[vtk-developers] AddObserver for vtkChartXY with a vtkColorTransferFunction

[Brad Hollister]

Hi,

With the Python wrapping, I'm trying to add an observer that allows 
the user to select a custom color when adding a new point to a 
vtkChartXY containing a vtkColorTranferFunction.

It is possible to catch 'StartEvent', 'ModifiedEvent', or 'EndEvent' 
from vtkColorTransferFunction. However, this requires a way to 
determine if a new point has been added for those events -- there 
doesn't appear to be a good / clean way to do this.

Why is it not possible to have 'PlacePointEvent' associated with the 
vtkColorTransferFunction instead, when a new point is added? Is there 
an event that is particular to a color point being added that I'm not 
aware of? I'd ideally like that type of event to trigger my callback.

Regards,
Brad