[Chameleon] Custom Query Widget

Eric Bridger eric at gomoos.org
Wed Jan 12 13:13:52 EST 2005


At the request of a user I struggled with this issue for quite a few
days. Last night the reason for my failure suddenly came to me, so I'm
posting to see if anyone has an alternative approach.

The request: The project I'm working on uses a time stamp to filter most
of the WMS and Postgis layers on the map. The user wanted a new query
type tool which would allow him to click a symbol on the map, query the
time stamp data behind the symbol, then use the returned results (a new
time stamp) to reset the time stamp for the whole map.

It finally came to me today (Chameleon of course hides a lot of the gory
details) that this cannot be accomplished simply with Chameleon because:
the map must be drawn (or created with the old filters) BEFORE any query
can be executed. Then the map would have to be re-drawn or re-created
with the new filter.

In a pure mapscript application, this can be done. I.e. create the
current map, i.e. set proper layers on, setFilters, zoom,etc. Execute
the query, then create a new map, set new Filters, save the image.

The question is whether this can be done in Chameleon?  If so, any ideas
on how to go about it? 

Eric

P.S. Congrats on the 2.0 Release.





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