[Xastir] [OZAPRS] XASTIR - maps

[Tom Russo]

On Tue, Nov 24, 2009 at 11:05:27AM -0800, we recorded a bogon-computron collision of the <archer at eskimo.com> flavor, containing:
> On Wed, 25 Nov 2009, Tony Hunt wrote:
> 
> > I cant answer the question as to if it really needs the setting of 16 . If 
> > you leave it at default 8 and use GM then all raster maps of a specific file 
> > type (gif I think) just turn out as black rectangles and squares. JPG from 
> > memory actually work ok.. Thats the effect anyway but it may be the other way 
> > around.
> >
> > Many of us have been uninstalling and recompiling/reinstalling with IM 
> > instead for close on a year I think.
> 
> Correct on all counts.  Can't remember which images come out black,
> but it's either GIF or JPEG, maybe both.  Xastir requires quantum
> depth of 16 as currently coded.

Naturally, the *best* way to address this whole thing is for someone on a 
system that has this problem to go in and debug the QuantumDepth==8 pieces
of the Xastir code.  

Looking over the code, I suspect that there are too many places in map_geo.c, 
map_WMS.c and map_tiger.c (the only ones that use Magick) where we're doing
more low-level bit-fiddling on color values than is normal in Magick 
applications, and in a couple of those places we're probably not doing it right
when the depth is 8.  That code needs a major refactor.  Now some systems are 
even shipping with Magick that has HDRI support enabled --- in which case 
pixels aren't even integers anymore, and our tacit assumption that we can 
bit-fiddle them directly makes the code not even compile on such systems.  
Since it's only going to get worse, we really need someone who can roll up 
some sleeves and just fix Xastir properly.

While they're at it, maybe it would be best to consolidate the duplicated
code in map_WMS, map_geo, and map_tiger.c so there aren't three places to
fix.  Duplicated code bad.

The number of lines of code that actually fiddles with color bits is not
very large, so it's just a matter of finding someone with time to work on it
and enough experience with Magick's (current) API to fix it.  

-- 
Tom Russo    KM5VY   SAR502   DM64ux          http://www.swcp.com/~russo/
Tijeras, NM  QRPL#1592 K2#398  SOC#236        http://kevan.org/brain.cgi?DDTNM
  In some cultures what I do would be considered normal. 
                                  -- Ineffective daily affirmation