Add server support for RRGetScreenResourcesCurrent

[Peter Clifton]

commit fc708394318ed92c612e2938b335c08c1ffebb28

    Add server support for RRGetScreenResourcesCurrent
    
    This depends on randrproto 1.2.99.1
    
    Signed-off-by: Keith Packard <keithp at keithp.com>


Added a useful function, which has been used to some effect in fixing
this bug:

https://bugs.edge.launchpad.net/ubuntu/+source/libxrandr/+bug/307306

However, I note that various other Xrandr calls end up causing a costly
outputs probe, such as:

ProcRRGetScreenSizeRange
ProcRRGetScreenResources
ProcRRGetScreenInfo
ProcRRSetScreenConfig

Was there a reason that these functions don't have "Current"
equivalents?

Is "RRGetInfo" supposed to be as expensive as it is on the intel driver?


Currently, we have the situation where GDK / gnome-settings-daemon /
gnome-power-manager listen for Xrandr notifications, _including_ output
property changes, and they trigger various Xrandr queries.

GDK actually generates a "monitors-changed" signal for every output
property change, and some programs listening to that signal then query
Xrandr directly.

This means a big lag for every brightness change (for example).

Are these clients handling things badly by wanting to probe the Xserver
for changes, rather than decoding the notifications themselves?

(For clients listening to GDK's "monitors-changed" signal, this doesn't
seem possible).

-- 
Peter Clifton

Electrical Engineering Division,
Engineering Department,
University of Cambridge,
9, JJ Thomson Avenue,
Cambridge
CB3 0FA

Tel: +44 (0)7729 980173 - (No signal in the lab!)