WKT.php

<?php

/**
 * This file is part of the Kdyby (http://www.kdyby.org)
 *
 * Copyright (c) 2008, 2012 Filip Procházka (filip.prochazka@kdyby.org)
 *
 * For the full copyright and license information, please view the file license.txt that was distributed with this source code.
 */

namespace Kdyby\Extension\GeoJson;

use Nette;


/**
 * PHP Geometry/WKT encoder/decoder
 *
 * Mainly inspired/adapted from OpenLayers( http://www.openlayers.org )
 *   Openlayers/format/WKT.js
 *
 * @copyright Camptocamp <info@camptocamp.com>
 * @author Filip Procházka <filip.prochazka@kdyby.org>
 */
class WKT extends Nette\Object
{

	const POINT = 'point';
	const MULTIPOINT = 'multipoint';
	const LINESTRING = 'linestring';
	const MULTILINESTRING = 'multilinestring';
	const LINEARRING = 'linearring';
	const POLYGON = 'polygon';
	const MULTIPOLYGON = 'multipolygon';
	const GEOMETRYCOLLECTION = 'geometrycollection';

	/**
	 * @var array
	 */
	private $regExes = array(
		'typeStr' => '/^\s*(\w+)\s*\(\s*(.*)\s*\)\s*$/',
		'spaces' => '/\s+/',
		'parenComma' => '/\)\s*,\s*\(/',
		'doubleParenComma' => '/\)\s*\)\s*,\s*\(\s*\(/',
		'trimParens' => '/^\s*\(?(.*?)\)?\s*$/'
	);


	/**
	 * Read WKT string into geometry objects
	 *
	 * @param string $WKT A WKT string
	 *
	 * @return Geometry\Geometry|Geometry\GeometryCollection
	 */
	public function read($WKT)
	{
		if (!preg_match($this->regExes['typeStr'], $WKT, $matches)) {
			return NULL;
		}

		return $this->parse(strtolower($matches[1]), $matches[2]);
	}


	/**
	 * Parse WKT string into geometry objects
	 *
	 * @param $type
	 * @param $str
	 *
	 * @return Geometry\Geometry|Geometry\GeometryCollection
	 */
	public function parse($type, $str)
	{
		$components = array();

		switch ($type) {
			case self::POINT:
				$coords = $this->pregExplode('spaces', $str);
				return new Geometry\Point($coords[0], $coords[1]);

			case self::MULTIPOINT:
				foreach (explode(',', trim($str)) as $point) {
					$components[] = $this->parse(self::POINT, $point);
				}
				return new Geometry\MultiPoint($components);

			case self::LINESTRING:
				foreach (explode(',', trim($str)) as $point) {
					$components[] = $this->parse(self::POINT, $point);
				}
				return new Geometry\LineString($components);

			case self::MULTILINESTRING:
				$lines = $this->pregExplode('parenComma', $str);
				foreach ($lines as $l) {
					$line = preg_replace($this->regExes['trimParens'], '$1', $l);
					$components[] = $this->parse(self::LINESTRING, $line);
				}
				return new Geometry\MultiLineString($components);

			case self::POLYGON:
				$rings = $this->pregExplode('parenComma', $str);
				foreach ($rings as $r) {
					$ring = preg_replace($this->regExes['trimParens'], '$1', $r);
					$linestring = $this->parse(self::LINESTRING, $ring);
					$components[] = new Geometry\LinearRing($linestring->getComponents());
				}
				return new Geometry\Polygon($components);

			case self::MULTIPOLYGON:
				$polygons = $this->pregExplode('doubleParenComma', $str);
				foreach ($polygons as $p) {
					$polygon = preg_replace($this->regExes['trimParens'], '$1', $p);
					$components[] = $this->parse(self::POLYGON, $polygon);
				}
				return new Geometry\MultiPolygon($components);

			case self::GEOMETRYCOLLECTION:
				$str = preg_replace('/,\s*([A-Za-z])/', '|$1', $str);
				$wktArray = explode('|', trim($str));
				foreach ($wktArray as $wkt) {
					$components[] = $this->read($wkt);
				}
				return new Geometry\GeometryCollection($components);

			default:
				return null;
		}
	}


	/**
	 * Split string according to first match of passed regEx index of $regExes
	 *
	 * @param string $regEx
	 * @param string $str
	 *
	 * @return array
	 */
	protected function pregExplode($regEx, $str)
	{
		$matches = array();
		preg_match($this->regExes[$regEx], $str, $matches);
		return empty($matches) ? array(trim($str)) : explode($matches[0], trim($str));
	}


	/**
	 * Serialize geometries into a WKT string.
	 *
	 * @param Geometry\Geometry $geometry
	 *
	 * @return string The WKT string representation of the input geometries
	 */
	public function write(Geometry\Geometry $geometry)
	{
		$type = strtolower(get_class($geometry));

		if (is_null($data = $this->extract($geometry))) {
			return null;
		}

		return strtoupper($type) . '(' . $data . ')';
	}


	/**
	 * Extract geometry to a WKT string
	 *
	 * @param Geometry\Geometry $geometry A Geometry object
	 *
	 * @return string
	 */
	public function extract(Geometry\Geometry $geometry)
	{
		$array = array();
		switch (strtolower(get_class($geometry))) {
			case self::POINT:
				/** @var Geometry\Point $geometry */
				return number_format($geometry->getX(), 1, '.', '') . ' ' .
					number_format($geometry->getY(), 1, '.', '');

			case self::MULTIPOINT:
			case self::LINESTRING:
			case self::LINEARRING:
				foreach ($geometry as $geom) {
					$array[] = $this->extract($geom);
				}
				return implode(',', $array);

			case self::MULTILINESTRING:
			case self::POLYGON:
			case self::MULTIPOLYGON:
				foreach ($geometry as $geom) {
					$array[] = '(' . $this->extract($geom) . ')';
				}
				return implode(',', $array);

			case self::GEOMETRYCOLLECTION:
				foreach ($geometry as $geom) {
					$array[] = strtoupper(get_class($geom)) . '(' . $this->extract($geom) . ')';
				}
				return implode(',', $array);

			default:
				return null;
		}
	}


	/**
	 * Loads a WKT string into a Geometry Object
	 *
	 * @param string $WKT
	 *
	 * @return Geometry\Geometry
	 */
	static public function load($WKT)
	{
		$instance = new self;
		return $instance->read($WKT);
	}


	/**
	 * Dumps a Geometry Object into a  WKT string
	 *
	 * @param Geometry\Geometry $geometry
	 *
	 * @return String A WKT string corresponding to passed object
	 */
	static public function dump(Geometry\Geometry $geometry)
	{
		$instance = new self;
		return $instance->write($geometry);
	}

}