Milti-touch with current hardware?

[Nardella]

I once owned a handheld with a very poor touch screen. I wanted to see what happened when I tried to use two styluses on it. Since the screen was of poor quality the cursor would jump seemingly randomly and quickly between three points, the exact point of each stylus and the point directly between them.


This would make multitouch with a slow refresh rate viable for the device.


The Pandora touch screen seems to do this as well, but seems to be better at picking the point between the two points of contact.


I am wondering if the driver could be tweaked to make the Pandora screen poorer at picking this centre point thus allowing for two point multi touch?

 

[Darkknight512]

No, it is a resistive touchscreen. As far as I know, you need some specialized hardware to make a multitouch resistive touchscreen.

 

[gotwake424]

No, it is a resistive touchscreen. As far as I know, you need some specialized hardware to make a multitouch resistive touchscreen.

IRC there was a guy who had made some agorthims(sp?) that made 2 different point register on resistive touch screens i'll see if i can find that article

 

[WizardStan]

No, it is a resistive touchscreen.

GRAH! Not this old nut again. There is nothing intrinsic about resistive touch screens that would necessarily prevent multi-touch, as has been proven. It's not a case of it being resistive, it's that the original screens weren't designed with multi-touch in mind and the same basic design has followed ever since.


So yes, it does require different hardware in order to get multi-touch. Two point multi-touch is fairly easy, there's a lot of companies selling two point resistive touch screens now, but I can't get quotes on any of them.


The mentioned algorithm isn't true multi-touch though, it just does a good simulation of it for the purposes of pinching and squeezing. When you touch two points, the input looks as if it has been touched by a very fat finger. The algorithm measures that fatness and takes changes in it as "multitouch" input. We could do this on the Pandora, it's just not that interesting.


True dual touch resistive screens are designed differently so that these two contact points are kept separate. Weird things happen if a third thing is contacted.


The design was extended and 10 point multi-touch screens have been demoed, but I don't expect them to appear, nor can I think of any proper use for them. Maybe three point would be useful, but not beyond that.

 

[Binky]

With existing single touch screens it would be possible to press (and hold) one point, then press other points with another finger: simply by waiting for the stylus/finger to move very quickly (without being taken off the screen) (because a second finger was placed). the software could then measure the distance moved, and double it to calculate the position of the second touch.


Problem is, something like that would be best used for modifier keys on a virtual keyboard, which would be pointless on the Pandora!