40 lines
1.3 KiB
C++
40 lines
1.3 KiB
C++
/*****************************************************************************
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*
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* This file is part of Mapnik (c++ mapping toolkit)
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*
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* Copyright (C) 2015 Artem Pavlenko
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*
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*****************************************************************************/
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// mapnik
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#include <mapnik/scale_denominator.hpp>
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#include <mapnik/global.hpp>
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// stl
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#include <cmath>
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namespace mapnik {
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static const double meters_per_degree = 6378137 * 2 * M_PI / 360;
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double scale_denominator(double map_scale, bool geographic)
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{
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double denom = map_scale / 0.00028;
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if (geographic) denom *= meters_per_degree;
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return denom;
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}
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}
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