[Insight-users] Problem with the creation of a SpatialObjectSource base class

[Julien Michel]

Dear ITK users,

Since I am developing a set of filters producing itk::SpatialObject, I 
did first implement a SpatialObjectSource, templated by the 
SpatialObject type, deriving from itk::ProcessObject and providing the 
right GetOutput() method, as well as setting up the ProcessObject in the 
constructor (NumberOfRequiredOutputs(), creation of the output pointer).

I derived this base class to implement a filter with no input, producing 
a SpatialObject. I implemented the SpatialObject creation into a 
GenerateData() method, as I always did for non-threaded filters. Now, no 
matted how I put it, my GenerateData() is not called when I Update() my 
filter, or some filters later in the pipeline.

After some investigations, I think I found what might be a bug in the 
itk::SpatialObject class :

As described in the high level classes itk::ProcessObject and 
itk::DataObject, the Update() method on a filter triggers the following 
sequence :

- ProcessObject::Update() :
Does some checking and calls the DataObject::Update() on its first output.

- DataObject::Update() :
Calls some function to prepare the update and then calls 
DataObject::UpdateOutputData().

- DataObject::UpdateOutputData() :
Check if the DataObject has to be updated (and as a source), and if so 
calls ProcessObject::UpdateOutputData(DataObject) on the source.

- ProcessObject::UpdateOutputData(DataObject):
Does some more checking and then calls the GenerateData() method.


However, this sequence is broken when using itk::SpatialObject as output 
of our itk::ProcessObject, because itk::SpatialObject reimplements the 
DataObject::Update() method, which only calls this->Modified() without 
calling the Superclass implementation, nor calling the 
DataObject::UpdateOutputData() method.

Does it sound like a bug to you ? If so, I would of course produce a bug 
report on BugTracker.

Thanks a lot,
Best regards,

Julien

-------------- next part --------------
A non-text attachment was scrubbed...
Name: julien.michel.vcf
Type: text/x-vcard
Size: 255 bytes
Desc: not available
Url : http://public.kitware.com/pipermail/insight-users/attachments/20070321/8211a3c2/julien.michel.vcf