[RFC] Multi-Touch (MT) support - arbitration or not

[Ping Cheng]

On Sun, Nov 7, 2010 at 8:30 AM, Daniel Stone <daniel at fooishbar.org> wrote:
>> 1.     Arbitrate all touch data in the kernel.
>>
>> This is the simplest solution for device driver developers. But I do
>> not feel it is end user and userland client friendly.
>>
>> [...]
>>
>> 3.    Report first finger touch as ABS_X/Y events when pen is not in prox;
>>        Report pen data as ABS_X/Y events when there is no finger touch;
>>        Report touch data as MT_TOOL_TOUCH and pen data as MT_TOOL_PEN
>> events when both pen and touch data are received. No ABS_X/Y are
>> reported when pen and tocuh or multi-touch data are received.
>>
>> I feel this one makes sense to userland since pen can be considered as
>> another touch.
>
> I'd say that either #1 or #3 is the best idea here, simply because they
> seem to be the most straightforward, and thus easier to support.
> Assuming that xf86-input-wacom will track the state itself and decide
> (using whatever criteria) which events should send core x/y motion, then
> all you need to do with ABS_[XY] is just make a best effort to have it
> more or less work for dumb userspace clients.

Sorry for the noise (hit a wrong key).

There are two major differences between #1 and #3:

1.   #3 does not report any ABS_XY data when both pen and touch data
are received (#1 still sends pen ABS_X/Y);
2.   #3 sends both pen and touch data as MT events when both types of
data are received (#1 only sends pen data).

Which option do you like? We could go with a simple option. But that
would close the door to those feature rich applications.

Ping

Ping