Place Fiducial Marker with EndPlacementEvent observer

Development
1

I am trying to execute a function after a fiducial marker is placed. I was trying to implement it with this:

def onMarkupEndInteraction(caller, event):
    # Do stuff
    pass

interactionNode = slicer.app.applicationLogic().GetInteractionNode()
selectionNode = slicer.app.applicationLogic().GetSelectionNode()
selectionNode.SetReferenceActivePlaceNodeClassName("vtkMRMLMarkupsFiducialNode")
pointListNode = slicer.mrmlScene.AddNewNodeByClass("vtkMRMLMarkupsFiducialNode")

pointListNode.AddObserver(interactionNode.EndPlacementEvent, onMarkupEndInteraction)
selectionNode.SetActivePlaceNodeID(pointListNode.GetID())
interactionNode.SetCurrentInteractionMode(1)

however, it seems to be executing onMarkupEndInteration before the fiducial marker is placed. I have been trying many different methods (as there are many different ways to initialize and place fiducial markers), but none seem to properly execute the observer for the fiducial marker.

2

You can observe events of the markups node, such as slicer.vtkMRMLMarkupsNode.PointPositionDefinedEvent.