Support adding points dynamically in Python

[lwu]

Mapnik's Python binding lacks sufficient functionality to easily implement the ability to add points dynamically (programmatically) in Python.

I have attached a patch which addresses this problem, by taking the patch attached to ticket #111 and implementing a number of Python binding codes which were not yet implemented.

Programmatic addition of data points in Python seems to be a frequent request on the mailing lists, and thus this functionality seems particularly useful to support.

[lwu]

Support for python-based point datasources

[lwu]

Example use: http://gist.github.com/8702

[springmeyer]

lwu,

nice patch.

I was able to patch and rebuilt mapnik on mac 10.5 with no problems. I then downloaded your sample code and it worked perfectly.

These were my steps:

cd ~/src/mapnik-svn-trunk
wget http://trac.mapnik.org/raw-attachment/ticket/113/python_point_datasource.patch
patch -p0 -i python_point_datasource.patch # then rebuild mapnik...
cd ~/projects/mapnik-utils/trunk/sample_data
wget http://edcftp.cr.usgs.gov/pub/data/nationalatlas/statesp020.tar.gz
tar svf statesp020.tar.gz
rm statesp020.tar.gz
echo 'GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137,298.257223563]],PRIMEM["Greenwich",0],UNIT["Degree",0.017453292519943295]]' > statesp020.prj

[lwu]

I've been working on an interactive map renderer and just realized that a variant of memory_datasource would also be useful for interactive map applications, as a way to cache Features which are otherwise discarded after a feature_style_processor invokes apply_to_layer() to request Features from a spatial DB etc.

[artem]

Applied in r790, thanks! It would be great to extend this functionality to support all geometry types and provide different storage types.

[springmeyer]

will appear in the 0.6.0 release, so back-assigning to 0.6.0 milestone.

Lwu can you open another ticket on supporting Line and Polygon geometries?