[vtk-developers] Change to Widgets

Tim Peeters T.Peeters at tue.nl
Mon Sep 24 10:44:26 EDT 2007


Hi Utkarsh,

Why are you doing this after the render call? To me it seems that the 
event means that the interaction ended and not that the rendering ended.

I have some code where I wait for an EndInteraction event of 
vtkImageTracerWidget and other widgets to update a seeding region and 
automatically generate new seed points for streamline tracing, trace the 
streamlines, and re-render the scene (all depending on some flags which 
can be set by the user). I didn't try it, but I guess your change can 
result in 2 render passes where only one is needed. The first one before 
you call InvokeEvent, and the second after you invoke the event and my 
code updates the scene.

Tim.

Utkarsh Ayachit wrote:
> Hi Folks,
> 
> I am in the process of changing all the widgets so that they fire the 
> vtkCommand::EndInteractionEvent after the render call.
> 
> To elaborate, almost all widgets do something similar to the following 
> code on end interaction (typically mouse up):
> 
> ....(change internal state to note that interaction has ended)
> this->InvokeEvent(vtkCommand::EndInteraction);
> this->Render();
> 
> 
> I am changing this to:
> 
> ....(change internal state to note that interaction has ended)
> this->Render();
> this->InvokeEvent(vtkCommand::EndInteraction);
> 
> Does anyone see any issues with this?
> 
> Thanks,
> Utkarsh



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