Hi everyone,
I wanted express my interest in working on the ideas posted by Rob Coup
(Cascadenik: Native C++ implementation of node.js Carto and Cascadenik/Carto:
SLD Converter). I was thinking that the two ideas could be combined into a more
general project that focuses on implementing a set of native C++ parsers (Carto
and Cascadenik) and generators (xml, Carto, Cascadenik, and SLD) for Mapnik.
This would allow Mapnik to be more flexible on the type of stylesheet it
natively accepts as well as allowing for translation between formats.
After a little bit of research it seems like this is possible using Boost
Spirit which already appears to be used extensively in Mapnik (parsing: wkt,
svg, colors, etc). I've been playing around with Spirit for the last couple
days and I'm very impressed with how slick it is. I've written a simple json
parser (http://github.com/rundel/carto-parser) to handle carto mml files.
Depending on the version it parses the json into an AST and then outputs the
original json via Spirit Karma or by printing values as it traverses the AST.
Parsing of Carto will obviously be much more complex but seems like a fun
project and a working Carto parser should be straightforward to modify to
handle Cascadenik stylesheets. It also seems like it would be straightforward
to implement generators using Karma that would take a Map object and produce a
desired format.
My relevant biographical information - I'm a fifth year graduate student in
Statistics at UCLA working on a dissertation in the area of spatial and
ecological statistics. In the last couple of years I've gotten interested in
accessible mapping/spatial visualization tools. Carto and Tilemill are some of
the most exciting developments I've seen in this area. I successfully
participated in the GSoC last summer through the R Project where I worked on
the rgeos package, an R wrapper for the geos library. The package and its
source is available from CRAN
(http://cran.r-project.org/web/packages/rgeos/index.html). In the longer term I
would love to create R bindings for Mapnik since R's current spatial
visualization options are somewhat limited.
Any comments or feedback would be greatly appreciated, I'm working on a more
detailed proposal that will hopefully be up on the GSoC site in the next day or
so. I will post a link as soon as it is ready.
-Colin
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