[RFC] Multitouch support, step one

[Simon Thum]

Am 15.03.2010 23:02, schrieb Peter Hutterer:
> On Mon, Mar 15, 2010 at 06:34:48PM +0100, Simon Thum wrote:
>> I also see the inherent racyness here, but I guess one could work that
>> out by a few routines in libXi which support the MT conventions hammered
>> out here. For example, a routine which skims through events and helps to
>> associate axis labels to events such that races are prevented. I
>> wouldn't worry about things not forbidden in the current spec, as MT so
>> far seems to involve some constraints on how clients interact with the
>> serer anyway.
> 
> This is less a libXi issue as more an issue in how clients may handle the
> events. It's in fact quite similar to how motion events can be treated.
> XIDeviceChangedEvents describe the state of a device as current when the
> event was generated. A client that sees multiple events from the same device
> in the queue may thus skip to the last one to get the info. Not much you can
> do in libXi.
Yes. But that wasn't what I tried to say :)

I wanted to suggest that libXi (or libXfancyMT) provides a purely optional
reference implementation which avoids those issues and can be reused.
Much like everything
X.org is a reference impl, yes, but sill...

IMO, since your approach essentially 'tunnels' the Xi spec, such issues
need more care.

Cheers,

Simon