itkNearestNeighborExtrapolateImageFunction.h

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/*=========================================================================
 *
 *  Copyright Insight Software Consortium
 *
 *  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_ASSIGN(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