On 05/17/2010 11:19 AM, Andrea Aime wrote:
> Hi,
> I've finally been able to commit the unit of measure support
> Milton developed on GeoTools trunk (that makes it available
> for GeoServer trunk too, of course).
>
> If you're interested in the topic please test :-)
>
> Oh, if you need a reminder of what UOM support does,
> there is a quick example here:
> http://osgeo-org.1803224.n2.nabble.com/Surprise-surprise-uom-support-about-to-land-td4803450.html#a4803450
>
> But in short, it allows one to specify the unit of measure
> of stroke widths, icons sizes and the like in meters
> or feet instead of just pixels.
>
> Along with Michael improved classfication functions this
> brings us closer to having all the bits to supports SE/SLD 1.1
> (the biggest missing item right now is a parser/encoder)
>
> Cheers
> Andrea
>
>
This is a really cool feature, so I'm pretty excited about ripping it
off for GeoServer CSS :) However, when I looked at the spec I was
really surprised to see that UOM is an attribute of the symbolizer
instead of the parameter (a Symbolizer isn't a measurement!!) I also
saw this little tidbit:
> It is also possible to use pixel values inside a Symbolizer that uses
> a uom: px
> has to be appended to the corresponding values in this case (e.g. 5px
> stands for 5 pixel).
By my reading, the UomRescalingVisitor doesn't handle this option. (And
it seems like fully supporting this via a visitor will be a problem;
with weird enough filter functions in a parameter the "px" suffix might
appear and disappear for different features in the same symbolizer.)
In either case, I won't be able to faithfully represent styles like this
one (hopefully pretty rare, but quite naturally encoded in CSS):
* {
stroke-width: 2m;
stroke-dashoffset: 2ft;
}
but it would be nice to at least be able to mix in pixel values with
real-world measures. Anyone care to point out how I misread the visitor
code? I'm crossing my fingers.
--
David Winslow
OpenGeo - http://opengeo.org/
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