Polylabel-rs

A Rust implementation of the Polylabel algorithm

Visualised: The orange dot is the polygon centroid. The teal dot is the ideal label position.

You can generate this visualisation yourself by cloning this repo, switching to the visualise branch, and opening the visualise.ipynb Jupyter notebook, then stepping through the cells. You can also easily visualise a Polygon of your own using the notebook.

How to Use

extern crate polylabel;
use polylabel::polylabel;

extern crate geo;
use geo::{Point, LineString, Polygon};

let coords = vec![
    (0.0, 0.0),
    (4.0, 0.0),
    (4.0, 1.0),
    (1.0, 1.0),
    (1.0, 4.0),
    (0.0, 4.0),
    (0.0, 0.0)
];
let ls = LineString(coords.iter().map(|e| Point::new(e.0, e.1)).collect());
let poly = Polygon::new(ls, vec![]);
let label_pos = polylabel(&poly, &0.10);
// Point(0.5625, 0.5625)

Documentation

https://docs.rs/polylabel

FFI

Call polylabel_ffi with the following three mandatory arguments:

• Array (a void pointer to an array of two-element c_doubles, the exterior Polygon ring)
• WrapperArray (a void pointer to an array of Arrays, the interior Polygon rings, empty if there are none)
• tolerance, a c_float

The function returns a struct with two c_double fields:

• x_pos
• y_pos

A Python example is available in ffi.py

Binaries

Binary libs for:

• x86_64 *nix (built using manylinux1, thus easy to include in Python 2.7 / 3.5 / 3.6 wheels) and OS X
• i686 and x86_64 Windows

are available in releases.

License

MIT