vb.net arcobjects enable customized context menu item only if a feature is selected

Question

The solution may be very simple, but I haven't made it work.

I want to enable a data view context menu item only if a feature (in polyline layer) is selected, all other places the item should in grey. May I say what I need to do is check whether a feature is selected? I searched for this but don't find a proper solution. Or any other concerns?

I am using ArcObjects 10.2.2 and VB.NET.

Answer 1

If you're making an ArcGIS Add-In (rather than the old extension format), then I believe you can enable / disable buttons or menu items inside your button class like this:

Protected Overrides Sub OnUpdate()
 Enabled = bSelected
End Sub

Where bSelected is your boolean indicating whether or not your feature is selected. You can check if a feature in a particular featurelayer is selected like this:

Dim pFeatureSelection As IFeatureSelection = pLayer
If pFeatureSelection.SelectionSet.Count = 0 Then
 bSelected = False
Else
 bSelected = True
End If

Or you could put them together to cut down on code. Try this:

Protected Overrides Sub OnUpdate()
 Dim pFeatureSelection As IFeatureSelection = pLayer
 If pFeatureSelection.SelectionSet.Count = 0 Then
 Enabled = False
 Else
 Enabled= True
 End If 
End Sub

EDIT: I've just realised you said context-menu, which I assume means a right click menu? In which case I'm not sure as I've never used context menus in ArcMap.

• tomfumb: may be a better option to only update bSelected in response to events in ISelectionEvents Interface so that you're only checking the selection count when it actually changes, and not every time ArcGIS fires the update event