ceph/src/boost/libs/geometry/example/with_external_libs/x02_gd_example.cpp

   1 // Boost.Geometry (aka GGL, Generic Geometry Library)
   2 //
   3 // Copyright (c) 2007-2012 Barend Gehrels, Amsterdam, the Netherlands.
   4 // Use, modification and distribution is subject to the Boost Software License,
   5 // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
   6 // http://www.boost.org/LICENSE_1_0.txt)
   7 //
   8 // GD example
   9
  10 // GD is a well-known and often used graphic library to write GIF (and other formats)
  11
  12 // To build and run this example:
  13 // 1) download GD from http://www.libgd.org (currently gd-2.0.35 is assumed)
  14 // 2) add 11 files
  15 //          gd.c, gd_gd.c, gd_gif_out.c, gd_io*.c, gd_security.c, gd_topal.c, gdhelpers.c, gdtables.c
  16 //    to the project or makefile or jamfile
  17 // 3) for windows, add define NONDLL to indicate GD is not used as a DLL
  18 //    (Note that steps 2 and 3 are done in the MSVC gd_example project file and property sheets)
  19
  20 #include <cmath>
  21 #include <cstdio>
  22 #include <vector>
  23
  24 #include <fstream>
  25 #include <sstream>
  26
  27
  28 #include <boost/foreach.hpp>
  29
  30 #include <boost/geometry.hpp>
  31 #include <boost/geometry/geometries/multi_polygon.hpp>
  32
  33 #include <boost/geometry/extensions/gis/latlong/latlong.hpp>
  34 #include <boost/geometry/extensions/gis/geographic/strategies/area_huiller_earth.hpp>
  35
  36
  37 #include <gd.h>
  38
  39 namespace bg = boost::geometry;
  40
  41
  42 // ----------------------------------------------------------------------------
  43 // Read an ASCII file containing WKT's
  44 // (note this function is shared by various examples)
  45 // ----------------------------------------------------------------------------
  46 template <typename Geometry>
  47 inline void read_wkt(std::string const& filename, std::vector<Geometry>& geometries)
  48 {
  49     std::ifstream cpp_file(filename.c_str());
  50     if (cpp_file.is_open())
  51     {
  52         while (! cpp_file.eof() )
  53         {
  54             std::string line;
  55             std::getline(cpp_file, line);
  56             if (! line.empty())
  57             {
  58                 Geometry geometry;
  59                 bg::read_wkt(line, geometry);
  60                 geometries.push_back(geometry);
  61             }
  62         }
  63     }
  64 }
  65
  66
  67 int main()
  68 {
  69     // Adapt if necessary
  70     std::string filename = "../data/world.wkt";
  71
  72
  73     // The world is measured in latlong (degrees), so latlong is appropriate.
  74     // We ignore holes in this sample (below)
  75     typedef bg::model::ll::point<bg::degree> point_type;
  76     typedef bg::model::polygon<point_type> polygon_type;
  77     typedef bg::model::multi_polygon<polygon_type> country_type;
  78
  79     std::vector<country_type> countries;
  80
  81     // Read (for example) world countries
  82     read_wkt(filename, countries);
  83
  84
  85     // Create a GD image.
  86     // A world map, as world.shp, is usually mapped in latitude-longitude (-180..180 and -90..90)
  87     // For this example we use a very simple "transformation"
  88     // mapping to 0..720 and 0..360
  89     const double factor = 2.0;
  90     gdImagePtr im = gdImageCreateTrueColor(int(360 * factor), int(180 * factor));
  91
  92     // Allocate three colors
  93     int blue = gdImageColorResolve(im, 0, 52, 255);
  94     int green = gdImageColorResolve(im, 0, 255, 0);
  95     int black = gdImageColorResolve(im, 0, 0, 0);
  96
  97     // Paint background in blue
  98     gdImageFilledRectangle(im, 0, 0, im->sx, im->sy, blue);
  99
 100     // Paint all countries in green
 101     BOOST_FOREACH(country_type const& country, countries)
 102     {
 103         BOOST_FOREACH(polygon_type const& polygon, country)
 104         {
 105             // Ignore holes, so take only exterior ring
 106             bg::model::ring<point_type> const& ring = bg::exterior_ring(polygon);
 107
 108             // If wished, suppress too small polygons.
 109             // (Note that even in latlong, area is calculated in square meters)
 110             double const a = bg::area(ring);
 111             if (std::fabs(a) > 5000.0e6)
 112             {
 113                 int const n = ring.size();
 114                 gdPoint* points = new gdPoint[n];
 115
 116                 for (int i = 0; i < n; i++)
 117                 {
 118                     // Translate lon/lat or x/y to GD x/y points
 119                     points[i].x = int(factor * (bg::get<0>(ring[i]) + 180.0));
 120                     points[i].y = im->sy - int(factor * (bg::get<1>(ring[i]) + 90.0));
 121                 }
 122
 123                 // Draw the polygon...
 124                 gdImageFilledPolygon(im, points, n, green);
 125                 // .. and the outline in black...
 126                 gdImagePolygon(im, points, n, black);
 127
 128                 delete[] points;
 129             }
 130         }
 131     }
 132
 133     // Use GD to create a GIF file
 134     std::FILE* out = std::fopen("world.gif", "wb");
 135     if (out != NULL)
 136     {
 137         gdImageGif(im, out);
 138         std::fclose(out);
 139     }
 140
 141     gdImageDestroy(im);
 142
 143     return 0;
 144 }