Option for showing legend items for solely such layer classes drawn in the map

[andreas.maul@…]

Some mapserver applications with e.g. geological or pedological layers have a 
lot of different classes for the different geological units.  Most of them are 
not simultaneously shown in the map but appear always in the legend which can 
be very extensive although not needed.
It would be nice to have the option for these cases that only such symbols 
emerge in the legend for such classes which are actually shown in the map.
Regards,
Andreas

[dmorissette]

See what I wrote about this in bug 1796 comment #2:

[layer_inextent] reminds me of an old request that we had to produce legends
that contain only classes that have at least one corresponding shape visible on
the map (we never did it in the end). This would require that we track the
number of features drawn per class in a layer, or at least track whether a class
was hit or not during map rendering, which we don't do at the moment. Plus, I
think it's possible for the legend to be generated without rendering a map, when
using MapScript for instance, so depending on the time at which the legend is
generated in a script execution you could get different results.