gestionnaire-de-taches-simple/lib/OSM/GeoJsonConverter.php

<?php

namespace OSM;

class GeoJsonConverter {

    public static function convertRelationToPolygon(
        \OSM\Element\Relation $relation
    ): \GeoJson\Geometry\Polygon
    {
        $positions = [];

        foreach ($relation->getOrderedOuterWays() as $way) {
            foreach ($way->points as $point) {
                $positions[] = new \GeoJson\Geometry\Point([
                    $point->longitude,
                    $point->latitude
                ]);
            }
        }

        return new \GeoJson\Geometry\Polygon([ $positions ]);
    }

}