https://github.com/urschrei/polyline-ffi

FFI Bindings for the rust-polyline crate
https://github.com/urschrei/polyline-ffi

computational-geometry ffi-bindings polyline

Last synced: 4 months ago
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FFI Bindings for the rust-polyline crate

• Host: GitHub
• URL: https://github.com/urschrei/polyline-ffi
• Owner: urschrei
• License: mit
• Created: 2016-07-25T09:39:26.000Z (almost 10 years ago)
• Default Branch: master
• Last Pushed: 2025-11-24T13:33:49.000Z (7 months ago)
• Last Synced: 2025-11-28T02:41:32.821Z (7 months ago)
• Topics: computational-geometry, ffi-bindings, polyline
• Language: Rust
• Homepage: https://docs.rs/polyline-ffi
• Size: 3.37 MB
• Stars: 1
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: license.txt

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# FFI Bindings for the [rust-polyline](https://github.com/georust/rust-polyline) Crate

A Python implementation using these bindings is available at [pypolyline](https://github.com/urschrei/pypolyline)

## A Note on Coordinate Order

This crate uses `Coordinate` and `LineString` types from the `geo-types` crate, which encodes coordinates in `(x, y)` order. The Polyline algorithm and first-party documentation assumes the _opposite_ coordinate order. It is thus advisable to pay careful attention to the order of the coordinates you use for encoding and decoding.

## `decode_polyline_ffi`

Convert a Polyline into an array of coordinates.  

Callers must pass two arguments:

- a pointer to a `NUL`-terminated character array (`char*`)

- an unsigned 32-bit `int` for precision (`5` for Google Polylines, `6` for OSRM and Valhalla Polylines)  

Returns an `Array` struct with two fields:

- `data`, a void pointer to a nested double-precision float array: e.g. `[[1.0, 2.0], [3.0, 4.0], [5.0, 6.0]]`

- `len`, an integer of type `size_t`, denoting the array length, e.g. `3`

Callers must then call `drop_float_array` to free the memory allocated by this function.

## `drop_float_array`

Free memory pointed to by `Array`, which Rust has allocated across the FFI boundary.  

Callers must pass the same `Array` struct that was received from `decode_polyline_ffi`.

## `encode_coordinates_ffi`

Convert coordinates into a Polyline.  

Callers must pass a struct, with two members:

- `data`, a void pointer to a nested double-precision float array: e.g. `[[1.0, 2.0], [3.0, 4.0], [5.0, 6.0]]`

- `len`, the array length, e.g. `3`

Returns a pointer to a C character array (`char*`).  

Callers must then call `drop_cstring` to free the memory allocated by this function.

## `drop_cstring`

Free memory pointed to by `char*`, which Rust has allocated across the FFI boundary.  

Callers must pass the same `char*` they receive from `encode_coordinates_ffi`.

# Binaries

Compressed binaries are available for Linux (64-bit), OSX (64-bit), and Windows (32-bit and 64-bit), from the [releases](https://github.com/urschrei/polyline-ffi/releases) page.  

The Linux binary has been built using the manylinux2014 Docker image, and is widely compatible.  

Both Linux and OSX binaries have been built with `rpath` support.

# License

[MIT](license.txt)