[PATCH weston 0/5] fix fbdev transforms

[Pekka Paalanen]

On Thu, 19 Mar 2015 07:13:18 +1000
Peter Hutterer <peter.hutterer at who-t.net> wrote:

> On Wed, Mar 18, 2015 at 01:14:52PM +0200, Pekka Paalanen wrote:
> > On Wed, 18 Mar 2015 11:45:01 +0100
> > Thilo Cestonaro <thilo at cestona.ro> wrote:
> > 
> > > Hey!
> > > 
> > > 
> > > > Is it broken only on fbdev or DRM also?
> > > 
> > > DRM is the same as Fbdev. The touch doesn't have the correct 
> > > orientation, but I can use weston-simple-touch to have a windows paint 
> > > simulation with just one brush and color :)
> > > 
> > > 
> > > > Can you try to use weston-simple-touch to see if the touch input is
> > > > just missing the rotation of the rotated screen?
> > > 
> > > Jup, touch is missing the correct orientation. with weston-simple-touch 
> > > I see red dots everywhere but not there, where I touch :).
> > > 
> > > 
> > > > If you don't rotate the screen, is touch working ok then?
> > > 
> > > Jup, without rotation it is working correctly.
> > 
> > Ok, so it's just a missing output transformation with the touchscreen
> > setup.
> > 
> > Peter, is one supposed to account for screen rotation already in the
> > touchscreen calibration, or should the compositor combine the
> > calibration with the current output rotation/flip? I mean, how would
> > this translate into libinput API usage and the touchscreen calibration
> > matrix from... udev?
> > 
> > I assume we should do the latter in case some compositor can change the
> > rotation at runtime (tablets etc.).
> 
> yep, the calibration is a static thing (which is why we allow it to be set
> by udev). And any calibration you set overwrites the udev one, you can still
> get that one later with libinput_device_config_calibration_get_default_matrix()
> The idea is that calibration need to only be applied once, then the
> compositor can forget about it.
> 
> if you're rotating the output that this device is associated with,
> you need to also rotate the input coordinates. The data from libinput is
> already calibrated, so it's just the pure rotation you need to apply.
> Do not rotate in the calibration matrix, unless the touchscreen is
> physically mounted with that rotation.
> 
> Does that make sense?

Hi Peter,

I think it does, yes. Just to reiterate, libinput will provide absolute
coordinates in the output space, and the compositor needs to convert
that to its own global space by applying the (inverse of) output
transformation matrix (global->output pixel coords). Right?

I haven't looked at the Weston code, but Thilo says it's broken. Thilo,
could you file a bug with all this information against Weston? If there
isn't one open already, that is.


Thanks,
pq