RFC: touch event clarification

RFC: touch event clarification

[Rafi Rubin]

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Dmitry: would you care to clarify the meaning of the basic touch events?  It
might also be helpful to add more comments to input.h or add something to the
Documents directory.


My current understanding:
BTN_TOOL_FINGER: touch pad single finger
BTN_TOOL_(DOUBLE|TRIPLE|QUAD)TAP: touch pad 2,3 and 4 fingers
BTN_TOUCH: touch screen single finger
BTN_[0-N]: not really for fingers.


Are the taps at all appropriate for touch screens?  How should the wacom
non-screen tablets be treated, should they act like touch pads both for absolute
and relative modes?

Should there be any difference between pad and screen devices with respect to
multitouch events (currently, I'm assuming not)?


Thanks,
Rafi
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Re: RFC: touch event clarification

[Dmitry Torokhov]

Hi Rafi,

> Dmitry: would you care to clarify the meaning of the basic touch events?  It
> might also be helpful to add more comments to input.h or add something to the
> Documents directory.
> 
> 
> My current understanding:
> BTN_TOOL_FINGER: touch pad single finger

Correct.

> BTN_TOOL_(DOUBLE|TRIPLE|QUAD)TAP: touch pad 2,3 and 4 fingers

Tapping with more than one finger, These events are tailored to
touchpads that can only report numberf or contacts but not discrete
coordinates for every contact,

> BTN_TOUCH: touch screen single finger

Right.

> BTN_[0-N]: not really for fingers.
> 

Right, these are miscellaneous buttons.

> 
> Are the taps at all appropriate for touch screens?

I do not think tap makes sense for touchscreens, the act of touching
should cause "select" or "action" event. Unlike other devices with
touchscreens you do not need to track movement of a pointer, your finger
ios a pointer and when you touch you mena to perform an action. At least
this is the model I'd operate with.

>  How should the wacom
> non-screen tablets be treated, should they act like touch pads both for absolute
> and relative modes?

Yes, since they are physically separate from treh screem tracking
pointer makes sense for tablets.

> Should there be any difference between pad and screen devices with respect to
> multitouch events (currently, I'm assuming not)?
>

Umm... if you are referring to gestures then I think they should exibit
similar behavior.

-- 
Dmitry