File: platform/plugins/Places/classes/Places/Polyline.php

<?php
/**
 * Places model
 * @module Places
 * @main Places
 */
/**
 * Static methods for the Polyline models.
 * @class Places_Polyline
 */
class Places_Polyline
{
	/**
	 * Default precision level of 1e-5.
	 *
	 * Overwrite this property in extended class to adjust precision of numbers.
	 * !!!CAUTION!!!
	 * 1) Adjusting this value will not guarantee that third party
	 *    libraries will understand the change.
	 * 2) Float point arithmetic IS NOT real number arithmetic. PHP's internal
	 *    float precision may contribute to undesired rounding.
	 *
	 * @var int $precision
	 */
	protected static $precision = 5;
	/**
	 * Apply Google Polyline algorithm to list of points.
	 *
	 * @param array $points List of points to encode. Can be a list of tuples,
	 *                      or a flat on dimensional array.
	 *
	 * @return string encoded string
	 */
	public static function encode( $points )
	{
		$points = self::flatten($points);
		$encodedString = '';
		$index = 0;
		$previous = array(0,0);
		foreach ( $points as $number ) {
			$number = (float)($number);
			$number = (int)round($number * pow(10, static::$precision));
			$diff = $number - $previous[$index % 2];
			$previous[$index % 2] = $number;
			$number = $diff;
			$index++;
			$number = ($number < 0) ? ~($number << 1) : ($number << 1);
			$chunk = '';
			while ( $number >= 0x20 ) {
				$chunk .= chr((0x20 | ($number & 0x1f)) + 63);
				$number >>= 5;
			}
			$chunk .= chr($number + 63);
			$encodedString .= $chunk;
		}
		return $encodedString;
	}
	/**
	 * Reverse Google Polyline algorithm on encoded string.
	 *
	 * @param string $string Encoded string to extract points from.
	 *
	 * @return array points
	 */
	public static function decode( $string )
	{
		$points = array();
		$index = $i = 0;
		$previous = array(0,0);
		while ($i < strlen($string)) {
			$shift = $result = 0x00;
			do {
				$bit = ord(substr($string, $i++)) - 63;
				$result |= ($bit & 0x1f) << $shift;
				$shift += 5;
			} while ($bit >= 0x20);
			$diff = ($result & 1) ? ~($result >> 1) : ($result >> 1);
			$number = $previous[$index % 2] + $diff;
			$previous[$index % 2] = $number;
			$index++;
			$points[] = $number * 1 / pow(10, static::$precision);
		}
		return $points;
	}
	/**
	 * Reduce multi-dimensional to single list
	 *
	 * @param array $array Subject array to flatten.
	 *
	 * @return array flattened
	 */
	public static function flatten( $array )
	{
		$flatten = array();
		array_walk_recursive(
			$array, // @codeCoverageIgnore
			function ($current) use (&$flatten) {
				$flatten[] = $current;
			}
		);
		return $flatten;
	}
	/**
	 * Concat list into pairs of points
	 *
	 * @param array $list One-dimensional array to segment into list of tuples.
	 *
	 * @return array pairs
	 */
	public static function pair( $list )
	{
		return is_array($list) ? array_chunk($list, 2) : array();
	}
};