Hello everybody, I've been working now with agg_renderer since I found a
problem with cairo_renderer and building symbolizers I haven't solved yet.
The scaling of building and text symbolizers (in point placement) was
relatively straightforward. However to scale polygon symbolizers in the same
way I did in cairo_renderer I require to make changes in AGG's add_path set
of functions. Making changes there is a bad idea in my opinion, but I would
like to know from you if it is a valid approach or has been used before for
other purposes (I read in its documentation that agg is meant to be
extended, but I'm sure those extensions are made in some other way).

If you have a chance, please take a look at my implementation:
http://trac.mapnik.org/changeset/1857. It would be very valuable to me to
know about the point of view of the community. I committed image of the maps
I've been rendering with each step I take, so looking at them is a good way
to see how the implementation works without compiling the examples. The name
of the files are labeled with the name of the renderer that produced them,
their size and scale factor applied.

Finally, as you may see in image 'cairo_wb1_800x600x1.png' (
http://trac.mapnik.org/browser/branches/mapnik_resolution/demo/c%2B%2B/sandbox/scale_building_symbolizer/img/cairo_wb1_800x600x1.png?rev=1857),
some lines are appearing across the image, which do not show up when
rendered with agg_renderer. The most probable reason is that I introduced
some bug when making the changes, but I would like to know if anyone has ran
into this problem.

Artem, I saw you were also experimenting with scale factor in agg_renderer
and your comment about discussing the way to expose it to the user with Dane
Springmeyer and me. Until now, I've just concentrated in making scaling look
good, but I'll look for alternatives tomorrow. My current implementation is
to have it as a data member in Map object.

Thanks in advance,

Carlos López
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