#ifndef __CPEXTENSIONS__ALGORITHMS__GRADIENTIMAGEFUNCTIONBASE__H__
#define __CPEXTENSIONS__ALGORITHMS__GRADIENTIMAGEFUNCTIONBASE__H__

#include <itkImageFunction.h>

namespace cpExtensions
{
  namespace Algorithms
  {
    /**
     * Base class to compute values based on image gradients (vector).
     */
    template< class _TGradient, class _TMask = itk::Image< unsigned char, _TGradient::ImageDimension > >
    class GradientImageFunctionBase
      : public itk::ImageFunction< _TGradient, typename _TGradient::PixelType::ValueType, typename _TGradient::PixelType::ValueType >
    {
    public:
      // Types from input arguments
      typedef _TGradient                     TGradient;
      typedef _TMask                         TMask;
      typedef typename _TGradient::PixelType TVector;
      typedef typename TVector::ValueType    TScalar;
      itkStaticConstMacro(
        Dimension, unsigned int, _TGradient::ImageDimension
        );

      // Standard itk types
      typedef GradientImageFunctionBase                          Self;
      typedef itk::ImageFunction< _TGradient, TScalar, TScalar > Superclass;
      typedef itk::SmartPointer< Self >                          Pointer;
      typedef itk::SmartPointer< const Self >                    ConstPointer;

      // Types from base itk::ImageFunction
      typedef typename Superclass::InputType           TInput;
      typedef typename Superclass::OutputType          TOutput;
      typedef typename Superclass::PointType           TPoint;
      typedef typename Superclass::ContinuousIndexType TContIndex;
      typedef typename Superclass::IndexType           TIndex;

    public:
      itkTypeMacro( GradientImageFunctionBase, itkImageFunction );

      itkGetConstObjectMacro( Mask, TMask );
      itkSetConstObjectMacro( Mask, TMask );

    public:
      virtual void Prepare( ) const;
      virtual TOutput Evaluate( const TPoint& p ) const cpExtensions_OVERRIDE;
      virtual TOutput EvaluateAtIndex( const TIndex& i ) const cpExtensions_OVERRIDE;
      virtual TOutput EvaluateAtContinuousIndex( const TContIndex& i ) const cpExtensions_OVERRIDE;

    protected:
      GradientImageFunctionBase( );
      virtual ~GradientImageFunctionBase( );

      virtual TOutput _Evaluate( const TIndex& i ) const = 0;

    private:
      // Purposely not implemented.
      GradientImageFunctionBase( const Self& );
      void operator=( const Self& );

    protected:
      typename _TMask::ConstPointer m_Mask;
    };

  } // ecapseman

} // ecapseman

#ifndef ITK_MANUAL_INSTANTIATION
#  include <cpExtensions/Algorithms/GradientImageFunctionBase.hxx>
#endif // ITK_MANUAL_INSTANTIATION

#endif // __CPEXTENSIONS__ALGORITHMS__GRADIENTIMAGEFUNCTIONBASE__H__

// eof - $RCSfile$