[Xastir] WMSradar Transparency

[Tom Russo]

On Fri, Sep 15, 2006 at 10:54:13AM -0700, we recorded a bogon-computron collision of the <archer at eskimo.com> flavor, containing:
> On Fri, 15 Sep 2006, Chip G. wrote:
> 
> > I tried manually downloading the radar
> > png file using the url in the same file (so I could try and determine
> > the correct transparency), but I only received a file describing an
> > error.
> 
> That's 'cuz Xastir adds stuff to the URL when it snags it.
> 
> Instead look in your ~/.xastir/tmp folder for the image you last
> downloaded.
> 
> The transparent value and how it is used can be affected by the
> color depth of your display.

Are you running CVS xastir or one of the releases?

What is your color depth?

For several months running, the transparent pixel value returned by the 
server has been 0x010101, not the 0x000000 that is explicitly requested in
the URL for the WMSRadar geo file.

On unpredictable occasions, the pixel value comes back 0x000000 instead.  But
these cases have been rare over the last few months.

Setting TRANSPARENT 0x010101 in WMSRadar.geo (as it currently is in CVS) has
been working on 16 and 24 bit displays for several months (I test it on both).
If you're running one of those color depths and are seeing opaque backgrounds,
then either:
  - There is some difference between your 16 or 24 bit display and the two I
    test on.
  - The WMS server is returning 0x000000 background pixels again --- it probably
    won't do so for very long.  

I just tried WMSRadar on my home machine (a 24-bit color depth display) and
the stock .geo worked fine for it with transparent background, eliminating 
the second case.

I can think of only one thing in the map_geo code that might be responsible
for different behavior on your system and mine:  please look at the 
file "magick-config.h" in whatever directory your install of ImageMagick has
placed its header files (/sw/include/magick, maybe?).  See what it says for
#define QuantumDepth.  All of my platforms have QuantumDepth 16, and there 
is special case code in map_geo.c that takes care of QuantumDepth 8 --- I have
been unable to test that special case code on any platform, and it could be
broken.

-- 
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