itkCacheableScalarFunction.h

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

  Program:   Insight Segmentation & Registration Toolkit
  Module:    $RCSfile: itkCacheableScalarFunction.h,v $
  Language:  C++
  Date:      $Date: 2003/09/10 14:29:36 $
  Version:   $Revision: 1.8 $

  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 __itkCacheableScalarFunction_h
#define __itkCacheableScalarFunction_h

#include "itkArray.h"
#include "itkExceptionObject.h"

namespace itk {
class CacheableScalarFunction
{
public:
  CacheableScalarFunction() ;

  virtual ~CacheableScalarFunction() {}

  typedef double MeasureType ;
  typedef Array<MeasureType>    MeasureArrayType;

  long GetNumberOfSamples() { return m_NumberOfSamples ; } 

  bool IsCacheAvailable() { return m_CacheAvailable ; } 
  
  double GetCacheUpperBound() { return m_CacheUpperBound ; } 

  double GetCacheLowerBound() { return m_CacheLowerBound ; } 

  virtual MeasureType Evaluate(MeasureType x) 
  { return x ; }

  double GetInterval() 
  { return m_TableInc ; }

  inline MeasureType GetCachedValue(MeasureType x)
  {
    if (x > m_CacheUpperBound || x < m_CacheLowerBound)
      {
      throw ExceptionObject(__FILE__,__LINE__);
      }
    // access table
    int index = (int) ((x - m_CacheLowerBound) / m_TableInc) ;
    return m_CacheTable[index] ;
  }

protected:
  void CreateCache(double lowerBound, double upperBound, long sampleSize) ;

private:
  long m_NumberOfSamples ;

  MeasureArrayType  m_CacheTable;

  double m_CacheUpperBound;

  double m_CacheLowerBound ;

  double m_TableInc ;

  bool m_CacheAvailable ;
  
} ; // end of class
} // end of namespace itk
#endif

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