itkImageConstIterator.h

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

  Program:   Insight Segmentation & Registration Toolkit
  Module:    $RCSfile: itkImageConstIterator.h,v $
  Language:  C++
  Date:      $Date: 2003/09/10 14:29:10 $
  Version:   $Revision: 1.17 $

  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 __itkImageConstIterator_h
#define __itkImageConstIterator_h

#include "itkImage.h"
#include "itkIndex.h"
#include "itkSize.h"
#include "itkOffset.h"

namespace itk
{

template<typename TImage>
class ITK_EXPORT ImageConstIterator
{
public:
  typedef ImageConstIterator 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;

  ImageConstIterator()
    : m_Region(),
      m_PixelAccessor()
  {
    m_Image = 0;
    m_Buffer = 0;
    m_Offset = 0;
    m_BeginOffset = 0;
    m_EndOffset = 0;
  }

  virtual ~ImageConstIterator() {};

  ImageConstIterator(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;
  }

  ImageConstIterator( const ImageType *ptr,
                      const RegionType &region )
  {
    m_Image = ptr;
    m_Buffer = m_Image->GetBufferPointer();
    m_Region = region;

    // Compute the start offset
    m_Offset = m_Image->ComputeOffset( m_Region.GetIndex() );
    m_BeginOffset = m_Offset;
    
    // Compute the end offset. If any component of m_Region.GetSize()
    // is zero, the region is not valid and we set the EndOffset
    // to be same as BeginOffset so that iterator end condition is met
    // immediately.
    if (m_Region.GetNumberOfPixels() == 0)
      {
      // region is empty, probably has a size of 0 along one dimension
      m_EndOffset = m_BeginOffset;
      }
    else
      {
      IndexType ind(m_Region.GetIndex());
      SizeType size(m_Region.GetSize());
      for (unsigned int i=0; i < ImageIteratorDimension; ++i)
        {
        ind[i] += (static_cast<IndexValueType>(size[i]) - 1);
        }
      m_EndOffset = m_Image->ComputeOffset( ind );
      m_EndOffset++;
      }

    m_PixelAccessor = ptr->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;
  }
  
  static unsigned int GetImageIteratorDimension() 
    {return ImageIteratorDimension;}

  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);
    };
  
  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);
    };

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

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

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

  const ImageType * GetImage() const
    { return m_Image.GetPointer(); };

  PixelType Get(void) const  
    { return m_PixelAccessor.Get(*(m_Buffer+m_Offset)); }
  
  const PixelType & Value(void) const  
    { return *(m_Buffer+m_Offset); }
 
  Self Begin(void) const;

  void GoToBegin()
    {
    m_Offset = m_BeginOffset;
    };

  Self End(void) const;

  void GoToEnd()
    {
    m_Offset = m_EndOffset;
    };

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

  bool IsAtEnd(void) const
    {
    return (m_Offset == m_EndOffset);
    }
  

protected: //made protected so other iterators can access 
  SmartPointer<const ImageType>  m_Image;
  RegionType                     m_Region;      // region to iterate over
  
  unsigned long  m_Offset;
  unsigned long  m_BeginOffset; // offset to first pixel in region
  unsigned long  m_EndOffset;  // offset to one pixel past last pixel in region

  const InternalPixelType      * m_Buffer;

  AccessorType                   m_PixelAccessor;
};

} // end namespace itk

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

#endif 

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