[Xastir] WMSradar Transparency

[Gerry Creager]

Can I tell you just HOW MUCH I hate ImageMagick for this?

Tom Russo wrote:
> 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.
> 

-- 
Gerry Creager -- gerry.creager at tamu.edu
Texas Mesonet -- AATLT, Texas A&M University	
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