text: /*=========================================================================
   *
   *  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 itkVectorInterpolateImageFunction_h
  #define itkVectorInterpolateImageFunction_h
  
  #include "itkImageFunction.h"
  #include "itkFixedArray.h"
  
  namespace itk
  {
  
  /** \class VectorInterpolateImageFunction
   * \brief Base class for all vector image interpolaters.
   *
   * VectorInterpolateImageFunction is the base for all ImageFunctions that
   * interpolates image with vector pixel types. This function outputs
   * a return value of type Vector<double,Dimension>.
   *
   * This class is templated input image type and the coordinate
   * representation type.
   *
   * \warning This hierarchy of functions work only for images
   * with Vector-based pixel types. For scalar images use
   * InterpolateImageFunction.
   *
   * \sa InterpolateImageFunction
   * \ingroup ImageFunctions ImageInterpolators
   * \ingroup ITKImageFunction
   */
  template< typename TInputImage, typename TCoordRep = double >
  class ITK_TEMPLATE_EXPORT VectorInterpolateImageFunction:
    public ImageFunction<
      TInputImage,
      typename NumericTraits< typename TInputImage::PixelType >::RealType,
      TCoordRep >
  {
  public:
    ITK_DISALLOW_COPY_AND_ASSIGN(VectorInterpolateImageFunction);
  
    /** Extract the vector dimension from the pixel template parameter. */
    static constexpr unsigned int Dimension = TInputImage::PixelType::Dimension;
  
    /** Dimension underlying input image. */
    static constexpr unsigned int ImageDimension = TInputImage::ImageDimension;
  
    /** Standard class type aliases. */
    using Self = VectorInterpolateImageFunction;
    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(VectorInterpolateImageFunction, ImageFunction);
  
    /** InputImageType type alias support */
    using InputImageType = typename Superclass::InputImageType;
    using PixelType = typename InputImageType::PixelType;
    using ValueType = typename PixelType::ValueType;
    using RealType = typename NumericTraits< ValueType >::RealType;
  
    /** Point type alias support */
    using PointType = typename Superclass::PointType;
  
    /** Index type alias support */
    using IndexType = typename Superclass::IndexType;
  
    /** ContinuousIndex type alias support */
    using ContinuousIndexType = typename Superclass::ContinuousIndexType;
  
    /** Output type is RealType of TInputImage::PixelType. */
    using OutputType = typename Superclass::OutputType;
  
    /** CoordRep type alias support */
    using CoordRepType = TCoordRep;
  
    /** Returns the interpolated image intensity at a
     * specified point position. No bounds checking is done.
     * The point is assume to lie within the image buffer.
     * ImageFunction::IsInsideBuffer() can be used to check bounds before
     * calling the method. */
    OutputType Evaluate(const PointType & point) const override
    {
      ContinuousIndexType index;
  
      this->GetInputImage()->TransformPhysicalPointToContinuousIndex(point, index);
      return ( this->EvaluateAtContinuousIndex(index) );
    }
  
    /** Interpolate the image at a continuous index position
     *
     * Returns the interpolated image intensity at a
     * specified index position. No bounds checking is done.
     * The point is assume to lie within the image buffer.
     *
     * Subclasses must override this method.
     *
     * ImageFunction::IsInsideBuffer() can be used to check bounds before
     * calling the method. */
    OutputType EvaluateAtContinuousIndex(
      const ContinuousIndexType & index) const override = 0;
  
    /** Interpolate the image at an index position.
     * Simply returns the image value at the
     * specified index position. No bounds checking is done.
     * The point is assume to lie within the image buffer.
     *
     * ImageFunction::IsInsideBuffer() can be used to check bounds before
     * calling the method. */
    OutputType EvaluateAtIndex(const IndexType & index) const override
    {
      OutputType output;
      PixelType  input = this->GetInputImage()->GetPixel(index);
  
      for ( unsigned int k = 0;
                k < this->GetInputImage()->GetNumberOfComponentsPerPixel(); k++ )
        {
        output[k] = static_cast< double >( input[k] );
        }
      return ( output );
    }
  
  protected:
    VectorInterpolateImageFunction() = default;
    ~VectorInterpolateImageFunction() override = default;
    void PrintSelf(std::ostream & os, Indent indent) const override
    { Superclass::PrintSelf(os, indent); }
  };
  } // end namespace itk
  
  #endif
  