[Geoserver-users] SLD - stroke-dashoffset in both ends

GeoServer GeoServer User
1

Hi list,

I have not found any way to style a line in a way that it is not visible for
some length i both ends. Have you?

<CssParameter name="stroke-dashoffset">60</CssParameter> will start drawing
the line 60 px from the starting point, but how should i do the same in the
endpoint?

regards, Jakob

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2

On Tue, Feb 25, 2014 at 1:00 PM, Jakob Ventin <jventin@anonymised.com> wrote:

Hi list,

I have not found any way to style a line in a way that it is not visible
for
some length i both ends. Have you?

I don't believe SLD offers any immediate way... but I can think of a slow
one
that might work using existing GeoServer extensions

<CssParameter name="stroke-dashoffset">60</CssParameter> will start drawing
the line 60 px from the starting point, but how should i do the same in the
endpoint?

Actually, the dashoffset just changes the starting point for the dashoffset
pattern,
so it cannot be replicated on the other side.

One thing that might work if your lines are mostly straight, but it's
somewhat complicated and inefficient,
is to extract the two end points, buffer them, and then perform a
difference,
using the many filter functions provided by GeoServer:
http://docs.geoserver.org/stable/en/user/filter/function_reference.html

See some examples here:
http://docs.geoserver.org/stable/en/user/styling/sld-extensions/geometry-transformations.html

That said, it would be better to write a custom filter function to shorten
a line instead, which
would require some java programming. I think it's also possible to write
filter functions
using a scripting language with the geoscript hooks, but I can't find
documentation
on how to do that. Maybe Justin (cc'ed) has some pointers

Cheers
Andrea

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