Hi, On 30 March 2013 16:55, Thiago Macieira <thiago.macie...@intel.com> wrote:
> On sábado, 30 de março de 2013 09.34.24, Matthias Clasen wrote: > > > Monotonic (ideally) time in an undefined domain, i.e. they're only > > > meaningful on relation to each other. > > > > What can you do with them ? For the use case that Giulio mentioned > > (double-click detection), I'd need to know at least if the difference > > between two times is seconds or milliseconds or microseconds... > > The protocol needs to specify the unit. It can't be dependent on the device > driver, that makes no sense. If it's in milliseconds, it will overflow > every > 49.7 days. If it's microseconds, it will overflow every 71.6 minutes. > Yes, they are in milliseconds, I just explained it poorly. > It also needs to specify which timestamps are in the same time domain. Can > two > timestamps be compared to each other only if: > > - they are in the same input device (same mouse, same keyboard), but not > across devices > - they are in the same seat, but not across seats > - they are in input event messages, but not other types of messages that > carry timestamps > - no restriction > Personally, I think either #1 or #2. Definitely not #3 or #4. We want to be able to use the evdev timestamps rather than gettimeofday() when we receive it, so we can ensure that if someone clicks twice slowly, and the compositor takes a while to process the same event, it's not interpreted as a double-click. > For example, imagine the case of trying to ensure that a Ctrl key was > pressed > before a mouse click happened, after the events were plucked out of the > event > stream. > > Or is there another, recommended way of doing that, such as by using the > serials? > Hmmm. I was going to say using the event order, but it all depends on which order the devices were read in. So I guess for this case we'd need to go with #2. Cheers, Daniel
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