itkImageReverseConstIterator.h

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 *
 *  Copyright Insight Software Consortium
 *
 *  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
 *
 *         http://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>

namespace itk
{
template< typename TImage >
class ITK_EXPORT ImageReverseConstIterator
{
public:
  typedef ImageReverseConstIterator Self;

  itkStaticConstMacro(ImageIteratorDimension, unsigned int,
                      TImage::ImageDimension);

  typedef typename TImage::IndexType      IndexType;

  typedef typename TImage::SizeType      SizeType;

  typedef typename TImage::OffsetType      OffsetType;

  typedef typename TImage::RegionType RegionType;

  typedef TImage ImageType;

  typedef typename TImage::PixelContainer  PixelContainer;
  typedef typename PixelContainer::Pointer PixelContainerPointer;

  typedef typename TImage::InternalPixelType InternalPixelType;

  typedef typename TImage::PixelType PixelType;

  typedef typename TImage::AccessorType AccessorType;

  typedef typename TImage::AccessorFunctorType AccessorFunctorType;

  ImageReverseConstIterator():m_PixelAccessor(), m_PixelAccessorFunctor()
  {
    m_Buffer = 0;
    m_Offset = 0;
    m_BeginOffset = 0;
    m_EndOffset = 0;
    m_PixelAccessorFunctor.SetBegin(m_Buffer);
  }

  virtual ~ImageReverseConstIterator() {}

  ImageReverseConstIterator(const Self & 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 = it.m_PixelAccessorFunctor;
    m_PixelAccessorFunctor.SetBegin(m_Buffer);
  }

  ImageReverseConstIterator(const ImageType *ptr, const RegionType & region)
  {
    SizeValueType offset;

    m_Image = ptr;
    m_Buffer = m_Image->GetBufferPointer();
    m_Region = region;

    // Compute the end offset, one pixel before the first pixel
    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_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);
  }

  Self & operator=(const Self & 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 );
  }

  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 );
  }

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

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

  const RegionType & GetRegion() const
  { return m_Region; }

  const PixelType Get(void) 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);
  }

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

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

  itkLegacyMacro(Self Begin() const);

  void GoToBegin()
  {
    m_Offset = m_BeginOffset;
  }

  itkLegacyMacro(Self End() const);

  void GoToEnd()
  {
    m_Offset = m_EndOffset;
  }

  bool IsAtBegin()
  {
    return ( m_Offset == m_BeginOffset );
  }

  bool IsAtEnd()
  {
    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;
};
} // end namespace itk

#ifndef ITK_MANUAL_INSTANTIATION
#include "itkImageReverseConstIterator.hxx"
#endif

#endif