An often used function is to get a specific layer from a current map document. The code below is for VB.NET and requires a map document and the alias name of the feature class. The first function returns all IGeoFeature layers in a map – these are layers based on vector geographic data. The second loops through these layers and compares the layer names.
Public Function GetFeatureLayers(ByRef pMap As IMap) As IEnumLayer
Dim pUID As New UIDClass
pUID.Value = "{E156D7E5-22AF-11D3-9F99-00C04F6BC78E}" 'IGeoFeatureLayer GUID
If pMap.LayerCount > 0 Then
GetFeatureLayers = pMap.Layers(pUID, True)
Else
Return Nothing
End If
End Function
Public Function GetFeatureLayerByAliasName(ByRef pMap As IMap, _
ByVal strLayerModelName As String) As IFeatureLayer
Dim pLayerEnum As IEnumLayer
Dim pFLayer As IFeatureLayer
pLayerEnum = GetFeatureLayers(pMap)
If pLayerEnum Is Nothing Then
Return Nothing
End If
pFLayer = DirectCast(pLayerEnum.Next, IFeatureLayer)
Do Until pFLayer Is Nothing
If pFLayer.Valid Then
If strLayerModelName = pFLayer.FeatureClass.AliasName Then
Return pFLayer
End If
End If
pFLayer = DirectCast(pLayerEnum.Next, IFeatureLayer)
Loop
'the layer was not found
Return Nothing
End Function
Rather than using the layer name visible in the table of contents which is easly changed by a user, I use the .AliasName of the feature class. This is automatically set to the name of the layer when added to a map. A user is much less likely to change this. There is however another name that is 100% not to change, it does however require an additional step when adding the layer shown below:
Dim pModelInfo As IModelInfo pModelInfo = CType(pFLayer.FeatureClass, IModelInfo) pModelInfo.ModelName = “AnyValueYouLike”
The code to find this layer is similar to the FindFeatureLayer, but relies on the IModelInfo interface.
Public Function GetFeatureLayerByModelName(ByRef pMap As IMap, _ ByVal strLayerModelName As String) As IFeatureLayer Dim pLayerEnum As IEnumLayer Dim pFLayer As IFeatureLayer Dim pModelInfo As IModelInfo pLayerEnum = GetFeatureLayers(pMap) If pLayerEnum Is Nothing Then Return Nothing End If pFLayer = DirectCast(pLayerEnum.Next, IFeatureLayer) Do Until pFLayer Is Nothing If pFLayer.Valid Then pModelInfo = DirectCast(pFLayer.FeatureClass, IModelInfo) If strLayerModelName = pModelInfo.ModelName Then Return pFLayer End If End If pFLayer = DirectCast(pLayerEnum.Next, IFeatureLayer) Loop 'the layer was not found Return Nothing End Function
geoDeveloper 