254 lines
6.2 KiB
C++
254 lines
6.2 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) 2006 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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//$Id$
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// mapnik
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#include <mapnik/proj_transform.hpp>
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#include <mapnik/coord.hpp>
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#include <mapnik/utils.hpp>
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// proj4
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#include <proj_api.h>
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// stl
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#include <vector>
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namespace mapnik {
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proj_transform::proj_transform(projection const& source,
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projection const& dest)
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: source_(source),
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dest_(dest)
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{
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is_source_longlat_ = source_.is_geographic();
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is_dest_longlat_ = dest_.is_geographic();
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is_source_equal_dest_ = (source_ == dest_);
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}
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bool proj_transform::equal() const
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{
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return is_source_equal_dest_;
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}
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bool proj_transform::forward (double & x, double & y , double & z) const
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{
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if (is_source_equal_dest_)
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return true;
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if (is_source_longlat_)
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{
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x *= DEG_TO_RAD;
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y *= DEG_TO_RAD;
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}
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#if defined(MAPNIK_THREADSAFE) && PJ_VERSION < 480
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mutex::scoped_lock lock(projection::mutex_);
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#endif
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if (pj_transform( source_.proj_, dest_.proj_, 1,
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0, &x,&y,&z) != 0)
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{
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return false;
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}
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if (is_dest_longlat_)
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{
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x *= RAD_TO_DEG;
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y *= RAD_TO_DEG;
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}
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return true;
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}
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bool proj_transform::backward (double & x, double & y , double & z) const
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{
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if (is_source_equal_dest_)
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return true;
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if (is_dest_longlat_)
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{
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x *= DEG_TO_RAD;
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y *= DEG_TO_RAD;
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}
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#if defined(MAPNIK_THREADSAFE) && PJ_VERSION < 480
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mutex::scoped_lock lock(projection::mutex_);
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#endif
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if (pj_transform( dest_.proj_, source_.proj_, 1,
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0, &x,&y,&z) != 0)
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{
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return false;
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}
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if (is_source_longlat_)
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{
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x *= RAD_TO_DEG;
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y *= RAD_TO_DEG;
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}
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return true;
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}
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bool proj_transform::forward (box2d<double> & box) const
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{
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if (is_source_equal_dest_)
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return true;
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double minx = box.minx();
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double miny = box.miny();
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double maxx = box.maxx();
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double maxy = box.maxy();
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double z = 0.0;
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if (!forward(minx,miny,z))
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return false;
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if (!forward(maxx,maxy,z))
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return false;
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box.init(minx,miny,maxx,maxy);
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return true;
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}
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bool proj_transform::backward (box2d<double> & box) const
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{
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if (is_source_equal_dest_)
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return true;
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double minx = box.minx();
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double miny = box.miny();
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double maxx = box.maxx();
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double maxy = box.maxy();
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double z = 0.0;
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if (!backward(minx,miny,z))
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return false;
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if (!backward(maxx,maxy,z))
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return false;
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box.init(minx,miny,maxx,maxy);
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return true;
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}
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void envelope_points(std::vector< coord<double,2> > & coords, box2d<double>& env, int points)
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{
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double width = env.width();
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double height = env.height();
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int steps;
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if (points <= 4) {
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steps = 0;
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} else {
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steps = static_cast<int>(ceil((points - 4) / 4.0));
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}
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steps += 1;
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double xstep = width / steps;
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double ystep = height / steps;
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for (int i=0; i<=steps; i++) {
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coords.push_back(coord<double,2>(env.minx() + i * xstep, env.miny()));
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coords.push_back(coord<double,2>(env.minx() + i * xstep, env.maxy()));
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}
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for (int i=1; i<steps; i++) {
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coords.push_back(coord<double,2>(env.minx(), env.miny() + i * ystep));
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coords.push_back(coord<double,2>(env.maxx(), env.miny() + i * ystep));
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}
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}
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box2d<double> calculate_bbox(std::vector<coord<double,2> > & points) {
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std::vector<coord<double,2> >::iterator it = points.begin();
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std::vector<coord<double,2> >::iterator it_end = points.end();
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box2d<double> env(*it, *(++it));
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for (; it!=it_end; ++it) {
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env.expand_to_include(*it);
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}
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return env;
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}
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/* More robust, but expensive, bbox transform
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* in the face of proj4 out of bounds conditions.
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* Can result in 20 -> 10 r/s performance hit.
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* Alternative is to provide proper clipping box
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* in the target srs by setting map 'maximum-extent'
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*/
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bool proj_transform::backward(box2d<double>& env, int points) const
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{
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if (is_source_equal_dest_)
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return true;
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std::vector<coord<double,2> > coords;
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envelope_points(coords, env, points);
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double z;
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for (std::vector<coord<double,2> >::iterator it = coords.begin(); it!=coords.end(); ++it) {
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z = 0;
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if (!backward(it->x, it->y, z)) {
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return false;
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}
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}
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box2d<double> result = calculate_bbox(coords);
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env.re_center(result.center().x, result.center().y);
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env.height(result.height());
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env.width(result.width());
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return true;
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}
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bool proj_transform::forward(box2d<double>& env, int points) const
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{
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if (is_source_equal_dest_)
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return true;
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std::vector<coord<double,2> > coords;
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envelope_points(coords, env, points);
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double z;
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for (std::vector<coord<double,2> >::iterator it = coords.begin(); it!=coords.end(); ++it) {
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z = 0;
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if (!forward(it->x, it->y, z)) {
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return false;
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}
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}
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box2d<double> result = calculate_bbox(coords);
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env.re_center(result.center().x, result.center().y);
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env.height(result.height());
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env.width(result.width());
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return true;
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}
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mapnik::projection const& proj_transform::source() const
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{
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return source_;
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}
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mapnik::projection const& proj_transform::dest() const
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{
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return dest_;
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}
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}
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