[IGSTK-Developers] Accessing ITK image

[Patrick Cheng]

Thanks Julien and Luis,

I don't think modifying the base class is a good idea. Different 
application developer are developing different class using ITK images, 
maybe segmentation, or registration. If they all ended up adding a line 
or two in the base class, this will look very messy.

What we need is helper class, maybe called ImageSpatialObjectToITKImage

This requires the receptor class has defined a ITKImageType, and a 
RequestSetITKImage() fuction.

I think this is a better way than modifying the base class. You only 
need to declare this class as a friend in your new registration class, 
and call the GetITKImage(igstkImageSpatialObject, your_new_class) later 
in your code.

Let me know what do you guys think of this solution.

Patrick



class ImageSpatialObjectToITKImage
{
public:

   template < class TImageSpatialObject, class TITKImageReceptor >
   static void
   GetITKImage( const TImageSpatialObject * imageSO,
                       TITKImageReceptor   * receptor )
     {
     //We need to setup the observer to catch the event here
     igstkObserverConstObjectMacro( ITKImage,
                              TImageSpatialObject::ITKImageModifiedEvent,
                              TITKImageReceptor::ITKImageType)

     ITKImageObserver::Pointer itkImageObserver = TKImageObserver::New();

     imageSO->AddObserver( ImageSOType::ITKImageModifiedEvent(),
                           itkImageObserver);

     imageSO->RequestGetITKImage(); //this will trigger an event

     if( itkImageObserver->GotITKImage() )
       {
       receptor->RequestSetITKImage( itkImageObserver->GetITKImage() );
       }
     // some error handling code

};

Julien Jomier wrote:
> I don't think adding a private shared class will improve the current 
> design. The current implementation should be ok.
> 
> As Luis is saying if a user is implementing new classes in IGSTK then he 
> should be considered as a developer and therefore adding one (or two) 
> lines in the base classes is fine.
> 
> Julien
> 
> Luis Ibanez wrote:
>>
>> Hi Patrick,
>>
>> The solution is already illustrated in the interface between the
>> ImageSpatialObjectRepresentationClass and the ImageSpatialObject.
>>
>> A private friend class can act as an intermediary to make possible
>> to pass the itkImage from the ImageSpatialObject to the Registration
>> class, without having to expose the itk Image in the public API
>> of the ImageSpatialObject.
>>
>> Note that when you refer to a "user" that is writing her/his own
>> registration class, this is actually "extending IGSTK" and therefore
>> the new code should be subject to the same software development process
>> as the rest of IGSTK. Exposing ITK or VTK classes in the public API
>> will sacrifice all the safety that has been the concern of IGSTK so far.
>>
>>
>> Please let me know if you find any difficulty in setting this same
>> infrastructure for the registration class, I will be happy to help
>> you with the code.
>>
>>
>>    Thanks
>>
>>
>>       Luis
>>
>>
>>
>> ======================
>> Patrick Cheng wrote:
>>> Hi everyone,
>>>
>>> For the new demo application, the registration class need to get 
>>> access to the ITK image, so that it can segment out the fiducial 
>>> points. Other ImageToImage registration also requires access to the 
>>> ITK image too.
>>>
>>> This posts a problem to the igstkImageSpatialObject class, if the 
>>> user need to use their own registration class, they need to modify 
>>> the igstkImageSpatialObject class and declare their registration 
>>> class to be a friend class.
>>>
>>> Is there a better solution to this problem?
>>>
>>> Patrick
>>> _______________________________________________
>>> IGSTK-Developers mailing list
>>> IGSTK-Developers at public.kitware.com
>>> http://public.kitware.com/cgi-bin/mailman/listinfo/igstk-developers
>>>
>>>
>>
>>
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>>
> 
> 
>