Hi Petr and all,

Am 20.02.2017 um 23:26 schrieb Petr Cvek [off-list ref]:

Hi

Dne 20.2.2017 v 17:50 H. Nikolaus Schaller napsal(a):

quoted

Hi Pavel,

quoted

Am 19.02.2017 um 23:19 schrieb Pavel Machek [off-list ref]:

hi!

quoted

quoted

quoted

But as said I don't think we need float or fixed point for practical systems
at all.

So you are going to loose precision. And if userspace decides to
calibrate it slightly differently from kernel, lost precision will
matter.

Really?

Really.

quoted

Example:

ADC values go 100 .. 3995 (i.e. touch margin is 100 steps in pre-calibration)

This is scaled to let's say 0..640.

Ok. Now userspace realizes that kernel alignemnt is off, and it would
want to scale it to 1..642.

Screen coordinates are still 0..639.

quoted

That will mean that single pixel will be
inaccessible, right?

Yes, that can happen if the additional user-space scale is > 1.0.

As long as it is small (I expect <1.01 = 1% error in scale) it is
barely noticeable.

Therefore, I asked before: how big in pixels is your finger or stylus?
Does this effect matter?

A resistive touch is a man-machine-interface where people press buttons of at
least 12x12 pixels size (or they are no longer visually recognizable).

Smallest kernel font is 4x6 (i think) and I'm regularly using 8x8. I would like
to be able to select a single letter in the console.

So you probably have exceptionally good eyes and reading a terminal on a touch
screen is not a typical use case (except for us hard-core programmers).

Anyways, if there is only a single pixel is not accessible due do rescaling and integer
truncation effects (which is what Pavel complained) you can still select single letters
in a 4x6 font.

---

So, let's close commenting this patch here since in my opinion everything is said
and the maintainers have decided not to accept it.

I hope that I have not forgotten anyone to answer.

Thank you very much to all participants for this discussion, because it was
really enlightening to me and contains a lot of new perspectives.

BR and thanks,
Nikolaus--
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