itkImageReverseConstIterator.h

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/*=========================================================================

  Program:   Insight Segmentation & Registration Toolkit
  Module:    $RCSfile: itkImageReverseConstIterator.h,v $
  Language:  C++
  Date:      $Date: 2003/09/10 14:29:12 $
  Version:   $Revision: 1.4 $

  Copyright (c) Insight Software Consortium. All rights reserved.
  See ITKCopyright.txt or http://www.itk.org/HTML/Copyright.htm for details.

     This software is distributed WITHOUT ANY WARRANTY; without even 
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR 
     PURPOSE.  See the above copyright notices for more information.

=========================================================================*/
#ifndef __itkImageReverseConstIterator_h
#define __itkImageReverseConstIterator_h

#include "itkIndex.h"
#include "itkSize.h"
#include "itkImage.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::IndexValueType   IndexValueType;
    
  typedef typename TImage::SizeType         SizeType;
  typedef typename TImage::SizeValueType    SizeValueType;
  
  typedef typename TImage::OffsetType       OffsetType;
  typedef typename TImage::OffsetValueType  OffsetValueType;
  
  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;

  ImageReverseConstIterator()
    :m_PixelAccessor()
  {
    m_Buffer = 0;
    m_Offset = 0;
    m_BeginOffset = 0;
    m_EndOffset = 0;
  }

  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;
  }

  ImageReverseConstIterator(ImageType *ptr,
                const RegionType &region)
  {
    unsigned long 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();
  }
  
  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();
  }

  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;
    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();
    
    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);
    };
  
#if 0

  bool
  operator<=(const Self &it) const
    {
    // an iterator is "less than" another if it "points to" a lower
    // memory location
    return (m_Buffer + m_Offset) <= (it.m_Buffer + it.m_Offset);
    };

  bool
  operator<(const Self &it) const
    {
    // an iterator is "less than" another if it "points to" a lower
    // memory location
    return (m_Buffer + m_Offset) < (it.m_Buffer + it.m_Offset);
    };

  bool
  operator>=(const Self &it) const
    {
    // an iterator is "greater than" another if it "points to" a higher
    // memory location
    return (m_Buffer + m_Offset) >= (it.m_Buffer + it.m_Offset);
    };

  bool
  operator>(const Self &it) const
    {
    // an iterator is "greater than" another if it "points to" a higher
    // memory location
    return (m_Buffer + m_Offset) > (it.m_Buffer + it.m_Offset);
    };
#endif

  
  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_PixelAccessor.Get(*(m_Buffer+m_Offset)); }
  
  void Set( const PixelType & value) const  
    { m_PixelAccessor.Set(*(m_Buffer+m_Offset),value); }

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

  Self Begin() const;

  void GoToBegin()
    {
    m_Offset = m_BeginOffset;
    };

  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::ConstPointer    m_Image;
  RegionType                          m_Region;      // region to iterate over
  
  unsigned long  m_Offset;
  unsigned long  m_BeginOffset; // offset to last pixel in region
  unsigned long  m_EndOffset;   // offset to one pixel before first pixel

  const InternalPixelType        *m_Buffer;

  AccessorType                    m_PixelAccessor;
};

} // end namespace itk

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

#endif 

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