[Qgis-developer] QWC and WMS FILTER in qgis mapserver

Alessandro Pasotti apasotti at gmail.com
Thu Jan 9 06:13:31 PST 2014


I'm trying to build an improved legend for QWC as explained in my previous

The idea was to create an helper script (like those already existing for
search) that returns json data and base64-encoded images to allow building
of the legend on the client. The script currently query GetStyles to get
the classes and get the image for each RULE with GetLegendGraphic, so far
so good.

The legend is then cached on the file system for speed.

The important missing point is that I would be able to build an interactive
legend, so that the user can for example click on individual classes and
change visibility or maybe highlight or zoom to extent, this is why I need

The work is almost done, but I've come to a stop with filter generation. I
can easily obtain ogc filters for each rule (they are in the SLD) but it
seems like the FILTER parameter in QGIS mapserver WMS follows its own

The only option I see now is to convert OGC FILTER to the custom QGIS
FILTER syntax. This is easy for simpler rules but can become difficult when
rules have complex conditions.

Any idea or suggestion ?

Since OGC FILTER parsing is already implemented in QGIS, would it be
possible make the WMS understand OGG FILTER encoding in addition to the
custom syntax?

Alessandro Pasotti
w3:   www.itopen.it
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