Topic: Single Point of Contact on Touchscreen?

Does the touchscreen detect one point of contact at a time, or can it detect multiple, simultaneous touches?  It seems to be just a single point, but I was thinking of the "pinch" function on Apple's iPhone, and wanted to see if something like that was possible on the chumby.

Re: Single Point of Contact on Touchscreen?

It's a resistive touchscreen, so yes, it only detects one contact at a time. Capacitive multi-touchscreens like the iPhone's are really cool technology, but aren't very widely manufactured/used yet.

Basically how the resistive screen works is by setting one point as an absolute, and by measuring the change in resistance in the panel when touched, and with a little math you can tell how far that point is from the one you defined earlier. Screens like the iPhone's will have a row and column of wires that form small capacitances at everywhere the wires cross, when your fingers are over those wires, you can measure a change in capacitance. And because you can read this device similarly to a memory device, you can resolve where multiple objects are touching the screen.

Re: Single Point of Contact on Touchscreen?

Thanks for the info - not surprising - I assumed it was not the same kind of screen, but I appreciate the explanation in the differences.

Re: Single Point of Contact on Touchscreen?

Yeah, multitouch screens are still pretty rare, and therefore pretty expensive.  I think Apple is the only company that makes wide use of multitouch input devices, on the iPhone and laptops, though I'm sure others are experimenting.

Of course, another issue is that most GUIs don't understand the concept of multipoint input devices - Flash, for instance, understands a single mouse/stylus, and the entire system is set up around that assumption.

Re: Single Point of Contact on Touchscreen?

I didn't even think about Flash's ability to interpret that data - but yes, that makes sense.

Thanks, Duane.