[OpenLayers-Dev] overviewmap and non-WMS baselayers

Steven M. Ottens steven at minst.net
Thu Oct 4 08:19:27 EDT 2007

Hi All,

I'm struggling to get overviewmap working with google sperical mercator. 
The closest I've gotten is that you need to resize the window to get the 
extent correct. I've used the following html file:

At last I decided to investigate if it works with normal/old fashioned 
google or any other non-WMS layer for that matter.
So I tried to just add an overviewmap to the plain google.html example 
resulting in this code:

But here I get the same error I initially got in google-sm:
bounds has no properties
 var center = bounds.getCenterLonLat();
This is to trace back to a missing baseLayer in the overviewMap; Map.js 
calls this function:
1282 getMaxExtent: function () {
1283     var maxExtent = null;
1284     if (this.baseLayer != null) {
1285         maxExtent = this.baseLayer.maxExtent;
1286     }
1287     return maxExtent;
1288 },

and this.baseLayer = null in this case

To investigate further I tried TMS this way:

And this time it gave me the wrong extent, just like google-sm in the 
first example. So now I am wondering if there's something in overviewmap 
wrong, or in the way I invoke overviewmap. If anyone with a better 
insight in OverviewMap.js can help me out, I'd really appreciate it.


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