mapnik/include/mapnik/transform_path_adapter.hpp
2021-01-05 14:39:07 +00:00

132 lines
3.3 KiB
C++

/*****************************************************************************
*
* This file is part of Mapnik (c++ mapping toolkit)
*
* Copyright (C) 2021 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_TRANSFORM_PATH_ADAPTER_HPP
#define MAPNIK_TRANSFORM_PATH_ADAPTER_HPP
#include <mapnik/proj_transform.hpp>
#include <mapnik/vertex.hpp>
#include <mapnik/config.hpp>
#include <cstddef>
namespace mapnik {
template <typename Transform, typename Geometry>
struct transform_path_adapter
{
// SFINAE value_type detector
template <typename T>
struct void_type
{
using type = void;
};
template <typename T, typename D, typename _ = void>
struct select_value_type
{
using type = D;
};
template <typename T, typename D>
struct select_value_type<T, D, typename void_type<typename T::value_type>::type>
{
using type = typename T::value_type;
};
using size_type = std::size_t;
using value_type = typename select_value_type<Geometry, void>::type;
transform_path_adapter(Transform const& _t,
Geometry & _geom,
proj_transform const& prj_trans)
: t_(&_t),
geom_(_geom),
prj_trans_(&prj_trans) {}
explicit transform_path_adapter(Geometry & _geom)
: t_(0),
geom_(_geom),
prj_trans_(0) {}
void set_proj_trans(proj_transform const& prj_trans)
{
prj_trans_ = &prj_trans;
}
void set_trans(Transform const& t)
{
t_ = &t;
}
unsigned vertex(double *x, double *y) const
{
unsigned command;
bool ok = false;
bool skipped_points = false;
while (!ok)
{
command = geom_.vertex(x,y);
if (command == SEG_END || command == SEG_CLOSE)
{
return command;
}
double z=0;
ok = prj_trans_->backward(*x, *y, z);
if (!ok) {
skipped_points = true;
}
}
if (skipped_points && (command == SEG_LINETO))
{
command = SEG_MOVETO;
}
t_->forward(x,y);
return command;
}
void rewind(unsigned pos) const
{
geom_.rewind(pos);
}
unsigned type() const
{
return static_cast<unsigned>(geom_.type());
}
Geometry const& geom() const
{
return geom_;
}
private:
Transform const* t_;
Geometry & geom_;
proj_transform const* prj_trans_;
};
}
#endif // MAPNIK_TRANSFORM_PATH_ADAPTER_HPP