Hi,
Having worked on one Mapnik project that required big, almost-OSM-
scale stylesheets, I've been a bit frustrated with the state of the
art for defining map appearance. So, I've built a stylesheet
preprocessor that parses a format explicitly based on HTML + CSS and
outputs the usual XML styles.
There's a basic introduction here:
http://teczno.com/cascadenik/doc/
...and complete code here (note some of the reqs in the Makefile):
http://code.google.com/p/mapnik-utils/source/browse/trunk/serverside/styles/
I'm looking for comments / feedback.
It's a fairly complete thought, incorporating a lot of the things I
believe would make styling maps accessible to designers:
- It's possible to refer to external files in predictable locations
including images and linked stylesheets.
- Style definitions can work in a class-oriented fashion, allowing you
to express ideas such as "all roads are red, but primary roads have a
yellow edge and they're different widths at each zoom level" -
currently this is difficult or at least enormously repetitive with
existing Mapnik styles.
- Rules for how these definitions combine and cascade are also
explicit, copied directly from the CSS spec.
- I've also started to introduce useful shorthands, e.g. it's possible
to express scale denominator boundaries in a reduced "zoom" notation
specifically for maps in the Google / VEarth / OSM projection.
Most properties are done:
http://code.google.com/p/mapnik-utils/source/browse/trunk/serverside/styles/style.py#48
Outstanding items still on my list to do include the shield
symbolizer, dashed lines, and Filters.
Also a full set of edge & corner cases hasn't yet been dealt with, but
there are tests:
http://code.google.com/p/mapnik-utils/source/browse/trunk/serverside/styles/test.py
Anyway, thoughts welcome.
-mike.
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michal migurski- [EMAIL PROTECTED]
415.558.1610
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