将polyline图形的要素类转为polygon形式的要素类

前一段时间写的，实现将polyline形式的FeatureClass转为polygon形式的FeatureClass，这部分相关的代码网上很多，采用Geoprocessor的方式使用DataManagementTools中的 FeatureToPolygon会简单一些，这里采用比较原始的方式，根据每个feature的Geometry转换而来，其中GetPathFromFeatureClass和CreatShapefile是另外写的函数。

Private Function FCCoventToPolygon(ByVal pFeatureClass As IFeatureClass) As IFeatureClass

'通过featureclass找到shp文件的路径

Dim SourceFileFullName As String

SourceFileFullName = GetPathFromFeatureClass(pFeatureClass)

Dim FilePath, FileName As String

FilePath = IO.Path.GetDirectoryName(SourceFileFullName)

FileName = IO.Path.GetFileNameWithoutExtension(SourceFileFullName)

'创建一个空的shp文件

Dim TempFeatureClass As IFeatureClass

TempFeatureClass = CreatShapefile(FilePath, "Temp_" & FileName)

'创建一个编辑工作区并启动编辑

Dim pWorkspaceFactory As IWorkspaceFactory

Dim pWorkspaceEdit As IWorkspaceEdit

pWorkspaceFactory = New ShapefileWorkspaceFactory

pWorkspaceEdit = pWorkspaceFactory.OpenFromFile(FilePath, 0)

pWorkspaceEdit.StartEditOperation()

pWorkspaceEdit.StartEditing(True)

'取出featureclass中的一个feature

Dim pFeatureCur As IFeatureCursor

pFeatureCur = pFeatureClass.Search(Nothing, False)

Dim pFeature As IFeature

pFeature = pFeatureCur.NextFeature()

Dim pPolyLine As IPolyline

Dim pPolygon As IPolygon

Dim pEndFeature As IFeature

Dim pGeoms As IGeometryCollection

Dim pClone As IClone

Dim pSegs As ISegmentCollection

Dim pGeometryCollection As IGeometryCollection

'开始遍历

While (Not pFeature Is Nothing)

'把一个polyline转存到一个GeometryCollection，以便取得里面的path（polyline的子对象是path）

pPolyLine = pFeature.ShapeCopy

pGeometryCollection = New Polygon

pClone = pPolyLine

pGeoms = pClone.Clone

'通过Polyline的每个Path创建为一个新的Ring,并把Ring增加到一个新的Polygon

For i As Long = 0 To pGeoms.GeometryCount - 1

pSegs = New Ring

pSegs.AddSegmentCollection(pGeoms.Geometry(i))

pGeometryCollection.AddGeometry(pSegs)

Next i

'生成的Polygon旋转的顺序可能不正确,为确保正确调用SimplifyPreserveFromTo

pPolygon = pGeometryCollection

pPolygon.SimplifyPreserveFromTo()

'在featureclass中新建要素并将刚生成的polygon保存进去

pEndFeature = TempFeatureClass.CreateFeature

pEndFeature.Shape = pPolygon

pEndFeature.Store()

pFeature = pFeatureCur.NextFeature()

End While

'关闭编辑

pWorkspaceEdit.StopEditOperation()

pWorkspaceEdit.StopEditing(True)

Return TempFeatureClass

End Function