itkZeroFluxNeumannImageNeighborhoodPixelAccessPolicy.h

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 *  Copyright NumFOCUS
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
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 *  distributed under the License is distributed on an "AS IS" BASIS,
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 *  See the License for the specific language governing permissions and
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#ifndef itkZeroFluxNeumannImageNeighborhoodPixelAccessPolicy_h
#define itkZeroFluxNeumannImageNeighborhoodPixelAccessPolicy_h
 
#include "itkIndex.h"
#include "itkOffset.h"
#include "itkSize.h"
 
namespace itk
{
 
template <typename TImage>
class ZeroFluxNeumannImageNeighborhoodPixelAccessPolicy final
{
private:
  using NeighborhoodAccessorFunctorType = typename TImage::NeighborhoodAccessorFunctorType;
  using PixelType = typename TImage::PixelType;
  using InternalPixelType = typename TImage::InternalPixelType;
 
  using ImageDimensionType = typename TImage::ImageDimensionType;
  static constexpr ImageDimensionType ImageDimension = TImage::ImageDimension;
 
  using IndexType = Index<ImageDimension>;
  using OffsetType = Offset<ImageDimension>;
  using ImageSizeType = Size<ImageDimension>;
  using ImageSizeValueType = SizeValueType;
 
  // Index value to the image buffer, indexing the current pixel.
  const IndexValueType m_PixelIndexValue;
 
  // A reference to the accessor of the image.
  const NeighborhoodAccessorFunctorType & m_NeighborhoodAccessor;
 
 
  // Private helper function. Clamps the index value between the interval
  // [0 .. imageSizeValue>.
  static IndexValueType
  GetClampedIndexValue(const IndexValueType indexValue, const ImageSizeValueType imageSizeValue) noexcept
  {
    return (indexValue <= 0) ? 0
           : (static_cast<ImageSizeValueType>(indexValue) < imageSizeValue)
             ? indexValue
             : static_cast<IndexValueType>(imageSizeValue - 1);
  }
 
  // Private helper function. Calculates and returns the index value of the
  // current pixel within the image buffer.
  static IndexValueType
  CalculatePixelIndexValue(const ImageSizeType & imageSize,
                           const OffsetType &    offsetTable,
                           const IndexType &     pixelIndex) noexcept
  {
    IndexValueType result = 0;
 
    for (ImageDimensionType i = 0; i < ImageDimension; ++i)
    {
      result += GetClampedIndexValue(pixelIndex[i], imageSize[i]) * offsetTable[i];
    }
    return result;
  }
 
public:
  // Deleted member functions:
  ZeroFluxNeumannImageNeighborhoodPixelAccessPolicy() = delete;
  ZeroFluxNeumannImageNeighborhoodPixelAccessPolicy &
  operator=(const ZeroFluxNeumannImageNeighborhoodPixelAccessPolicy &) = delete;
 
  // Explicitly-defaulted functions:
  ~ZeroFluxNeumannImageNeighborhoodPixelAccessPolicy() = default;
  ZeroFluxNeumannImageNeighborhoodPixelAccessPolicy(
    const ZeroFluxNeumannImageNeighborhoodPixelAccessPolicy &) noexcept = default;
 
  ZeroFluxNeumannImageNeighborhoodPixelAccessPolicy(const ImageSizeType &                   imageSize,
                                                    const OffsetType &                      offsetTable,
                                                    const NeighborhoodAccessorFunctorType & neighborhoodAccessor,
                                                    const IndexType &                       pixelIndex) noexcept
    : m_PixelIndexValue{ CalculatePixelIndexValue(imageSize, offsetTable, pixelIndex) }
    , m_NeighborhoodAccessor(neighborhoodAccessor)
  {}
  PixelType
  GetPixelValue(const InternalPixelType * const imageBufferPointer) const noexcept
  {
    return m_NeighborhoodAccessor.Get(imageBufferPointer + m_PixelIndexValue);
  }
 
  void
  SetPixelValue(InternalPixelType * const imageBufferPointer, const PixelType & pixelValue) const noexcept
  {
    m_NeighborhoodAccessor.Set(imageBufferPointer + m_PixelIndexValue, pixelValue);
  }
};
} // namespace itk
 
#endif