[PATCH weston 00/13] Add tablet support

[Peter Hutterer]

On 7/11/2015 09:13 , Jason Gerecke wrote:
> On Thu, Nov 5, 2015 at 8:31 PM, Peter Hutterer <peter.hutterer at who-t.net> wrote:
>>
>> This set adds support for graphics tablets to weston. It's not fully
>> complete, there are a couple of fixmes in it but the patchset is getting a
>> bit unwieldly. And there are some discussions on how to do things anyway.
>>
>> Note: This needs the tablet-support branch from libinput to work. And it is
>> on top of Jonas's wip/wayland-protocols github branch (ff0452cea150c).
>>
>> Tablet events are sent serially, terminated by a frame event. A toolkit
>> should accumulate them and then pass them on as one struct to the client. We
>> don't do that atm, it may be beyond libtoytoolkit's scope to really
>> integrate this properly.
>>
>> The tablet has a separate cursor. That's a conscious decision since the
>> focus handling on tablets closer to an absolute touch screen than a mouse,
>> but unlike touch you usually want a cursor shape to indicate the precise
>> position.
>>
>> The rest is fairly straightforward, though as said above, some details are
>> missing. Implementing this also showed that libinput needs a few extra
>> things added to it.
>>
>> Cheers,
>>    Peter
>
> Having trouble getting this patchset to work properly for me. Of the
> many times I've launched 'weston-tablet', only once did it work as
> expected. The rest of the time I get no response and more often than
> not a segfault when the pen leaves proximity (first backtrace). I've
> also seen a segfault when simply trying to exit Weston with
> CTRL+ALT+BACKSPACE (second backgrace).
>
> Haven't had time to track down the cause; all I know at the moment is
> that it seems the demo client's proximity_in_handler isn't actually
> being called for some reason...

I've seen this bug a few times but don't know what the cause of it is 
yet. I *think* it may be a libinput bug because the libinput event never 
appears in the log. The problem is that once the bug happens it happens 
repeatedly, but otherwise it's really hard to trigger. Unplugging the 
tablet usually stops it but not always, but I haven't seen it since Wed 
now so i'm struggling to reproduce it right now.

Also, fwiw so you don't have to handle the patchset itself:

http://github.com/whot/weston/tree/tablet-support-v3 (f4c8c77)
http://github.com/whot/wayland-protocols/tree/wip/wayland-tablet (8ded9b)
and libinput's tablet-support branch (ab6a409)

Cheers,
   Peter