mapnik/plugins/input/templates/helloworld/hello_datasource.hpp

#ifndef FILE_DATASOURCE_HPP
#define FILE_DATASOURCE_HPP

// mapnik
#include <mapnik/datasource.hpp>
#include <mapnik/params.hpp>
#include <mapnik/query.hpp>
#include <mapnik/feature.hpp>
#include <mapnik/box2d.hpp>
#include <mapnik/coord.hpp>
#include <mapnik/feature_layer_desc.hpp>

// boost
#include <boost/optional.hpp>
#include <memory>

// stl
#include <string>

class hello_datasource : public mapnik::datasource
{
public:
    // constructor
    // arguments must not change
    hello_datasource(mapnik::parameters const& params);

    // destructor
    virtual ~hello_datasource ();

    // mandatory: type of the plugin, used to match at runtime
    mapnik::datasource::datasource_t type() const;

    // mandatory: name of the plugin
    static const char * name();

    // mandatory: function to query features by box2d
    // this is called when rendering, specifically in feature_style_processor.hpp
    mapnik::featureset_ptr features(mapnik::query const& q) const;

    // mandatory: function to query features by point (coord2d)
    // not used by rendering, but available to calling applications
    mapnik::featureset_ptr features_at_point(mapnik::coord2d const& pt, double tol = 0) const;

    // mandatory: return the box2d of the datasource
    // called during rendering to determine if the layer should be processed
    mapnik::box2d<double> envelope() const;

    // mandatory: optionally return the overal geometry type of the datasource
    boost::optional<mapnik::datasource::geometry_t> get_geometry_type() const;

    // mandatory: return the layer descriptor
    mapnik::layer_descriptor get_descriptor() const;

private:
    // recommended - do intialization in a so-named init function
    // to reduce code in constructor
    void init(mapnik::parameters const& params);
    // recommended naming convention of datasource members:
    // name_, type_, extent_, and desc_
    static const std::string name_;
    mapnik::layer_descriptor desc_;
    mapnik::box2d<double> extent_;
};


#endif // FILE_DATASOURCE_HPP