ImageUtils.h

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// -*- lsst-c++ -*-

/* 
 * LSST Data Management System
 * Copyright 2008, 2009, 2010 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
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the LSST License Statement and 
 * the GNU General Public License along with this program.  If not, 
 * see <http://www.lsstcorp.org/LegalNotices/>.
 */
 
#ifndef LSST_AFW_IMAGE_IMAGEUTILS_H
#define LSST_AFW_IMAGE_IMAGEUTILS_H

#include <cmath>

namespace lsst {
namespace afw {
namespace image {
    enum xOrY {X, Y};

    const double PixelZeroPos = 0.0;    

    inline double indexToPosition(
        double ind 
    ) {
        return ind + PixelZeroPos;
    }
    
    inline int positionToIndex(
        double pos 
    ) {
        return static_cast<int>(std::floor(pos + 0.5 - PixelZeroPos));
    }
    
    inline int positionToIndex(
        double &residual, 
        double pos 
    ) {
        double fullIndex = pos - PixelZeroPos;
        double roundedIndex = std::floor(fullIndex + 0.5);
        residual = fullIndex - roundedIndex;
        return static_cast<int>(roundedIndex);
    }     
    inline std::pair<int, double> positionToIndex(double const pos,                
                                                  bool                             
    ) {
        double residual;                // fractional part of index
        int const ind = positionToIndex(residual, pos); // integral part

        return std::pair<int, double>(ind, residual);
    }     

}}} // lsst::afw::image

#endif // LSST_AFW_IMAGE_IMAGEUTILS_H