[vtkusers] Why the baggage in vtkInteractorStyle?

Elvis Stansvik elvis.stansvik at orexplore.com
Tue Aug 9 05:47:12 EDT 2016

2016-08-08 15:30 GMT+02:00 Elvis Stansvik <elvis.stansvik at orexplore.com>:

> Hi all,
> This is a bit of a general question about the interactor style system in
> VTK.
> Why does vtkInteractorStyle, which is described as the superclass of all
> interactor styles, have things functions like Dolly, Pan, Zoom et.c.? And
> why does it have keypress behaviors at all (e.g. 'j', 't', 'c', 'a', ...)?

I realize now that the docs are a little out of date, and that some of the
keyboard shortcuts I mention are now handled by vtkInteractorStyleSwitch.

But I'm still wondering why vtkInteractorStyle makes so many assumptions
about how a subclasser wishes to implement his/her style. I would have
expected a more "bare bone" base class.


> If it's supposed to be a general base class for interactor styles, why
> should it make assumptions like this about the camera movements the
> subclasser want to provide, and assumptions about keybindings?
> I'm looking for a base class to use, which is not making any such
> assumptions, since I want to provide a completely custom behavior, without
> having to guard myself against unwanted behavior coming from the base class.
> I've looked at, and even used vtkInteractorStyleUser, for this purpose
> (even if it's described as something mostly for the scripting languages),
> but I'm just wondering about the VTK design, why it was made this way?
> Thanks in advance,
> Elvis
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