[Xcb] [RFC v0 proto] Add XInput2 protocol description

[Peter Hutterer]

On Mon, Dec 03, 2012 at 06:54:20PM -0500, Peter Harris wrote:
> On Mon, Dec 3, 2012 at 5:03 PM, Peter Hutterer <peter.hutterer at who-t.net> wrote:
> > On Mon, Dec 03, 2012 at 04:21:35PM -0500, Peter Harris wrote:
> >> On 2012-12-03 16:05, Daniel Martin wrote:
> >> > I've choosen to make it in a seperate file, cause the extension name is
> >> > nearly the only thing both versions have in common and XI2 superseeds
> >> > the functionallity provided by XI.
> >>
> >> Except for the QueryVersion request, which is only present in the XI1
> >> description. I suppose it could be duplicated in xinput2.xml, but see below.
> >
> > I'm not sure I understand this comment. QueryVersion is an XI2-only request,
> > the equivalent in XI1 doesn't allow negotiating the client's version.
> > There is also XI1's GetExtensionVersion which is XI1-only and should remain
> > in xinput.xml.
> 
> You're right, I misspoke. I meant GetExtensionVersion.
> 
> If you don't GetExtensionVersion, how do you know it is safe[1] to
> issue XI2 requests (Including QueryVersion)?
> 
> Peter Harris
> 
> [1] I suppose an argument can be made that we're talking about XCB,
> which can sanely handle the BadRequest error an older server will
> generate.

The recommended way here is to call QueryExtension, GetExtensionVersion,
then QueryVersion, in that order. Or, as you indicated, you just hope for
the best and deal with the BadRequest if need be.

Cheers,
   Peter