[OpenLayers-Users] Mapping the globe with OpenLayers
Ryan Hofschneider
ryan.hofschneider at gmail.com
Tue Jul 22 14:50:08 EDT 2008
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
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