[Paraview] What part of the pipeline is producing the request for UPDATE_EXTENT?

[Mike Jackson]

Pretty sure that was where we were going to end up BUT as far as I  
can tell, the order of execution is :
RequestInformation()
SetVOI() // From the GUI in ParaView
RequestData();

So we never really get a chance to get the VOI until RequestData  
fires.. Is that what you have seen?

Mike
On Feb 12, 2008, at 11:21 PM, Kent Eschenberg wrote:

> Mike,
>
> I accomplished what you want with one of our custom readers. In my  
> opinion the documentation for RequestInformation, RequestData,  
> extents, etc. is so poor that it is useless.
>
> At RequestInformation I read enough of the input to get the overall  
> input array size; apply the user-selected VOI; and return the  
> desired subset as the whole extent. At RequestData I read the rest.  
> I just don't bother letting VTK/ParaView manage the selection of  
> the VOI. This has worked for 2.6.1 through 3.2.1.
>
> Kent
> Pittsburgh Supercomputing Center
>
> Mike Jackson wrote:
>> I can do that but I don't think it will work.
>> In paraview, I have managed to set an auto-generated UI for the  
>> VOI. Now, the user opens our file, RequestInformation is run (I  
>> can put some sane defaults for the VOI) and things are ok so far.  
>> Now the user clicks "Apply" and then SetVOI is called with the  
>> values from the GUI and then RequestData() is called after that.  
>> So where do I update WHOLE_EXTENT? Or just take the values from  
>> the VOI, create a vtkImageObject from that, and then just  
>> ShallowCopy to the output object?
>> I'm a bit confused at this point. If our case is NOT a standard  
>> use case for the pipeline than I guess I can look more seriously  
>> into developing a full blown Plugin for our data file.
>> Mike