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

[Kent Eschenberg]

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