Matthew Ayres solar.granulation at
Mon Mar 1 07:26:54 PST 2010

On Mon, Mar 1, 2010 at 3:26 PM, Matthew Ayres
<solar.granulation at>wrote:

> On Mon, Mar 1, 2010 at 3:05 PM, Bradley T. Hughes <
> at> wrote:
>> On 03/01/2010 03:34 PM, ext Daniel Stone wrote:
>>> Hi,
>>> On Mon, Mar 01, 2010 at 02:56:57PM +0100, Bradley T. Hughes wrote:
>>>> This is where the context confusion comes in. How do we know what the
>>>> user(s) is/are trying to do solely based on a set of x/y/z/w/h
>>>> coordinates? In some cases, a single device with multiple axes is
>>>> enough,
>>>> but in other cases it is not.
>>> Sure.  But in this case you don't get any extra information from having
>>> multiple separate devices vs. a single device.  The only difference --
>>> aside from being able to direct events to multiple windows -- is the
>>> representation.
>> Correct. However, I think that being able to direct events to multiple
>> windows is the main reason we're having this particular discussion. How do
>> we do it, given the current state of the art?
> This question made me feel like I was at an icecream stall, trying to pick
> a flavour I like that doesn't have too many bugs in it :P
>  If the hardware is intelligent enough to be able to pick out different
>>> fingers, then cool, we can split it all out into separate focii and it's
>>> quite easy.
>> I don't think hardware is that intelligent... yet. I forget the name of
>> the program (not CCV as far as I know), but there does exist a program that
>> implements the TUIO protocol WITH support for object-id's. It can do object
>> recognition under special circumstances by looking for and identifying
>> infrared reflectors placed on the table's surface (and these reflectors are
>> often attached to an object). Programs could then map these object id's to
>> something meaningful (object id 5, mapped to "Brad's phone", could sync my
>> email, for example). I don't know of anything that tries to identify
>> individual fingers, though.
> reacTIVision.  My very involvement here is a result of wanting to use
> reacTIVision's fiducial markers in MPX.  I consider the availability of
> fiducial tracking vital and imagine each registered fiducial being slaved to
> a unique MD.
> I have high hopes of Ryan Huffman's xf86-input-tuio driver and am looking
> forward to inclusion of certain features to ease this behaviour.
>>  Failing that, how are we supposed to do it? Say two people have a
>>> logical button press active (mouse button, finger down, pen down,
>>> whatever) at once.  Now a third button press comes along ... what do we
>>> do? Is it a gesture related to one of the two down? If so, which one
>>> (and which order do we ask them in, etc).  A couple of years ago we
>>> still could've guessed, but as Qt and GTK are now doing client-side
>>> windows, it's really hard to even make a _guess_ in the server.
>> Right, and this was Peter's point... the X server can't know it and
>> shouldn't try to guess. What I did in Qt was to deliver the 3rd touch point
>> together with its closest neighbor (if the 3rd touch point was not over a
>> widget explicitly asking for touch events, that is).
> To me this sounds almost to be saying that touch events should be handled
> no differently than mouse events, but that doesn't seem right.  A mouse is
> always present, it always has a position.  A touch-sensitive slave/physical
> device may always be attached, but unless something is touching it, isn't it
> essentially absent?
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