itkImageRegionConstIterator.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 itkImageRegionConstIterator_h
#define itkImageRegionConstIterator_h
 
#include "itkImageIterator.h"
#include <type_traits> // For remove_const_t.
 
namespace itk
{
template <typename TImage>
class ITK_TEMPLATE_EXPORT ImageRegionConstIterator : public ImageConstIterator<TImage>
{
public:
  using Self = ImageRegionConstIterator;
  using Superclass = ImageConstIterator<TImage>;

  static constexpr unsigned int ImageIteratorDimension = Superclass::ImageIteratorDimension;


  using typename Superclass::IndexType;
  using typename Superclass::SizeType;
  using typename Superclass::OffsetType;
  using typename Superclass::RegionType;
  using typename Superclass::ImageType;
  using typename Superclass::PixelContainer;
  using typename Superclass::PixelContainerPointer;
  using typename Superclass::InternalPixelType;
  using typename Superclass::PixelType;
  using typename Superclass::AccessorType;

  itkOverrideGetNameOfClassMacro(ImageRegionConstIterator);

  ImageRegionConstIterator()
    : ImageConstIterator<TImage>()
  {}

  ImageRegionConstIterator(const TImage * ptr, const RegionType & region)
    : ImageConstIterator<TImage>(ptr, region)
    , m_SpanBeginOffset(this->m_BeginOffset)
    , m_SpanEndOffset(this->m_BeginOffset + static_cast<OffsetValueType>(this->m_Region.GetSize()[0]))
  {}

  ImageRegionConstIterator(const ImageIterator<TImage> & it)
  {
    this->ImageConstIterator<TImage>::operator=(it);
 
    IndexType ind = this->GetIndex();
    m_SpanEndOffset = this->m_Offset + static_cast<OffsetValueType>(this->m_Region.GetSize()[0]) -
                      (ind[0] - this->m_Region.GetIndex()[0]);
    m_SpanBeginOffset = m_SpanEndOffset - static_cast<OffsetValueType>(this->m_Region.GetSize()[0]);
  }

  ImageRegionConstIterator(const ImageConstIterator<TImage> & it)
  {
    this->ImageConstIterator<TImage>::operator=(it);
 
    IndexType ind = this->GetIndex();
    m_SpanEndOffset = this->m_Offset + static_cast<OffsetValueType>(this->m_Region.GetSize()[0]) -
                      (ind[0] - this->m_Region.GetIndex()[0]);
    m_SpanBeginOffset = m_SpanEndOffset - static_cast<OffsetValueType>(this->m_Region.GetSize()[0]);
  }

  void
  GoToBegin()
  {
    Superclass::GoToBegin();
 
    // reset the span offsets
    m_SpanBeginOffset = this->m_BeginOffset;
    m_SpanEndOffset = this->m_BeginOffset + static_cast<OffsetValueType>(this->m_Region.GetSize()[0]);
  }

  void
  GoToEnd()
  {
    Superclass::GoToEnd();
 
    // reset the span offsets
    m_SpanEndOffset = this->m_EndOffset;
    m_SpanBeginOffset = m_SpanEndOffset - static_cast<OffsetValueType>(this->m_Region.GetSize()[0]);
  }

  void
  SetIndex(const IndexType & ind) override
  {
    Superclass::SetIndex(ind);
    m_SpanEndOffset = this->m_Offset + static_cast<OffsetValueType>(this->m_Region.GetSize()[0]) -
                      (ind[0] - this->m_Region.GetIndex()[0]);
    m_SpanBeginOffset = m_SpanEndOffset - static_cast<OffsetValueType>(this->m_Region.GetSize()[0]);
  }

  Self &
  operator++()
  {
    if (++this->m_Offset >= m_SpanEndOffset)
    {
      this->Increment();
    }
    return *this;
  }

  Self &
  operator--()
  {
    if (--this->m_Offset < m_SpanBeginOffset)
    {
      this->Decrement();
    }
    return *this;
  }
 
protected:
  OffsetValueType m_SpanBeginOffset{}; // one pixel before the beginning of the span
                                       // (row)
  OffsetValueType m_SpanEndOffset{};   // one pixel past the end of the span (row)
 
private:
  void
  Increment(); // advance in a direction other than the fastest moving
 
  void
  Decrement(); // go back in a direction other than the fastest moving
};
 
// Deduction guide for class template argument deduction (CTAD).
template <typename TImage>
ImageRegionConstIterator(SmartPointer<TImage>, const typename TImage::RegionType &)
  -> ImageRegionConstIterator<std::remove_const_t<TImage>>;
 
} // end namespace itk
 
#ifndef ITK_MANUAL_INSTANTIATION
#  include "itkImageRegionConstIterator.hxx"
#endif
 
#endif