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How do I get the selected LegendItem?

KirkKuykendall

When I use the templated legend sample, I see that there is either zero or one selected item in the tree at any given time.

Is there a method on the Legend that returns the currently selected LayerItemViewModel?

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abdulrenish

The extension is a good suggestion. For me, i have two map controls, and I use a same Legend (TOC) for selecting layers for the two Maps. When i click on First Map, the legend will popup there and i can select one layer for map 1. And when i right click on mp 2, same legend will popup there, but here I need to disable the Map1 selected layer. Please find me a solution.

DominiqueBroux

Try with something like:

 
Public NotInheritable Class LegendExtension
Private Sub New()
End Sub
<System.Runtime.CompilerServices.Extension> _
Public Shared Function SelectedItems(legend As Legend) As IEnumerable(Of LegendItemViewModel)
If legend Is Nothing Then
Return Nothing
End If
Return legend.LayerItems.Descendants().Where(Function(item) item.IsSelected)
End Function
 
<System.Runtime.CompilerServices.Extension> _
Private Shared Function Descendants(layerItems As IEnumerable(Of LayerItemViewModel)) As IEnumerable(Of LegendItemViewModel)
Dim result As New List(Of LegendItemViewModel)()
If layerItems Is Nothing Then
Return result
End If
 
For Each layerItem As var In layerItems
result.Add(layerItem)
 
' return legend items
If layerItem.LegendItems IsNot Nothing Then
result.AddRange(layerItem.LegendItems)
End If
 
' return recursively layer items
If layerItem.LayerItems IsNot Nothing Then
result.AddRange(layerItem.LayerItems.Descendants())
End If
Next
Return result
End Function
End Class

JDog

Thanks SharpGIS,
Unfortunately that doesn't convert the "yield" C# which happens to be the difficult part translating to VB.

SomeGISGuy

http://www.developerfusion.com/tools/convert/csharp-to-vb/

JDog

Thanks Dominique,
Anybody know a quick fix to port the code to VB.net?

DominiqueBroux

To get the selected Legend Item(s), you have first:
1) to put in your project the LegendExtension class code that I gave in this thread
2) call MyLegend.SelectedItems() when you want to get the selected items

You don't have to change the toolkit project, it's only in your project.

JDog

Hi Dominique,
I would like to implement this feature. How or where would I go about plugging this into the Silverlight Toolkit Legend Control? Sorry, I'm new to the Silverlight world as well as the Toolkit.

Any help would be appreciated!

Regards,
JDog

KirkKuykendall

Thanks for the help!

AndrewWhite

Here's how I worked around it.

I added a button to the LayerTemplate and on the click event handler, I store the LayerItemViewModel that was clicked.

DominiqueBroux

The LegendItemViewModel class has a property called 'IsSelected', so, despite that there is no 'SelectionChanged' event (as Jennifer mentionned) if you want to get the selected items, you can loop on all legend items and test this property.

The touchy part is that you have to go though the legend items tree hierarchy.

Example of legend extension class returning the selected items:
public static class LegendExtension { public static IEnumerable<LegendItemViewModel> SelectedItems(this Client.Toolkit.Legend legend) { if (legend == null) return null; return legend.LayerItems.Descendants().Where(item => item.IsSelected); } private static IEnumerable<LegendItemViewModel> Descendants(this IEnumerable<LayerItemViewModel> layerItems) { if (layerItems == null) yield break; foreach (var layerItem in layerItems) { yield return layerItem; // return legend items if (layerItem.LegendItems != null) { foreach (var item in layerItem.LegendItems) yield return item; } // return recursively layer items if (layerItem.LayerItems != null) { foreach (var item in layerItem.LayerItems.Descendants()) yield return item; } } } }Then you can get the Selected items by 'MyLegend.SelectedItems()'.

I see that there is either zero or one selected item in the tree at any given time.

That's true with the default legend template, but we can imagine that one changes it to allow multiple selection. It's why my 'SelectedItems' returns a collection, but you can simplify to only one item if you assume that only one item is selectable at once.

JenniferNery

We currently do not have SelectionChanged event, you can subscribe to MouseLeftButtonDown event on the container inside DataTemplate and get the LayerItemViewModel this way:

var layerItemViewModel= ((sender as StackPanel).DataContext as ESRI.ArcGIS.Client.Toolkit.Primitives.LayerItemViewModel);

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