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+// Boost.Geometry (aka GGL, Generic Geometry Library)
+//
+// Copyright (c) 2009-2012 Mateusz Loskot, London, UK.
+//
+// Use, modification and distribution is subject to the Boost Software License,
+// Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+// Boost.Geometry (aka GGL, Generic Geometry Library)
+// SOCI example
+
+// d: using WKB to retrieve geometries
+
+// SOCI is a generic C++ template interface to access relational databases
+
+// To build and run this example, see comments in example a
+// Alternatively compile composing and executing compiler command directoy in examples directory,
+// for example using GCC compiler:
+// g++ -I../../../boost -I/home/mloskot/usr/include/soci \
+// -I /home/mloskot/usr/include/soci/postgresql -I/usr/include/postgresql \
+// -L/home/mloskot/usr/lib -lsoci_core-gcc-3_0 -lsoci_postgresql-gcc-3_0 x03_c_soci_example.cpp
+
+#include <soci.h>
+#include <soci-postgresql.h>
+
+#include <exception>
+#include <iostream>
+#include <iterator>
+#include <string>
+#include <vector>
+
+#include <boost/geometry.hpp>
+
+#include <boost/geometry/geometries/geometries.hpp>
+#include <boost/geometry/geometries/point_xy.hpp>
+
+#include <boost/geometry/extensions/gis/io/wkb/read_wkb.hpp>
+#include <boost/geometry/extensions/gis/io/wkb/utility.hpp>
+
+int main()
+{
+ try
+ {
+ // establish database connection
+ soci::session sql(soci::postgresql, "dbname=ggl user=ggl password=ggl");
+
+ // construct schema of table for trees (point geometries)
+ sql << "DELETE FROM geometry_columns WHERE f_table_name = 'parcels'";
+ sql << "DROP TABLE IF EXISTS parcels CASCADE";
+ sql << "CREATE TABLE parcels (id INTEGER)";
+ sql << "SELECT AddGeometryColumn('parcels', 'geom', -1, 'GEOMETRY', 2)";
+
+ // insert sample data using plain WKT input
+ sql << "INSERT INTO parcels VALUES(1, ST_GeomFromText('POLYGON ((10 10, 10 20, 20 20, 20 15, 10 10))', -1))";
+ sql << "INSERT INTO parcels VALUES(2, ST_GeomFromText('POLYGON ((0 0, 4 0, 4 4, 0 4, 0 0))', -1))";
+ sql << "INSERT INTO parcels VALUES(3, ST_GeomFromText('POLYGON((1 1,2 1,2 2,1 2,1 1))', -1))";
+
+ // query data in WKB form and read to geometry object
+ soci::rowset<std::string> rows = (sql.prepare << "SELECT encode(ST_AsBinary(geom), 'hex') AS wkb FROM parcels");
+
+ // calculate area of each parcel
+ for (soci::rowset<std::string>::iterator it = rows.begin(); it != rows.end(); ++it)
+ {
+ // parse WKB and construct geometry object
+ std::string const& hex = *it;
+ std::vector<unsigned char> wkb;
+ if (!boost::geometry::hex2wkb(*it, std::back_inserter(wkb)))
+ throw std::runtime_error("hex2wkb translation failed");
+
+ boost::geometry::model::polygon<boost::geometry::model::d2::point_xy<double> > parcel;
+ if (!boost::geometry::read_wkb(wkb.begin(), wkb.end(), parcel))
+ throw std::runtime_error("read_wkb failed");
+
+ double a = boost::geometry::area(parcel);
+ std::cout << "Parcel geometry: " << boost::geometry::wkt(parcel) << std::endl
+ << "\thas area is " << a << " in coordinate units" << std::endl;
+ }
+ }
+ catch (std::exception const &e)
+ {
+ std::cerr << "Error: " << e.what() << '\n';
+ }
+ return 0;
+}
+