itkLineConstIterator.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 itkLineConstIterator_h
#define itkLineConstIterator_h
 
#include "itkIndex.h"
#include "itkImage.h"
 
namespace itk
{
template <typename TImage>
class ITK_TEMPLATE_EXPORT LineConstIterator
{
public:

  using Self = LineConstIterator;

  static constexpr unsigned int ImageIteratorDimension = TImage::ImageDimension;

  using IndexType = typename TImage::IndexType;

  using OffsetType = typename TImage::OffsetType;

  using SizeType = typename TImage::SizeType;

  using RegionType = typename TImage::RegionType;

  using SpacingType = typename TImage::SpacingType;

  using PointType = typename TImage::PointType;

  using ImageType = TImage;

  using PixelContainer = typename TImage::PixelContainer;
  using PixelContainerPointer = typename PixelContainer::Pointer;

  using InternalPixelType = typename TImage::InternalPixelType;

  using PixelType = typename TImage::PixelType;

  using AccessorType = typename TImage::AccessorType;

  itkVirtualGetNameOfClassMacro(LineConstIterator);

  static unsigned int
  GetImageIteratorDimension()
  {
    return TImage::ImageDimension;
  }

  const IndexType
  GetIndex()
  {
    return m_CurrentImageIndex;
  }

  const PixelType
  Get() const
  {
    return m_Image->GetPixel(m_CurrentImageIndex);
  }

  bool
  IsAtEnd() const
  {
    return m_IsAtEnd;
  }

  void
  GoToBegin();

  void
  operator++();

  Self &
  operator=(const Self & it);

  LineConstIterator(const ImageType * imagePtr, const IndexType & firstIndex, const IndexType & lastIndex);

  virtual ~LineConstIterator() = default;
 
protected: // made protected so other iterators can access
  typename ImageType::ConstWeakPointer m_Image{};

  RegionType m_Region{};

  bool m_IsAtEnd{};

  IndexType m_CurrentImageIndex{};
  IndexType m_StartIndex{};
  IndexType m_LastIndex{};
  IndexType m_EndIndex{}; // one past the end of the line in the m_MainDirection

  // The dimension with the largest difference between start and end
  unsigned int m_MainDirection{};
 
  // Accumulated error for the other dimensions
  IndexType m_AccumulateError{};
 
  // Increment for the error for each step. Two times the difference between
  // start and end
  IndexType m_IncrementError{};
 
  // If enough is accumulated for a dimension, the index has to be
  // incremented. Will be the number of pixels in the line
  IndexType m_MaximalError{};
 
  // Direction of increment. -1 or 1
  IndexType m_OverflowIncrement{};
 
  // After an overflow, the accumulated error is reduced again. Will be
  // two times the number of pixels in the line
  IndexType m_ReduceErrorAfterIncrement{};
};
} // end namespace itk
 
#ifndef ITK_MANUAL_INSTANTIATION
#  include "itkLineConstIterator.hxx"
#endif
 
#endif