[vtk-developers] RE: VTK Widgets redesign

[Dean Inglis]

I think David is on the right track with additional
*ButtonDrag events that in the long run could simplify
things.  For example, dropping seed points or free-hand
tracing as is done with vtkImageTracerWidget requires logic 
that keeps track of whether a mouse click/release pair 
occurred or whether a mouse click/move/release sequence etc. 

I'm also not in favor of a generic "Move" event
as is currently enumerated in vtkWidgetEvent.

>I think we should discourage the use of a generic "Move" widget event as 
>much as
>possible.  It's best if the WidgetEventTranslator is sophisticated 
>enough to translate
>the "MouseMoveEvent" into a more meaningful widget event (Scale, 
>Translate, etc).

With regard to multi-widget management, perhaps the API could enforce
widgets to have a shutoff mechanism, something like
 
void SetInteraction(int onoff)=0;

as is done in vtkImagePlaneWidget, vtkImageTracerWidget, and more 
elaborately in vtkBoxWidget for example, where the widget is visible, 
but not interactive. I presume that vtkWidgetEventTranslator
would coordinate such activity?

I think Prabhu has proposed some great ideas for widget management: 
reminds me of the Alt-Tab key function on MS windows where you get to 
pick from among currently running apps.  This could be done as a 
2D overlay widget(perhaps modelled after vtkLegendBoxActor?), and 
perhaps one could have the thing generate its own icons(?) 
or text names(?) of the widgets added to it at run time...

just my $.02
Dean