Date: Thu, 21 Aug 2003 14:22:22 +0100
From: Jamie Lokier <jamie@shareable.org>
To: Andries Brouwer <aebr@win.tue.nl>
Cc: "Maciej W. Rozycki" <macro@ds2.pg.gda.pl>,
       Neil Brown <neilb@cse.unsw.edu.au>, Vojtech Pavlik <vojtech@suse.cz>,
       linux-kernel@vger.kernel.org
Subject: Re: Input issues - key down with no key up
Message-ID: <20030821132222.GA28416@mail.jlokier.co.uk>
References: <20030821000302.GC24970@mail.jlokier.co.uk> <Pine.GSO.3.96.1030821133902.2489C-100000@delta.ds2.pg.gda.pl> <20030821144835.B3480@pclin040.win.tue.nl>
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Andries Brouwer wrote:
> > > But for programs which want to monitor a key and know its state
> > > continuously (this presently includes the software autorepeater, but
> > > it also includes games), none of the behaviours is right.
> > 
> >  X11 is another example of software that wants to know the state of keys
> > continuously.  And that's not a piece of software to ignore easily. 
> 
> You are both inventing the situation that games, or X11, ask the kernel
> for a bitmap of pressed keys. But they don't. The mechanism doesn't
> even exist.

I have no idea what X wants.  What non-X "action" games want is simple
(I have written a few): to know when the user is pushing particular keys.

Those games achieve this by observing a DOWN event when a key is
pressed, an UP when it is released, to change their knowledge of a key
state, and ignoring events which don't change their knowledge of the
state: auto-repeat DOWN events or spurious UP events.

-- Jamie
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