Time for Action – Using scales

Using scales is another way we can control the zoom levels on our map. Let's take a look.

1. Create your map object using minScale and maxScale as follows:

   map = new OpenLayers.Map('map_element', { 
       controls: [ 
           new OpenLayers.Control.Navigation(), 
           new OpenLayers.Control.PanZoomBar(), 
           new OpenLayers.Control.LayerSwitcher() 
       ], 
       maxScale: 27683990.15625, 
       minScale: 221471921.25
   });

2. You should see something like this:

   

3. Now, let's go back to the code and recreate our map object. This time, we'll pass in a scales array.

   //Create a map with an empty array of controls 
   map = new OpenLayers.Map('map_element', { 
       controls: [ 
           new OpenLayers.Control.Navigation(), 
           new OpenLayers.Control.PanZoomBar(), 
           new OpenLayers.Control.LayerSwitcher() 
       ], 
       scales: [ 55367980.3125, 27683990.15625, 13841995.078125, 6920997.5390625],
   });

4. You should see something like this:

   

What Just Happened?

We just used scales to...