我在openlayers中有以下代码
<script defer="defer" type="text/javascript">
var map = new OpenLayers.Map('map');
var wms = new OpenLayers.Layer.WMS("OpenLayers WMS",
"http://vmap0.tiles.osgeo.org/wms/vmap0", { layers: 'basic' });
var dm_wms = new OpenLayers.Layer.WMS(
"Canadian Data",
"http://www2.dmsolutions.ca/cgi-bin/mswms_gmap",
{
layers: "bathymetry,land_fn,park,drain_fn,drainage," +
"prov_bound,fedlimit,rail,road,popplace",
transparent: "true",
format: "image/png"
}, { isBaseLayer: true }
);
var vectorLayer = new OpenLayers.Layer.Vector("Overlay");
map.setBaseLayer(vectorLayer);
OpenLayers.Geometry.Point(77.391026, 28.535516), { some: 'data' }, { externalGraphic: 'Image/map-icons/Banquet_and_Marriage_halls.png', graphicHeight: 21, graphicWidth: 21 });
var center = new OpenLayers.Geometry.Point(77.391026, 28.535516);
center.transform(new OpenLayers.Projection("EPSG:4326"), map.getProjectionObject());
map.setCenter(new OpenLayers.LonLat(77, 28), 4);
var markers = new OpenLayers.Layer.Markers("Markers");
var ll = new OpenLayers.LonLat(77.391026, 28.535516);
var popupClass = OpenLayers.Popup.Anchored;
var popupContentHTML = '<div style="height:40px;">Hello Noida</div>';
addMarker(ll, popupClass, popupContentHTML, true);
ll = new OpenLayers.LonLat(74.613647, 30.914007);
popupClass = OpenLayers.Popup.Anchored;
popupContentHTML = '<div style="height:40px;">Hello Punjab</div>';
addMarker(ll, popupClass, popupContentHTML, true);
map.addLayers([wms, dm_wms, markers]);
var feature;
var popup = null;
function addMarker(ll, popupClass, popupContentHTML, closeBox, overflow) {
feature = new OpenLayers.Feature(markers, ll);
feature.closeBox = closeBox;
feature.popupClass = popupClass;
feature.data.popupContentHTML = popupContentHTML;
feature.data.overflow = (overflow) ? "auto" : "hidden";
var marker = feature.createMarker();
var markerClick = function (evt) {
//alert(popup);
if (popup != null)
popup.hide();
popup = this.createPopup(this.closeBox);
popup.contentSize = new OpenLayers.Size(10, 20);
map.addPopup(popup);
popup.show();
};
marker.events.register("mousedown", feature, markerClick);
markers.addMarker(marker);
}
</script>
如果我删除 map.setCenter(),一切都会正常工作。但是当我尝试在我的代码中使用它时,我的地图突然消失了。我的控制台窗口中也出现以下错误:
Cannot call method 'containsLonLat' of null
我在这个网站上尝试了所有可能的方法,但没有到达任何地方.. 可能是什么问题?