itkCentralDifferenceImageFunction.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 itkCentralDifferenceImageFunction_h
#define itkCentralDifferenceImageFunction_h

#include "itkImageFunction.h"
#include "itkCovariantVector.h"
#include "itkInterpolateImageFunction.h"
#include "itkDefaultConvertPixelTraits.h"

namespace itk
{
template<
  typename TInputImage,
  typename TCoordRep = float,
  typename TOutputType = CovariantVector<double, TInputImage::ImageDimension >
  >
class ITK_TEMPLATE_EXPORT CentralDifferenceImageFunction:
  public ImageFunction< TInputImage,
                        TOutputType,
                        TCoordRep >
{
public:
  ITK_DISALLOW_COPY_AND_ASSIGN(CentralDifferenceImageFunction);

  static constexpr unsigned int ImageDimension = TInputImage::ImageDimension;

  using Self = CentralDifferenceImageFunction;
  using Superclass = ImageFunction< TInputImage,
                         TOutputType,
                         TCoordRep >;
  using Pointer = SmartPointer< Self >;
  using ConstPointer = SmartPointer< const Self >;

  itkTypeMacro(CentralDifferenceImageFunction, ImageFunction);

  itkNewMacro(Self);

  using InputImageType = TInputImage;

  using InputPixelType = typename InputImageType::PixelType;

  using InputPixelConvertType = DefaultConvertPixelTraits< InputPixelType >;

  using OutputType = typename Superclass::OutputType;

  using OutputConvertType = DefaultConvertPixelTraits<OutputType>;

  using OutputValueType = typename OutputConvertType::ComponentType;

  using ScalarDerivativeType = CovariantVector<OutputValueType, Self::ImageDimension >;

  using IndexType = typename Superclass::IndexType;

  using ContinuousIndexType = typename Superclass::ContinuousIndexType;

  using PointType = typename Superclass::PointType;

  using SpacingType = typename TInputImage::SpacingType;

  using InterpolatorType = InterpolateImageFunction< TInputImage, TCoordRep >;
  using InterpolatorPointer = typename InterpolatorType::Pointer;

  void SetInputImage(const TInputImage *inputData) override;

  virtual void SetInterpolator(InterpolatorType *interpolator);

  itkGetModifiableObjectMacro(Interpolator, InterpolatorType );

  OutputType EvaluateAtIndex(const IndexType & index) const override;

  OutputType Evaluate(const PointType & point) const override;

  OutputType EvaluateAtContinuousIndex( const ContinuousIndexType & cindex) const override;

  itkSetMacro(UseImageDirection, bool);
  itkGetConstMacro(UseImageDirection, bool);
  itkBooleanMacro(UseImageDirection);

protected:
  CentralDifferenceImageFunction();
  ~CentralDifferenceImageFunction() override = default;
  void PrintSelf(std::ostream & os, Indent indent) const override;

private:

  template<typename T>
  struct OutputTypeSpecializationStructType
  {
    using Type = T;
  };

  template< typename Type >
  inline void EvaluateAtIndexSpecialized( const IndexType & index, OutputType & derivative, OutputTypeSpecializationStructType<OutputType>) const;
  template< typename Type >
  inline void EvaluateAtIndexSpecialized( const IndexType & index, OutputType & derivative, OutputTypeSpecializationStructType<Type>) const;

  template< typename Type >
  inline void EvaluateAtContinuousIndexSpecialized( const ContinuousIndexType & index, OutputType & derivative, OutputTypeSpecializationStructType<OutputType>) const;
  template< typename Type >
  inline void EvaluateAtContinuousIndexSpecialized( const ContinuousIndexType & index, OutputType & derivative, OutputTypeSpecializationStructType<Type>) const;

  // NOTE: for some unknown reason, making these methods inline (as those above are inlined) makes them run *slower*.
  template< typename Type >
  void EvaluateSpecialized( const PointType & point, OutputType & derivative, OutputTypeSpecializationStructType<OutputType>) const;
  template< typename Type >
  void EvaluateSpecialized( const PointType & point, OutputType & derivative, OutputTypeSpecializationStructType<Type>) const;

  // flag to take or not the image direction into account
  // when computing the derivatives.
  bool m_UseImageDirection;

  // interpolator
  InterpolatorPointer   m_Interpolator;
};
} // end namespace itk

#ifndef ITK_MANUAL_INSTANTIATION
#include "itkCentralDifferenceImageFunction.hxx"
#endif

#endif