如何进行层与层之间的逻辑运算

 

本例要实现的是将两个同一GeometryType图层联合成为一个图层，输出Shape文件，并且加载到Map中显示出来。

l   要点

定义ITable的两个接口变量，通过两个图层FeatureClass实例化。然后由接口IFeatureClassName、IWorkspaceName和IDatasetName实现创建一个新的shape文件。再创建IBasicGeoprocessor接口对象，使用IBasicGeoprocessor.Union方法实现两个图层的联合。

l   程序说明

过程UIButtonControl1_Click是实现模块。

l   代码

Option Explicit

Private Sub UIButtonControl1_Click()

    Dim pMxDoc                  As IMxDocument

    Dim pLayer                  As ILayer

    Dim pInputTable             As ITable

    Dim pOverlayTable           As ITable

    Dim pFeatClassName          As IFeatureClassName

    Dim pNewWSName              As IWorkspaceName

    Dim pDatasetName            As IDatasetName

    Dim dtol                    As Double

    Dim pBasicGeop              As IBasicGeoprocessor

    Dim pOutputFeatClass        As IFeatureClass

    Dim pOutputFeatLayer        As IFeatureLayer

    Dim App                     As VBProject

On Error GoTo ErrorHandler:

    Set pMxDoc = ThisDocument

    Set pLayer = pMxDoc.FocusMap.Layer(0)

    Set App = ThisDocument.VBProject

    ' Get the input table

    ' Use the Itable interface from the Layer (not from the FeatureClass)

    Set pInputTable = pLayer

    ' Get the overlay layer and table

    ' Use the Itable interface from the Layer (not from the FeatureClass)

    Set pLayer = pMxDoc.FocusMap.Layer(1)

    Set pOverlayTable = pLayer

    ' 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

    ' Define the output feature class name

Set pFeatClassName = New FeatureClassName

' Set output location and feature class name

Set pNewWSName = New WorkspaceName

pNewWSName.WorkspaceFactoryProgID = "esriCore.ShapeFileWorkspaceFactory.1"

    pNewWSName.PathName = App.FileName & "\.."

    Set pDatasetName = pFeatClassName

    pDatasetName.Name = "Union_result"

    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

    dtol = 0#

    ' Perform the union

    Set pBasicGeop = New BasicGeoprocessor

    Set pOutputFeatClass = pBasicGeop.Union(pInputTable, False, pOverlayTable, False, _dtol, pFeatClassName)

    ' Add the output layer to the map

    Set pOutputFeatLayer = New FeatureLayer

    Set pOutputFeatLayer.FeatureClass = pOutputFeatClass

    pOutputFeatLayer.Name = pOutputFeatClass.AliasName

    pMxDoc.FocusMap.AddLayer pOutputFeatLayer

    Exit Sub

ErrorHandler:

    MsgBox Err.Description

End Sub