itkDefaultVectorPixelAccessor.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
 *
 *  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 itkDefaultVectorPixelAccessor_h
#define itkDefaultVectorPixelAccessor_h
 
#include "itkMacro.h"
#include "itkVariableLengthVector.h"
#include "itkIntTypes.h"
#include <algorithm> // for std::min
 
namespace itk
{
template <typename TType>
class ITK_TEMPLATE_EXPORT DefaultVectorPixelAccessor
{
public:
  using VectorLengthType = unsigned int;

  using ExternalType = VariableLengthVector<TType>;

  using InternalType = TType;

  inline void
  Set(InternalType & output, const ExternalType & input, const SizeValueType offset) const
  {
    InternalType * truePixel = (&output) + offset * m_OffsetMultiplier;
 
    // A well-formed caller passes a source of length 0 (sentinel / no-op)
    // or exactly m_VectorLength. Anything else is a caller bug that was
    // silently masked by the pre-1d87efa5 allocation behavior; catch it
    // in debug builds.
    itkAssertInDebugAndIgnoreInReleaseMacro(input.GetSize() == 0 || input.GetSize() == m_VectorLength);
 
    const VectorLengthType copyLength = std::min<VectorLengthType>(m_VectorLength, input.GetSize());
 
    for (VectorLengthType i = 0; i < copyLength; ++i)
    {
      truePixel[i] = input[i];
    }
  }

  [[nodiscard]] inline ExternalType
  Get(const InternalType & input, const SizeValueType offset) const
  {
    // Do not create a local for this method, to use return value
    // optimization.
    return ExternalType((&input) + (offset * m_OffsetMultiplier), m_VectorLength);
  }

  void
  SetVectorLength(VectorLengthType l)
  {
    m_VectorLength = l;
    m_OffsetMultiplier = (l - 1);
  }

  [[nodiscard]] VectorLengthType
  GetVectorLength() const
  {
    return m_VectorLength;
  }
 
  DefaultVectorPixelAccessor() = default;

  DefaultVectorPixelAccessor(VectorLengthType l)
    : m_VectorLength(l)
    , m_OffsetMultiplier(l - 1)
  {}
 
  ~DefaultVectorPixelAccessor() = default;
 
private:
  VectorLengthType m_VectorLength{ 0 };
  VectorLengthType m_OffsetMultiplier{ 0 };
};
} // end namespace itk
 
#endif