xref: /plugin/openlayersmap/StaticMap.php (revision d768c53817b6707a5904421c74f317a4deabf5ed)

<?php
/*
 * Copyright (c) 2012-2014 Mark C. Prins <mprins@users.sf.net>
 *
 * In part based on staticMapLite 0.03 available at http://staticmaplite.svn.sourceforge.net/viewvc/staticmaplite/
 *
 * Copyright (c) 2009 Gerhard Koch <gerhard.koch AT ymail.com>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
include_once(realpath(dirname(__FILE__)).'/../geophp/geoPHP/geoPHP.inc');
/**
 * @author Mark C. Prins <mprins@users.sf.net>
 * @author Gerhard Koch <gerhard.koch AT ymail.com>
 *
 */
class StaticMap {
	// these should probably not be changed
	protected $tileSize = 256;

	// the final output
	var $doc = '';

	protected $tileInfo = array(
			// OSM sources
			'openstreetmap'=>array(
					'txt'=>'(c) OpenStreetMap CC-BY-SA',
					'logo'=>'osm_logo.png',
					'url'=>'http://tile.openstreetmap.org/{Z}/{X}/{Y}.png'),
			// cloudmade
			'cloudmade' =>array(
					'txt'=>'CloudMade tiles',
					'logo'=>'cloudmade_logo.png',
					'url'=> 'http://tile.cloudmade.com/BC9A493B41014CAABB98F0471D759707/2/256/{Z}/{X}/{Y}.png'),
			'fresh' =>array(
					'txt'=>'CloudMade tiles',
					'logo'=>'cloudmade_logo.png',
					'url'=> 'http://tile.cloudmade.com/BC9A493B41014CAABB98F0471D759707/997/256/{Z}/{X}/{Y}.png'),
			// OCM sources
			'cycle'=>array(
					'txt'=>'OpenCycleMap tiles',
					'logo'=>'cycle_logo.png',
					'url'=>'http://tile.opencyclemap.org/cycle/{Z}/{X}/{Y}.png'),
			'transport'=>array(
					'txt'=>'OpenCycleMap tiles',
					'logo'=>'cycle_logo.png',
					'url'=>'http://tile2.opencyclemap.org/transport/{Z}/{X}/{Y}.png'),
			'landscape'=>array(
					'txt'=>'OpenCycleMap tiles',
					'logo'=>'cycle_logo.png',
					'url'=>'http://tile3.opencyclemap.org/landscape/{Z}/{X}/{Y}.png'),
			// H&B sources
			'hikeandbike'=>array(
					'txt'=>'Hike & Bike Map',
					'logo'=>'hnb_logo.png',
					'url'=>'http://toolserver.org/tiles/hikebike/{Z}/{X}/{Y}.png'),
			//'piste'=>array(
			//		'txt'=>'OpenPisteMap tiles',
			//		'logo'=>'piste_logo.png',
			//		'url'=>''),
			//'sea'=>array(
			//		'txt'=>'OpenSeaMap tiles',
			//		'logo'=>'sea_logo.png',
			//		'url'=>''),
			// MapQuest
			'mapquest'=>array(
					'txt'=>'MapQuest tiles',
					'logo'=>'mq_logo.png',
					'url'=>'http://otile3.mqcdn.com/tiles/1.0.0/map/{Z}/{X}/{Y}.png')
	);
	protected $tileDefaultSrc = 'openstreetmap';

	// set up markers
	protected $markerPrototypes = array(
			// found at http://www.mapito.net/map-marker-icons.html
			// these are 17x19 px with a pointer at the bottom left
			'lighblue' => array('regex'=>'/^lightblue([0-9]+)$/',
					'extension'=>'.png',
					'shadow'=>false,
					'offsetImage'=>'0,-19',
					'offsetShadow'=>false
			),
			// openlayers std markers are 21x25px with shadow
			'ol-marker'=> array('regex'=>'/^marker(|-blue|-gold|-green|-red)+$/',
					'extension'=>'.png',
					'shadow'=>'marker_shadow.png',
					'offsetImage'=>'-10,-25',
					'offsetShadow'=>'-1,-13'
			),
			// these are 16x16 px
			'ww_icon'=> array('regex'=>'/ww_\S+$/',
					'extension'=>'.png',
					'shadow'=>false,
					'offsetImage'=>'-8,-8',
					'offsetShadow'=>false
			),
			// assume these are 16x16 px
			'rest' => array('regex'=>'/^(?!lightblue([0-9]+)$)(?!(ww_\S+$))(?!marker(|-blue|-gold|-green|-red)+$)(.*)/',
					'extension'=>'.png',
					'shadow'=>'marker_shadow.png',
					'offsetImage'=>'-8,-8',
					'offsetShadow'=>'-1,-1'
							)
	);
	protected $centerX, $centerY, $offsetX, $offsetY, $image;
	protected $zoom, $lat, $lon, $width, $height, $markers, $maptype, $kmlFileName, $gpxFileName, $geojsonFileName, $autoZoomExtent;
	protected $tileCacheBaseDir, $mapCacheBaseDir, $mediaBaseDir;
	protected $useTileCache = true;
	protected $mapCacheID = '';
	protected $mapCacheFile = '';
	protected $mapCacheExtension = 'png';

	/**
	 * Constructor.
	 * @param float $lat Latitude (x) of center of map
	 * @param float $lon Longitude (y) of center of map
	 * @param int $zoom Zoomlevel
	 * @param int $width Width in pixels
	 * @param int $height Height in pixels
	 * @param string $maptype Name of the map
	 * @param mixed $markers array of markers
	 * @param string $gpx GPX filename
	 * @param string $kml KML filename
	 * @param string $mediaDir Directory to store/cache maps
	 * @param string $tileCacheBaseDir Directory to cache map tiles
	 * @param boolean $autoZoomExtent Wheter or not to override zoom/lat/lon and zoom to the extent of gpx/kml and markers
	 */
	public function __construct($lat, $lon, $zoom, $width, $height, $maptype, $markers, $gpx, $kml, $geojson, $mediaDir, $tileCacheBaseDir, $autoZoomExtent=TRUE){
		$this->zoom = $zoom;
		$this->lat = $lat;
		$this->lon = $lon;
		$this->width = $width;
		$this->height = $height;
		// validate + set maptype
		$this->maptype = $this->tileDefaultSrc;
		if(array_key_exists($maptype,$this->tileInfo)) {
			$this->maptype = $maptype;
		}
		$this->markers = $markers;
		$this->kmlFileName = $kml;
		$this->gpxFileName = $gpx;
		$this->geojsonFileName = $geojson;
		$this->mediaBaseDir = $mediaDir;
		$this->tileCacheBaseDir= $tileCacheBaseDir.'/olmaptiles';
		$this->useTileCache = $this->tileCacheBaseDir !=='';
		$this->mapCacheBaseDir = $mediaDir.'/olmapmaps';
		$this->autoZoomExtent = $autoZoomExtent;
	}

	/**
	 *
	 * @param number $long
	 * @param number $zoom
	 * @return number
	 */
	public function lonToTile($long, $zoom){
		return (($long + 180) / 360) * pow(2, $zoom);
	}
	/**
	 *
	 * @param number $lat
	 * @param number $zoom
	 * @return number
	 */
	public function latToTile($lat, $zoom){
		return (1 - log(tan($lat * pi()/180) + 1 / cos($lat* M_PI/180)) / M_PI) /2 * pow(2, $zoom);
	}

	/**
	 *
	 */
	public function initCoords(){
		$this->centerX = $this->lonToTile($this->lon, $this->zoom);
		$this->centerY = $this->latToTile($this->lat, $this->zoom);
		$this->offsetX = floor((floor($this->centerX)-$this->centerX)*$this->tileSize);
		$this->offsetY = floor((floor($this->centerY)-$this->centerY)*$this->tileSize);
	}

	/**
	 * make basemap image.
	 */
	public function createBaseMap(){
		$this->image = imagecreatetruecolor($this->width, $this->height);
		$startX = floor($this->centerX-($this->width/$this->tileSize)/2);
		$startY = floor($this->centerY-($this->height/$this->tileSize)/2);
		$endX = ceil($this->centerX+($this->width/$this->tileSize)/2);
		$endY = ceil($this->centerY+($this->height/$this->tileSize)/2);
		$this->offsetX = -floor(($this->centerX-floor($this->centerX))*$this->tileSize);
		$this->offsetY = -floor(($this->centerY-floor($this->centerY))*$this->tileSize);
		$this->offsetX += floor($this->width/2);
		$this->offsetY += floor($this->height/2);
		$this->offsetX += floor($startX-floor($this->centerX))*$this->tileSize;
		$this->offsetY += floor($startY-floor($this->centerY))*$this->tileSize;

		for($x=$startX; $x<=$endX; $x++){
			for($y=$startY; $y<=$endY; $y++){
				$url = str_replace(array('{Z}','{X}','{Y}'),array($this->zoom, $x, $y), $this->tileInfo[$this->maptype]['url']);
				$tileData = $this->fetchTile($url);
				if($tileData){
					$tileImage = imagecreatefromstring($tileData);
				} else {
					$tileImage = imagecreate($this->tileSize,$this->tileSize);
					$color = imagecolorallocate($tileImage, 255, 255, 255);
					@imagestring($tileImage,1,127,127,'err',$color);
				}
				$destX = ($x-$startX)*$this->tileSize+$this->offsetX;
				$destY = ($y-$startY)*$this->tileSize+$this->offsetY;
				imagecopy($this->image, $tileImage, $destX, $destY, 0, 0, $this->tileSize, $this->tileSize);
			}
		}
	}

	/**
	 * Place markers on the map and number them in the same order as they are listed in the html.
	 */
	public function placeMarkers(){
		$count=0;
		$color=imagecolorallocate ($this->image,0,0,0 );
		$bgcolor=imagecolorallocate ($this->image,200,200,200 );
		$markerBaseDir = dirname(__FILE__).'/icons';
		// loop thru marker array
		foreach($this->markers as $marker) {
			// set some local variables
			$markerLat = $marker['lat'];
			$markerLon = $marker['lon'];
			$markerType = $marker['type'];
			// clear variables from previous loops
			$markerFilename = '';
			$markerShadow = '';
			$matches = false;
			// check for marker type, get settings from markerPrototypes
			if($markerType){
				foreach($this->markerPrototypes as $markerPrototype){
					if(preg_match($markerPrototype['regex'],$markerType,$matches)){
						$markerFilename = $matches[0].$markerPrototype['extension'];
						if($markerPrototype['offsetImage']){
							list($markerImageOffsetX, $markerImageOffsetY)  = split(",",$markerPrototype['offsetImage']);
						}
						$markerShadow = $markerPrototype['shadow'];
						if($markerShadow){
							list($markerShadowOffsetX, $markerShadowOffsetY)  = split(",",$markerPrototype['offsetShadow']);
						}
					}
				}
			}
			// create img resource
			if(file_exists($markerBaseDir.'/'.$markerFilename)){
				$markerImg = imagecreatefrompng($markerBaseDir.'/'.$markerFilename);
			} else {
				$markerImg = imagecreatefrompng($markerBaseDir.'/marker.png');
			}
			// check for shadow + create shadow recource
			if($markerShadow && file_exists($markerBaseDir.'/'.$markerShadow)){
				$markerShadowImg = imagecreatefrompng($markerBaseDir.'/'.$markerShadow);
			}
			// calc position
			$destX = floor(($this->width/2)-$this->tileSize*($this->centerX-$this->lonToTile($markerLon, $this->zoom)));
			$destY = floor(($this->height/2)-$this->tileSize*($this->centerY-$this->latToTile($markerLat, $this->zoom)));
			// copy shadow on basemap
			if($markerShadow && $markerShadowImg){
				imagecopy($this->image, $markerShadowImg, $destX+intval($markerShadowOffsetX), $destY+intval($markerShadowOffsetY),
				0, 0, imagesx($markerShadowImg), imagesy($markerShadowImg));
			}
			// copy marker on basemap above shadow
			imagecopy($this->image, $markerImg, $destX+intval($markerImageOffsetX), $destY+intval($markerImageOffsetY),
			0, 0, imagesx($markerImg), imagesy($markerImg));
			// add label
			imagestring ($this->image , 3 , $destX-imagesx($markerImg)+1 , $destY+intval($markerImageOffsetY)+1 , ++$count , $bgcolor );
			imagestring ($this->image , 3 , $destX-imagesx($markerImg) , $destY+intval($markerImageOffsetY) , $count , $color );
		};
	}

	/**
	 *
	 * @param string $url
	 * @return string
	 */
	public function tileUrlToFilename($url){
		return $this->tileCacheBaseDir."/".str_replace(array('http://'),'',$url);
	}

	/**
	 *
	 * @param string $url
	 */
	public function checkTileCache($url){
		$filename = $this->tileUrlToFilename($url);
		if(file_exists($filename)){
			return file_get_contents($filename);
		}
	}

	public function checkMapCache(){
		$this->mapCacheID = md5($this->serializeParams());
		$filename = $this->mapCacheIDToFilename();
		if(file_exists($filename)) return true;
	}

	public function serializeParams(){
		return join("&",array($this->zoom,$this->lat,$this->lon,$this->width,$this->height, serialize($this->markers),$this->maptype, $this->kmlFileName, $this->gpxFileName, $this->geojsonFileName));
	}

	public function mapCacheIDToFilename(){
		if(!$this->mapCacheFile){
			$this->mapCacheFile = $this->mapCacheBaseDir."/".$this->maptype."/".$this->zoom."/cache_".substr($this->mapCacheID,0,2)."/".substr($this->mapCacheID,2,2)."/".substr($this->mapCacheID,4);
		}
		return $this->mapCacheFile.".".$this->mapCacheExtension;
	}

	/**
	 * Recursively create the directory.
	 * @param string $pathname The directory path.
	 * @param int $mode File access mode. For more information on modes, read the details on the chmod manpage.
	 */
	public function mkdir_recursive($pathname, $mode){
		is_dir(dirname($pathname)) || $this->mkdir_recursive(dirname($pathname), $mode);
		return is_dir($pathname) || @mkdir($pathname, $mode);
	}

	/**
	 * Write a tile into the cache.
	 * @param string $url
	 * @param mixed $data
	 */
	public function writeTileToCache($url, $data){
		$filename = $this->tileUrlToFilename($url);
		$this->mkdir_recursive(dirname($filename),0777);
		file_put_contents($filename, $data);
	}

	/**
	 * Fetch a tile and (if configured) store it in the cache.
	 * @param string $url
	 */
	public function fetchTile($url){
		if($this->useTileCache && ($cached = $this->checkTileCache($url))) return $cached;

		$_UA = 'Mozilla/4.0 (compatible; DokuWikiSpatial HTTP Client; '.PHP_OS.')';
		if(function_exists("curl_init")){
			// use cUrl
			$ch = curl_init();
			curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
			curl_setopt($ch, CURLOPT_USERAGENT, $_UA);
			curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 10);
			curl_setopt($ch, CURLOPT_URL, $url);
			$tile = curl_exec($ch);
			curl_close($ch);
		} else {
			// use file_get_contents
			global $conf;
			$opts = array(
					'http'=>array(
							'method'=>"GET",
							'header'=>"Accept-language: en\r\n" .
									"User-Agent: $_UA\r\n".
									"accept: image/png\r\n",
							'proxy' => "tcp://".$conf['proxy']['host'] . ":" . $conf['proxy']['port'],
							'request_fulluri' => true,
					)
			);
			$context = stream_context_create($opts);
			$tile = file_get_contents($url, false, $context);
		}
		if($tile && $this->useTileCache){
			$this->writeTileToCache($url,$tile);
		}
		return $tile;
	}

	/**
	 * Draw gpx trace on the map.
	 */
	public function drawGPX(){
		$col = imagecolorallocatealpha($this->image, 0, 0, 255, .4*127);
		$gpxgeom = geoPHP::load(file_get_contents($this->gpxFileName),'gpx');
		$this->drawGeometry($gpxgeom, $col);
	}

	/**
	 * Draw geojson on the map.
	 */
	public function drawGeojson(){
		$col = imagecolorallocatealpha($this->image, 255, 0, 255, .4*127);
		$gpxgeom = geoPHP::load(file_get_contents($this->geojsonFileName),'json');
		$this->drawGeometry($gpxgeom, $col);
	}

	/**
	 * Draw kml trace on the map.
	 */
	public function drawKML(){
		// TODO get colour from kml node (not currently supported in geoPHP)
		$col = imagecolorallocatealpha($this->image, 255, 0, 0, .4*127);
		$kmlgeom = geoPHP::load(file_get_contents($this->kmlFileName),'kml');
		$this->drawGeometry($kmlgeom, $col);
	}

	/**
	 * Draw geometry or geometry collection on the map.
	 * @param Geometry $geom
	 * @param int $colour drawing colour
	 */
	private function drawGeometry($geom, $colour){
		switch ($geom->geometryType()) {
			case 'GeometryCollection':
				// recursively draw part of the collection
				for ($i = 1; $i < $geom->numGeometries()+1; $i++) {
					$_geom = $geom->geometryN($i);
					$this->drawGeometry($_geom, $colour);
				}
				break;
			case 'MultiPolygon':
				// TODO implement / do nothing
				break;
			case 'MultiLineString':
				// TODO implement / do nothing
				break;
			case 'MultiPoint':
				// TODO implement / do nothing
				break;
			case 'Polygon':
				$this->drawPolygon($geom, $colour);
				break;
			case 'LineString':
				$this->drawLineString($geom, $colour);
				break;
			case 'Point':
				$this->drawPoint($geom, $colour);
				break;
			default:
				//draw nothing
				break;
		}
	}

	/**
	 * Draw a line on the map.
	 * @param LineString $line
	 * @param int $colour drawing colour
	 */
	private function drawLineString($line, $colour){
		imagesetthickness($this->image,2);
		for ($p = 1; $p < $line->numGeometries(); $p++) {
			// get first pair of points
			$p1 = $line->geometryN($p);
			$p2 = $line->geometryN($p+1);
			// translate to paper space
			$x1 = floor(($this->width/2)-$this->tileSize*($this->centerX-$this->lonToTile($p1->x(), $this->zoom)));
			$y1 = floor(($this->height/2)-$this->tileSize*($this->centerY-$this->latToTile($p1->y(), $this->zoom)));
			$x2 = floor(($this->width/2)-$this->tileSize*($this->centerX-$this->lonToTile($p2->x(), $this->zoom)));
			$y2 = floor(($this->height/2)-$this->tileSize*($this->centerY-$this->latToTile($p2->y(), $this->zoom)));
			// draw to image
			imageline ($this->image, $x1, $y1, $x2, $y2, $colour);
		}
		imagesetthickness($this->image,1);
	}

	/**
	 * Draw a point on the map.
	 * @param Point $point
	 * @param int $colour drawing colour
	 */
	private function drawPoint($point, $colour){
		imagesetthickness($this->image,2);
		// translate to paper space
		$cx = floor(($this->width/2)-$this->tileSize*($this->centerX-$this->lonToTile($point->x(), $this->zoom)));
		$cy = floor(($this->height/2)-$this->tileSize*($this->centerY-$this->latToTile($point->y(), $this->zoom)));
		$r = 5;
		// draw to image
		// imageellipse($this->image, $cx, $cy,$r, $r, $colour);
		imagefilledellipse ($this->image, $cx, $cy, $r, $r, $colour);
		// don't use imageellipse because the imagesetthickness function has
		// no effect. So the better workaround is to use imagearc.
		imagearc($this->image, $cx, $cy, $r, $r, 0, 359, $colour);
		imagesetthickness($this->image,1);
	}

	/**
	 * Draw a polygon on the map.
	 * @param Polygon $polygon
	 * @param int $colour drawing colour
	 */
	private function drawPolygon($polygon, $colour){
		// TODO implementation of drawing holes,
		// maybe draw the polygon to an in-memory image and use imagecopy, draw polygon in col., draw holes in bgcol?

		//print_r('Polygon:<br />');
		//print_r($polygon);

		$extPoints = array();
		// extring is a linestring actually..
		$extRing = $polygon->exteriorRing();

		for ($i = 1; $i < $extRing->numGeometries(); $i++) {
			$p1 = $extRing->geometryN($i);
			$x = floor(($this->width/2)-$this->tileSize*($this->centerX-$this->lonToTile($p1->x(), $this->zoom)));
			$y = floor(($this->height/2)-$this->tileSize*($this->centerY-$this->latToTile($p1->y(), $this->zoom)));
			$extPoints[]=$x;
			$extPoints[]=$y;
		}
		//print_r('points:('.($i-1).')<br />');
		//print_r($extPoints);
		//imagepolygon ($this->image, $extPoints, $i-1, $colour );
		imagefilledpolygon($this->image, $extPoints, $i-1, $colour );
	}

	/**
	 * add copyright and origin notice and icons to the map.
	 */
	public function drawCopyright(){
		$logoBaseDir = dirname(__FILE__).'/'.'logo/';
		$logoImg = imagecreatefrompng($logoBaseDir.$this->tileInfo['openstreetmap']['logo']);
		$textcolor = imagecolorallocate($this->image, 0, 0, 0);
		$bgcolor = imagecolorallocate($this->image, 200, 200, 200);

		imagecopy($this->image, $logoImg, 0, imagesy($this->image)-imagesy($logoImg), 0, 0, imagesx($logoImg), imagesy($logoImg));
		imagestring($this->image , 1, imagesx($logoImg)+2 ,imagesy($this->image)-imagesy($logoImg)+1 ,$this->tileInfo['openstreetmap']['txt'], $bgcolor );
		imagestring($this->image , 1, imagesx($logoImg)+1 ,imagesy($this->image)-imagesy($logoImg) ,$this->tileInfo['openstreetmap']['txt'] ,$textcolor );

		// additional tile source info, ie. who created/hosted the tiles
		if ($this->maptype!='openstreetmap') {
			$iconImg = imagecreatefrompng($logoBaseDir.$this->tileInfo[$this->maptype]['logo']);
			imagecopy($this->image, $iconImg, imagesx($logoImg)+1, imagesy($this->image)-imagesy($iconImg), 0, 0, imagesx($iconImg), imagesy($iconImg));
			imagestring($this->image, 1, imagesx($logoImg)+imagesx($iconImg)+4, imagesy($this->image)-ceil(imagesy($logoImg)/2)+1, $this->tileInfo[$this->maptype]['txt'], $bgcolor );
			imagestring($this->image, 1, imagesx($logoImg)+imagesx($iconImg)+3, imagesy($this->image)-ceil(imagesy($logoImg)/2), $this->tileInfo[$this->maptype]['txt'], $textcolor );
		}
	}

	/**
	 * make the map.
	 */
	public function makeMap(){
		$this->initCoords();
		$this->createBaseMap();
		if(!empty($this->markers))$this->placeMarkers();
		if(file_exists($this->kmlFileName)) $this->drawKML();
		if(file_exists($this->gpxFileName)) $this->drawGPX();
		if(file_exists($this->geojsonFileName)) $this->drawGeojson();

		$this->drawCopyright();
	}

	/**
	 * Calculate the lat/lon/zoom values to make sure that all of the markers and gpx/kml are on the map.
	 * @param float $paddingFactor buffer constant to enlarge (>1.0) the zoom level
	 */
	private function autoZoom($paddingFactor=1.0){
		$geoms = array();
		$geoms[] = new Point($this->lon, $this->lat);
		if(!empty($this->markers)){
			foreach($this->markers as $marker){
				$geoms[] = new Point($marker['lon'],$marker['lat']);
			}
		}
		if(file_exists($this->kmlFileName)){
			$geoms[] = geoPHP::load(file_get_contents($this->kmlFileName),'kml');
		}
		if(file_exists($this->gpxFileName)) {
			$geoms[] = geoPHP::load(file_get_contents($this->gpxFileName),'gpx');
		}
		if(file_exists($this->geojsonFileName)) {
			$geoms[] = geoPHP::load(file_get_contents($this->geojsonFileName),'geojson');
		}

		if (count($geoms)<=1) return;

		$geom = new GeometryCollection($geoms);
		$centroid=$geom->centroid();
		$bbox=$geom->getBBox();

		// determine vertical resolution, this depends on the distance from the equator
		//	$vy00 = log(tan(M_PI*(0.25 + $centroid->getY()/360)));
		$vy0 = log(tan(M_PI*(0.25 + $bbox['miny']/360)));
		$vy1 = log(tan(M_PI*(0.25 + $bbox['maxy']/360)));
		$zoomFactorPowered = ($this->height/2) / (40.7436654315252 * ($vy1 - $vy0));
		$resolutionVertical = 360 / ($zoomFactorPowered * $this->tileSize);
		// determine horizontal resolution
		$resolutionHorizontal = ($bbox['maxx']-$bbox['minx']) / $this->width;
		$resolution = max($resolutionHorizontal, $resolutionVertical) * $paddingFactor;
		$zoom = log(360 / ($resolution * $this->tileSize), 2);

		$this->zoom = floor($zoom);
		$this->lon=$centroid->getX();
		$this->lat=$centroid->getY();
	}

	/**
	 * get the map, this may return a reference to a cached copy.
	 * @return string url relative to media dir
	 */
	public function getMap(){
		if($this->autoZoomExtent) $this->autoZoom() ;

		// use map cache, so check cache for map
		if(!$this->checkMapCache()){
			// map is not in cache, needs to be build
			$this->makeMap();
			$this->mkdir_recursive(dirname($this->mapCacheIDToFilename()),0777);
			imagepng($this->image,$this->mapCacheIDToFilename(),9);
		}
		$this->doc =$this->mapCacheIDToFilename();
		// make url relative to media dir
		return str_replace($this->mediaBaseDir, '', $this->doc);
	}
}