[OpenLayers-Dev] refreshing an image with new parameters

Art Lembo artlembo at gmail.com
Tue Jan 5 19:07:22 EST 2010


I'm using Manifold GIS as a back-end GIS server.  It works really great,
except the WMS capabilities are horribly slow.  One thing that is fast is
the ability to generate an image of the GIS output by passing a url to a
Manifold IMS site:


var graphic = new OpenLayers.Layer.Image (
   'My Map',
   'http://blah,blah,blah/map.asp?[layers],[centerX],[centerY],[ScaleX],[ScaleY],[spatialSQL
process],etc...

so, this works really fast (instantaneous), and gets me a layer inside my
OpenLayers site.  And, I can even pass it an analysis function and it does
that too.

Now, when I zoom in or pan, obviously it just works with that initial image
(i.e. var graphic) that was grabbed from the init function.  So, of course
zoom-ins begin to pixelate rather quickly.

I would like the ability to refresh the initial image every time I zoom in
or pan, using new centerX,centerY, and scales.  That is, some function that
gets thrown before the the image is redrawn.

I guess it is an image Refresh, but that doesn't quite do it.  My hope is
to:

1.  When the user zooms in I grab the new centerX, centerY, and scales from
the browser, and reconstruct the url to hit the server again and show me an
updated version, which will now be the zoomed in version of the layers.

Any advice?

thanks!
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