itkImageReverseConstIterator.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 itkImageReverseConstIterator_h
#define itkImageReverseConstIterator_h
 
#include "itkSize.h"
#include "itkImageConstIterator.h"
#include <memory>
#include <type_traits> // For remove_const_t.
 
namespace itk
{
template <typename TImage>
class ITK_TEMPLATE_EXPORT ImageReverseConstIterator
{
public:
  using Self = ImageReverseConstIterator;

  static constexpr unsigned int ImageIteratorDimension = TImage::ImageDimension;

  itkVirtualGetNameOfClassMacro(ImageReverseConstIterator);

  using IndexType = typename TImage::IndexType;

  using SizeType = typename TImage::SizeType;

  using OffsetType = typename TImage::OffsetType;

  using RegionType = typename TImage::RegionType;

  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;

  using AccessorFunctorType = typename TImage::AccessorFunctorType;

  ImageReverseConstIterator()
    : m_Buffer(0)
    , m_PixelAccessor()
    , m_PixelAccessorFunctor()
  {
    m_PixelAccessorFunctor.SetBegin(m_Buffer);
  }

  virtual ~ImageReverseConstIterator() = default;

  ImageReverseConstIterator(const Self & it)
    : m_Image(it.m_Image)
    , m_Region(it.m_Region)
    , m_Offset(it.m_Offset)
    , m_BeginOffset(it.m_BeginOffset)
    , m_EndOffset(it.m_EndOffset)
    , m_Buffer(it.m_Buffer)
    , m_PixelAccessor(it.m_PixelAccessor)
    , m_PixelAccessorFunctor(it.m_PixelAccessorFunctor)
  {
    // copy the smart pointer
 
 
    m_PixelAccessorFunctor.SetBegin(m_Buffer);
  }

  ImageReverseConstIterator(const TImage * ptr, const RegionType & region)
    : m_Image(ptr)
    , m_Region(region)
    , m_Buffer(m_Image->GetBufferPointer())
  {
 
 
    // Compute the end offset, one pixel before the first pixel
    SizeValueType offset = m_Image->ComputeOffset(m_Region.GetIndex());
    m_EndOffset = offset - 1;
 
    // Compute the begin offset, the last pixel in the region
    IndexType ind(m_Region.GetIndex());
    SizeType  size(m_Region.GetSize());
    for (unsigned int i = 0; i < TImage::ImageDimension; ++i)
    {
      ind[i] += (size[i] - 1);
    }
    m_BeginOffset = m_Image->ComputeOffset(ind);
    m_Offset = m_BeginOffset;
 
    m_PixelAccessor = ptr->GetPixelAccessor();
    m_PixelAccessorFunctor.SetPixelAccessor(m_PixelAccessor);
    m_PixelAccessorFunctor.SetBegin(m_Buffer);
  }

  ImageReverseConstIterator(const ImageConstIterator<TImage> & it)
    : m_Image(it.GetImage())
    , m_Region(it.GetRegion())
    , m_EndOffset(m_Image->ComputeOffset(m_Region.GetIndex()) - 1)
    , m_Buffer(m_Image->GetBufferPointer())
  {
 
 
    const IndexType ind = it.ComputeIndex();
 
    m_Offset = m_Image->ComputeOffset(ind);
 
    // Compute the end offset, one pixel before the first pixel
 
 
    // Compute the begin offset, the last pixel in the region
    IndexType regInd(m_Region.GetIndex());
    SizeType  regSize(m_Region.GetSize());
    for (unsigned int i = 0; i < TImage::ImageDimension; ++i)
    {
      regInd[i] += (regSize[i] - 1);
    }
    m_BeginOffset = m_Image->ComputeOffset(regInd);
 
    m_PixelAccessor = m_Image->GetPixelAccessor();
    m_PixelAccessorFunctor.SetPixelAccessor(m_PixelAccessor);
    m_PixelAccessorFunctor.SetBegin(m_Buffer);
  }

  Self &
  operator=(const Self & it)
  {
    if (this != &it)
    {
      m_Image = it.m_Image; // copy the smart pointer
      m_Region = it.m_Region;
 
      m_Buffer = it.m_Buffer;
      m_Offset = it.m_Offset;
      m_BeginOffset = it.m_BeginOffset;
      m_EndOffset = it.m_EndOffset;
      m_PixelAccessor = it.m_PixelAccessor;
      m_PixelAccessorFunctor.SetPixelAccessor(m_PixelAccessor);
      m_PixelAccessorFunctor.SetBegin(m_Buffer);
    }
    return *this;
  }

  Self &
  operator=(const ImageConstIterator<TImage> & it)
  {
    m_Image = it.GetImage();
    m_Region = it.GetRegion();
    m_Buffer = m_Image->GetBufferPointer();
 
    IndexType ind = it.GetIndex();
 
    m_Offset = m_Image->ComputeOffset(ind);
 
    // Compute the end offset, one pixel before the first pixel
    m_EndOffset = m_Image->ComputeOffset(m_Region.GetIndex()) - 1;
 
    // Compute the begin offset, the last pixel in the region
    IndexType regInd(m_Region.GetIndex());
    SizeType  regSize(m_Region.GetSize());
    for (unsigned int i = 0; i < TImage::ImageDimension; ++i)
    {
      regInd[i] += (regSize[i] - 1);
    }
    m_BeginOffset = m_Image->ComputeOffset(regInd);
 
    m_PixelAccessor = m_Image->GetPixelAccessor();
    m_PixelAccessorFunctor.SetPixelAccessor(m_PixelAccessor);
    m_PixelAccessorFunctor.SetBegin(m_Buffer);
    return *this;
  }

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

  bool
  operator==(const Self & it) const
  {
    // two iterators are the same if they "point to" the same memory location
    return (m_Buffer + m_Offset) == (it.m_Buffer + it.m_Offset);
  }
 
  ITK_UNEQUAL_OPERATOR_MEMBER_FUNCTION(Self);
 

  const IndexType
  GetIndex()
  {
    return m_Image->ComputeIndex(m_Offset);
  }

  virtual void
  SetIndex(const IndexType & ind)
  {
    m_Offset = m_Image->ComputeOffset(ind);
  }

  [[nodiscard]] const RegionType &
  GetRegion() const
  {
    return m_Region;
  }

  [[nodiscard]] const PixelType
  Get() const
  {
    return m_PixelAccessorFunctor.Get(*(m_Buffer + m_Offset));
  }

  void
  Set(const PixelType & value) const
  {
    this->m_PixelAccessorFunctor.Set(*(const_cast<InternalPixelType *>(this->m_Buffer + this->m_Offset)), value);
  }

  [[nodiscard]] const PixelType &
  Value() const
  {
    return *(m_Buffer + m_Offset);
  }

  const PixelType &
  Value()
  {
    return *(m_Buffer + m_Offset);
  }

  void
  GoToBegin()
  {
    m_Offset = m_BeginOffset;
  }

  void
  GoToEnd()
  {
    m_Offset = m_EndOffset;
  }

  [[nodiscard]] bool
  IsAtBegin() const
  {
    return m_Offset == m_BeginOffset;
  }

  [[nodiscard]] bool
  IsAtEnd() const
  {
    return m_Offset == m_EndOffset;
  }
 
protected: // made protected so other iterators can access
  typename ImageType::ConstWeakPointer m_Image{};
 
  RegionType m_Region{}; // region to iterate over
 
  SizeValueType m_Offset{};
  SizeValueType m_BeginOffset{}; // offset to last pixel in region
  SizeValueType m_EndOffset{};   // offset to one pixel before first pixel
 
  const InternalPixelType * m_Buffer{};
 
  AccessorType        m_PixelAccessor{};
  AccessorFunctorType m_PixelAccessorFunctor{};
};
 
// Deduction guide for class template argument deduction (CTAD).
template <typename TImage>
ImageReverseConstIterator(SmartPointer<TImage>, const typename TImage::RegionType &)
  -> ImageReverseConstIterator<std::remove_const_t<TImage>>;
 
} // end namespace itk
 
#endif