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 control the zoom-event?

ischas · Answer 1 · 2013-04-11T17:27:22.393

7

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);
  }
}

edited Apr 11 '13 at 17:27

answered Mar 28 '13 at 08:04

ischas

169
2
12

It's more efficient to store the `getZoom` value in a variable like `zoom = map.getZoom();` and then check it out on the if statements like `if (zoom == 3)`. In this way you're avoiding to call `getZoom` each time. – Mahdi Apr 11 '13 at 09:02

score 3 · Accepted Answer · answered May 23 '12 at 13:16

3

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.

answered May 23 '12 at 13:16

j_freyre

4,623
2
30
47

I want that every change of the zoom to do something.Th event that I inserted is zoom_changed but it is not working.maybe you have the list of all the events – user1365697 May 24 '12 at 06:44

How to load layers depending on zoom level?

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