94 lines
3.3 KiB
C++
94 lines
3.3 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) 2014 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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#ifndef MAPNIK_WELL_KNOWN_SRS_HPP
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#define MAPNIK_WELL_KNOWN_SRS_HPP
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// mapnik
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#include <mapnik/global.hpp> // for M_PI on windows
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#include <mapnik/enumeration.hpp>
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// boost
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#include <boost/optional.hpp>
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// stl
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#include <cmath>
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namespace mapnik {
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enum well_known_srs_enum : std::uint8_t {
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WGS_84,
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G_MERC,
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well_known_srs_enum_MAX
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};
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DEFINE_ENUM( well_known_srs_e, well_known_srs_enum );
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static const double EARTH_RADIUS = 6378137.0;
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static const double EARTH_DIAMETER = EARTH_RADIUS * 2.0;
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static const double EARTH_CIRCUMFERENCE = EARTH_DIAMETER * M_PI;
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static const double MAXEXTENT = EARTH_CIRCUMFERENCE / 2.0;
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static const double M_PI_by2 = M_PI / 2;
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static const double D2R = M_PI / 180;
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static const double R2D = 180 / M_PI;
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static const double M_PIby360 = M_PI / 360;
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static const double MAXEXTENTby180 = MAXEXTENT / 180;
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static const double MAX_LATITUDE = R2D * (2 * std::atan(std::exp(180 * D2R)) - M_PI_by2);
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static const std::string MAPNIK_LONGLAT_PROJ = "+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs";
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static const std::string MAPNIK_GMERC_PROJ = "+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0.0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs +over";
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boost::optional<well_known_srs_e> is_well_known_srs(std::string const& srs);
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boost::optional<bool> is_known_geographic(std::string const& srs);
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static inline bool lonlat2merc(double * x, double * y , int point_count)
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{
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for(int i=0; i<point_count; i++) {
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if (x[i] > 180) x[i] = 180;
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else if (x[i] < -180) x[i] = -180;
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if (y[i] > MAX_LATITUDE) y[i] = MAX_LATITUDE;
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else if (y[i] < -MAX_LATITUDE) y[i] = -MAX_LATITUDE;
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x[i] = x[i] * MAXEXTENTby180;
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y[i] = std::log(std::tan((90 + y[i]) * M_PIby360)) * R2D;
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y[i] = y[i] * MAXEXTENTby180;
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}
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return true;
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}
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static inline bool merc2lonlat(double * x, double * y , int point_count)
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{
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for(int i=0; i<point_count; i++)
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{
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if (x[i] > MAXEXTENT) x[i] = MAXEXTENT;
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else if (x[i] < -MAXEXTENT) x[i] = -MAXEXTENT;
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if (y[i] > MAXEXTENT) y[i] = MAXEXTENT;
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else if (y[i] < -MAXEXTENT) y[i] = -MAXEXTENT;
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x[i] = (x[i] / MAXEXTENT) * 180;
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y[i] = (y[i] / MAXEXTENT) * 180;
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y[i] = R2D * (2 * std::atan(std::exp(y[i] * D2R)) - M_PI_by2);
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}
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return true;
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}
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}
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#endif // MAPNIK_WELL_KNOWN_SRS_HPP
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