[Development] Extending touch semantic information and Qt backends

[Ariel Molina]

On Thu, Feb 11, 2016 at 6:31 AM, Rutledge Shawn <
Shawn.Rutledge at theqtcompany.com> wrote:

>
> > On 11 Feb 2016, at 11:35, Александр Волков <a.volkov at rusbitech.ru>
> wrote:
> > Angle is not enough, because for compatibility with older apps
> TouchPoint::rect() should be as close as possible to the rotated rect.
> > See https://codereview.qt-project.org/#/c/114238/
> > In other words it should be a projection of the rotated rect, so you
> should introduce a separate method to get the rotated rect.
>
::blob() and ::blobAngle()  ?


> TUIO models the touchpoint as a rotated ellipse though, right?
> http://www.tuio.org/?specification  And I think that’s nice, for finger
> touchpoints at least (although markers could be any shape).  It can be
> assumed to be the ellipse inscribed in a rect; but I don’t think for the
> next-gen API that it makes sense to change the dimensions just because it’s
> rotated, because that makes it hard to visualize the ellipse, and hard to
> turn the size of the contact patch into a pressure (if you have hardware
> which gives you the contact patch but not the pressure).
>
> Typical capacitive touchscreens (or window-system APIs) don’t provide the
> contact patch either, do they?  I’m not sure why it’s not more common.
>

I think they will become more common as the haptic interaction grows.
Apple, for example is now supporting haptic pressure sensors (do they
detect shape?) and also the Apple-led reborn of pen computing will forcibly
need shape/rotation recognition, see palm rejection:
https://vine.co/v/etUgZKl0laX



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-- 
Ariel Molina R.

http://edis.mx
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