[Xcb] Your GSOC proposal: "Complete input support for XCB"

Christoph Reimann chrr at arcor.de
Thu Apr 8 08:00:21 PDT 2010

Hi once more!
Again thank you very much for your comments, it helped a lot!
In the meanwhile I've looked through the Xlib documentation and
xcb/util source code and started reading about XKB on Ivan Pascal's

Arnaud, I see now why you think it worthwhile to have the Xlib util
functions related to input stuff, this would indeed be a good starting
point (and it should be straight forward as well).
You wrote that XKB is likely to be replaced by s.th. else - can you be
more specific? I am uncertain about the relation between XInput/XI2
and XKB/XKB2 anyway, I thought until recently that XInput is merely
enabling access to more than one keyboard e.g.? But from the
specification it appears to me that XInput has its own
keycode<->keysym mapping(??).

Peter, I did not have the time to look at the XInput/XKB XML
descriptions yet. You posted a patch that "
lets Wireshark parse the new syntax" - can you perhaps give me some
hint what is technically necessary in order to get language bindings
out of this?

As soon as the XKB language binding on the protocol side is done, the
input related functions in the xcb/util module would need to be
adapted. Here again I am uncertain about XI/XI2 - it appears that Xlib
has no util functions related to XInput (but it makes use of the XKB
extension automatically), is that correct?

Sorry for all the questions, please don't waste your time for me if
you don't have an answer readily at hand!!


On 7 April 2010 13:53, Peter Harris <git at peter.is-a-geek.org> wrote:
> On Wed, Apr 7, 2010 at 4:37 AM, Christoph Reimann wrote:
>> In the post at http://lists.freedesktop.org/archives/xorg-devel/2010-March/006612.html
>> it is stated that "most of XKB" has been specified in xcb/proto - it
>> is necessary to finish the protocol layer first?).
> I probably should have worded that more carefully.
> As far as I know, the protocol layer is finished. I said "most"
> because we will very probably find at least one small omission (or
> other bug[1]) in the protocol description while working on the libxcb
> implementation. The XKEYBOARD extension is fairly large, and we
> haven't tested the protocol description thoroughly yet (in part due to
> lack of libxcb support).
> Peter Harris
> [1] Indeed, I have found (and fixed) a bug in the protocol description
> since I wrote that:
> http://cgit.freedesktop.org/xcb/proto/commit/?id=2d873a3dc8c0

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