) = m_pMap.SpatialReference                 End With                 ''''''''''''''''''''''''''''''''''''''''''''                 Set pInCursor = pFInClass.Update(pFilter, False)   '叠加分析出的图元,准备更新的                 Set pfeatureIn = pInCursor.NextFeature                 Do While Not pfeatureIn Is Nothing                 '如果完全在多边形内                     Set pTopo = pfeatureIn.Shape                     Set pGeom = pfeatureIn.Shape                     Set pGeom = pTopo.Difference(pfeatureOut.Shape)    '叠加的差异部分                                         If Not pGeom Is Nothing And pGeom.IsEmpty = False Then '                    Set mArea = pGeom '                    If (mArea.Area > 100) Then                         Set pfeatureIn.Shape = pGeom                         pfeatureIn.Store                     Else '                        pfeatureIn.Delete                         pInCursor.DeleteFeature                     End If                     Set pfeatureIn = pInCursor.NextFeature                                                     Loop             '''''''''''''''''''''''''''''''''''''''''''''             Set pfeatureOut = pOutCur.NextFeature         Loop