touch screen calibration?

[chueh8]

How does Android process the "touch event" from the linux kernel /dev/
input/eventX ?
Does it use the tslib like Qtopia?
There are some "touch" related info in "MotionEvent" in the
documents...
Well, I don't know how it get the "raw" touch data, or how it perform
the calibration to the touch device..
Ant hint for that?
Thanks.

-chueh8

[Dianne Hackborn]

All our devices at this point use capacitive touch screens, which don't need calibration.

--
Dianne Hackborn
Android framework engineer
hac...@android.com

Note: please don't send private questions to me, as I don't have time to provide private support.  All such questions should be posted on public forums, where I and others can see and answer them.

[Billy Maron]

On Fri, Feb 6, 2009 at 12:38 AM, Dianne Hackborn <hac...@android.com> wrote:

All our devices at this point use capacitive touch screens, which don't need calibration.

whoa? what?

 

[Dianne Hackborn]

Er which part of that is surprising? :}

[Billy Maron]

On 2/6/09, Dianne Hackborn <hac...@android.com> wrote:
> Er which part of that is surprising? :}

I thought you were claiming that capacitive touch screens don't need
calibration. That surprised me.

[Dianne Hackborn]

They don't by the user.  You'll notice that neither the G1 nor the iPhone require the user to calibrate their screen like you usually see on resistive screens such have traditionally been in Palm and Windows Mobile devices.

[chueh8]

Perhaps no need for the user, but needed for the manufacturer...
I just like to know the data send from kernel need to be the one
calibrated or just the raw data..
For other Linux touch screen driver support,, usually there is a tslib
like run for calibrated the raw data from kernel..
so what does the Android do?

On Feb 7, 11:20 am, Dianne Hackborn <hack...@android.com> wrote:
> They don't by the user.  You'll notice that neither the G1 nor the iPhone
> require the user to calibrate their screen like you usually see on resistive
> screens such have traditionally been in Palm and Windows Mobile devices.
>
>
>

> On Fri, Feb 6, 2009 at 3:00 PM, Billy Maron <billyma...@gmail.com> wrote:

>
> > On 2/6/09, Dianne Hackborn <hack...@android.com> wrote:
> > > Er which part of that is surprising? :}
>
> > I thought you were claiming that capacitive touch screens don't need
> > calibration. That surprised me.
>

> > > On Thu, Feb 5, 2009 at 10:07 PM, Billy Maron <billyma...@gmail.com>
> > wrote:
>
> > > > On Fri, Feb 6, 2009 at 12:38 AM, Dianne Hackborn <hack...@android.com>

> > > wrote:
>
> > > > > All our devices at this point use capacitive touch screens, which
> > don't
> > > need calibration.
>
> > > > whoa? what?
>
> > > --
> > > Dianne Hackborn
> > > Android framework engineer

> > > hack...@android.com

>
> > > Note: please don't send private questions to me, as I don't have time to
> > > provide private support.  All such questions should be posted on public
> > > forums, where I and others can see and answer them.
>
> --
> Dianne Hackborn
> Android framework engineer

> hack...@android.com

[Dianne Hackborn]

It is all handled in the kernel and/or screen firmware.  I don't know for sure, I basically know that all that needs to be done with the data coming out of the driver is to scale the coordinates to the pixel size of the screen.

hac...@android.com

[vishal bhoj]

It has to be calibrated data. Android assumes it to be calibrated

--
with regards vishal

[vinay]

>It has to be calibrated data. Android assumes it to be calibrated

that means dirver should have hard coded XMAX,XMIN, YMAX, YMIN as per the touch screen calibrated earlier ?

[vishal bhoj]

yes, that is the modifications you have to do on the touchscreen driver . If you search you will find these kind of modifications on other driver done. you can follow them and add it. something like this


input_set_abs_params(input_dev, ABS_Y, pdata->y_min,
            pdata->y_max, 0, 0);
    input_set_abs_params(input_dev, ABS_X, pdata->x_min,
            pdata->x_max, 0, 0);

--
with regards vishal