[vtkusers] Question about vtkInteractorStyleUser

[Elvis Stansvik]

Hi,

I found this old thread about vtkInteractorStyleUser:

    http://www.vtk.org/pipermail/vtkusers/2010-September/062584.html

In it, David Gobbi explained:

> The vtkInteractorStyleUser is still the correct way to write a fully
> customized vtkInteractorStyle in the wrapper languages.  It isn't the
> only option, i.e. you can add observers to the other interactor
> styles, but it is different from the rest because it doesn't define
> any "default" interaction of its own.

Is this still true?

In my case, I have a large, roughly cylindrical volume (tomography of a
drill core), where the camera should only ever see the cylinder from the
side, with the line of sight perpendicular to the center line of the core.
Rotation of the camera should also be limited to rotation around the center
line of the core (z axis), with no possibility of roll, and I think I want
to support this rotation only through a Qt slider, not by mouse interaction
in the VTK window. Movement of the camera (and focal point) up and down the
core should be through a Qt scrollbar. The last camera operation I want to
support is zooming, and just like with rotation, I'd like this to be done
through a Qt slider.

Apart from that, I only want to selectively add certain interactions in the
VTK window, to allow the user to annotate the core visually by adding
markers of various kinds through mouse clicks and click-drags.

It's because the set of interactions I want to support in the VTK window
are so few, and quite specialized, I was looking at vtkInteractorStyleUser.
Does it seems reasonable to use this interactor style in my case, or are
there other approaches I should consider?

The only example I can find of vtkInteractorStyleUser usage is this C++
example:

    http://www.vtk.org/Wiki/VTK/Examples/Cxx/Interaction/InteractorStyleUser

But it seems this example just sets the vtkInteractorStyleUser on the
interactor, not really making use of it (e.g. overriding its virtual On*
methods)? Instead it adds observers to the interactor itself. Or is setting
a vtkInteractorStyleUser on the interactor a prerequisite to be able to
observe those events in this way?

Thankful for any advice / clarifications on how vtkInteractorStyleUser is
meant to be used.

Cheers,
Elvis
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