SincCoeffs.h

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// -*- lsst-c++ -*-
/*
 * LSST Data Management System
 * Copyright 2008-2014 LSST Corporation.
 *
 * This product includes software developed by the
 * LSST Project (http://www.lsst.org/).
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
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 * GNU General Public License for more details.
 *
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#ifndef LSST_MEAS_BASE_SincCoeffs_h_INCLUDED
#define LSST_MEAS_BASE_SincCoeffs_h_INCLUDED

#include <map>

#include "lsst/afw/image/Image.h"
#include "lsst/afw/geom/ellipses/Axes.h"

namespace lsst { namespace meas { namespace base {

template<typename PixelT>
class SincCoeffs {
public:

    typedef afw::image::Image<PixelT> CoeffT;

    static void cache(float rInner, float rOuter);

    static PTR(CoeffT const)
    get(afw::geom::ellipses::Axes const & outerEllipse, float const innerRadiusFactor=0.0);

    static PTR(CoeffT)
    calculate(afw::geom::ellipses::Axes const& outerEllipse, double const innerFactor=0.0);

private:

    // A comparison function that doesn't require equality closer than machine epsilon
    template <typename T>
    struct FuzzyCompare {
        bool operator()(T x, T y) const {
            if (isEqual(x, y)) {
                return false;
            }
            return (x - y < 0) ? true : false;
        }
        bool isEqual(T x, T y) const {
            return ::fabs(x - y) < std::numeric_limits<T>::epsilon();
        }
    };

    typedef std::map<float, PTR(CoeffT), FuzzyCompare<float> > CoeffMap;
    typedef std::map<float, CoeffMap, FuzzyCompare<float> > CoeffMapMap;
    SincCoeffs() : _cache() {};
    SincCoeffs(SincCoeffs const&); // unimplemented: singleton
    void operator=(SincCoeffs const&); // unimplemented: singleton

    static SincCoeffs& getInstance();

    /*
     * Search the cache for coefficients for an aperture
     *
     * If the coefficients are not cached, a null shared_ptr will be returned.
     */
    PTR(CoeffT const)
    _lookup(afw::geom::ellipses::Axes const & outerEllipse, double const innerRadiusFactor=0.0) const;

    CoeffMapMap _cache;                 //< Cache of coefficients
};

}}} // namespace lsst::meas::base

#endif // !LSST_MEAS_BASE_SincCoeffs_h_INCLUDED