itkNearestNeighborExtrapolateImageFunction.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.
 *  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 itkNearestNeighborExtrapolateImageFunction_h
#define itkNearestNeighborExtrapolateImageFunction_h
 
#include "itkExtrapolateImageFunction.h"
 
namespace itk
{
template <typename TInputImage, typename TCoordRep = float>
class NearestNeighborExtrapolateImageFunction : public ExtrapolateImageFunction<TInputImage, TCoordRep>
{
public:
  ITK_DISALLOW_COPY_AND_MOVE(NearestNeighborExtrapolateImageFunction);
 
  using Self = NearestNeighborExtrapolateImageFunction;
  using Superclass = ExtrapolateImageFunction<TInputImage, TCoordRep>;
  using Pointer = SmartPointer<Self>;
  using ConstPointer = SmartPointer<const Self>;
 
  itkTypeMacro(NearestNeighborExtrapolateImageFunction, InterpolateImageFunction);
 
  itkNewMacro(Self);
 
  using OutputType = typename Superclass::OutputType;
 
  using InputImageType = typename Superclass::InputImageType;
 
  static constexpr unsigned int ImageDimension = Superclass::ImageDimension;
 
  using IndexType = typename Superclass::IndexType;
  using IndexValueType = typename IndexType::IndexValueType;
 
  using ContinuousIndexType = typename Superclass::ContinuousIndexType;
 
  OutputType
  EvaluateAtContinuousIndex(const ContinuousIndexType & index) const override
  {
    IndexType nindex;
 
    for (unsigned int j = 0; j < ImageDimension; j++)
    {
      nindex[j] = Math::RoundHalfIntegerUp<IndexValueType>(index[j]);
      if (nindex[j] < this->GetStartIndex()[j])
      {
        nindex[j] = this->GetStartIndex()[j];
      }
      else if (nindex[j] > this->GetEndIndex()[j])
      {
        nindex[j] = this->GetEndIndex()[j];
      }
    }
    return static_cast<OutputType>(this->GetInputImage()->GetPixel(nindex));
  }
 
  OutputType
  EvaluateAtIndex(const IndexType & index) const override
  {
    IndexType nindex;
 
    for (unsigned int j = 0; j < ImageDimension; j++)
    {
      if (index[j] < this->GetStartIndex()[j])
      {
        nindex[j] = this->GetStartIndex()[j];
      }
      else if (index[j] > this->GetEndIndex()[j])
      {
        nindex[j] = this->GetEndIndex()[j];
      }
      else
      {
        nindex[j] = index[j];
      }
    }
    return static_cast<OutputType>(this->GetInputImage()->GetPixel(nindex));
  }
 
protected:
  NearestNeighborExtrapolateImageFunction() = default;
  ~NearestNeighborExtrapolateImageFunction() override = default;
  void
  PrintSelf(std::ostream & os, Indent indent) const override
  {
    Superclass::PrintSelf(os, indent);
  }
};
} // end namespace itk
 
#endif