Re: [pointerevents] Notes with normative (SHOULD/MUST) statements (#405)

> ... where a User Agent can use the same pointerId for the same physical pen for multi-pen experiences

Thanks @bmathwig, yes that's a useful use-case we need to support.  IIRC we faced issues with detecting the "same physical pen" in the past.  Moving a pen off the digitizer range then bringing in a different pen made the second pen indistinguishable from the first one.  Didn't investigate if it was caused by a limitation in the hardware or the device driver or the OS (FYI it was several years ago, we used Windows Surface).  If a low-level unique pen-id is available these days, that's all we need.

Also note that we don't have to maintain the removed pen as an "active pointer" to support this use case.  In fact, maintaining a pen as "forever active" like this would be problematic when the pen has no chance of coming back (say its battery died): if the "dead" pen was the first pen seen by the digitizer, by definition it would remain the primary pointer forever and a replacement pen won't ever produce compatibility mouse events (as a non-primary device of type "pen").

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Received on Wednesday, 1 September 2021 14:40:02 UTC