How to load layers depending on zoom level?

Question

I want to control the zoom in OpenLayers.

When the zoom is 3 I want to load KML1 and when the zoom is 4 i want to load KML2.

Could you please advise me how I can

Answer 1

a way to accomplish that is to register an event on event "zoomend" on your map with something like

map.events.register(type, obj, listener);

You can find more info there: http://dev.openlayers.org/releases/OpenLayers-2.11/doc/apidocs/files/OpenLayers/Map-js.html

Maybe you should also load both of your kml and then hide / show the correct layer depend on the zoom level.

Answer 2

As j_freyre mentioned you should register a function, which changes the visibility of your KML-layers, to the "zoomend"-event. In your case it has to look like this:

map.events.register("zoomend", map, zoomChanged);

zoomChanged()
{
  zoom = map.getZoom();
  if (zoom == 3)
  {
    kml1.setVisibility (true);
    kml2.setVisibility (false);
  }
  else if (zoom == 4)
  {
    kml1.setVisibility (false);
    kml2.setVisibility (true);
  }
}