[BRLTTY] Filter keyboard keypresses on Linux

Mario Lang mlang at delysid.org
Sat Dec 15 16:37:18 EST 2007

Dave Mielke <dave at mielke.cc> writes:

> Can anyone tell me how Speakup intercepts key events?

Speakup intercepts all sorts of things by directly patching
the kernel.

> If we use this scheme how will we be interacting with it?

I guess its a bit unpredictable if we are dealing with something
that patches into the kernel.  It depends on the patch how
it interacts with input device clients from user space.

> Does it intercept them first, do we, does one scheme disable or
> conflict with the otehr, etc?

If speakup intercepts on the hardware level (which I guess they do), I guess
it will see they keypress anyway.  I highly doubt speakup
uses the input layer API, they dont like using APIs :-).

But, given the current kernel API, this approach (input devices)
is the right way to go for a user space application.  If we want
to intercept keypresses, we really want to do it this way. I'd go as far
as claiming if this conflicts with some other patches, the
patches are broken, not the input device approach.


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