[RFC] PDA as a TCP graphic tablet?

[Ivor Hewitt]

Guennadi Liakhovetski wrote:
> Hi all
> 
> I have a device (Tuxscreen), capable of running Linux with a
> VGA-resolution (I think) LCD display with a touchscreen. So, I had an idea
> to use it as a graphic tablet. A quick google revield no existing
> software. So, I would just code a server on the device, that would get
> events from /dev/eventX, and send them over TCP to a PC, where a client
> would just export, say, a named pipe, which X would open as a device node.
> That's all nice and simple, now, I don't know how best to present this
> device to X. The touchscreen can deliver only x, y, and pressure. The
> device has a keyboard, so, I can switch between, say, those 3 modes that
> wacom tablets use (stylus, eraser, cursor)? Don't think many have
> Tuxscreens, but a possibility to use any Linux PDA as a graphic tablet
> (ok, pretty poor, but still) would be interesting to many?
> 
> So, what is the sensible way to bind to X? I would prefer not to have to
> write a new X-driver... Abusing the wacom driver would be dirty... I see a
> number of drivers in input/, but have no idea if one of them would be
> suitable for that. Don't think evdev would do? As an application I am
> thinking about Gimp.
> 
> If there is already a driver I could reasonable (ab)use, ideally it should
> only use read/write on the fd. If it uses ioctl's, well, that would mean I
> would have to write a kernel driver too. Not too dramatic, but not exactly
> the ideal solution.
> 
You might want to look at the code for synergy2
(http://synergy2.sourceforge.net/) for ideas/code/inspiration.

Rather than an X driver -since the device isn't a directly connected
peripheral but another networked machine - I'd say you want a client app
that listens for your messages and moves the mouse/sends events in the
manner of synergy.

Cheers,
Ivor