docs: Add information about serials and timestamps

Add some information about serials, timestamps and their uses
to the Input section in the protocol overview.
This commit is contained in:
Matthias Clasen 2013-03-30 14:09:25 -04:00 committed by Kristian Høgsberg
parent c110fbcb75
commit 3bda215130

View File

@ -240,6 +240,22 @@
be mapped as 'popup', which combines transient window semantics
with a pointer grab.
</para>
<para>
To avoid race conditions, input events that are likely to
trigger further requests (such as button presses, key events,
pointer motions) carry serial numbers, and requests such as
wl_surface.set_popup require that the serial number of the
triggering event is specified. The server maintains a
monotonically increasing counter for these serial numbers.
</para>
<para>
Input events also carry timestamps with millisecond granularity.
Their base is undefined, so they can't be compared against
system time (as obtained with clock_gettime or gettimeofday).
They can be compared with each other though, and for instance
be used to identify sequences of button presses as double
or triple clicks.
</para>
<para>
See <xref linkend="protocol-spec-interface-wl_seat"/> for the
protocol description.