/*****************************************************************************

*

* This file is part of Mapnik (c++ mapping toolkit)

*

* Copyright (C) 2014 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

*

*****************************************************************************/

// mapnik

#include <mapnik/global.hpp>

#include <mapnik/box2d.hpp>

#include <mapnik/projection.hpp>

#include <mapnik/proj_transform.hpp>

#include <mapnik/coord.hpp>

#ifdef MAPNIK_USE_PROJ4

// proj4

#include <proj_api.h>

#endif

// stl

#include <vector>

#include <stdexcept>

namespace mapnik {

proj_transform::proj_transform(projection const& source,

projection const& dest)

: source_(source),

dest_(dest),

is_source_longlat_(false),

is_dest_longlat_(false),

is_source_equal_dest_(false),

wgs84_to_merc_(false),

merc_to_wgs84_(false)

{

is_source_equal_dest_ = (source_ == dest_);

if (!is_source_equal_dest_)

{

is_source_longlat_ = source_.is_geographic();

is_dest_longlat_ = dest_.is_geographic();

boost::optional<well_known_srs_e> src_k = source.well_known();

boost::optional<well_known_srs_e> dest_k = dest.well_known();

bool known_trans = false;

if (src_k && dest_k)

{

if (*src_k == WGS_84 && *dest_k == G_MERC)

{

wgs84_to_merc_ = true;

known_trans = true;

}

else if (*src_k == G_MERC && *dest_k == WGS_84)

{

merc_to_wgs84_ = true;

known_trans = true;

}

}

if (!known_trans)

{

#ifdef MAPNIK_USE_PROJ4

source_.init_proj4();

dest_.init_proj4();

#else

throw std::runtime_error(std::string("Cannot initialize proj_transform for given projections without proj4 support (-DMAPNIK_USE_PROJ4): '") + source_.params() + "'->'" + dest_.params() + "'");

#endif

}

}

}

bool proj_transform::equal() const

{

return is_source_equal_dest_;

}

bool proj_transform::is_known() const

{

return merc_to_wgs84_ || wgs84_to_merc_;

}

bool proj_transform::forward (double & x, double & y , double & z) const

{

return forward(&x, &y, &z, 1);

}

bool proj_transform::forward (geometry::point<double> & p) const

{

double z = 0;

return forward(&(p.x), &(p.y), &z, 1);

}

unsigned int proj_transform::forward (geometry::line_string<double> & ls) const

{

std::size_t size = ls.size();

if (size == 0) return 0;

if (is_source_equal_dest_)

return 0;

if (wgs84_to_merc_)

{

lonlat2merc(ls);

return 0;

}

else if (merc_to_wgs84_)

{

merc2lonlat(ls);

return 0;

}

geometry::point<double> * ptr = ls.data();

double * x = reinterpret_cast<double*>(ptr);

double * y = x + 1;

double * z = NULL;

if(!forward(x, y, z, size, 2))

{

return size;

}

return 0;

}

bool proj_transform::forward (double * x, double * y , double * z, int point_count, int offset) const

{

if (is_source_equal_dest_)

return true;

if (wgs84_to_merc_)

{

return lonlat2merc(x,y,point_count);

}

else if (merc_to_wgs84_)

{

return merc2lonlat(x,y,point_count);

}

#ifdef MAPNIK_USE_PROJ4

if (is_source_longlat_)

{

int i;

for(i=0; i<point_count; i++) {

x[i*offset] *= DEG_TO_RAD;

y[i*offset] *= DEG_TO_RAD;

}

}

if (pj_transform( source_.proj_, dest_.proj_, point_count,

offset, x,y,z) != 0)

{

return false;

}

if (is_dest_longlat_)

{

int i;

for(i=0; i<point_count; i++) {

x[i*offset] *= RAD_TO_DEG;

y[i*offset] *= RAD_TO_DEG;

}

}

#endif

return true;

}

bool proj_transform::backward (double * x, double * y , double * z, int point_count, int offset) const

{

if (is_source_equal_dest_)

return true;

if (wgs84_to_merc_)

{

return merc2lonlat(x,y,point_count);

}

else if (merc_to_wgs84_)

{

return lonlat2merc(x,y,point_count);

}

#ifdef MAPNIK_USE_PROJ4

if (is_dest_longlat_)

{

int i;

for(i=0; i<point_count; i++) {

x[i*offset] *= DEG_TO_RAD;

y[i*offset] *= DEG_TO_RAD;

}

}

if (pj_transform( dest_.proj_, source_.proj_, point_count,

offset, x,y,z) != 0)

{

return false;

}

if (is_source_longlat_)

{

int i;

for(i=0; i<point_count; i++) {

x[i*offset] *= RAD_TO_DEG;

y[i*offset] *= RAD_TO_DEG;

}

}

#endif

return true;

}

bool proj_transform::backward (double & x, double & y , double & z) const

{

return backward(&x, &y, &z, 1);

}

bool proj_transform::backward (geometry::point<double> & p) const

{

double z = 0;

return backward(&(p.x), &(p.y), &z, 1);

}

unsigned int proj_transform::backward (geometry::line_string<double> & ls) const

{

std::size_t size = ls.size();

if (size == 0) return 0;

if (is_source_equal_dest_)

return 0;

if (wgs84_to_merc_)

{

merc2lonlat(ls);

return 0;

}

else if (merc_to_wgs84_)

{

lonlat2merc(ls);

return 0;

}

geometry::point<double> * ptr = ls.data();

double * x = reinterpret_cast<double*>(ptr);

double * y = x + 1;

double * z = NULL;

if(!backward(x, y, z, size, 2))

{

return size;

}

return 0;

}

bool proj_transform::forward (box2d<double> & box) const

{

if (is_source_equal_dest_)

return true;

double llx = box.minx();

double ulx = box.minx();

double lly = box.miny();

double lry = box.miny();

double lrx = box.maxx();

double urx = box.maxx();

double uly = box.maxy();

double ury = box.maxy();

double z = 0.0;

if (!forward(llx,lly,z))

return false;

if (!forward(lrx,lry,z))

return false;

if (!forward(ulx,uly,z))

return false;

if (!forward(urx,ury,z))

return false;

double minx = std::min(ulx, llx);

double miny = std::min(lly, lry);

double maxx = std::max(urx, lrx);

double maxy = std::max(ury, uly);

box.init(minx,

miny,

maxx,

maxy);

return true;

}

bool proj_transform::backward (box2d<double> & box) const

{

if (is_source_equal_dest_)

return true;

double llx = box.minx();

double ulx = box.minx();

double lly = box.miny();

double lry = box.miny();

double lrx = box.maxx();

double urx = box.maxx();

double uly = box.maxy();

double ury = box.maxy();

double z = 0.0;

if (!backward(llx,lly,z))

return false;

if (!backward(lrx,lry,z))

return false;

if (!backward(ulx,uly,z))

return false;

if (!backward(urx,ury,z))

return false;

double minx = std::min(ulx, llx);

double miny = std::min(lly, lry);

double maxx = std::max(urx, lrx);

double maxy = std::max(ury, uly);

box.init(minx,

miny,

maxx,

maxy);

return true;

}

// Returns points in clockwise order. This allows us to do anti-meridian checks.

void envelope_points(std::vector< coord<double,2> > & coords, box2d<double>& env, int points)

{

double width = env.width();

double height = env.height();

int steps;

if (points <= 4) {

steps = 0;

} else {

steps = static_cast<int>(std::ceil((points - 4) / 4.0));

}

steps += 1;

double xstep = width / steps;

double ystep = height / steps;

coords.resize(points);

for (int i=0; i<steps; i++) {

// top: left>right

coords[i] = coord<double, 2>(env.minx() + i * xstep, env.maxy());

// right: top>bottom

coords[i + steps] = coord<double, 2>(env.maxx(), env.maxy() - i * ystep);

// bottom: right>left

coords[i + steps * 2] = coord<double, 2>(env.maxx() - i * xstep, env.miny());

// left: bottom>top

coords[i + steps * 3] = coord<double, 2>(env.minx(), env.miny() + i * ystep);

}

}

// determine if an ordered sequence of coordinates is in clockwise order

bool is_clockwise(const std::vector< coord<double,2> > & coords)

{

int n = coords.size();

coord<double,2> c1, c2;

double a = 0.0;

for (int i=0; i<n; i++) {

c1 = coords[i];

c2 = coords[(i + 1) % n];

a += (c1.x * c2.y - c2.x * c1.y);

}

return a <= 0.0;

}

box2d<double> calculate_bbox(std::vector<coord<double,2> > & points) {

std::vector<coord<double,2> >::iterator it = points.begin();

std::vector<coord<double,2> >::iterator it_end = points.end();

box2d<double> env(*it, *(++it));

for (; it!=it_end; ++it) {

env.expand_to_include(*it);

}

return env;

}

// More robust, but expensive, bbox transform

// in the face of proj4 out of bounds conditions.

// Can result in 20 -> 10 r/s performance hit.

// Alternative is to provide proper clipping box

// in the target srs by setting map 'maximum-extent'

bool proj_transform::backward(box2d<double>& env, int points) const

{

if (is_source_equal_dest_)

return true;

if (wgs84_to_merc_ || merc_to_wgs84_)

{

return backward(env);

}

std::vector<coord<double,2> > coords;

envelope_points(coords, env, points); // this is always clockwise

double z;

for (std::vector<coord<double,2> >::iterator it = coords.begin(); it!=coords.end(); ++it) {

z = 0;

if (!backward(it->x, it->y, z)) {

return false;

}

}

box2d<double> result = calculate_bbox(coords);

if (is_source_longlat_ && !is_clockwise(coords))

{

// we've gone to a geographic CS, and our clockwise envelope has

// changed into an anticlockwise one. This means we've crossed the antimeridian, and

// need to expand the X direction to +/-180 to include all the data. Once we can deal

// with multiple bboxes in queries we can improve.

double miny = result.miny();

result.expand_to_include(-180.0, miny);

result.expand_to_include(180.0, miny);

}

env.re_center(result.center().x, result.center().y);

env.height(result.height());

env.width(result.width());

return true;

}

bool proj_transform::forward(box2d<double>& env, int points) const

{

if (is_source_equal_dest_)

return true;

if (wgs84_to_merc_ || merc_to_wgs84_)

{

return forward(env);

}

std::vector<coord<double,2> > coords;

envelope_points(coords, env, points); // this is always clockwise

double z;

for (std::vector<coord<double,2> >::iterator it = coords.begin(); it!=coords.end(); ++it) {

z = 0;

if (!forward(it->x, it->y, z)) {

return false;

}

}

box2d<double> result = calculate_bbox(coords);

if (is_dest_longlat_ && !is_clockwise(coords))

{

// we've gone to a geographic CS, and our clockwise envelope has

// changed into an anticlockwise one. This means we've crossed the antimeridian, and

// need to expand the X direction to +/-180 to include all the data. Once we can deal

// with multiple bboxes in queries we can improve.

double miny = result.miny();

result.expand_to_include(-180.0, miny);

result.expand_to_include(180.0, miny);

}

env.re_center(result.center().x, result.center().y);

env.height(result.height());

env.width(result.width());

return true;

}

mapnik::projection const& proj_transform::source() const

{

return source_;

}

mapnik::projection const& proj_transform::dest() const

{

return dest_;

}

}