[ITK] templating typdef question

[Dr Bernhard Schaffer]

Hi,

This is my second email to this list. I'm still not so familiar with
typedefs in coding, and I've the current problem:

 

I have my own "image" objects which can be 2D or 3D and of different number
type.  If I assume they are only 2D and float I can do something like this:

(The cyan lines show methods of  'my' object.)

 

 

const unsigned int DIMENSION = 2;

 

          typedef itk::ImportImageFilter<float, DIMENSION >
ImportFilterType;

ImportFilterType::Pointer importFilter = ImportFilterType::New();

 

ImportFilterType::SizeType  size;

          size[0]  = MYIMAGE.GetXSIZE();

size[1]  = MYIMAGE.GetYSIZE();

 

          ImportFilterType::IndexType start;

          start.Fill( 0 );

 

          ImportFilterType::RegionType region;

          region.SetIndex( start );

          region.SetSize(  size  );

importFilter->SetRegion( region );

 

const itk::SpacePrecisionType origin[ DIMENSION ] = { 0.0, 0.0 };

          importFilter->SetOrigin( origin );

 

          const itk::SpacePrecisionType  spacing[ DIMENSION ] =  { 1.0, 1.0
};

importFilter->SetSpacing( spacing );

 

          const bool importImageFilterWillOwnTheBuffer = false;     

 

          float *localBuffer = MYIMAGE.GETPOINTER();

          importFilter->SetImportPointer( localBuffer, size[0]*size[1],
importImageFilterWillOwnTheBuffer );

 

          typedef itk::Image< float,DIMENSION >   InputImageType;

          typedef itk::Image< float,DIMENSION >   OutputImageType;

 

          typedef itk::CurvatureFlowImageFilter< InputImageType,
OutputImageType >  FilterType;

          FilterType::Pointer filter = FilterType::New();

 

          filter->SetInput( importFilter->GetOutput() );

          filter->SetTimeStep( timeStep );

          filter->SetNumberOfIterations( iterations );

          filter->Update();

          typedef itk::ImageRegionIterator< OutputImageType >
IteratorType;

          OutputImageType::Pointer filtered = filter->GetOutput();

          [.]

 

If my image is 3D I can do accordingly: (Yellow is the difference to above)

 

const unsigned int DIMENSION = 3;

 

          typedef itk::ImportImageFilter<float, DIMENSION >
ImportFilterType;

ImportFilterType::Pointer importFilter = ImportFilterType::New();

 

ImportFilterType::SizeType  size;

          size[0]  = MYIMAGE.GetXSIZE();

size[1]  = MYIMAGE.GetYSIZE();

size[2]  = MYIMAGE.GetZSIZE();

 

 

          ImportFilterType::IndexType start;

          start.Fill( 0 );

 

          ImportFilterType::RegionType region;

          region.SetIndex( start );

          region.SetSize(  size  );

importFilter->SetRegion( region );

 

const itk::SpacePrecisionType origin[ DIMENSION ] = { 0.0, 0.0, 0.0 };

          importFilter->SetOrigin( origin );

 

          const itk::SpacePrecisionType  spacing[ DIMENSION ] =  { 1.0, 1.0,
1.0 };

importFilter->SetSpacing( spacing );

 

          const bool importImageFilterWillOwnTheBuffer = false;     

float *localBuffer = MYIMAGE.GETPOINTER();

          importFilter->SetImportPointer( localBuffer,
size[0]*size[1]*size[2], importImageFilterWillOwnTheBuffer );

 

          typedef itk::Image< float,DIMENSION >   InputImageType;

          typedef itk::Image< float,DIMENSION >   OutputImageType;

 

          typedef itk::CurvatureFlowImageFilter< InputImageType,
OutputImageType >  FilterType;

          FilterType::Pointer filter = FilterType::New();

 

          filter->SetInput( importFilter->GetOutput() );

          filter->SetTimeStep( timeStep );

          filter->SetNumberOfIterations( iterations );

          filter->Update();

          typedef itk::ImageRegionIterator< OutputImageType >
IteratorType;

          OutputImageType::Pointer filtered = filter->GetOutput();

          [.]

 

The problem I have is the following. I can query my object about its
dimensionality, but I can't do the following:

 

const unsigned int DIMENSION = MYIMAGE.GETDIMENSIONALITY();

 

because the typedefs are evaluated on compilation not on runtime.   So my
way around this is, to actually duplicate  all the code and have both my
examples in a switch-case:

 

          switch(MYIMAGE.GETDIMENSIONALITY())

          {

          case(2):

                    {

. EXAMPLE 2D as above

}

                   break;

          case(3): 

                    {

. EXAMPLE 3D as above

}

                   break;

}

 

Which is rather obvious code duplication. Is there a better way to do this?
(there has to!)  The problem branches out, if I also allow the type float to
be specified by my object as in

          switch(MYIMAGE.GETDATATYPE())

          {

          case(1):.float.;

          case(2):.double.;

          case(3):.

          .

} 

 

 

I would very much appreciate a few lines of (pseudo-) code showing me how I
can do this better. 

 

Thank you very much,

   Best regards,

   Bernhard

 

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