Function polyline_ffi::encode_coordinates_ffi [−] [src]

pub extern fn encode_coordinates_ffi(coords: Array, precision: uint32_t) -> *mut c_char

Convert an array of coordinates into a Polyline

Callers must pass two arguments:

  • a Struct with two fields:
    • data, a void pointer to an array of floating-point lat, lon coordinates: [[1.0, 2.0]]
    • len, the length of the array being passed. Its type must be size_t: 1
  • an unsigned 32-bit int for precision (5 for Google Polylines, 6 for OSRM and Valhalla Polylines)

Examples

extern crate libc;
use libc::{c_void, size_t};
use std::ffi::CStr;
use std::slice;
let input = vec![[1.0, 2.0], [3.0, 4.0]].as_slice();
let array = Array { data: input.as_ptr() as *const c_void, len: input.len() as size_t };
let output = "_ibE_seK_seK_seK".to_string();
let pl = encode_coordinates_ffi(array, 5);
let result = unsafe { CStr::from_ptr(pl).to_str().unwrap() };
assert_eq!(result, output);
drop_cstring(pl);

A decoding failure will always return a string: "Couldn't decode Polyline"

Implementations calling this function must call drop_cstring with the returned c_char pointer, in order to free the memory it allocates.

Safety

This function is unsafe because it accesses a raw pointer which could contain arbitrary data