[Xastir] interrupting a map redraw?

[Gerry Creager N5JXS]

Ooh!  Sounds like it's time to rediscover unmaskable interrupts!

Curt Mills, WE7U wrote:
> On Thu, 3 Jul 2003 wes at johnston.net wrote:
> 
> 
>>Is there any way to abort a map draw if a user hits the PG UP, PG DN or arrow
>>keys while the redraw is happening?  It sure would speed up moving around the
>>map.
> 
> 
> Sometime later today some new mods will be available via the
> anonymous CVS server.  It doesn't work quite like one would expect
> yet, but it's certainly better than it was.  We now just set some
> variables in the keyboard/mouse callback routines called da_input and
> da_resize, then actually do the map drawing/screen update in our main
> loop instead of the callback (before that we did all the map drawing
> for events in the callback).  With this little tweak it allows us to
> interrupt map drawing and restart it on certain keyboard/mouse
> events.
> 
> You can see this new operation easily if you have a lot of maps
> selected and then keep resizing the window.  Before:  Xastir would
> draw each and every resize in sequence.  Now, it'll get interrupted
> between maps or even during loading of one map, exit, and restart
> with the last resize that it has recognized so far.
> 
> I ran through all the map_*.c code and added checks for
> "interrupt_drawing_now" all over the place.  If we get an interrupt,
> we clean up and return from the map drawing (freeing up processor
> time for the next draw).
> 
> I have some more local mods that I haven't committed yet which
> involve waiting a second or two after certain keyboard/mouse
> operations before starting the redraw.  This allows multiple events
> to get recognized by X11 before we start our redraw, which can get
> rid of that uninterruptible first redraw.  If we can instead find an
> X11 call that will process all of the keyboard/mouse operations in
> the queue, we can just do that one call and then start my redraw
> instead of waiting XX seconds.
> 
> What happens in the new CVS code is that you may run all the way
> through the _first_ redraw before X11 recognizes that there are more
> keyboard/mouse events waiting in the queue.  After that first redraw
> completes without being interrupted, lots of events in the queue get
> processed, and then the next set of redraws are all interrupted,
> letting the _last_ one actually run to completion.  Not a perfect
> solution, but certainly better/faster than it was.  Like I said, I'm
> looking for a "process every input in the queue" command, which I
> might be able to call between each map or even every time just before
> I check for "interrupt_drawing_now".
> 
> Some of the mods were committed rather early this morning, so I guess
> I'll revise my estimate and say that they'll be available on the anon
> CVS server sometime saturday.
> 
> Curt, WE7U.				archer at eskimo.com
> http://www.eskimo.com/~archer
>   Lotto:  A tax on people who are bad at math. - unknown
> Windows:  Microsoft's tax on computer illiterates. - WE7U.
> The world DOES revolve around me:  I picked the coordinate system!"
> 
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-- 
Gerry Creager -- gerry.creager at tamu.edu
Network Engineering -- AATLT, Texas A&M University	
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