kml - Openlayers obtaining centroid of a vector layer feature and using it to set the center of the map -

the code below uses absolute position center of map want set center according vector layer feature brought in kml file - possible? i've looked @ getcentroid can't syntax right?

map = new openlayers.map("map"); var mapnik = new openlayers.layer.osm(); //set centre position converting wgs mercator var wgs84 = new openlayers.projection("epsg:4326"); var fromprojection = new openlayers.projection("epsg:4326");   // transform wgs 1984 var toprojection   = new openlayers.projection("epsg:900913"); // spherical mercator projection var position       = new openlayers.lonlat(4.891280,52.373690).transform( fromprojection, toprojection);  var layer = new openlayers.layer.vector("vectorlayer", {     projection: wgs84,     strategies: [new openlayers.strategy.fixed()],     protocol: new openlayers.protocol.http({         url: "kmlfile.kml",   //<-- relative or absolute url .osm file         format: new openlayers.format.kml()     }),     stylemap: new openlayers.stylemap({       "default": {             //pointradius: "${radius}",             fillcolor: "blue",             fillopacity: 0.1,             strokecolor: "#5555ff",             strokewidth: 2,             strokeopacity: 0.8        }         ,       "select": {           fillcolor: "#8aeeef",           strokecolor: "#32a8a9"       }     }) });  map.addlayers([mapnik, layer]);  map.addcontrol(new openlayers.control.layerswitcher());  var scaleline = new openlayers.control.scaleline(); map.addcontrol(scaleline);   //set centre of map , zoom level map.setcenter(position, 10 ); 

try (where layer vector based on code):

var bounds = layer.geometry.bounds; map.zoomtoextent(bounds); 

or

var bounds = layer.geometry.bounds; map.setcenter(bounds.getcenterlonlat());