Re: [PATCH 3/4] input - wacom : support one finger touch the touchscreen way

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

Hi Chis,

> Extra clarification on whats going on here:
> 
> Patch #1 removes BTN_TOOL_TRIPLETAP; among other supporting 2 finger
> touch code.  In that context, it was used as an awkward indication to
> xf86-input-wacom that device supported 2 finger touch.

Which is great, no argument there.

> In this patch #3, it removes BTN_TOOL_DOUBLETAP; which was an awkward
> indication to xf86-input-wacom that device supports 1 finger touch.
> Once this patch is applied, applications must deduce touchscreen input
> supports 1 finger touch same way as they do for other touchscreens
> (not seeing BTN_TOOL_FINGER and no stylus related BTN_'s as well).

Also makes sense - I only noticed that it was gone without
replacement, and Ping's and your answer gives ample rationale for its
removal.

> Patch #4 adds BTN_TOOL_DOUBLETAP back but using normal meaning that
> the device supports 2 finger touch.

Right, thanks.

> I had reviewed this patch series in context of some related changes
> from Ping to xf86-input-wacom.  I wanted to document doubletap part of
> that review on this list though.
> 
> Ping originally didn't want to add that back in.  At least one of the
> reasons was that there were no known applications that supported both
> "touchscreens" (absolute mode) and the BTN_TOOL_DOUBLETAP at same
> time.

Given the current state of userland, a touchscreen should not emit
doubletaps, true.

> I did look around quite a bit after Ping's comment and I couldn't come
> up with anything (mtdev, xf86-input-evdev, etc).  So its a good point.
>  When something supports ABS_MT_*, thats given much more weight then
> BTN_TOOL_DOUPLETAP would; which is the case here.

Yes - unless the device is of the SEMI_MT kind, the finger-counting
BTN_TOOL_* events really have no meaning.
 
> Anyways, I requested if Ping would add BTN_TOOL_DOUBLETAP in to align
> with current hid-ntrig and since it didn't seem to hurt and could
> possibly help some future app.  Please double check me here if it is
> in fact a good idea to add DOUBLETAP in for touchscreens.

In fact, I think it hurts a bit, so removing it is a good idea.

Thanks,
Henrik