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<div class="moz-cite-prefix"><font face="Times New Roman, Times,
serif">On 01/24/2013 05:35 PM, Stephen Woodbridge wrote:<br>
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<blockquote cite="mid:510162D5.7080600@swoodbridge.com" type="cite"><font
face="Times New Roman, Times, serif">On 1/24/2013 11:13 AM, Jan
Hartmann wrote:
<br>
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<blockquote type="cite"><font face="Times New Roman, Times, serif">Does
anyone know a trick to do this:
<br>
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I'm making geographical indexes for the map series in our map
library.
<br>
Each map sheets is displayed as a polygonal linestring, based
on its
<br>
corner coordinates. Lots of sheets have exactly the same
boundaries, so
<br>
it's not clear where a polygon indicates just one map sheet of
several.
<br>
It's easy, of course, to write a PostGIS query to return a
different
<br>
color code when map boundaries exactly coincide, but I was
wondering
<br>
whether something like that could be done by mapserver on its
own, like
<br>
XOR-ing a line with what is already there. Any ideas?
<br>
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Hi Jan,
<br>
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For polygons you could use a small negative buffer to shrink the
polygon slightly. You can do this in postgis, and you might be
able to do it with mapserver if geos is compiled in. See:
<br>
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<a class="moz-txt-link-freetext" href="http://mapserver.org/development/rfc/ms-rfc-48.html">http://mapserver.org/development/rfc/ms-rfc-48.html</a>
<br>
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<font face="Times New Roman, Times, serif">No, that is not what I
meant. I'm looking for a trick for mapserver to color a linestring
differently when drawing over a linestring that it has already
drawn in a previous layer. In computer graphics you can do this by
using an XOR brush. Essentially, the screen frame buffer functions
as a sort of memory. I don not want to use PostGIS or GOS, too
complex. I doubt if this can be done by MapServer, but you never
know.<br>
<br>
Jan</font> <br>
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