geos

Rust bindings for GEOS C API.

The supported geos version is >= 3.5

Disclaimer

GEOS can be a tad strict on the validity on the input geometry and is prone to crash on invalid input, so they need to be checked in the wrapper. This project is checked with valgrind, but if you stumble on a crash feel free to open an issue explaining the problem.

Usage example

You can check the examples in the examples/ directory.

Constructing geometries from WKT:

extern crate geos;

let gg1 = geos::Geometry::new_from_wkt("POLYGON ((0 0, 0 5, 6 6, 6 0, 0 0))").expect("invalid WKT");
let gg2 = geos::Geometry::new_from_wkt("POLYGON ((1 1, 1 3, 5 5, 5 1, 1 1))").expect("invalid WKT");
let gg3 = gg1.difference(&gg2).expect("difference failed");
assert_eq!(
    gg3.to_wkt_precision(0).expect("to_wkt failed"),
    "POLYGON ((0 0, 0 5, 6 6, 6 0, 0 0), (1 1, 5 1, 5 5, 1 3, 1 1))",
);

"Preparing" the geometries for faster predicates (intersects, contains, etc.) computation on repetitive calls:

extern crate geos;

let g1 = geos::Geometry::new_from_wkt("POLYGON ((0 0, 0 5, 5 5, 5 0, 0 0))").expect("invalid WKT");
let g2 = geos::Geometry::new_from_wkt("POLYGON ((1 1, 1 3, 5 5, 5 0, 1 1))").expect("invalid WKT");

let pg1 = geos::PreparedGeometry::new(&g1).expect("PreparedGeometry::new failed");
let result = pg1.intersects(&g2).expect("intersects failed");
assert_eq!(result, true);

Conversion from rust-geo

rust-geo's objects can be converted into GEOS to use all geos algorithms.

Complete example can be found in examples/from_geo.rs

extern crate geos;
extern crate geo_types;

use geos::from_geo::TryInto;
use geo_types::{LineString, Coordinate, Polygon};

// first we create a Geo object
let exterior = LineString(vec![
    Coordinate::from((0., 0.)),
    Coordinate::from((0., 1.)),
    Coordinate::from((1., 1.)),
]);
let interiors = vec![
    LineString(vec![
        Coordinate::from((0.1, 0.1)),
        Coordinate::from((0.1, 0.9)),
        Coordinate::from((0.9, 0.9)),
    ]),
];
let p = Polygon::new(exterior, interiors);
// and we can create a Geos geometry from this object
let geom: geos::Geometry = (&p).try_into().expect("failed conversion");
// do some stuff with geom

Voronoi

Voronoi diagrams computation are available in the bindings.

For those to be easier to use with rust-geo some helpers are available in voronoi.rs.

extern crate geo_types;

use geo_types::Point;
let points = vec![
    Point::new(0., 0.),
    Point::new(0., 1.),
    Point::new(1., 1.),
    Point::new(1., 0.),
];

let voronoi = geos::compute_voronoi(&points, None, 0., false).expect("compute_voronoi failed");

Contributing

Only a subset of geos has been implemented, feel free to add wrappers for missing features.

All added features needs to be tested and this being a C wrapper, valgrind runs on all examples/tests to check that no bugs / memory leaks are lurking.