Openlayers - coordinates from pixel incorrect

Question

I'm trying to get coordinates from a mouse click on the map.

The coordinates are right until I scroll the map. After that they are wrong - they are shifted from the position of the click. If I change the zoomlevel, next coordinates are right until I scroll the map again.

First I thought getLayerPxFromViewPortPx returns wrong value, because if I scroll to the left and to the top and click there it gives me a pixel with negative x and y. But I suppose it is the way it works and x and y are relative to the layers center.

Here is what I have:

map.events.register("click", map, function(e){
        var opx = map.getLayerPxFromViewPortPx(e.xy) ;
        var lonlat = map.getLonLatFromPixel(opx);
        console.log(lonlat)

        var marker = new OpenLayers.Marker(lonlat);
        markers.addMarker(marker)

What else could be failing?

Answer 1

I changed getLonLatFromPixel() with var lonlat = map.getLonLatFromViewPortPx(e.xy) and now it seems working. However I'm still curious why did the previous fail.