ceph/src/boost/libs/geometry/example/with_external_libs/x03_d_soci_example.cpp

   1 // Boost.Geometry (aka GGL, Generic Geometry Library)
   2 //
   3 // Copyright (c) 2009-2012 Mateusz Loskot, London, UK.
   4 //
   5 // Use, modification and distribution is subject to the Boost Software License,
   6 // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
   7 // http://www.boost.org/LICENSE_1_0.txt)
   8 // Boost.Geometry (aka GGL, Generic Geometry Library)
   9 // SOCI example
  10
  11 // d: using WKB to retrieve geometries
  12
  13 // SOCI is a generic C++ template interface to access relational databases
  14
  15 // To build and run this example, see comments in example a
  16 // Alternatively compile composing and executing compiler command directoy in examples directory,
  17 //    for example using GCC compiler:
  18 //    g++ -I../../../boost -I/home/mloskot/usr/include/soci \
  19 //        -I /home/mloskot/usr/include/soci/postgresql -I/usr/include/postgresql \
  20 //        -L/home/mloskot/usr/lib -lsoci_core-gcc-3_0 -lsoci_postgresql-gcc-3_0 x03_c_soci_example.cpp
  21
  22 #include <soci.h>
  23 #include <soci-postgresql.h>
  24
  25 #include <exception>
  26 #include <iostream>
  27 #include <iterator>
  28 #include <string>
  29 #include <vector>
  30
  31 #include <boost/geometry.hpp>
  32
  33 #include <boost/geometry/geometries/geometries.hpp>
  34 #include <boost/geometry/geometries/point_xy.hpp>
  35
  36 #include <boost/geometry/extensions/gis/io/wkb/read_wkb.hpp>
  37 #include <boost/geometry/extensions/gis/io/wkb/utility.hpp>
  38
  39 int main()
  40 {
  41     try
  42     {
  43         // establish database connection
  44         soci::session sql(soci::postgresql, "dbname=ggl user=ggl password=ggl");
  45
  46         // construct schema of table for trees (point geometries)
  47         sql << "DELETE FROM geometry_columns WHERE f_table_name = 'parcels'";
  48         sql << "DROP TABLE IF EXISTS parcels CASCADE";
  49         sql << "CREATE TABLE parcels (id INTEGER)";
  50         sql << "SELECT AddGeometryColumn('parcels', 'geom', -1, 'GEOMETRY', 2)";
  51
  52         // insert sample data using plain WKT input
  53         sql << "INSERT INTO parcels VALUES(1, ST_GeomFromText('POLYGON ((10 10, 10 20, 20 20, 20 15, 10 10))', -1))";
  54         sql << "INSERT INTO parcels VALUES(2, ST_GeomFromText('POLYGON ((0 0, 4 0, 4 4, 0 4, 0 0))', -1))";
  55         sql << "INSERT INTO parcels VALUES(3, ST_GeomFromText('POLYGON((1 1,2 1,2 2,1 2,1 1))', -1))";
  56
  57         // query data in WKB form and read to geometry object
  58         soci::rowset<std::string> rows = (sql.prepare << "SELECT encode(ST_AsBinary(geom), 'hex') AS wkb FROM parcels");
  59
  60         // calculate area of each parcel
  61         for (soci::rowset<std::string>::iterator it = rows.begin(); it != rows.end(); ++it)
  62         {
  63             // parse WKB and construct geometry object
  64             std::string const& hex = *it;
  65             std::vector<unsigned char> wkb;
  66             if (!boost::geometry::hex2wkb(*it, std::back_inserter(wkb)))
  67                 throw std::runtime_error("hex2wkb translation failed");
  68
  69             boost::geometry::model::polygon<boost::geometry::model::d2::point_xy<double> > parcel;
  70             if (!boost::geometry::read_wkb(wkb.begin(), wkb.end(), parcel))
  71                 throw std::runtime_error("read_wkb failed");
  72
  73             double a = boost::geometry::area(parcel);
  74             std::cout << "Parcel geometry: " << boost::geometry::wkt(parcel) << std::endl
  75                 << "\thas area is " << a << " in coordinate units" << std::endl;
  76         }
  77     }
  78     catch (std::exception const &e)
  79     {
  80         std::cerr << "Error: " << e.what() << '\n';
  81     }
  82     return 0;
  83 }
  84