[Spice-devel] keypress-delay should be configurable or auto-tuned

[Marc-André Lureau]

Hi

----- Original Message -----
> Hi All,
> 
> spice-gtk commit 0d5ad7e22d55552ef4be8368dcfbae879fb0b77e (widget:
> differentiate key press & release from press only events) introduced a
> short delay in sending key press events, which was designed to reduce
> unwanted key repeat.
> 
> However, on low-latency networks, this delay (default is 100ms) is quite
> noticeable and causes a "laggy" feel when using spice.

Personally, I have never felt a "lag", probably because there is no delay when
you release the key. It is only delayed if you stay pressed.

What use case do you have? (regular typing or else) 

> Currently I have recompiled spice-gtk with a 10ms delay and the overall
> feel is MUCH improved.  It's quite shocking how such a small thing can
> have such a large effect.
> 
> The actual delay used is a property in the spice widget, but is not
> exposed as a user controllable value (afaict), nor is the value
> automatically adjusted by, say, the RTT to the spice server.
> 
> I'd like to, at the minimum, add a "---spice-keypress-delay <n>"
> argument to remote-viewer, but in today's world, exposing settings to
> users is practically forbidden, so I'm doing a temperature check before

Indeed, we have a lot of "variability" already. I tend to prefer
environment variable for such misc/advanced things instead.

> I do anything. The alternative would be to auto-tune the value. If the
> auto-tune route is the way to go, I can come up with some ideas, but
> that can stay on hold.

I'd rather welcome auto-tune solution or better alternatives, see this bug for
other issue & thought on the matter: https://bugzilla.redhat.com/show_bug.cgi?id=1086650