[OpenLayers-Users] Mapping the globe with OpenLayers

[Ryan Hofschneider]

On Jul 22, 2008, at 11:03 AM, Jani Patokallio wrote:

> 5) Can I render arbitrary text instead of icons on the map?  I'd  
> like to
> label airports with codes (JFK, LHR, NRT, ...), but there are 17,576  
> of
> them.

I last looked at this around the time that OpenLayers 2.5 was newly  
released, so there may be a better way by now (or perhaps all along).

There has also been some recent, preliminary work on vector labels  
(see http://openlayers.org/pipermail/dev/2008-July/003153.html).

What I did for OpenLayers 2.5, in brief:

1. Incorporated the Marker.Label patch:
http://trac.openlayers.org/ticket/751

2. Created a subclass of OpenLayers.Feature.WFS (e.g.,  
OpenLayers.Feature.WFS.Foo). To use a specific subclass during layer  
instantiation:
var foolayer = new OpenLayers.Layer.WFS( "Foo", "/geoserver/wfs",  
params, {featureClass: OpenLayers.Feature.WFS.Foo);

3. Overrode processXMLNode() to initialize a variable with the desired  
label value.

4. Overrode defaultIcon() in my subclass to use a transparent png.

5. Overrode createMaker to call OpenLayers.Marker.Label instead of  
OpenLayers.Marker


You probably realize this, but those 17K points aren't going to  
perform well in a global view -- check out the option that controls  
feature download based on zoom level.

Cheers,
Ryan