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Re: [pointerevents] Add OS image dragging to non-normative reasons for pointercancel

From: Arthur Stolyar via GitHub <sysbot+gh@w3.org>
Date: Wed, 10 May 2017 20:43:51 +0000
To: public-pointer-events@w3.org
Message-ID: <issue_comment.created-300606717-1494449030-sysbot+gh@w3.org>
> I noted that your use case for counting how many fingers are down is also flawed. You cannot rely on the pairing of the events at all. You may receive a pointerup without receiving a pointerdown and vice versa.

That's weird. Why isn't that guaranteed? How someone should be able to implement multi-touch events if `pointerup` may not be called? I thought that the purpose of `pointercancel` -- if `pointerup` cannot be sent because finger/mouse/whatever is interrupted or out of surface then `pointercancel` is guaranteed to be called. Also many scripts indeed register `pointermove` on `pointerdown` and unregister on `pointerup`/`pointercancel`. This also brings question about `lostpointercapture` which is supposed to be called on `pointerup`/`pointerdown` (i.e. implicit capture loose).

IMO, if this is true when that's a bug in either browser or in the spec. And that also makes Touch Events more attractable since they always report touches count.

GitHub Notification of comment by NekR
Please view or discuss this issue at https://github.com/w3c/pointerevents/issues/205#issuecomment-300606717 using your GitHub account
Received on Wednesday, 10 May 2017 20:43:58 UTC

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