/usr/include/mapnik/polygon_clipper.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_POLYGON_CLIPPER_HPP
#define MAPNIK_POLYGON_CLIPPER_HPP
// stl
#include <iostream>
#include <deque>
// mapnik
#include <mapnik/box2d.hpp>
#include <mapnik/geometry.hpp>
// boost
#include <boost/foreach.hpp>
#include <boost/tuple/tuple.hpp>
#include <boost/geometry.hpp>
#include <boost/geometry/geometries/point_xy.hpp>
#include <boost/geometry/geometries/box.hpp>
#include <boost/geometry/geometries/polygon.hpp>
#include <boost/geometry/geometries/register/point.hpp>
BOOST_GEOMETRY_REGISTER_POINT_2D(mapnik::coord2d, double, cs::cartesian, x, y)
// register mapnik::box2d<double>
namespace boost { namespace geometry { namespace traits
{
template<> struct tag<mapnik::box2d<double> > { typedef box_tag type; };
template<> struct point_type<mapnik::box2d<double> > { typedef mapnik::coord2d type; };
template <>
struct indexed_access<mapnik::box2d<double>, min_corner, 0>
{
typedef coordinate_type<mapnik::coord2d>::type ct;
static inline ct get(mapnik::box2d<double> const& b) { return b.minx();}
static inline void set(mapnik::box2d<double> &b, ct const& value) { b.set_minx(value); }
};
template <>
struct indexed_access<mapnik::box2d<double>, min_corner, 1>
{
typedef coordinate_type<mapnik::coord2d>::type ct;
static inline ct get(mapnik::box2d<double> const& b) { return b.miny();}
static inline void set(mapnik::box2d<double> &b, ct const& value) { b.set_miny(value); }
};
template <>
struct indexed_access<mapnik::box2d<double>, max_corner, 0>
{
typedef coordinate_type<mapnik::coord2d>::type ct;
static inline ct get(mapnik::box2d<double> const& b) { return b.maxx();}
static inline void set(mapnik::box2d<double> &b, ct const& value) { b.set_maxx(value); }
};
template <>
struct indexed_access<mapnik::box2d<double>, max_corner, 1>
{
typedef coordinate_type<mapnik::coord2d>::type ct;
static inline ct get(mapnik::box2d<double> const& b) { return b.maxy();}
static inline void set(mapnik::box2d<double> &b , ct const& value) { b.set_maxy(value); }
};
}}}
namespace mapnik {
using namespace boost::geometry;
template <typename Geometry>
struct polygon_clipper
{
typedef mapnik::coord2d point_2d;
typedef model::polygon<mapnik::coord2d> polygon_2d;
typedef std::deque<polygon_2d> polygon_list;
polygon_clipper(Geometry & geom)
: clip_box_(),
geom_(geom)
{
}
polygon_clipper( box2d<double> const& clip_box,Geometry & geom)
: clip_box_(clip_box),
geom_(geom)
{
init();
}
void set_clip_box(box2d<double> const& clip_box)
{
clip_box_ = clip_box;
init();
}
unsigned type() const
{
return geom_.type();
}
void rewind(unsigned path_id)
{
output_.rewind(path_id);
}
unsigned vertex (double * x, double * y)
{
return output_.vertex(x,y);
}
private:
void init()
{
polygon_2d subject_poly;
double x,y;
double prev_x, prev_y;
geom_.rewind(0);
unsigned ring_count = 0;
while (true)
{
unsigned cmd = geom_.vertex(&x,&y);
if (cmd == SEG_END) break;
if (cmd == SEG_MOVETO)
{
prev_x = x;
prev_y = y;
if (ring_count == 0)
{
append(subject_poly, make<point_2d>(x,y));
}
else
{
subject_poly.inners().push_back(polygon_2d::inner_container_type::value_type());
append(subject_poly.inners().back(),make<point_2d>(x,y));
}
++ring_count;
}
else if (cmd == SEG_LINETO)
{
if (std::abs(x - prev_x) < 1e-12 && std::abs(y - prev_y) < 1e-12)
{
std::cerr << std::setprecision(12) << "coincident vertices:(" << prev_x << ","
<< prev_y << ") , (" << x << "," << y << ")" << std::endl;
continue;
}
prev_x = x;
prev_x = y;
if (ring_count == 1)
{
append(subject_poly, make<point_2d>(x,y));
}
else
{
append(subject_poly.inners().back(),make<point_2d>(x,y));
}
}
}
polygon_list clipped_polygons;
try
{
boost::geometry::intersection(clip_box_, subject_poly, clipped_polygons);
}
catch (boost::geometry::exception const& ex)
{
std::cerr << ex.what() << std::endl;
}
BOOST_FOREACH(polygon_2d const& poly, clipped_polygons)
{
bool move_to = true;
BOOST_FOREACH(point_2d const& c, boost::geometry::exterior_ring(poly))
{
if (move_to)
{
move_to = false;
output_.move_to(c.x,c.y);
}
else
{
output_.line_to(c.x,c.y);
}
}
output_.close_path();
// interior rings
BOOST_FOREACH(polygon_2d::inner_container_type::value_type const& ring, boost::geometry::interior_rings(poly))
{
move_to = true;
BOOST_FOREACH(point_2d const& c, ring)
{
if (move_to)
{
move_to = false;
output_.move_to(c.x,c.y);
}
else
{
output_.line_to(c.x,c.y);
}
}
output_.close_path();
}
}
}
box2d<double> clip_box_;
Geometry & geom_;
mapnik::geometry_type output_;
};
}
#endif //MAPNIK_POLYGON_CLIPPER_HPP
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