[OSM-dev] Mapnik Q: enhance resolution?

Tom Hughes tom at compton.nu
Thu Mar 13 00:02:16 GMT 2008

In message <75F0D302-DE4C-462D-8F5F-357CE4928E6C at gmail.com>
          Artem Pavlenko <artem.mapnik at googlemail.com> wrote:

> > Great! Thanks Tom! rundemo.py outputs nice pdf and svg on os x
> > 10.4. I'll give it a try on 64-bit ubuntu later on.
> Couple things I noticed when viewing demo.svg in Inkscape :
> 1. Inkscape is extremely slow

Can't say I've noticed this - it all struck me as pretty fast in fact.

> 2. two 'provinces' polygons are un-clipped and go far beyond drawing
> extent. Is there access to clipping in cairo (on vectors or in
> rasterizer? ) or this is something we need to fix ourselves?

This is deliberate - there is code in cairo_renderer to do it but it
is ifdefed out at the moment.

The reason is that with the current release version of cairo adding
the clipping makes mapnik very slow rendering to cairo surfaces. It
also makes the resulting PDF very slow to render in evince as evince
is using cairo to render it and hits the same bug.

The current git head cairo code does not have this problem and is
capable of clipping without any noticeable slowdown.


Tom Hughes (tom at compton.nu)

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