[OpenLayers-Dev] How to dynamically set maxExtent and

Matt Priour mpriour at kestrelcomputer.com
Thu May 26 11:25:30 EDT 2011

First, this question is suited to the user's list not the developer's list. The developer's list is for questions or discussions about developments in the actual OpenLayers library, not using OpenLayers for development.

You can just set the restricted extent directly on the layers of interest once the selection is made

Thirdly if you want to precisely control things yourself you can listen to and react to the map's 'movestart' & 'moveend' events. and also the 'move' event if you want finer control.

Cache the location when movestart fires
Test the current location (extent, zoom, etc) as move or moveend fires
If using move event, then if the location is within the limit then change the cached location to the current location
When moveend fires, if the map is outside of the acceptable bounds for the area you are focusing on, then move it back to the cached location programattically (ie map.setCenter(....) )

Matt Priour
Kestrel Computer Consulting

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Message: 1
Date: Wed, 25 May 2011 09:04:55 -0700
From: "Mark K. Zanfardino" <mzanfardino at gmail.com>
Subject: [OpenLayers-Dev] How to dynamically set maxExtent and
To: OpenLayers-Dev Dev <dev at openlayers.org>
Message-ID: <4DDD28A7.9080504 at gmail.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

What I'm trying to do:
I'm rending a map for an entire county. I have a simply html select 
option of extents that I wish to use to set focus on the map. I need to 
restrict the user from being able to zoom 'out' (pull back and see the 
entire county) or slide 'away' (drag the map to another area) after an 
option has been selected.

I currently initialize the map to the county view when the page loads 
(see http://pastebin.com/jSmnHtwS for HTML). I have written a function 
which will zoom to a new extent based on the selection of the option 
list (see http://pastebin.com/WBX0rmxz for JavaScript). All this works 
fine, but I'm stuck with how I can restrict the user from zooming 'out' 
or slipping 'away' from the focused extent.

I'm looking for any suggestions on what might be the best approach to 
achieve my objective.


Mark Zanfardino

PS - My apologies if this shows up as a duplicate. I received a notice 
that the first email I sent was quarantined do to the attachment of the 

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