google-map-polyline-encoding-tool
Google Maps Polyline Encoding Tool
A simple PHP class for translating polyline into an
encoded strings for Google Maps.
Install
Use composer.
$ 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.
Requires
google-map-polyline-encoding-tool
polyline-encoder
php_polyline
PHP
5.3
5.4
C-API
Supports
google-map-polyline-encoding-tool
polyline-encoder
php_polyline
Google
✔
✔
✔
Bing
✔
Precision
✔
✔
✔
Tuple
✔
✔
Traits
✔
Abstraction
✔