[vtkusers] Re: How to subclass RenderWindow for use with GTK

[Sean McInerney]

I have done something similar to what you seek for use with FLTK due to 
limitations found in the freely availible VTK/FLTK solutions. My 
implementation, however, ranks toward the ugly and effortful side. In a 
nutshell:

1a. Derive a new RenderWindow class from vtkOpenGLRenderWindow (e.g. 
vtkGTKOpenGLRenderWindow). Using vtkXOpenGLRenderWindow as a model, 
reimplement all the X and Xt calls with GDK and GTK calls.

1b. Similarly derive a new Interactor class from 
vtkRenderWindowInteractor using vtkXRenderWindowInteractor as a model.
N.B. You MAY be able to implement all of you event handling code here as 
vtkXRenderWindowInteractor does, though you may (and will probably) want 
to use GDK/GTK's event handling via a sub-class of GTK's OpenGL window 
widget (see item 3 below).
1c. (Optional) ... If you have an excess of free time, derive a 
non-OpenGL RenderWindow class from vtkRenderWindow using 
vtkXRenderWindow as a model.

2. Derive a new ObjectFactory class from vtkObjectFactory (e.g. 
vtkGTKObjectFactory) so that creating the familiar parent objects 
(vtkRenderWindow, etc.) actually instantiates your spiffy new 
GTK-specialized sub-classes. Albeit, in use, you'll need a pointer to 
your specialized sub-class to access any methods not found in the 
ancestor (hint: use ...::SafeDownCast()).

3. (Maybe optional) Derive a new widget from GTK's OpenGL window widget 
via GTK's object hierarchy mechanism (I am unable to be of much help 
here). Your new specialized GTK object should then invoke event methods 
of its associated Interactor within its handler method when it receives 
an event (from GDK/GTK).

If you work continuously for a couple days, you should have a usable 
(but probably buggy) implementation ready before you collapse.

-Sean