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The latest trackpad drivers can identify the position of two or
three touch points [1], and experimental touch screen drivers can
report even more. For video of examples of what this enables, see:
http://www.youtube.com/watch?v=mZ0TWCViRB8
http://www.youtube.com/watch?v=89sz8ExZndc
What would it take for the DOM Mouse events to support multi-touch?
Currently, MouseEvent specifies {clientX, ClientY} and {screenX,
screenY}. This would need to be generalized to an array of such
locations, but in such as way as to provide backwards compatibility
for existing scripts when only a single pointer location is
involved.
Extending DOM MouseEvent to support multi-touch would be useful
for SVG-based Web applications even if the underlying Windowing
system isn't yet capable of exploiting multi-touch.
Note higher level events such as scroll and zoom are valuable for
device independence, but it takes a long time indeed for such
concepts to establish themselves to the point where they can be
standardized. Lower level events are easier to standardize and
encourages the experimentation needed for eventual agreement on
standardizing high level events.
[1] The Synaptics touchpad driver for XOrg/XFree86 can recognize
two finger taps for the middle button and three finger taps for
right button events, See http://web.telia.com/~u89404340/touchpad/
As yet there is no way to access the finger positions directly,
but this is just a matter of time. The hardware provides for
locational accuracy to 1/1000th of an inch as well as pressure
detection (equating to greater capacitance).
p.s. according to wikipedia, virtually all of the significant
touchscreen technology patents were filed during the 1970's and
1980's and have expired. Touchscreen component manufacturing and
product design are no longer encumbered by royalties or legalities
with regard to patents and the manufacturing of touchscreen-enabled
displays on all kinds of devices is widespread. See,
http://en.wikipedia.org/wiki/Touch_screen
Dave Raggett <[EMAIL PROTECTED]> W3C lead for multimodal interaction
http://www.w3.org/People/Raggett +44 1225 866240 (or 867351)
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