itkCacheableScalarFunction.h

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/*=========================================================================
 *
 *  Copyright Insight Software Consortium
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *         http://www.apache.org/licenses/LICENSE-2.0.txt
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *=========================================================================*/
#ifndef __itkCacheableScalarFunction_h
#define __itkCacheableScalarFunction_h

#include "itkArray.h"
#include "itkIntTypes.h"

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

  virtual ~CacheableScalarFunction() {}

  typedef double               MeasureType;
  typedef Array< MeasureType > MeasureArrayType;

  SizeValueType 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, SizeValueType sampleSize);

private:
  SizeValueType m_NumberOfSamples;

  MeasureArrayType m_CacheTable;

  double m_CacheUpperBound;

  double m_CacheLowerBound;

  double m_TableInc;