Removing/excluding items from legend in an ArcFM Silverlight viewer

Question

I'm customizing an ArcFM Silverlight viewer (which is essentially an ArcGIS Silverlight viewer in a different package and with some additional tools). I managed to make a legend via the Legend Class and Sample: Legend with Templates.

The last three layers (InsetMapMarker, TextTemporary, and BufferLayer) are things automatically generated by the ArcFM viewer tools. It will confuse to end users to see them ("what's a buffer layer, I'm not making any buffers"), and potentially mess with functionality if they turn them on or off. So I really ought to exclude them from the legend.

I was very happy to find this Q&A How do I exclude raster layers from legend? (Silverlight, ArcGIS Server) and adapted the code snippet to exclude the last three layers (see below). However, this has no effect -- they're still visible in the legend.

private void Legend_Refreshed(object sender, Legend.RefreshedEventArgs e)
{
    LayerItemViewModel removeLayerItemVM = null;

    if (e.LayerItem.LayerItems != null)
    {
        foreach (LayerItemViewModel layerItemVM in e.LayerItem.LayerItems)
        {
            if (layerItemVM.IsExpanded)
                layerItemVM.IsExpanded = false;
            if (layerItemVM.Label == "InsetMapMarker")
                removeLayerItemVM = layerItemVM;
            if (layerItemVM.Label == "TextTemporary")
                removeLayerItemVM = layerItemVM;
            if (layerItemVM.Label == "BufferLayer")
                removeLayerItemVM = layerItemVM;
        }

        if (removeLayerItemVM != null)
            e.LayerItem.LayerItems.Remove(removeLayerItemVM);
    }
    else
    {
        e.LayerItem.IsExpanded = false;
    }
}

I know very little about C# and the Silverlight API, and guessing isn't getting me very far. What am I missing?

Answer 1

I eventually found a solution to this in a discussion on Esri's GeoNet: Controlling Layers in Legend Control. The method is to include a LayerIDs="[list]" property in the legend declaration.

So for instance, you only want to display your baselayer in the legend:

<esri:Map>
<esri:ArcGISTiledMapServiceLayer ID="baseLayer" Url="..." />
</esri:Map>

in legend:

<esri:legend Map="{Binding ElementName=MyMap}" 
LayerItemsMode="Tree" 
LayerIDs="baseLayer" 
ShowOnlyVisibleLayers="True" />

To add layers to your legend, just separate them by a comma.

This worked in my case, since I have a limited set of layers and they are not going to change frequently (if ever). There are additional suggestions later in that discussion about removing all graphics layer, etc., however I didn't need a solution that advanced and so haven't tested it.