Re: XInput 2 support

[Po Lu]

Eli Zaretskii <eliz@gnu.org> writes:

> Who or what will promise us that XInput 2 will not be removed by those
> same developers?

XInput 2 is currently the standard modern input handling extension on
X-Windows, and GTK uses it to provide input features such as smooth
scrolling and touchscreen support on X-Windows whenever available.  The
legacy Core Input code is not as well maintained, and is missing certain
features.

> Much of the code seems to be just a copy of the existing code in
> xterm.c, just with different events.  Would it be possible to
> preprocess XInput 2 events into X events, and then call the existing
> code, instead of copy/paste-ing it?

I've already done that where possible (see the variables `ev' and `bv'
under "case GenericEvent:").  Everywhere else, I'm not comfortable with
preprocessing these XI events into X events.

> Also, do these changes have any effect on user-visible behavior, or on
> how users must set up their systems or how they use Emacs?  If so,
> there should be suitable changes to the documentation.

None at all.  The code falls back to Core Input if the X Server does not
have XInput2 installed, and the behaviour is identical when using both.
Thanks.