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

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