[vtkusers] vtkStreamingDemandDrivenPipeline ques

[Brad King]

Dean Inglis wrote:
> prior to all the pipeline re-work,
> I could load 3D image data with a vtkImageReader
> with ReleaseDataFlagOff.  I added some
> callbacks to show read progression in a
> GUI progress bar.  The reader output was passed
> onto a vtkOutlineFilter, 3 vtkImagePlaneWidgets
> and a vtkImageActor for one of the widget's
> outputs for 2D display.
> 
> Now I am getting errors:
> 
> ERROR: In C:\Builder\Sources\VTK\Filtering\vtkExecutive.cxx, line 701
> vtkStreamingDemandDrivenPipeline (091AE708): ProcessRequest invoked during
> another request.  Returning failure to algorithm vtkImageReader(091AA25C).
> 
> and interaction with the widget apparently causes
> the reader to re-read its data from disc
> since the progress meter is activated.
> 
> Any thoughts?

This message means something is causing a recursive update of a pipeline
during an update.  If your GUI has an observer that calls something on
the filters that may be triggering a recursive update.  I've just 
committed some changes that will cause the offending request to be 
included in the error message.  That should help you track it down.

-Brad