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/*========================================================================= |
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Program: Insight Segmentation & Registration Toolkit |
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Module: $RCSfile: itkLineConstIterator.txx.html,v $ |
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Language: C++ |
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Date: $Date: 2006/01/17 19:15:41 $ |
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Version: $Revision: 1.4 $ |
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Copyright (c) Insight Software Consortium. All rights reserved. |
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See ITKCopyright.txt or http://www.itk.org/HTML/Copyright.htm for details. |
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This software is distributed WITHOUT ANY WARRANTY; without even |
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the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR |
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PURPOSE. See the above copyright notices for more information. |
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=========================================================================*/ |
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DEF |
#ifndef _itkLineConstIterator_txx |
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DEF |
#define _itkLineConstIterator_txx |
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#include "itkLineConstIterator.h" |
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namespace itk |
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{ |
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template<class TImage> |
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LineConstIterator<TImage> |
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::LineConstIterator(const ImageType *imagePtr, const IndexType &firstIndex, const IndexType &lastIndex) |
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{ |
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unsigned int i; |
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m_Image = imagePtr; |
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m_StartIndex = firstIndex; |
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m_LastIndex = lastIndex; |
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IndexType difference; |
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for (i = 0; i < TImage::ImageDimension; ++i) |
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{ |
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difference[i] = lastIndex[i] - firstIndex[i]; |
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} |
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IndexValueType maxDistance = 0; |
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int maxDistanceDimension = 0; |
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for (i = 0; i < TImage::ImageDimension; ++i) |
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{ |
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IndexValueType distance = abs(difference[i]); |
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if (distance > maxDistance) |
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{ |
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maxDistance = distance; |
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maxDistanceDimension = i; |
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} |
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m_IncrementError[i] = 2*distance; |
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m_OverflowIncrement[i] = (difference[i] < 0 ? -1 : 1); |
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} |
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m_MainDirection = maxDistanceDimension; |
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m_MaximalError.Fill(maxDistance); |
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m_ReduceErrorAfterIncrement.Fill(2*maxDistance); |
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// Need to set m_EndIndex to be one pixel past the m_LastIndex along |
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// the bresenham line. THis is tricky to |
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// do. m_EndIndex[m_MainDirection] is always offset by one from the |
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// m_LastIndex[m_MainDirection]. The other indices may or may not |
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// be incremented depending on the accumulated error to that point. |
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// |
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// To avoid traversing the line to determine whether the other |
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// components need to be adjusted, we merely set the main direction |
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// to be incremented and keep the remaining indices to be same as |
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// LastIndex. THen in the test for IsAtEnd, we just check the |
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// MainDirection component of the index. |
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for (i = 0; i < TImage::ImageDimension; ++i) |
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{ |
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if (i == m_MainDirection) |
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{ |
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m_EndIndex[i] = m_LastIndex[i] + m_OverflowIncrement[i]; |
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} |
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else |
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{ |
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m_EndIndex[i] = m_LastIndex[i]; |
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} |
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} |
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m_Region = m_Image->GetBufferedRegion(); |
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this->GoToBegin(); |
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} |
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template<class TImage> |
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LineConstIterator<TImage> & |
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LineConstIterator<TImage> |
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::operator=(const Self & it) |
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{ |
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m_Image = it.m_Image; // copy the smart pointer |
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m_Region = it.m_Region; |
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m_IsAtEnd = it.m_IsAtEnd; |
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m_CurrentImageIndex = it.m_CurrentImageIndex; |
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m_StartIndex = it.m_StartIndex; |
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m_LastIndex = it.m_LastIndex; |
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m_EndIndex = it.m_EndIndex; |
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m_MainDirection = it.m_MainDirection; |
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m_AccumulateError = it.m_AccumulateError; |
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m_IncrementError = it.m_IncrementError; |
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m_MaximalError = it.m_MaximalError; |
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m_OverflowIncrement = it.m_OverflowIncrement; |
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m_ReduceErrorAfterIncrement = it.m_ReduceErrorAfterIncrement; |
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return *this; |
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} |
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template<class TImage> |
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void |
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LineConstIterator<TImage> |
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::GoToBegin() |
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{ |
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m_CurrentImageIndex = m_StartIndex; |
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m_AccumulateError.Fill(0); |
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m_IsAtEnd = (m_StartIndex[m_MainDirection] == m_EndIndex[m_MainDirection]); |
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} |
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template<class TImage> |
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void |
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LineConstIterator<TImage> |
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::operator++() |
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{ |
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// We need to modify m_AccumulateError, m_CurrentImageIndex, m_IsAtEnd |
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for (unsigned int i = 0; i < TImage::ImageDimension; ++i) |
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{ |
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if (i == m_MainDirection) |
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{ |
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m_CurrentImageIndex[i] += m_OverflowIncrement[i]; |
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} |
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else |
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{ |
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m_AccumulateError[i] += m_IncrementError[i]; |
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if (m_AccumulateError[i] >= m_MaximalError[i]) |
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{ |
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m_CurrentImageIndex[i] += m_OverflowIncrement[i]; |
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m_AccumulateError[i] -= m_ReduceErrorAfterIncrement[i]; |
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} |
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} |
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} |
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if (m_CurrentImageIndex[m_MainDirection] == m_EndIndex[m_MainDirection]) |
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{ |
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m_IsAtEnd = true; |
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} |
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else if( ! m_Region.IsInside( m_CurrentImageIndex ) ) |
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{ |
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// The new index is outside the acceptable region. We can iterate no |
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// farther, call this the end. NOTE THAT INPUT IS STILL INCREMENTED. |
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m_IsAtEnd = true; |
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itkWarningMacro(<<"Line left region; unable to finish tracing it"); |
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} |
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} |
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} // end namespace itk |
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#endif |
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