153 lines
4.7 KiB
PHP
153 lines
4.7 KiB
PHP
<?php
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/**
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* Polyline
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*
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* PHP Version 5.3
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*
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* A simple class to handle polyline-encoding for Google Maps
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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* @category Mapping
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* @package Polyline
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* @author E. McConville <emcconville@emcconville.com>
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* @copyright 2009-2015 E. McConville
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* @license http://www.gnu.org/licenses/lgpl.html LGPL v3
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* @version GIT: $Id: 09435fd8b7f75460f71da06ded31194c13216b0b $
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* @link https://github.com/emcconville/google-map-polyline-encoding-tool
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*/
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/**
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* Polyline encoding & decoding class
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*
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* Convert list of points to encoded string following Google's Polyline
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* Algorithm.
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*
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* @category Mapping
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* @package Polyline
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* @author E. McConville <emcconville@emcconville.com>
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* @license http://www.gnu.org/licenses/lgpl.html LGPL v3
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* @link https://github.com/emcconville/google-map-polyline-encoding-tool
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*/
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class Polyline
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{
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/**
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* Default precision level of 1e-5.
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*
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* Overwrite this property in extended class to adjust precision of numbers.
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* !!!CAUTION!!!
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* 1) Adjusting this value will not guarantee that third party
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* libraries will understand the change.
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* 2) Float point arithmetic IS NOT real number arithmetic. PHP's internal
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* float precision may contribute to undesired rounding.
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*
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* @var int $precision
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*/
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protected static $precision = 5;
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/**
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* Apply Google Polyline algorithm to list of points.
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*
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* @param array $points List of points to encode. Can be a list of tuples,
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* or a flat, one-dimensional array.
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*
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* @return string encoded string
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*/
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final public static function encode( $points )
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{
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$points = self::flatten($points);
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$encodedString = '';
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$index = 0;
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$previous = array(0,0);
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foreach ( $points as $number ) {
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$number = (float)($number);
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$number = (int)round($number * pow(10, static::$precision));
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$diff = $number - $previous[$index % 2];
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$previous[$index % 2] = $number;
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$number = $diff;
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$index++;
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$number = ($number < 0) ? ~($number << 1) : ($number << 1);
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$chunk = '';
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while ( $number >= 0x20 ) {
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$chunk .= chr((0x20 | ($number & 0x1f)) + 63);
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$number >>= 5;
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}
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$chunk .= chr($number + 63);
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$encodedString .= $chunk;
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}
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return $encodedString;
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}
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/**
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* Reverse Google Polyline algorithm on encoded string.
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*
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* @param string $string Encoded string to extract points from.
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*
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* @return array points
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*/
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final public static function decode( $string )
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{
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$points = array();
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$index = $i = 0;
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$previous = array(0,0);
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while ($i < strlen($string)) {
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$shift = $result = 0x00;
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do {
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$bit = ord(substr($string, $i++)) - 63;
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$result |= ($bit & 0x1f) << $shift;
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$shift += 5;
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} while ($bit >= 0x20);
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$diff = ($result & 1) ? ~($result >> 1) : ($result >> 1);
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$number = $previous[$index % 2] + $diff;
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$previous[$index % 2] = $number;
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$index++;
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$points[] = $number * 1 / pow(10, static::$precision);
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}
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return $points;
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}
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/**
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* Reduce multi-dimensional to single list
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*
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* @param array $array Subject array to flatten.
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*
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* @return array flattened
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*/
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final public static function flatten( $array )
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{
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$flatten = array();
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array_walk_recursive(
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$array, // @codeCoverageIgnore
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function ($current) use (&$flatten) {
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$flatten[] = $current;
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}
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);
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return $flatten;
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}
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/**
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* Concat list into pairs of points
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*
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* @param array $list One-dimensional array to segment into list of tuples.
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*
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* @return array pairs
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*/
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final public static function pair( $list )
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{
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return is_array($list) ? array_chunk($list, 2) : array();
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}
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}
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