Demos and Tutorials using Journal

[Gavin A. Bell]

Tim_Buxton at UM.CC.UMICH.EDU writes:
>For anyone who has to do a "demo" of anything on an IRIS, there is 
>now a really great tool for recording a whole demonstration once,
>including all keystrokes and mouse movements at the speed you want, 
>then playing it back any number of times, at selectable faster
>or slower speeds.   It is called the "journal"
>facility and just came out with 3.1g, I believe.

... goes on to mention two problems with journalling: playback
on different machines, and not being able to pause the playback.

The real problem with journalling is synchronization; playing back a
journal recording of 'dog' twice in a row, you will end up in two
different places, since small changes in when the program gets mouse
events have large effects later.  If this isn't critical (in demos
where you won't crash if the 'bank left 20 degrees' is interpreted as
'bank left 18 degrees'), it can work fairly well.  Having different
scripts for different machines is one solution to the speed problem;
recording on the slowest machine often works, too.  However, a lot of
different things can affect machine speed-- how loaded it is, if disk
files have to be accessed over NFS, etc.

The pause problem is much easier.  You have the journalling code on
your system; look in the files /usr/NeWS/lib/NeWS/journal.ps and
/usr/NeWS/lib/NeWS/journalUI.ps.  I've often considered adding a few
options to the journalling stuff, including a pause feature (I've just
never had the time to do it).

There is one bug you should know about:  If a GL program does a
setvaluator() call, it will cause the journal file to stop.  The
journal playback gets confused, and thinks that the user has done
something to stop the journalling.

--gavin