[RFC] MPX XInput Protocol extensions - big issues....
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Mon Mar 3 23:35:03 PST 2008
Jim Gettys wrote:
> How will we associate users with input devices? We'll certainly be
> dealing with input devices that can identify who is using them (e.g.
> Diamond Touch, remote devices, etc.)
I don't think this should be part of the X server. I did try to find a
solution to this problem and it's a bit bigger than expected. ATM, I
think adding it to ICCCM/EMWH is the proper solution.
The reason is simple: X doesn't really care about the semantics of how
the devices are used, it'll just send events when appropriate. When you
introduce a user object, you suddenly have to worry about a lot of other
- is the user an operating system user? or just a guest?
- can the user even be identified? or can you just differ between users
(e.g. DiamondTouch can only differ, but not identify)
- If two devices are to be used by the same user, which one is in the
dominant hand? Is there a concept of a dominant hand? If more than two
devices are used, the dominant hand may change depending on which
devices are to be used.
All these are very context-dependent problems and can change, even in
between applications. The idea I had to sort-of solve this add a user
object to ICCCM. Assign device ids to the users, assign login names if
available. The information is there if apps need it, otherwise it
doesn't matter. ICCCM allows us to be a lot more flexible too.
I don't have a complete solution to this yet. I ran into the roadblocks
mentioned above and they need sorting out.
But my opinion is that it should not be in the server.
> How will that interact with Eamon's security framework?
Eamon's work has been merged into MPX. there were a few occurances that
needed sorting out, Eamon helped me with that. But, bar various bugs, it
does not interfere with the security framework.
As for the user object, see above.
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