Crate geos

Expand description

geos

Rust bindings for GEOS C API.

The supported geos version is >= 3.5

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:

use geos::Geom;

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:

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 geo

geo’s objects can be converted into GEOS to use all geos algorithms.

Complete example can be found in examples/from_geo.rs

use geos::from_geo::TryInto;
use geos::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 geo some helpers are available in voronoi.rs.

use geos::compute_voronoi;
use geos::geo_types::Point;

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

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

Static build

By default, this crate links dynamically. If you want to link statically, use the static feature.

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.