[mapserver-users] Highlighting a polygon

[Robert Sanson]

Dear Subha
 
I would set up two states layers in Mapserver. One is a generic one that responds to GetFeatureInfo requests from OpenLayers. The second one has a FILTER section. On the click handler in OpenLayers, once you click on a state and get it's name via a GetFeatureInfo request, then load the second States layer by passing the name of the state to mapserver with variable substitution.
 
I do something similar with Roads. My second layer would be defined something like the following:
 
 LAYER
  NAME crs_roads
  GROUP "CRS"
  TYPE LINE
  STATUS ON
  DATA ../data/nztm/crs/roads_1207
  FILTERITEM 'NAME'
  FILTER '%road%'
In OpenLayers I would send the WMS request like:
 
selrd = new OpenLayers.Layer.WMS( "Selected Road",
                         "http://10.65.192.1/cgi-bin/gsswms.exe?road="+rdname ( 'http://10.65.192.1/cgi-bin/gsswms.exe?road="+rdname' )+"&",
                          {layers: ['crs_roads'], transparent: 'true', format: "image/png"},
                          {singleTile: true, isBaseLayer: false, maxResolution: 500000, visibility: true} );
              map.addLayer(selrd);
 
where rdname is variable holding the road name (in your case State name) retrieved from the click event.
 
Kind regards,
 
Robert Sanson

>>> Subha Ramakrishnan <subha at gslab.com> 29/09/2008 5:14 p.m. >>>
Hi,

I am using openlayers and mapserver to overlay an image of the states of 
india on google map.
Is there a way to color/highlight a state on clicking, using mapserver?
I am not using any mapscript. So are there any settings to be done in 
map file which will enable this? And how do i send a request from 
openlayers to get the image from mapserver?

Expecting a reply.

Thanks.
Subha
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