README

A simple PHP class for translating polyline into an encoded strings for Google Maps.

Install

$ curl -sS https://getcomposer.org/installer | php
$ cat > composer.json <<EOF
{
   "require": {
      "emcconville/google-map-polyline-encoding-tool" : ">=1.2.1"
   }
}
EOF
$ php composer.phar install

Old fashion way.

$ git clone git://github.com/emcconville/google-map-polyline-encoding-tool.git
$ cp src/Polyline.php /path/to/your/application/includes/Polyline.php

Usage

Encoding

// Points to encode
$points = array(
        array(41.89084,-87.62386),
        array(41.89086,-87.62279),
        array(41.89028,-87.62277),
        array(41.89028,-87.62385),
        array(41.89084,-87.62386)
    );

$encoded = Polyline::encode($points);
//=> wxt~Fd`yuOCuErBC?vEoB@

Decoding

// String to decode
$encoded = "kiw~FpoavObBA?fAzEC";

$points = Polyline::decode($encoded);
//=> array(
//     41.90374,-87.66729,41.90324,-87.66728,
//     41.90324,-87.66764,41.90214,-87.66762
//   );

// Or list of tuples
$points = Polyline::pair($points);
//=> array(
//     array(41.90374,-87.66729),
//     array(41.90324,-87.66728),
//     array(41.90324,-87.66764),
//     array(41.90214,-87.66762)
//   );

Examples

See examples directory for creative ideas, and please contribute new use-cases / hacks.

Well-Known Binary converter.
Preview encoded strings with a SVG transcoder.

Specify precision

Precision defaults to 1e-5 (0.00001) which is expected by Google Map API. Other API's like OSRM expect a precision of 1e-6. You can adjust the precision you want by sub-classing Polyline, and overwrite the $precision static property.

class PolylineOSRM extends Polyline
{
    protected static $precision = 6;
}
$points = PolylineOSRM::decode($line);
$line = PolylineOSRM::encode($points);

Caution

Adjusting the precision level will not guarantee improved accuracy. Existing issues with PHP's internal float point arithmetic can contribute accuracy issues.
Third party libraries will not automatically know what level of precision was used during encoding.

Family

This library exists as a PHP reference point for Google's Encoded Polyline Algorithm Format. There is also a C implementation, and a namespace/trait library under active development.

emcconville / google-map-polyline-encoding-tool

Maintainers

Details