multi-tutch?

Bastian Muck bastian.muck at gmx.de
Thu May 29 17:20:42 CEST 2008


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I have a little idea. Imagine, you put your finger somewhere on the 
right side of the screen. The "average" point is also somewhere at the 
right side. When you put another finger e.g. at the left side the 
"average" point jumps somewhere to the middle. This "jump" is where we 
could guess, that at least two fingers touch the screen. You can't use  
features  like zooming on iPhone, but it should be possible to switch 
scrolling into something else. So with one finger you could scroll the 
screen an with two fingers you could move something.
The only problem ist the accuracy of it.

Greetings Bastian

Joerg Reisenweber schrieb:
| Am Do  29. Mai 2008 schrieb boris.stender at gmx.de:
|> Hi Joerg,
|> as it seems that my mail did not reach the community list (I am not a
| subscriber, just monitoring the archives) may I ask you directly the 
question
| regarding "multi tutch" :-) . See below:
|>
|> Hi all,
|> if the geometric average point is returned if multiple points are touched
| wouldn't it be possible to have a fake multi touch, e.g., by doing the
| following:
|> Press point A
|> -> Vector A is returned
|> Additionally press desired point B
|> -> X = (A+B)/2 is returned
|> -> calculate B = 2*X-A
|>
|> Questions:
|> Would this be managable?
|> What time difference would be required between first and second (and
| third ...) touch, to recognize such a multi-touch action and reliable
| distinguish it from a single touch at position X?
|> And one more comment: If that would work you could also detect 
multi-touch
| gestures (even if limited), e.g., use the first point statically (maybe a
| focus centre) and handle the second point dynamically (maybe for 
zooming in
| and out).
|>
|> Boris
|
|
| there are two resistors in the touchpad, one for X and one for Y. We 
only see
| them changing on a touch, thus giving us the coords. A concurrent second
| touch just changes the R values even more, but we get no info about 
whether
| we touched a second point or we moved the finger. So what you suggest is a
| gesture recognition. Things become nasty because even the "geometric 
middle"
| isn't true but depends on pressure of one to pressure of other touchpoint
| etc.
| You really get too few info out of the device to do anything 
reasonable with
| it beyond singletouch (at least that's the way it is now. I plan to see
| whether we can exploit dynamic pulse response of this design to get some
| additional info. Same way you're testing cat5-cable for breaks. Don't hold
| your breath though, chances are bad. And it's not on top of my todo-list)
|
| cheers
| jOERG
|
| -------------------------
|
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| http://lists.openmoko.org/mailman/listinfo/community

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