如何访问 arcobjects 中底图的子图层？

Question

ILayer layer = mapControl.get_Layer(1); //layer 1 is usa_base_map 

我有一个 ILayer，现在我想访问并打开和关闭各种子层，例如街道层或铁路层。你能告诉我如何访问这些层吗？

Answer 1

我认为您需要将图层组投射到 ICompositeLayer (链接）。

Answer 2

访问底图子图层
以下代码示例演示如何访问底图子图层、检索内层、更新内层的属性以及向底图图层通知更改。该通知会使图层的内部缓存失效，以便重新绘制内容以反映更新。在此示例中，更新清除了要素图层的定义表达式。
[C#]

private void UpdateBasemapSublayerAndNotify(IBasemapLayer basemapLayer, IMap map)
{
    ICompositeLayer basemapCompositeLayer = basemapLayer as ICompositeLayer;
    IBasemapSubLayer basemapSubLayer = basemapCompositeLayer.get_Layer(0)as
        IBasemapSubLayer;
    ILayer innerLayer = basemapSubLayer.Layer;
    IFeatureLayer featureLayer = innerLayer as IFeatureLayer;
    if (featureLayer != null)
    {
        IFeatureLayerDefinition featureLayerDef = featureLayer as
            IFeatureLayerDefinition;
        featureLayerDef.DefinitionExpression = "";
    }
    //When performing operations against the wrapped layer that change properties, you must 
    //notify the basemaplayer so the display cache can be recreated if necessary.
    basemapLayer.NotifyLayerChanged(basemapSubLayer as ILayer,
        esriLayerEventHint.esriLayerEventHintProperties, null);
    IActiveView activeView = map as IActiveView;
    activeView.PartialRefresh(esriViewDrawPhase.esriViewGeography, basemapLayer as
        object, null);
}

[VB.NET]

Private Sub UpdateBasemapSublayerAndNotify(ByVal basemapLayer As IBasemapLayer, ByVal map As IMap)
    Dim basemapCompositeLayer As ICompositeLayer = TryCast(basemapLayer, ICompositeLayer)
    Dim basemapSubLayer As IBasemapSubLayer = TryCast(basemapCompositeLayer.get_Layer(0), IBasemapSubLayer)
    Dim innerLayer As ILayer = basemapSubLayer.Layer
    Dim featureLayer As IFeatureLayer = TryCast(innerLayer, IFeatureLayer)
    If featureLayer IsNot Nothing Then
        Dim featureLayerDef As IFeatureLayerDefinition = TryCast(featureLayer, IFeatureLayerDefinition)
        featureLayerDef.DefinitionExpression = ""
    End If

    'When performing operations against the wrapped layer that change properties, you must
    'notify the basemaplayer so the display cache can be recreated if necessary.
    basemapLayer.NotifyLayerChanged(TryCast(basemapSubLayer, ILayer), esriLayerEventHint.esriLayerEventHintProperties, Nothing)

    Dim activeView As IActiveView = TryCast(map, IActiveView)

    activeView.PartialRefresh(esriViewDrawPhase.esriViewGeography, TryCast(basemapLayer, Object), Nothing)
End Sub