text: /*=========================================================================
   *
   *  Copyright NumFOCUS
   *
   *  Licensed under the Apache License, Version 2.0 (the "License");
   *  you may not use this file except in compliance with the License.
   *  You may obtain a copy of the License at
   *
   *         http://www.apache.org/licenses/LICENSE-2.0.txt
   *
   *  Unless required by applicable law or agreed to in writing, software
   *  distributed under the License is distributed on an "AS IS" BASIS,
   *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   *  See the License for the specific language governing permissions and
   *  limitations under the License.
   *
   *=========================================================================*/
  #ifndef itkMatrixIndexSelectionImageFilter_h
  #define itkMatrixIndexSelectionImageFilter_h
  
  #include "itkUnaryFunctorImageFilter.h"
  
  namespace itk
  {
  namespace Functor
  {
  template <typename TInput, typename TOutput>
  class MatrixIndexSelection
  {
  public:
    MatrixIndexSelection() { m_I = m_J = 0; }
    ~MatrixIndexSelection() = default;
  
    void
    GetIndices(unsigned int & i, unsigned int & j) const
    {
      i = m_I;
      j = m_J;
    }
    void
    SetIndices(unsigned int i, unsigned int j)
    {
      m_I = i;
      m_J = j;
    }
  
    bool
    operator==(const MatrixIndexSelection & other) const
    {
      return m_I == other.m_I && m_J == other.m_J;
    }
  
    ITK_UNEQUAL_OPERATOR_MEMBER_FUNCTION(MatrixIndexSelection);
  
    inline TOutput
    operator()(const TInput & A) const
    {
      return static_cast<TOutput>(A[m_I][m_J]);
    }
  
  private:
    unsigned int m_I;
    unsigned int m_J;
  };
  } // namespace Functor
  
  /** \class MatrixIndexSelectionImageFilter
   *
   * \brief Extracts the selected indices of a matrix image that is the input
   * pixel type
   *
   * This filter is templated over the input image type and
   * output image type.
   *
   * The filter expect the input image pixel type to be a matrix and
   * the output image pixel type to be a scalar. The only requirement on
   * the type used for representing the vector is that it must provide an
   * operator(i,j).
   *
   * \ingroup IntensityImageFilters  MultiThreaded
   * \ingroup ITKImageIntensity
   */
  
  template <typename TInputImage, typename TOutputImage>
  class MatrixIndexSelectionImageFilter
    : public UnaryFunctorImageFilter<
        TInputImage,
        TOutputImage,
        Functor::MatrixIndexSelection<typename TInputImage::PixelType, typename TOutputImage::PixelType>>
  {
  public:
    ITK_DISALLOW_COPY_AND_MOVE(MatrixIndexSelectionImageFilter);
  
    /** Standard class type aliases. */
    using Self = MatrixIndexSelectionImageFilter<Image<Matrix<unsigned short, 2, 2>, 2>, Image<unsigned char, 2>>;
    using Superclass = UnaryFunctorImageFilter<
      TInputImage,
      TOutputImage,
      Functor::MatrixIndexSelection<typename TInputImage::PixelType, typename TOutputImage::PixelType>>;
    using Pointer = SmartPointer<Self>;
    using ConstPointer = SmartPointer<const Self>;
  
    /** Run-time type information (and related methods).   */
    itkTypeMacro(MatrixIndexSelectionImageFilter, UnaryFunctorImageFilter);
  
    /** Method for creation through the object factory. */
    itkNewMacro(Self);
  
    /** Get/Set methods for the index */
    void
    SetIndices(unsigned int i, unsigned int j)
    {
      this->GetFunctor().SetIndices(i, j);
      this->Modified();
    }
  
    void
    GetIndices(unsigned int & i, unsigned int & j) const
    {
      return this->GetFunctor().GetIndices(i, j);
    }
  
  #ifdef ITK_USE_CONCEPT_CHECKING
    // Begin concept checking
    itkConceptMacro(InputHasNumericTraitsCheck, (Concept::HasNumericTraits<typename TInputImage::PixelType::ValueType>));
    // End concept checking
  #endif
  
  protected:
    MatrixIndexSelectionImageFilter() = default;
    ~MatrixIndexSelectionImageFilter() override = default;
  };
  } // end namespace itk
  
  #endif
  