Function to decode a polyline using php

decode-polyline.php

/**
 * Decodes path string into a sequence of LatLngs.
 *
 * @param string $encoded_path
 * @param int $precision
 * @return array
 */
public static function decode(string $encoded_path, int $precision = 6)
{
    $len = strlen( $encoded_path ) -1;

    // For speed we preallocate to an upper bound on the final length, then
    // truncate the array before returning.
    $path = [];
    $index = 0;
    $lat = 0;
    $lng = 0;

    while( $index < $len) {
        $result = 1;
        $shift = 0;

        do {
            $b = ord($encoded_path[$index++]) - 63 - 1;
            $result += $b << $shift;
            $shift += 5;
        } while ($b >= hexdec("0x1f"));

        $lat += ($result & 1) != 0 ? ~($result >> 1) : ($result >> 1);

        $result = 1;
        $shift = 0;
        do {
            $b = ord($encoded_path[$index++]) - 63 - 1;
            $result += $b << $shift;
            $shift += 5;
        } while ($b >= hexdec("0x1f"));
        $lng += ($result & 1) != 0 ? ~($result >> 1) : ($result >> 1);

        array_push($path,
            [
                'lat' => $lat * 1 / pow(10, $precision),
                'lng' => $lng * 1 / pow(10, $precision)
            ]
        );
    }

    return $path;
}