Skip to content
This repository
Fetching contributors…

Octocat-spinner-32-eaf2f5

Cannot retrieve contributors at this time

file 326 lines (272 sloc) 8.399 kb
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325
/*****************************************************************************
*
* This file is part of Mapnik (c++ mapping toolkit)
*
* Copyright (C) 2006 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
*
*****************************************************************************/

//$Id$

// mapnik
#include <mapnik/proj_transform.hpp>
#include <mapnik/coord.hpp>
#include <mapnik/utils.hpp>

// proj4
#include <proj_api.h>

// stl
#include <vector>

static const float MAXEXTENT = 20037508.34;
static const float M_PI_by2 = M_PI / 2;
static const float D2R = M_PI / 180;
static const float R2D = 180 / M_PI;
static const float M_PIby360 = M_PI / 360;
static const float MAXEXTENTby180 = MAXEXTENT/180;

namespace mapnik {
    
proj_transform::proj_transform(projection const& source,
                               projection const& dest)
    : source_(source),
      dest_(dest)
{
    is_source_longlat_ = source_.is_geographic();
    is_dest_longlat_ = dest_.is_geographic();
    is_source_equal_dest_ = (source_ == dest_);
    if (source.params() == "+init=epsg:3857" && dest.params() == "+init=epsg:4326")
    {
        wgs84_to_merc_ = true;
    }
    else
    {
        wgs84_to_merc_ = false;
    }
}

bool proj_transform::equal() const
{
    return is_source_equal_dest_;
}


bool proj_transform::forward (double & x, double & y , double & z) const
{
    return forward(&x, &y, &z, 1);
}

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

    if (is_source_equal_dest_)
        return true;

    if (wgs84_to_merc_) {
        int i;
        for(i=0; i<point_count; i++) {
            x[i] = (x[i] / MAXEXTENT) * 180;
            y[i] = (y[i] / MAXEXTENT) * 180;
            y[i] = R2D * (2 * atan(exp(y[i] * D2R)) - M_PI_by2);
            if (x[i] > 180) x[i] = 180;
            if (x[i] < -180) x[i] = -180;
            if (y[i] > 85.0511) y[i] = 85.0511;
            if (y[i] < -85.0511) y[i] = -85.0511;
        }
        return true;
    }
    
        if (is_source_longlat_)
    {
        int i;
        for(i=0; i<point_count; i++) {
            x[i] *= DEG_TO_RAD;
            y[i] *= DEG_TO_RAD;
        }
    }

    do {
#if defined(MAPNIK_THREADSAFE) && PJ_VERSION < 480
        mutex::scoped_lock lock(projection::mutex_);
#endif
        if (pj_transform( source_.proj_, dest_.proj_, point_count,
                          0, x,y,z) != 0)
        {
            return false;
        }
    } while(false);

    if (is_dest_longlat_)
    {
        int i;
        for(i=0; i<point_count; i++) {
            x[i] *= RAD_TO_DEG;
            y[i] *= RAD_TO_DEG;
        }
    }

    return true;
}

bool proj_transform::backward (double * x, double * y , double * z, int point_count) const
{
    if (is_source_equal_dest_)
        return true;

    if (wgs84_to_merc_) {
        int i;
        for(i=0; i<point_count; i++) {
            x[i] = x[i] * MAXEXTENTby180;
            y[i] = log(tan((90 + y[i]) * M_PIby360)) / D2R;
            y[i] = y[i] * MAXEXTENTby180;
            if (x[i] > MAXEXTENT) x[i] = MAXEXTENT;
            if (x[i] < -MAXEXTENT) x[i] = -MAXEXTENT;
            if (y[i] > MAXEXTENT) y[i] = MAXEXTENT;
            if (y[i] < -MAXEXTENT) y[i] = -MAXEXTENT;
        }
        return true;
    }

    if (is_dest_longlat_)
    {
        int i;
        for(i=0; i<point_count; i++) {
            x[i] *= DEG_TO_RAD;
            y[i] *= DEG_TO_RAD;
        }
    }

    do {
#if defined(MAPNIK_THREADSAFE) && PJ_VERSION < 480
        mutex::scoped_lock lock(projection::mutex_);
#endif

        if (pj_transform( dest_.proj_, source_.proj_, point_count,
                          0, x,y,z) != 0)
        {
            return false;
        }
    } while(false);

    if (is_source_longlat_)
    {
        int i;
        for(i=0; i<point_count; i++) {
            x[i] *= RAD_TO_DEG;
            y[i] *= RAD_TO_DEG;
        }
    }

    return true;
}

bool proj_transform::backward (double & x, double & y , double & z) const
{
    return backward(&x, &y, &z, 1);
}


bool proj_transform::forward (box2d<double> & box) const
{
    if (is_source_equal_dest_)
        return true;

    double minx = box.minx();
    double miny = box.miny();
    double maxx = box.maxx();
    double maxy = box.maxy();
    double z = 0.0;
    if (!forward(minx,miny,z))
        return false;
    if (!forward(maxx,maxy,z))
        return false;
    box.init(minx,miny,maxx,maxy);
    return true;
}

bool proj_transform::backward (box2d<double> & box) const
{
    if (is_source_equal_dest_)
        return true;

    double minx = box.minx();
    double miny = box.miny();
    double maxx = box.maxx();
    double maxy = box.maxy();
    double z = 0.0;
    if (!backward(minx,miny,z))
        return false;
    if (!backward(maxx,maxy,z))
        return false;
    box.init(minx,miny,maxx,maxy);
    return true;
}

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>(ceil((points - 4) / 4.0));
    }
    
    steps += 1;
    double xstep = width / steps;
    double ystep = height / steps;
    
    for (int i=0; i<=steps; i++) {
        coords.push_back(coord<double,2>(env.minx() + i * xstep, env.miny()));
        coords.push_back(coord<double,2>(env.minx() + i * xstep, env.maxy()));

    }
    for (int i=1; i<steps; i++) {
        coords.push_back(coord<double,2>(env.minx(), env.miny() + i * ystep));
        coords.push_back(coord<double,2>(env.maxx(), env.miny() + i * ystep));
    }
}

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;
    
    std::vector<coord<double,2> > coords;
    envelope_points(coords, env, points);
    
    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);
    
    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;
    
    std::vector<coord<double,2> > coords;
    envelope_points(coords, env, points);
    
    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);
    
    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_;
}
 
}
Something went wrong with that request. Please try again.