itkBSplineInterpolationWeightFunctionBase.h

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 *  Copyright UMC Utrecht and contributors
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 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
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 *  See the License for the specific language governing permissions and
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#ifndef itkBSplineInterpolationWeightFunctionBase_h
#define itkBSplineInterpolationWeightFunctionBase_h
 
#include "itkFunctionBase.h"
#include "itkContinuousIndex.h"
#include "itkIndexRange.h"
#include "itkMath.h"
#include "itkMatrix.h"
#include "itkBSplineKernelFunction2.h"
#include "itkBSplineDerivativeKernelFunction.h"
#include "itkBSplineSecondOrderDerivativeKernelFunction2.h"
 
namespace itk
{
template <typename TCoordinate = float, unsigned int VSpaceDimension = 2, unsigned int VSplineOrder = 3>
class ITK_TEMPLATE_EXPORT BSplineInterpolationWeightFunctionBase
  : public FunctionBase<ContinuousIndex<TCoordinate, VSpaceDimension>,
                        FixedArray<double, Math::UnsignedPower(VSplineOrder + 1, VSpaceDimension)>>
{
public:
  ITK_DISALLOW_COPY_AND_MOVE(BSplineInterpolationWeightFunctionBase);

  using Self = BSplineInterpolationWeightFunctionBase;
  using Superclass = FunctionBase<ContinuousIndex<TCoordinate, VSpaceDimension>,
                                  FixedArray<double, Math::UnsignedPower(VSplineOrder + 1, VSpaceDimension)>>;
  using Pointer = SmartPointer<Self>;
  using ConstPointer = SmartPointer<const Self>;

  itkOverrideGetNameOfClassMacro(BSplineInterpolationWeightFunctionBase);

  itkStaticConstMacro(SpaceDimension, unsigned int, VSpaceDimension);

  itkStaticConstMacro(SplineOrder, unsigned int, VSplineOrder);

  static constexpr unsigned long NumberOfWeights = Math::UnsignedPower(VSplineOrder + 1, VSpaceDimension);

  using WeightsType = FixedArray<double, NumberOfWeights>;

  using IndexType = Index<VSpaceDimension>;
  using SizeType = Size<VSpaceDimension>;

  using ContinuousIndexType = ContinuousIndex<TCoordinate, VSpaceDimension>;

  WeightsType
  Evaluate(const ContinuousIndexType & index) const override;

  WeightsType
  Evaluate(const ContinuousIndexType & cindex, const IndexType & startIndex) const;

  static IndexType
  ComputeStartIndex(const ContinuousIndexType & index);

  static constexpr SizeType SupportSize{ SizeType::Filled(VSplineOrder + 1) };
 
protected:
  BSplineInterpolationWeightFunctionBase() = default;
  ~BSplineInterpolationWeightFunctionBase() override = default;

  using KernelType = BSplineKernelFunction2<VSplineOrder>;
  using KernelPointer = typename KernelType::Pointer;
  using DerivativeKernelType = BSplineDerivativeKernelFunction<VSplineOrder>;
  using DerivativeKernelPointer = typename DerivativeKernelType::Pointer;
  using SecondOrderDerivativeKernelType = BSplineSecondOrderDerivativeKernelFunction2<VSplineOrder>;
  using SecondOrderDerivativeKernelPointer = typename SecondOrderDerivativeKernelType::Pointer;
  using WeightArrayType = typename KernelType::WeightArrayType;

  using OneDWeightsType = Matrix<double, Self::SpaceDimension, VSplineOrder + 1>;

  virtual void
  Compute1DWeights(const ContinuousIndexType & index,
                   const IndexType &           startIndex,
                   OneDWeightsType &           weights1D) const = 0;

  void
  PrintSelf(std::ostream & os, Indent indent) const override;
 
private:
  using TableType = FixedArray<IndexType, NumberOfWeights>;

  const TableType m_OffsetToIndexTable{ [] {
    TableType     table;
    std::copy_n(ZeroBasedIndexRange<SpaceDimension>(SupportSize).cbegin(), NumberOfWeights, table.begin());
    return table;
  }() };
};
 
} // end namespace itk
 
#ifndef ITK_MANUAL_INSTANTIATION
#  include "itkBSplineInterpolationWeightFunctionBase.hxx"
#endif
 
#endif