mapnik/bindings/python/mapnik_datasource.cpp

/*****************************************************************************
 * 
 * This file is part of Mapnik (c++ mapping toolkit)
 *
 * Copyright (C) 2006 Artem Pavlenko, Jean-Francois Doyon
 *
 * 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
 *
 *****************************************************************************/
//$Id$
// boost
#include <boost/python.hpp>
#include <boost/python/detail/api_placeholder.hpp>
// stl
#include <sstream>
#include <vector>

// mapnik
#include <mapnik/box2d.hpp>
#include <mapnik/datasource.hpp>
#include <mapnik/datasource_cache.hpp>
#include <mapnik/feature_layer_desc.hpp>
#include <mapnik/memory_datasource.hpp>


using mapnik::datasource;
using mapnik::point_datasource;
using mapnik::memory_datasource;
using mapnik::layer_descriptor;
using mapnik::attribute_descriptor;

namespace  
{
//user-friendly wrapper that uses Python dictionary
using namespace boost::python;
boost::shared_ptr<mapnik::datasource> create_datasource(const dict& d)
{
    mapnik::parameters params;
    boost::python::list keys=d.keys();
    for (int i=0; i<len(keys); ++i)
    {
        std::string key = extract<std::string>(keys[i]);
        object obj = d[key];
        extract<std::string> ex0(obj);
        extract<int> ex1(obj);
        extract<double> ex2(obj);
            
        if (ex0.check())
        {
            params[key] = ex0();
        }
        else if (ex1.check())
        {
            params[key] = ex1();
        }
        else if (ex2.check())
        {
            params[key] = ex2();
        }
    }
        
    return mapnik::datasource_cache::create(params);
}
    
std::string describe(boost::shared_ptr<mapnik::datasource> const& ds)
{
    std::stringstream ss;
    if (ds)
    {
        ss << ds->get_descriptor() << "\n";
    }
    else
    {
        ss << "Null\n";
    }
    return ss.str();
}
    
std::string encoding(boost::shared_ptr<mapnik::datasource> const& ds)
{
    layer_descriptor ld = ds->get_descriptor();
    return ld.get_encoding();
}

std::string name(boost::shared_ptr<mapnik::datasource> const& ds)
{
    layer_descriptor ld = ds->get_descriptor();
    return ld.get_name();
}

boost::python::list fields(boost::shared_ptr<mapnik::datasource> const& ds)
{
    boost::python::list flds;
    if (ds)
    {
        layer_descriptor ld = ds->get_descriptor();
        std::vector<attribute_descriptor> const& desc_ar = ld.get_descriptors();
        std::vector<attribute_descriptor>::const_iterator it = desc_ar.begin();
        std::vector<attribute_descriptor>::const_iterator end = desc_ar.end();
        for (; it != end; ++it)
        {
            flds.append(it->get_name());
        }
    }
    return flds;
}
boost::python::list field_types(boost::shared_ptr<mapnik::datasource> const& ds)
{
    boost::python::list fld_types;
    if (ds)
    {
        layer_descriptor ld = ds->get_descriptor();
        std::vector<attribute_descriptor> const& desc_ar = ld.get_descriptors();
        std::vector<attribute_descriptor>::const_iterator it = desc_ar.begin();
        std::vector<attribute_descriptor>::const_iterator end = desc_ar.end();
        for (; it != end; ++it)
        {  
            unsigned type = it->get_type();
            fld_types.append(type);
        }
    }
    return fld_types;
}}

void export_datasource()
{
    using namespace boost::python;
    
    class_<datasource,boost::shared_ptr<datasource>,
        boost::noncopyable>("Datasource",no_init)
        .def("envelope",&datasource::envelope)
        .def("descriptor",&datasource::get_descriptor) //todo
        .def("features",&datasource::features)
        .def("fields",&fields)
        .def("_field_types",&field_types)
        .def("encoding",&encoding) //todo expose as property
        .def("name",&name)
        .def("features_at_point",&datasource::features_at_point)
        .def("params",&datasource::params,return_value_policy<copy_const_reference>(), 
             "The configuration parameters of the data source. "  
             "These vary depending on the type of data source.")
        ;
    
    def("Describe",&describe);
    def("CreateDatasource",&create_datasource);

    class_<point_datasource, bases<datasource>, boost::noncopyable>("PointDatasource", init<>())
        .def("add_point",&point_datasource::add_point)
        ;


    class_<memory_datasource, bases<datasource>, boost::noncopyable>("MemoryDatasource", init<>())
        .def("add_feature",&memory_datasource::push,
             "Adds a Feature:\n"
             ">>> ms = MemoryDatasource()\n"
             ">>> feature = Feature(1)\n"
             ">>> ms.add_feature(Feature(1))\n")
        .def("num_features",&memory_datasource::size)
        ;
}