itkLineConstIterator.h

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

  Program:   Insight Segmentation & Registration Toolkit
  Module:    $RCSfile: itkLineConstIterator.h,v $
  Language:  C++
  Date:      $Date: 2005/07/18 12:14:36 $
  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 __itkLineConstIterator_h
#define __itkLineConstIterator_h

#include "itkIndex.h"
#include "itkImage.h"

namespace itk
{

template<class TImage>
class ITK_EXPORT LineConstIterator
{
public:
  typedef LineConstIterator Self;

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

  typedef typename TImage::IndexType          IndexType;
  typedef typename TImage::IndexValueType     IndexValueType;

  typedef typename TImage::OffsetType         OffsetType;
  typedef typename TImage::OffsetValueType    OffsetValueType;

  typedef typename TImage::SizeType           SizeType;
  typedef typename TImage::SizeValueType      SizeValueType;

  typedef typename TImage::RegionType         RegionType;

  typedef typename TImage::SpacingType        SpacingType;

  typedef typename TImage::PointType          PointType;
  
  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;

  itkTypeMacro(LineConstIterator, None);
  
  static unsigned int GetImageIteratorDimension() 
    {
    return TImage::ImageDimension;
    }

  const IndexType GetIndex()
    {
    return m_CurrentImageIndex;
    }

  const PixelType & Get(void) const
    {
    return m_Image->GetPixel(m_CurrentImageIndex );
    }
 
  bool IsAtEnd()
    {
    return m_IsAtEnd;
    }
  
  void GoToBegin();

  void operator++();

  Self &operator=(const Self& it);

  LineConstIterator(const ImageType *imagePtr, const IndexType &firstIndex, const IndexType &lastIndex);

  virtual ~LineConstIterator() {};


protected: //made protected so other iterators can access 
  typename ImageType::ConstWeakPointer m_Image;

  RegionType m_Region;

  bool m_IsAtEnd;

  IndexType m_CurrentImageIndex;
  IndexType m_StartIndex;
  IndexType m_LastIndex;
  IndexType m_EndIndex;  // one past the end of the line in the m_MainDirection

  // The dimension with the largest difference between start and end
  unsigned int m_MainDirection; 

  // Accumulated error for the other dimensions
  IndexType m_AccumulateError;

  // Increment for the error for each step. Two times the difference between
  // start and end
  IndexType m_IncrementError;

  // If enough is accumulated for a dimension, the index has to be
  // incremented. Will be the number of pixels in the line
  IndexType m_MaximalError; 

  // Direction of increment. -1 or 1
  IndexType m_OverflowIncrement; 

  // After an overflow, the accumulated error is reduced again. Will be
  // two times the number of pixels in the line
  IndexType m_ReduceErrorAfterIncrement; 
};

} // end namespace itk

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

#endif 

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