[Maposmatic-dev] Details on why we use Cairo scaling?

[Thomas Petazzoni]

Hello d2,

Between ocitysmap and ocitysmap2, one of the major change is that we
are now using Cairo-based scaling of surfaces. Unfortunately, this
creates a number of problems that are hard to solve, apparently because
we are the only ones doing this kind of scaling with Mapnik-rendered
Cairo surfaces:

 * We have the long-standing halo text problem. Since last month when
   you did some investigation on this problem, no-one cared to answer
   on the Mapnik side, so I have the feeling that the chances to get
   that bug fixed are quite small.

 * The scaling is apparently also causing problems with the MapQuest
   stylesheet: all arrows for one-way streets are completely mis-placed.

Due to these issues, I am starting to wonder whether we should continue
to use Cairo scaling. In the past, we didn't use Cairo scaling this
way, and still we were able to render maps.

Could you refresh our minds on why such a change was needed, and
generally was is the general design of the current rendering in terms
of Cairo surfaces transformation? That would help us in deciding what
to do next about those problems.

Thanks!

Thomas
-- 
Thomas Petazzoni                http://thomas.enix.org
MapOSMatic                      http://www.maposmatic.org
Logiciels Libres à Toulouse     http://www.toulibre.org
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