itkBSplineInterpolationWeightFunction.h

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 *
 *  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
 *
 *         https://www.apache.org/licenses/LICENSE-2.0.txt
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 *  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.
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#ifndef itkBSplineInterpolationWeightFunction_h
#define itkBSplineInterpolationWeightFunction_h
 
#include "itkFunctionBase.h"
#include "itkContinuousIndex.h"
#include "itkArray.h"
#include "itkArray2D.h"
#include "itkIndexRange.h"
#include "itkMath.h"
 
namespace itk
{
template <typename TCoordRep = float, unsigned int VSpaceDimension = 2, unsigned int VSplineOrder = 3>
class ITK_TEMPLATE_EXPORT BSplineInterpolationWeightFunction
  : public FunctionBase<ContinuousIndex<TCoordRep, VSpaceDimension>,
                        FixedArray<double, Math::UnsignedPower(VSplineOrder + 1, VSpaceDimension)>>
{
public:
  ITK_DISALLOW_COPY_AND_MOVE(BSplineInterpolationWeightFunction);
 
  using Self = BSplineInterpolationWeightFunction;
  using Superclass = FunctionBase<ContinuousIndex<TCoordRep, VSpaceDimension>,
                                  FixedArray<double, Math::UnsignedPower(VSplineOrder + 1, VSpaceDimension)>>;
 
  using Pointer = SmartPointer<Self>;
  using ConstPointer = SmartPointer<const Self>;
 
  itkNewMacro(Self);
 
  itkTypeMacro(BSplineInterpolationWeightFunction, FunctionBase);
 
  static constexpr unsigned int SpaceDimension = VSpaceDimension;
 
  static constexpr unsigned int SplineOrder = VSplineOrder;
 
  using WeightsType = typename Superclass::OutputType;
 
  static constexpr unsigned int NumberOfWeights{ WeightsType::Length };
 
  using IndexType = Index<VSpaceDimension>;
  using SizeType = Size<VSpaceDimension>;
 
  using ContinuousIndexType = ContinuousIndex<TCoordRep, VSpaceDimension>;
 
  static constexpr SizeType SupportSize{ SizeType::Filled(VSplineOrder + 1) };
  // Declaration here, definition must be outside of class until C++17, see .hxx file for linker definition
 
  WeightsType
  Evaluate(const ContinuousIndexType & index) const override;
 
  virtual void
  Evaluate(const ContinuousIndexType & index, WeightsType & weights, IndexType & startIndex) const;
 
#if !defined(ITK_LEGACY_REMOVE)
 
  itkLegacyMacro(SizeType GetSupportSize() const) { return Self::SupportSize; };
 
  itkLegacyMacro(unsigned int GetNumberOfWeights() const) { return Self::NumberOfWeights; }
#endif
 
protected:
  BSplineInterpolationWeightFunction() = default;
  ~BSplineInterpolationWeightFunction() override = default;
 
private:
  using TableType = FixedArray<IndexType, NumberOfWeights>;
 
  const TableType m_OffsetToIndexTable{ [] {
    TableType     table;
    // Note: Copied the constexpr value `SupportSize` to a local variable, to prevent a GCC
    // (Ubuntu 7.5.0-3ubuntu1~18.04) link error, "undefined reference to `SupportSize`", and Clang
    // (Mac10.13-AppleClang-dbg-x86_64-static) "Undefined symbols for architecture x86_64".
    const auto    supportSize = SupportSize;
    std::copy_n(ZeroBasedIndexRange<SpaceDimension>(supportSize).cbegin(), NumberOfWeights, table.begin());
    return table;
  }() };
};
} // end namespace itk
#ifndef ITK_MANUAL_INSTANTIATION
#  include "itkBSplineInterpolationWeightFunction.hxx"
#endif
 
#endif