Le lundi 11 juillet 2005 à 13:00 +0200, Vojtech Pavlik a écrit :
> On Mon, Jul 11, 2005 at 12:39:31PM +0200, Stelian Pop wrote:
>
> > > > Using a function like
> > > >
> > > > return (x_old * 3 + x) / 4;
> > > >
> > > > eliminates the need for a FIFO, and has similar (if not better)
> > > > properties to floating average, because its coefficients are
> > > > [ .25 .18 .14 .10 ... ].
> > >
> > > Agreed.
> >
> > Except that this does not work well enough.
>
> I guess the quick motion compensation in input bites you. The above
> equation should do even more smoothing than regular 4-point floating
> average.
Possible. The 'fuzz' parameter in input core serves too many usages
ihmo. Let me try removing the quick motion compensation and see...
> > I already thought about this, one problem is that the sensors do not
> > report the pressure but only the amount of surface touched. A person
> > with thick fingers will always generate higher pressures then one with
> > thin ones, no matter how hard they push on the touchpad.
>
> That's what all other touchpads do.
I thought the hardware is capable of calculating real pressure...
> > I don't think this value is reliable enough to be reported to the
> > userspace as ABS_PRESSURE...
>
> I believe it'd still be more useful than a two-value (0 and 100) output.
Ok, I'll do it.
> > + /*
> > + * in the future, we could add here code to search for
> > + * a second finger...
> > + * for now, scrolling using the synaptics X driver is
> > + * much more simpler to achieve.
> > + */
>
> This could be quite useful, too, for right and middle button taps (2 and
> 3 fingers) - since the Macs lack these buttons.
Indeed. But this can be a later improvement, let's make one finger work
for now :)
Stelian.
--
Stelian Pop <[email protected]>
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