[Xastir] New code testing

[Curt Mills]

On Wed, 23 Jul 2003, Curt Mills, WE7U wrote:

> Implemented in CVS.  Thanks for that idea.  It's very slick!
>
> It appears to be the operation that I would normally expect from
> doing a zoom/pan in the middle of a map draw, and it's still very
> fast.  We don't currently draw the weather alerts/symbols/tracks on
> top of it if we get a map draw interrupt though.

I ran this new code mobile between work and a SAR meeting last
night, then again on the way home.  I tried running it zoomed in too
far to see what would happen, and the results were interesting.
This is on a PP200 with 32MB RAM running ZipSlack 8.0, plus a few
files from Slackware's X11 disks.

First:  I had no segfaults.  The hard drive remained very busy (LED
was quite active).  Timing was set to read the GPS position every 2
seconds.  While map drawing was going on, Xastir wasn't reading the
GPS.  This resulted in straight track lines on the map where curved
lines should have been present.  Once I zoomed out, normal operation
happened immediately and I got curved lines again, except at the
point where I flipped to the next map screen and again got a short
straight segment, but it was mostly unnoticeable at reasonable zoom
levels.

So...  What to do about it?

In a way it's operation that I expect, having Xastir ignore GPS
input while it's busy doing other things.  I suspect with radio
interfaces it's not such a problem, as they'll queue up and get
serviced if/when Xastir isn't busy anymore.

In another way, I wish I could do something about it, perhaps
interleaving the drawing of maps with the servicing of incoming
data?

Obviously the _right_ way to fix this is to decouple the map drawing
and the interface code by putting each in separate threads or
separate apps.  Xastir-2 will do this, so perhaps what we have now
is good enough?

I guess it depends on whether Xastir is still segfaulting for some
people while in TrackMe mode and while using close-in zoom levels.

-- 
Curt Mills, WE7U                    hacker_NO_SPAM_ at tc.fluke.com
Senior Methods Engineer/SysAdmin
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