[Insight-users] [Fwd: factories for FFTW filters - update]

[Jakub Bican]

Hi Gaetan,

as i more and more understand the problem of factories, it is clear to 
me, that this is the most elegant solution.

Your suggestion have to be complicated only a little bit more by 
determining, if the actual PixelType matches the type of FFTW library 
linked: i.e. use FFTW only if FFTWF is defined and PixelType is float or 
FFTWD is defined and pixeltype is double.

There should be also check if there is some factory for the class, as it 
is in itkNewMacro (in case someone will use dynamic library with new FFT 
implementation)

Is it possible to make such change to ITK cvs version?

I hope this will help to many people that are writing filters using FFT.

Thanks,

       Jakub




Gaetan Lehmann napsal(a):
>
> Hi Jakub,
>
> That's only my point of view, but don't you think that the factory is 
> quite complicated for that case ?
> IMHO opinion, a customized New() method in 
> RealToComplexConjugateImageFilter would do the job without problem. 
> Something like:
>
> static Pointer New()
>   {
> #if defined(USE_FFTWF)
>   return FFTWRealToComplexConjugateImageFilter<PixelType, 
> ImageDimension>::New().GetPointer();
> #else
>   return VnlFFTRealToComplexConjugateImageFilter<PixelType, 
> ImageDimension>::New().GetPointer();
> #endif
>   }
>
> Regards,
>
> Gaetan
>
>
>
> On Thu, 26 Oct 2006 11:51:13 +0200, Jakub Bican 
> <jakub.bican at matfyz.cz> wrote:
>
>>
>> Hi,
>>
>> things seem more clear now: I have to make just one class 
>> (FFTFactory:ObjectFactoryBase) that calls RegisterOverride() in its 
>> constructor to override creation of RealToComplexConjugateImageFilter 
>> and ComplexConjugateToRealImageFilter by available implementation 
>> from VNL or FFTW.
>>
>> But the questions remains the same:
>> 1) how to register this factory as "implicit default factory" - 
>> without need to register it manually in every filter or every program 
>> that uses FFT
>>
>> 2) what happens if there will be new FFT implementation in dynamic 
>> library, that will override in the same way - which factory will have 
>> priority? (if the dynamic one overrides the default one, then it is 
>> ok - that is the intention, but does it really happen?)
>>
>>
>> Regards,
>>
>>         Jakub
>>
>>
>>
>>
>> -------- Původní zpráva --------
>>
>> Hello,
>>
>> i would like to implement a factory mechanism for FFT filters. The 
>> point is that if the user selects "USE_FFTW" once during 
>> configuration, then the factory mechanism will provide him FFTW-based 
>> classes instead of standard VNL implementation. And user can also 
>> create his own dll with some fft implementation and attach it 
>> dynamically to his project.
>>
>> I studied the tutorial 
>> (http://www.na-mic.org/Wiki/images/2/24/Insight-DesignPatterns.ppt) 
>> including examples.
>>
>> I would like to ask someone if i understand well what i have to do:
>>
>> step A) create factories FFTWFFTFactory and VNLFFTFactory (derived 
>> from following class), that will override creation of 
>> RealToComplexConjugateImageFilter and 
>> ComplexConjugateToRealImageFilter types so that an instance from 
>> appropriate implementation is created.
>>
>> step B) create class FFTFactoryBase (derived from ObjectFactoryBase) 
>> that will be implemented similary to TransformFactoryBase and that 
>> will register one of the above factories, depending on if the FFTW is 
>> used or not
>> (this is difference to TransformFactoryBase, which registers all 
>> known factories, while the new class will register only one depending 
>> on configuration)
>>
>>
>> And i have some questions:
>>
>> 1) what is the correct way of registering FFTFactoryBase 
>> automatically, so that it registers appropriate factory "at the 
>> beginning"?
>> I don't want to register it explicitly at the beginning of every 
>> program that will use FFT - i just want to call 
>> RealToComplexConjugateImageFilter::New() and get FFTW implementation 
>> if i attached FFTW library to ITK or VNL implementation otherwise.
>>
>> 2) what happens if someone loads dll into ITK_AUTOLOAD_PATH with a 
>> new FFT implementation and corresponding factory? What will be 
>> overriden by what?
>>
>> Thanks in advance for guidance and answers,
>>
>>    Jakub
>>
>>
>>
>>
>>
>> _______________________________________________
>> Insight-users mailing list
>> Insight-users at itk.org
>> http://www.itk.org/mailman/listinfo/insight-users
>
>
>
> --Gaëtan Lehmann
> Biologie du Développement et de la Reproduction
> INRA de Jouy-en-Josas (France)
> tel: +33 1 34 65 29 66    fax: 01 34 65 29 09
> http://voxel.jouy.inra.fr
>
>