touchscreens in multiscreen setups
peter.hutterer at who-t.net
Thu Dec 17 21:04:48 PST 2009
late reply, but better than never I suppose...
On Mon, Aug 03, 2009 at 03:23:39PM +0200, Peter Korsgaard wrote:
> How are touchscreens in multiscreen setups supposed to work nowadays?
> The issue with touchscreens is that their input events have to be
> transformed according to configuration of the screen they are
> physically connected to.
> For a concrete example, I have a dual screen setup with nextwindow USB
> (HID) touchscreens. This used to work nicely with the evtouch driver,
> where you could configure each touchscreen to bind to a specific
> screen number in xorg.conf, which evtouch would then use to deliver
> the input events transformed to that screen.
> Now, with xrandr instead of Xinerama there is only one screen and the
> above doesn't work (the coordinates gets scaled to the entire screen
> instead of the individual outputs).
> What is the suggested solution for this? Add randr output tracking to
> evtouch or should evdev handle this instead?
there's two parts to it:
- xf86InputSetScreen seems broken, this should be fixed in the server.
though it's probably optimised for the Xinerama scenario, I think it
should be possible to set it up for randr output or CRTC tracking in a
- randr notification. with screens being added and removed, there's no
driver interface that I know of that input drivers can use to get notified
about this stuff. Obviously the simple thing to do would be to handle this
stuff in the server - if a screen goes away the device defaults back to
whatever screen is still there. this would be without the driver knowing
though - not ideal.
I don't think either is a particularly large undertaking, so it's worth
tackling if you have the hardware and the test setups to actually do it.
Keith, any comments to either one?
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