// file plugin #include "hello_datasource.hpp" #include "hello_featureset.hpp" // boost #include <boost/make_shared.hpp> using mapnik::datasource; using mapnik::parameters; DATASOURCE_PLUGIN(hello_datasource) hello_datasource::hello_datasource(parameters const& params, bool bind) : datasource(params), type_(datasource::Vector), desc_(*params_.get<std::string>("type"), *params_.get<std::string>("encoding","utf-8")), extent_() { if (bind) { this->bind(); } } void hello_datasource::bind() const { if (is_bound_) return; // every datasource must have some way of reporting its extent // in this case we are not actually reading from any data so for fun // let's just create a world extent in Mapnik's default srs: // '+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs' (equivalent to +init=epsg:4326) // see http://spatialreference.org/ref/epsg/4326/ for more details extent_.init(-180,-90,180,90); is_bound_ = true; } hello_datasource::~hello_datasource() { } // This name must match the plugin filename, eg 'hello.input' std::string const hello_datasource::name_="hello"; std::string hello_datasource::name() { return name_; } int hello_datasource::type() const { return type_; } mapnik::box2d<double> hello_datasource::envelope() const { if (!is_bound_) bind(); return extent_; } mapnik::layer_descriptor hello_datasource::get_descriptor() const { if (!is_bound_) bind(); return desc_; } mapnik::featureset_ptr hello_datasource::features(mapnik::query const& q) const { if (!is_bound_) bind(); // if the query box intersects our world extent then query for features if (extent_.intersects(q.get_bbox())) { return boost::make_shared<hello_featureset>(q.get_bbox(),desc_.get_encoding()); } // otherwise return an empty featureset pointer return mapnik::featureset_ptr(); } mapnik::featureset_ptr hello_datasource::features_at_point(mapnik::coord2d const& pt) const { if (!is_bound_) bind(); // features_at_point is rarely used - only by custom applications, // so for this sample plugin let's do nothing... return mapnik::featureset_ptr(); }