本文是一些和layer相关的函数，如获得某一类型的所有layer，根据图层名获得layer，获得某layer所属的grouplayer等。
''' <summary>
''' 得到pMap中所有的FeatureLayer图层
''' </summary>
''' <param name="pMap">IMap对象</param>
''' <returns>查询图层列表</returns>
''' <remarks></remarks>
Public Shared Function GetAllFeatureLayer(ByVal pMap As IMap) As IEnumLayer
If pMap Is Nothing OrElse pMap.LayerCount = 0 Then Return Nothing
Dim pEnumLayer As IEnumLayer
Dim pId As New UID
Try
pId.Value = "{" & GetType(IFeatureLayer).GUID.ToString & "}" ''查找出所有的IFeatureLayer对象（包括IAnnotationLayer）
pEnumLayer = pMap.Layers(pId, True)
Return pEnumLayer
Catch ex As Exception
Return Nothing
End Try
End Function
''' <summary>
''' 获得当前地图中所有某一类型的图层
''' </summary>
''' <param name="pMap">IMap对象</param>
''' <param name="pType">图层类型,形式如:GetType(ILayer)</param>
''' <returns>该类型图层的list</returns>
''' <remarks></remarks>
Public Shared Function GetAllLayers(ByVal pMap As IMap, ByVal pType As Type) As List(Of ILayer)
If pMap Is Nothing OrElse pMap.LayerCount = 0 Then Return Nothing
Dim pLayers As New List(Of ILayer)
Dim pEnumLayer As IEnumLayer
Dim pId As New UID
Try
pId.Value = "{" & pType.GUID.ToString & "}" ''查找出所有的IFeatureLayer对象（包括IAnnotationLayer）
pEnumLayer = pMap.Layers(pId, True)
Dim pLayer As ILayer = pEnumLayer.Next()
While Not pLayer Is Nothing
pLayers.Add(pLayer)
pLayer = pEnumLayer.Next()
End While
Return pLayers
Catch ex As Exception
Return Nothing
End Try
End Function
''' <summary>
''' 在地图中选择出对应为pFClass的第一个图层
''' </summary>
''' <param name="pMap">IMap对象</param>
''' <param name="pFClass">IFeatureClass对象</param>
''' <returns></returns>
''' <remarks></remarks>
Public Shared Function GetLayerByFeatureClass(ByVal pMap As IMap, ByVal pFClass As IFeatureClass) As IFeatureLayer
If pMap Is Nothing OrElse pFClass Is Nothing Then Return Nothing
Dim pEnumLayer As IEnumLayer
Dim pId As New UID
Try
pId.Value = "{" & GetType(IFeatureLayer).GUID.ToString & "}" ''查找出所有的IFeatureLayer对象（包括IAnnotationLayer）
pEnumLayer = pMap.Layers(pId, True)
Dim pLayer As IFeatureLayer = pEnumLayer.Next()
While Not pLayer Is Nothing
If pLayer.FeatureClass Is pFClass Then
Return pLayer
End If
pLayer = pEnumLayer.Next()
End While
Return Nothing
Catch ex As Exception
Return Nothing
End Try
End Function
''' <summary>
''' 查询pLayer所在的IGroupLayer
''' </summary>
''' <param name="pMap">IMap对象</param>
''' <param name="pLayer">ILayer对象</param>
''' <returns>IGroupLayer对象</returns>
''' <remarks>
''' 无或异常返回Nothing
''' </remarks>
Public Shared Function GetGroupLayerByLayer(ByVal pMap As IMap, ByVal pLayer As ILayer) As IGroupLayer
If pMap Is Nothing OrElse pLayer Is Nothing Then Return Nothing
Dim pEnumLayer As IEnumLayer
Dim pId As New UID
Try
pId.Value = "{" & GetType(IGroupLayer).GUID.ToString & "}" ''查找出所有的IFeatureLayer对象（包括IAnnotationLayer）
pEnumLayer = pMap.Layers(pId, True)
Dim pGLayer As IGroupLayer = pEnumLayer.Next()
While Not pGLayer Is Nothing
Dim i As Integer
For i = 0 To CType(pGLayer, ICompositeLayer).Count - 1
If CType(pGLayer, ICompositeLayer).Layer(i) Is pLayer Then
Return pGLayer
End If
Next
pGLayer = pEnumLayer.Next()
End While
Return Nothing
Catch ex As Exception
Return Nothing
End Try
End Function
''' <summary>
''' 查找出pFeature所在的图层
''' </summary>
''' <param name="pFeature">IFeature对象</param>
''' <param name="pMap">IMap对象</param>
''' <returns>查询图层</returns>
''' <remarks>
''' 通过比对IMap中图层的FeatureClass.AliasName和IFeature.Class.AliasName进行判断
''' </remarks>
Public Shared Function SearchLayer(ByVal pFeature As IFeature, ByVal pMap As IMap) As IFeatureLayer
Try
If pFeature Is Nothing Or pMap Is Nothing OrElse pMap.LayerCount = 0 Then Return Nothing
Dim pEnumLayer As IEnumLayer
Dim pLayer As IFeatureLayer
Dim pId As New UID
pId.Value = "{" & GetType(IFeatureLayer).GUID.ToString & "}"
pEnumLayer = pMap.Layers(pId, True)
pEnumLayer.Reset()
pLayer = pEnumLayer.Next
While pLayer IsNot Nothing
If pLayer.FeatureClass IsNot Nothing Then
If pLayer.FeatureClass.AliasName = pFeature.Class.AliasName Then '当pLayer中没有对象时，pLayer.FeatureClass为空
Return (pLayer)
End If
End If
pLayer = pEnumLayer.Next
End While
Return Nothing
Catch ex As Exception
Return Nothing
End Try
End Function
''' <summary>
''' 查询Map中的图层名为sLayerName的图层
''' </summary>
''' <param name="pMap">IMap对象</param>
''' <param name="sLayerName">图层名称</param>
''' <returns></returns>
''' <remarks></remarks>
Public Shared Function GetLayerByName(ByVal pMap As IMap, ByVal sLayerName As String) As ILayer
If pMap Is Nothing OrElse pMap.LayerCount = 0 Then Return Nothing
Try
Dim pId As New UID
pId.Value = "{" & GetType(ILayer).GUID.ToString & "}"
Dim pEnumLayer As IEnumLayer = pMap.Layers(pId, True)
pEnumLayer.Reset()
Dim pLayer As ILayer
pLayer = pEnumLayer.Next
While pLayer IsNot Nothing
If pLayer.Name = sLayerName Then
Exit While
End If
pLayer = pEnumLayer.Next
End While
Return pLayer
Catch ex As Exception
Return Nothing
End Try
End Function
''' <summary>
''' 根据图层名称取得其图层所在编号，如果没有此图层，则返回－1
''' </summary>
''' <param name="LayerName"></param>
''' <param name="pMap"></param>
''' <returns></returns>
''' <remarks></remarks>
Public Shared Function GetFeatureLayerIndex(ByVal LayerName As String, ByVal pMap As IMap) As Integer
If pMap Is Nothing OrElse pMap.LayerCount = 0 Then Return -1
Dim Counter As Long
Try
For Counter = 0 To pMap.LayerCount - 1
If TypeOf pMap.Layer(Counter) Is IFeatureLayer Then
If pMap.Layer(Counter).Name = LayerName Then
Return Counter
End If
End If
Next Counter
Return -1
Catch ex As Exception
Return -1
End Try
End Function
''' <summary>
''' 根据文件路径创建layer
''' </summary>
''' <param name="pFilePath">文件全路径</param>
''' <returns>返回创建的layer</returns>
''' <remarks></remarks>
Shared Function CreateLayerFromPath(ByVal pFilePath As String) As ILayer
Try
'Get the ILayerFactoryHelper interface
Dim pLayerFactoryHelper As ILayerFactoryHelper
pLayerFactoryHelper = New LayerFactoryHelper
'Get the IEnumLayer interface through the ILayerFatcoryHelper interface
Dim pFileName As IFileName = New FileName
pFileName.Path = pFilePath
Dim pEnumLayer As IEnumLayer
pEnumLayer = pLayerFactoryHelper.CreateLayersFromName(pFileName)
pEnumLayer.Reset()
'Get the ILayer interface
Dim pLayer As ILayer
pLayer = pEnumLayer.Next
'Loop through layers
Dim pReLayer As ILayer = Nothing
Do While Not pLayer Is Nothing
'Add the layer to the map
pReLayer = pLayer
pLayer = pEnumLayer.Next
Loop
Return pReLayer
Catch ex As Exception
Return Nothing
End Try
End Function