146 lines
4.3 KiB
C++
146 lines
4.3 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) 2010 Hermann Kraus
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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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// Mapnik
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#include <mapnik/metawriter.hpp>
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#include <mapnik/metawriter_json.hpp>
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// Boost
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#include <boost/foreach.hpp>
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#include <boost/algorithm/string.hpp>
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// STL
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#include <iomanip>
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#include <cstdio>
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namespace mapnik {
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metawriter_json::metawriter_json(metawriter_properties dflt_properties, std::string fn)
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: metawriter(dflt_properties), fn_(fn), count(0)
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{
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}
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metawriter_json::~metawriter_json()
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{
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stop();
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}
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void metawriter_json::start()
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{
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if (f.is_open())
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{
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std::cerr << "ERROR: GeoJSON metawriter is already active!\n";
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}
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f.open(fn_.c_str(), std::fstream::out | std::fstream::trunc);
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if (f.fail()) perror((std::string("Failed to open file ") + fn_).c_str());
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f << "{ \"type\": \"FeatureCollection\", \"features\": [\n";
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}
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void metawriter_json::stop()
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{
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if (f.is_open())
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{
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f << " ] }\n";
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f.close();
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}
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}
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void metawriter_json::add_box(box2d<double> box, Feature const &feature,
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proj_transform const& prj_trans, CoordTransform const &t,
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const metawriter_properties& properties)
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{
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metawriter_properties props;
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if (properties.empty())
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{
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props = dflt_properties_;
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}
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else
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{
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props = properties;
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}
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if (props.empty())
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{
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std::cerr << "WARNING: No expression available for GeoJSON metawriter.\n";
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return;
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}
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/* Coordinate transform in renderer:
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input: layer srs
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prj_trans.backwards() [prj_trans: map -> layer]
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intermediate: map srs
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t_.forward()
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output: pixels
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Our transform:
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input: pixels
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t_.backward()
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intermediate: map srs (available via prj_trans.source())
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trans.forward()
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output: WGS84
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*/
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proj_transform trans(prj_trans.source(), projection("+proj=latlong +datum=WGS84"));
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//t_ coord transform has transform for box2d combined with prj_trans
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box = t.backward(box, trans);
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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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if (count++) f << ",\n";
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f << std::fixed << std::setprecision(8) << "{ \"type\": \"Feature\",\n \"geometry\": { \"type\": \"Polygon\",\n \"coordinates\": [ [ [" <<
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minx << ", " << miny << "], [" <<
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maxx << ", " << miny << "], [" <<
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maxx << ", " << maxy << "], [" <<
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minx << ", " << maxy << "] ] ] }," <<
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"\n \"properties\": {";
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std::map<std::string, value> fprops = feature.props();
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int i = 0;
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BOOST_FOREACH(std::string p, props)
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{
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std::map<std::string, value>::const_iterator itr = fprops.find(p);
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std::string text;
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if (itr != fprops.end())
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{
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//Property found
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text = boost::replace_all_copy(boost::replace_all_copy(itr->second.to_string(), "\\", "\\\\"), "\"", "\\\"");
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}
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if (i++) f << ",";
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f << "\n \"" << p << "\":\"" << text << "\"";
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}
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f << "\n} }";
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}
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metawriter_properties metawriter::parse_properties(boost::optional<std::string> str)
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{
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metawriter_properties properties;
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if (str) {
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std::string str_ = boost::algorithm::erase_all_copy(*str, " ");
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boost::split(properties, str_, boost::is_any_of(","), boost::token_compress_on);
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}
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return properties;
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}
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};
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