[PATCH 2/2] docs: Add information about serials and timestamps

[Jason Ekstrand]

On Sat, Mar 30, 2013 at 1:09 PM,  <matthias.clasen at gmail.com> wrote:
> From: Matthias Clasen <mclasen at redhat.com>
>
> Add some information about serials, timestamps and their uses
> to the Input section in the protocol overview.
> ---
>  doc/Wayland/en_US/Protocol.xml | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
>
> diff --git a/doc/Wayland/en_US/Protocol.xml b/doc/Wayland/en_US/Protocol.xml
> index b94e9ca..5c7ef76 100644
> --- a/doc/Wayland/en_US/Protocol.xml
> +++ b/doc/Wayland/en_US/Protocol.xml
> @@ -241,6 +241,22 @@
>        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.

I think this should be re-worded.  It's correct, it just seems
awkward.  For example:

Input events also carry timestamps in milliseconds.  The base for
these timestamps is left up to the compositor.  Therefore, they should
not be compared against anything except other compositor-provided
timestamps.

> +    </para>
> +    <para>
>        See <xref linkend="protocol-spec-interface-wl_seat"/> for the
>        protocol description.
>      </para>
> --
> 1.8.2
>
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