[OpenLayers-Users] Accessing a callback | Getting a polygon's vertices

[Harry Lam]

Hello community!  This is my first post; I hope I'm not asking too trivial a
question.  :)  I'll get right into it:



Based on this example --
http://www.openlayers.org/dev/examples/drag-feature.html -- I have put a
similar control on my website where I can draw a polygon on my map.  So what
I want to do is get the coordinates of my polygon’s vertices after I finish
drawing it.



According to

http://dev.openlayers.org/releases/OpenLayers-2.8/doc/apidocs/files/OpenLayers/Handler/Polygon-js.html

there are callback functions called ‘point’ and ‘done’ that should be able
to give me what I want.



My question is how do I get control of those functions?  I think I am a
little lacking in syntax knowledge as to how to set it up.


For example I have:

var drawpoly = new OpenLayers.Control.DrawFeature(vectorLayer,
OpenLayers.Handler.Polygon);

map.addControl(drawpoly);

which takes care of enabling the drawing feature.  But I don’t know how to
get to the done() callback function from here.



On a separate note, I found this example online:

var drawpoly = new OpenLayers.Control.DrawFeature(vectorLayer,
OpenLayers.Handler.Polygon, {'featureAdded': polygonAdded});

...

polygonAdded = function (feature) {

 //Yay, I can do stuff here!

}

which is pretty close to what I want, but I think the object passed to it is
not the polygon object I want to manipulate.  (Or is it?)


If anyone has a better way to get the coordinates of a polygon (I assume I'd
get an x-y pixel value first and would have to convert to lat/lng), I'd love
to hear that, too.  But knowing how to get to the callbacks would also be
useful in future applications.  :)



Thanks for reading and considering!


--Harry

mr.harry.lam at gmail.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.osgeo.org/pipermail/openlayers-users/attachments/20091014/f4682c76/attachment.html