cvrDistanceType.h

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/*
 * Copyright (C) 1998-2004
 * Lehrstuhl fuer Technische Informatik, RWTH-Aachen, Germany
 *
 *
 * This file is part of the Computer Vision and Robotics Library (CVR-Lib)
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/**
 * \file   cvrDistanceType.h
 *         This file contains the class distanceType<T> which specifies three
 *         types that are recommended for the result of a distance calculation
 *         between two instances of T. The three types are:
 *         - \c distance_type is used when a simple distance is calculated
 *           between two instances of T which does not involve accumulation of
 *           squares or typical floating point operations.
 *         - \c square_distance_type is used for the result of distances
 *           that involve the square of the type T.
 *         - \c fp_distance_type is used for distances that involve floating
 *           point operations such as the sqrt or log functions.
 * \author Peter Doerfler
 * \date   11.05.2003
 * $Id: cvrDistanceType.h,v 1.3 2007/04/18 21:13:40 alvarado Exp $
 */

#ifndef _CVR_DISTANCE_TYPE_H_
#define _CVR_DISTANCE_TYPE_H_

#include "cvrObject.h"
#include "cvrTypeInfo.h"

namespace cvr {

  /**
   * This class defines the appropriate return types when calculating
   * the distance between two values of type T. These can be simple
   * types like \c int or \c double or \c lti types like \c vector<T>,
   * rgbaPixel, etc. There are three different distance types:
   * - \c distance_type is used when a simple distance is calculated
   *   between two instances of T which does not involve accumulation of
   *   squares or typical floating point operations.
   * - \c square_distance_type is used for the result of distances
   *   that involve the square of the type T.
   * - \c fp_distance_type is used for distances that involve floating
   *   point operations such as the sqrt or log functions.
   *
   * @ingroup gTypes
   */
  template<class T>
  class distanceType {
  public:
    /**
     * Suggested distance type for distances that use simple
     * accumulation of type elements (for example l1Distantor).
     */
    typedef typename distanceType<typename T::value_type>::distance_type
    distance_type;

    /**
     * Suggested distance type for distances that use
     * accumulation of squares of type elements (for example l2SqrDistantor).
     */
    typedef typename distanceType<typename T::value_type>::square_distance_type
    square_distance_type;

    /**
     * Suggested distance type for distances that use accumulation of
     * type elements or their squares and use a typical floating point (fp)
     * operation like sqrt or log on that. (for example l2Distantor).
     */
    typedef typename distanceType<typename T::value_type>::fp_distance_type
    fp_distance_type;

  private:
    /**
     * Disable constructor of instances of this class
     */
    distanceType() {};
  };

  // ------------------------
  // template specializations
  // ------------------------

  template<>
  class distanceType<ubyte> {
  public:
    typedef typeInfo<ubyte>::accumulation_type distance_type;
    typedef typeInfo<ubyte>::square_accumulation_type square_distance_type;
    typedef float fp_distance_type;
  private:
    distanceType() {};
  };

  template<>
  class distanceType<byte> {
  public:
    typedef typeInfo<byte>::accumulation_type distance_type;
    typedef typeInfo<byte>::square_accumulation_type square_distance_type;
    typedef float fp_distance_type;
  private:
    distanceType() {};
  };

  template<>
  class distanceType<short int> {
  public:
    typedef typeInfo<short int>::accumulation_type distance_type;
    typedef typeInfo<short int>::square_accumulation_type square_distance_type;
    typedef float fp_distance_type;
  private:
    distanceType() {};
  };

  template<>
  class distanceType<unsigned short int> {
  public:
    typedef typeInfo<unsigned short int>::accumulation_type distance_type;
    typedef typeInfo<unsigned short int>::square_accumulation_type
    square_distance_type;
    typedef float fp_distance_type;
  private:
    distanceType() {};
  };

  template<>
  class distanceType<int> {
  public:
    typedef typeInfo<int>::accumulation_type distance_type;
    typedef typeInfo<int>::square_accumulation_type square_distance_type;
    typedef double fp_distance_type;
  private:
    distanceType() {};
  };

  template<>
  class distanceType<unsigned int> {
  public:
    typedef typeInfo<unsigned int>::accumulation_type distance_type;
    typedef typeInfo<unsigned int>::square_accumulation_type square_distance_type;
    typedef double fp_distance_type;
  private:
    distanceType() {};
  };

  template<>
  class distanceType<float> {
  public:
    typedef typeInfo<float>::accumulation_type distance_type;
    typedef typeInfo<float>::square_accumulation_type square_distance_type;
    typedef double fp_distance_type;
  private:
    distanceType() {};
  };

  template<>
  class distanceType<double> {
  public:
    typedef typeInfo<double>::accumulation_type distance_type;
    typedef typeInfo<double>::square_accumulation_type square_distance_type;
    typedef double fp_distance_type;
  private:
    distanceType() {};
  };

}


#endif