I would like to be able to specify a color replacement table for the new SVG-based symbolizers.
E.g. there is all those nice icons like http://www.sjjb.co.uk/mapicons/svg/accommodation_alpinehut.svg that Brian converts to (mono-)colored PNGs with a script, like http://www.sjjb.co.uk/mapicons/png/accommodation_alpinehut.p.32.png and http://www.sjjb.co.uk/mapicons/png/accommodation_alpinehut.n.32.png and even http://www.sjjb.co.uk/mapicons/png/accommodation_alpinehut.glow.32.png
What the conversion script does is basically just a sed on a certain color in the SVG file.
While I don't expect this halo effect just yet, it would be nice to be able to do that from within Mapnik.
I could also use a feature like this for hiking symbols, which (in the east of Germany and in Czech) are often the same simple shapes like a dot, bar, slash etc., but come in different colors.
/cc @cmarqu - I think he was the original ticket filer back in the trac days
This is working and in place now in master: see #1410. Things like alpha are now supported as of cd66495. This will only work with simple shapes or single paths - or at least cases where it is okay for all paths to accept the same colors.