Allow Shield Symbolizer to build an image filename from k:v pairs

[artemp]

Thousands of distinct highway shields add visual cues to the North American highway lifestyle. ShieldSymbolizer expects all shields to start with a single base graphic. Shields from ubiquitous red over blue Interstate shields to collector-tempting Historic Route 66 shields are ignored by the default ShieldSymbolizer.

A plea for the ability to create a filename for the base graphic element from k:v pairs is discussed[1] as a method to allow OSM users of mapnik to easily add the vast variety of highway shields to their map of everything.

[1] http://weait.com/content/badges-badges

Pretty please?

[artemp]

[migurski] ++?

There's a bigger, hairier and more general issue that this opens up, and that's the introduction of data-driven symbolizer parameters. E.g., the ability to put a string like "{$foo}" into a value and have it read a value from the data source. This would open up Mapnik for cloropleths, better shields, etc.

[artemp]

[migurski] See URI templates for an example of this kind of thing in a different domain: http://bitworking.org/news/URI_Templates

[artemp]

[springmeyer] Yes, exactly migurski. see also #359

[artemp]

[springmeyer] pushing to 0.7.0 for consideration (since the 0.6.1 release is next week)

[artemp]

[springmeyer] see also: http://blog.geoserver.org/2008/12/08/dynamic-symbolizers-part-1/

[artemp]

[artem] Replying to [comment:1 migurski]:

++?

There's a bigger, hairier and more general issue that this opens up, and that's the introduction of data-driven symbolizer parameters. E.g., the ability to put a string like "{$foo}" into a value and have it read a value from the data source. This would open up Mapnik for cloropleths, better shields, etc.

I agree, this should be implemented in most generic way.

[artemp]

[springmeyer] for those following this ticket, work has started on this in trunk, please provide any feedback:

http://mapnik.org/news/2009/dec/08/future_mapnik2/
http://trac.mapnik.org/wiki/Mapnik2

[artemp]

[springmeyer] this is done in mapnik2 for a while now of course. closing.