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 itkExtrapolateImageFunction_h
  #define itkExtrapolateImageFunction_h
  
  #include "itkImageFunction.h"
  
  namespace itk
  {
  /**
   *\class ExtrapolateImageFunction
   * \brief Base class for all image extrapolaters.
   *
   * ExtrapolateImageFunction is the base for all ImageFunctions that
   * extrapolates image intensity at a non-integer pixel position
   * outside the image buffer.
   * This class is templated over the input image type and the
   * coordinate representation type (e.g. float or double ).
   *
   * \warning This hierarchy of functions work only for images
   * with scalar pixel types.
   *
   * \ingroup ImageFunctions
   *
   *
   * \ingroup ITKImageFunction
   */
  template <typename TInputImage, typename TCoordRep = float>
  class ExtrapolateImageFunction
    : public ImageFunction<TInputImage, typename NumericTraits<typename TInputImage::PixelType>::RealType, TCoordRep>
  {
  public:
    ITK_DISALLOW_COPY_AND_MOVE(ExtrapolateImageFunction);
  
    /** Standard class type aliases. */
    using Self = ExtrapolateImageFunction;
    using Superclass =
      ImageFunction<TInputImage, typename NumericTraits<typename TInputImage::PixelType>::RealType, TCoordRep>;
    using Pointer = SmartPointer<Self>;
    using ConstPointer = SmartPointer<const Self>;
  
    /** Run-time type information (and related methods). */
    itkTypeMacro(ExtrapolateImageFunction, ImageFunction);
  
    /** OutputType type alias support */
    using typename Superclass::OutputType;
  
    /** InputImageType type alias support */
    using typename Superclass::InputImageType;
  
    /** Dimension underlying input image. */
    static constexpr unsigned int ImageDimension = Superclass::ImageDimension;
  
    /** Point type alias support */
    using typename Superclass::PointType;
  
    /** Index type alias support */
    using typename Superclass::IndexType;
  
    /** ContinuousIndex type alias support */
    using typename Superclass::ContinuousIndexType;
  
    /** RealType type alias support */
    using RealType = typename NumericTraits<typename TInputImage::PixelType>::RealType;
  
    /** Extrapolate the image at a point position
     *
     * Returns the extrapolated image intensity at a
     * specified point position.
     */
    OutputType
    Evaluate(const PointType & point) const override
    {
      ContinuousIndexType index;
  
      this->GetInputImage()->TransformPhysicalPointToContinuousIndex(point, index);
      return (this->EvaluateAtContinuousIndex(index));
    }
  
    /** Extrapolate the image at a continuous index position
     *
     * Returns the extrapolated image intensity at a
     * specified point position.
     */
    OutputType
    EvaluateAtContinuousIndex(const ContinuousIndexType & index) const override = 0;
  
    /** Extrapolate the image at an index position.
     *
     * Returns the extrapolated image intensity at a
     * specified point position.
     */
    OutputType
    EvaluateAtIndex(const IndexType & index) const override = 0;
  
  protected:
    ExtrapolateImageFunction() = default;
    ~ExtrapolateImageFunction() override = default;
    void
    PrintSelf(std::ostream & os, Indent indent) const override
    {
      Superclass::PrintSelf(os, indent);
    }
  };
  } // end namespace itk
  
  #endif
  