/usr/include/mapnik/well_known_srs.hpp is in libmapnik-dev 2.2.0+ds1-6build2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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*
* This file is part of Mapnik (c++ mapping toolkit)
*
* Copyright (C) 2013 Artem Pavlenko
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
*****************************************************************************/
#ifndef MAPNIK_WELL_KNOWN_SRS_HPP
#define MAPNIK_WELL_KNOWN_SRS_HPP
// mapnik
#include <mapnik/global.hpp> // for M_PI on windows
#include <mapnik/enumeration.hpp>
// boost
#include <boost/optional.hpp>
// stl
#include <cmath>
namespace mapnik {
enum well_known_srs_enum {
WGS_84,
G_MERC,
well_known_srs_enum_MAX
};
DEFINE_ENUM( well_known_srs_e, well_known_srs_enum );
static const double EARTH_RADIUS = 6378137.0;
static const double EARTH_DIAMETER = EARTH_RADIUS * 2.0;
static const double EARTH_CIRCUMFERENCE = EARTH_DIAMETER * M_PI;
static const double MAXEXTENT = EARTH_CIRCUMFERENCE / 2.0;
static const double M_PI_by2 = M_PI / 2;
static const double D2R = M_PI / 180;
static const double R2D = 180 / M_PI;
static const double M_PIby360 = M_PI / 360;
static const double MAXEXTENTby180 = MAXEXTENT / 180;
static const double MAX_LATITUDE = R2D * (2 * std::atan(std::exp(180 * D2R)) - M_PI_by2);
static const std::string MAPNIK_LONGLAT_PROJ = "+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs";
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";
boost::optional<well_known_srs_e> is_well_known_srs(std::string const& srs);
boost::optional<bool> is_known_geographic(std::string const& srs);
static inline bool lonlat2merc(double * x, double * y , int point_count)
{
for(int i=0; i<point_count; i++) {
if (x[i] > 180) x[i] = 180;
else if (x[i] < -180) x[i] = -180;
if (y[i] > MAX_LATITUDE) y[i] = MAX_LATITUDE;
else if (y[i] < -MAX_LATITUDE) y[i] = -MAX_LATITUDE;
x[i] = x[i] * MAXEXTENTby180;
y[i] = std::log(std::tan((90 + y[i]) * M_PIby360)) * R2D;
y[i] = y[i] * MAXEXTENTby180;
}
return true;
}
static inline bool merc2lonlat(double * x, double * y , int point_count)
{
for(int i=0; i<point_count; i++)
{
if (x[i] > MAXEXTENT) x[i] = MAXEXTENT;
else if (x[i] < -MAXEXTENT) x[i] = -MAXEXTENT;
if (y[i] > MAXEXTENT) y[i] = MAXEXTENT;
else if (y[i] < -MAXEXTENT) y[i] = -MAXEXTENT;
x[i] = (x[i] / MAXEXTENT) * 180;
y[i] = (y[i] / MAXEXTENT) * 180;
y[i] = R2D * (2 * std::atan(std::exp(y[i] * D2R)) - M_PI_by2);
}
return true;
}
}
#endif // MAPNIK_WELL_KNOWN_SRS_HPP
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