libinput requirements for feature parity with X

[Peter Hutterer]

On Thu, Jan 30, 2014 at 01:42:20PM -0800, Bill Spitzak wrote:
> Ping Cheng wrote:
> 
> >    graphics tablets:
> >    * extended axis event support
> >    * tool change notification (could be just button events? not sure)
> >
> >
> >Will tool id, serial number, and tool type be supported here?
> 
> Shouldn't each tool be a different pointing device? 

That largely depends on where tools are expected to be unified. Some pens
(Intuos 4, 5, Pro series) have unique IDs. So if you take them from one
tablet to the next, the ID obviously stays the same so in theory you could
attach a color to that tool and have it span multiple tablets.

I think this is something the client stack should provide, if at all. That
leaves libinput with the tablet as the main device, and the tool as a
subfeature on it.

> It at least
> needs to know which tool is being used when moving it, it can't be
> deferred until the first button is being pushed.
> 
> Are tablets capable of handling more than one tool at a time? If

In the Wacom range the answer to that is "some old serial ones did, but none
of the tablets that came out in recent years". And I think it's unlikely to
happen again.

> this is at all plausable I think they all have to be different
> pointers since otherwise there is no way to indicate which x/y
> position is which tool. Otherwise I guess a "tool changed" event
> would work.

You can augment events through other means to indicate the tool in use, you
don't need several devices.

Cheers,
   Peter