[OSM-talk] simplifying mapnik layout definition

Andreas Barth aba at not.so.argh.org
Tue May 27 16:26:36 BST 2008


* Tom Hughes (tom at compton.nu) [080527 17:08]:
> In message <20080527144058.GP2178 at mails.so.argh.org>
>         Andreas Barth <aba at not.so.argh.org> wrote:
> 
> > The differences are only within the scales. So it would make sense to
> > split the scales off - and make them as small as possible. The smaller
> > it is, the easier one can make changes. So this could be written as:
> >
> > <Style name="tunnels-casing">
> >       <Rules filter="([highway] = 'motorway' or [highway]='motorway_link') and ([tunnel] = 'yes' or [tunnel] ='true')"/>
> >       <CssParameter name="stroke">#506077</CssParameter>
> >       <CssParameter name="stroke-dasharray">4,2</CssParameter>
> >       <ScaleDenominator max="200000" min="100000">
> >         <CssParameter name="stroke-width">3</CssParameter>
> >       </ScaleDenominator>
> >       <ScaleDenominator max="100000" min="20000">
> >         <CssParameter name="stroke-width">5.5</CssParameter>
> >       </ScaleDenominator>
> >     </Rules>
> >
> >
> > This drops the (IMHO unnecessary) LineSymbolizer (one can make it up
> > from the stuff around it) and emphasizes the differences. If this looks
> > ok-ish, I could write an converter from the new to the old format as an
> > starter.
> 
> That doesn't look valid to me though, as you aren't telling it
> what symbolizer to use to draw the object. Have you actually checked
> that mapnik accepts that syntax and does the right thing?

I don't think that mapnik accepts that syntax. I however think it
shouldn't be too hard to create an converter from that syntax to the one
mapnik understands, and that would be what I'd do.



Cheers,
Andi
-- 
  http://home.arcor.de/andreas-barth/




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