[mapserver-users] UTFGrid and Cluster, feature distinction: 0, single or clustered

[Alexandre Dubé]

Hello MapServer community,

   I'm using the new UTFGrid [1] feature in MapServer in addition with 
Clusters [2] in an OpenLayers mapping application.  I'm trying to 
implement the following feature: when the user clicks on a single point, 
a popup gets shown (this works already) and when he/she clicks on a 
clustered feature, then it must show different popup, without any info 
about the features inside, nor the extent of the features, but 
containing a simple link to invite the user to zoom in more.

   So basically, I'm looking for a way for the returned utfgrid data to 
know if the clicked element on the map is either: a single feature, a 
clustered feature or nothing at all.  I thought I was close to a 
solution, but it didn't work as I expected.  I thought of using the 
FeatureCount inside the UTFDATA and then use the value returned to 
determine the correct type:

         UTFDATA '{"c":[Cluster:FeatureCount]}'

   But the utf data only returns 2 values: 1 and 2.  It returns 1 when 
it's a single feature, else 2 whenever it's a clustered feature 
(regardless of the actual real feature count) and it also returns 2 when 
the user clicks on no feature at all.  I'm not sure if my approach is a 
correct one, though...

   Does someone have any idea how I could accomplish what I'm trying to 
do ?  I'm using a trunk version of MapServer I haven't updated for a 
couple months.

Many thanks,

Alexandre

[1] http://mapserver.org/development/rfc/ms-rfc-93.html
[2] http://mapserver.org/mapfile/cluster.html