[vtkusers] How to be notified when an interaction style is set (from Python)?

[Elvis Stansvik]

Den 20 juni 2016 4:12 em skrev "David Gobbi" <david.gobbi at gmail.com>:
>
> On Mon, Jun 20, 2016 at 7:02 AM, Elvis Stansvik <
elvis.stansvik at orexplore.com> wrote:
>>
>> Hi all,
>>
>> In my custom interaction style (derived from vtkInteractionStyleUser), I
have a need to be notified when the interaction style is set on an
interactor.
>>
>> The reason I need this is that the purpose of my interaction style is to
lock the camera position to a cylinder around my subject: The user should
be able to zoom in/out, rotate around the subject on a circle, change the
azimuth, and pan up/down along the subject (which has the shape of standing
cylinder), but not perform other camera movements. The focal point should
always be on the axis through the middle of my subject which is parallel to
the Y ("vertical") axis. I therefore would like to do some initialization
of the camera when the interactor is first set on the interactor style
(and, I guess equivalently, when the interaction style is set on the
interactor).
>>
>> In C++ I think I could override SetInteractor on the interactor style,
but in Python that won't work. Is there some event I could listen for which
fires when the interaction style gets a new interactor?
>
>
> Only the ModifiedEvent, but it fires a lot and therefore observing it is
inefficient.  If you have your own interactor class (and if you use it
throughout your application), then you can override its
SetInteractorStyle() method since that method is called from the Python
side.

Ah, that's true. I have control over the interactor used, so I could
subclass it for just this purpose. Thanks!

Elvis
>
>  - David
>
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