[Xastir] Weather maps are now black

[Tom Russo]

On Mon, Jun 18, 2007 at 09:39:40PM -0600, we recorded a bogon-computron collision of the <needhame1 at plateautel.net> flavor, containing:
> 
> 	Not sure what I did, IF I did it, but tonight when I try to load weather maps 
> on top of tiger maps, the whole thing turns black with station icons on top.
> 
> 	Are the weather map sites down?  Or have I created a problem locally?

This happens now and then if you are using a 24-bit display.  You can tell
if that's the case by looking at the output of "xdpyinfo" in a terminal
window.

The script that generates the weather images at the server seems to have some 
kind of bug where it occasionally changes the color value of the background 
pixels from 0x000000 to 0x010101 and back without warning.  Xastir can handle 
at most one transparent color, and that color is coded into the WMSRadar.geo 
file as a hex number.

When the user is using a 16-bit display, xastir does some manipulation of
the pixel values to squash them down into sixteen bits before it checks 
whether the color is supposed to be transparent --- and in doing so the 
difference between 0x000000 and 0x010101 is obliterated, so this bug is
invisible to anyone running a 16-bit display.  But users of 24-bit displays
get to see the effect you're seeing.

Some folks here will tell you to run a 16-bit X server because that's 
the most supported color depth in Xastir, but I find that suggestion unhelpful 
because Xastir isn't the only thing I use my X display for, and I prefer 
24-bit color for my other applications.

Until Gerry can find the source of the seemingly random changes in background
color produced by the weather radar script, the best you can do is to edit
the WMSRadar.geo file to change the TRANSPARENT value.  If it's 0x010101
then change it to 0x000000 (or vice-versa).  It might fix the map.  You will
probably have to change it back a day or two later, though.

This has been going on for quite some time --- at least a year, maybe more.
Gerry has never been able to locate the source of the problem.

-- 
Tom Russo    KM5VY   SAR502   DM64ux          http://www.swcp.com/~russo/
Tijeras, NM  QRPL#1592 K2#398  SOC#236 AHTB#1 http://kevan.org/brain.cgi?DDTNM
"And, isn't sanity really just a one-trick pony anyway? I mean all you get is
 one trick, rational thinking, but when you're good and crazy, oooh, oooh,
 oooh, the sky is the limit!"  --- The Tick