Re: Mixed "pen" and multitouch input devices

["Henrik Rydberg" <rydberg@euromail.se>]

> The proper way to send events through evdev when there are two different
> "tools" (pen and touch) is to use BTN_TOOL_*. In your example above, it
> would be:
> 
> # finger touch (Note lack of tool, it's assumed to be finger)
>     ABS_MT_SLOT 0
>     ABS_MT_TRACKING_ID 42
>     ABS_MT_POSITION_X finger_x
>     ABS_MT_POSITION_Y finger_y
>     SYN_MT_REPORT
>     ABS_X finger_x
>     ABS_Y finger_y
>     SYN_REPORT
> # finger release
>     ABS_MT_SLOT 0
>     ABS_MT_TRACKING_ID -1
>     SYN_REPORT
> # pen motion
>     BTN_TOOL_PEN 1
>     ABS_X pen_x
>     ABS_Y pen_y
>     SYN_REPORT
> # finger touch begin
>     ABS_MT_SLOT 0
>     ABS_MT_TRACKING_ID 42
>     ABS_MT_POSITION_X finger_x
>     ABS_MT_POSITION_Y finger_y
>     SYN_MT_REPORT
>     BTN_TOOL_PEN 0
>     ABS_X finger_x
>     ABS_Y finger_y
>     SYN_REPORT
> etc.
> 
> Then, xf86-input-evdev ignores ABS_{X,Y} events when there is no
> BTN_TOOL_* active.

On the subject how pen and touch could work going forward, the MT
protocol is prepared to deal with tool type per slot. It makes a lot
of sense to move away from the above example, towards a fully parallel
representation of pen and touch data. Today's multitouch interfaces
are really tremendously restrictive; I am looking forward to the day
when one does not need to worry about touching or resting on a surface
in order to operate it.

In short, why not make xf86-input-evdev aware of MT_TOOL_TYPE?

Thanks,
Henrik