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Re: WebEvents-ISSUE-4: Does preventDefault on touchmove cause a dragging motion to fire a click event? [Touch Events spec]

From: Peter-Paul Koch <pp.koch@gmail.com>
Date: Tue, 15 Feb 2011 22:35:20 +0100
Message-ID: <AANLkTik_UuA=f7K7vEdjp5pr86=4rbCb3CWzmsgij_n2@mail.gmail.com>
To: Andrew Grieve <agrieve@google.com>
Cc: public-webevents@w3.org
>> >> > [[
>> >> > If preventDefault() is called on all touchmove events, should a click
>> >> > be
>> >> > fired even after dragging and taking your finger off the screen?
>> >> >  -This is the case with iOS
>> >> >  -I can't think of why this would be desirable.
>> >> > ]]
>> >>
>> >> I'd say Yes, the click event should fire. One user action triggers
>> >> several events here, and the fact that you prevent the default of one
>> >> should not influence the firing of other events. It may not be very
>> >> desirable, but it is logical. (As far as I'm concerned.)
>> >
>> > I think if the answer is yes, then just the opposite is happening -
>> > preventDefault is affecting the firing of other events. The question
>> > here is
>> > about a swipe that would not normally have fired a click, but does only
>> > because preventDefault() was called on all of the touchmove events.
>> Oh wow, do you mean that's what actually happens? That's Evil, if it's
>> true.
>> Is there a test page for this effect somewhere?
> Hmm, it's not exactly what I had thought. You need to tap-and-hold until the
> browser thinks you might be clicking. Without preventDefault(), the browser
> will enter native scroll mode and cancel the click. With preventDefault(),
> the browser will never enter native scroll mode, and so the click will
> always fire no matter how much you move your finger. This is all on iOS.
> Test page:
> http://dl.dropbox.com/u/6648754/webtests/touchmoveghostclick.html

Safari iOS does as you say, as does BlackBerry WebKit. Android WebKit,
Dolfin for bada, and Opera Mobile do not show the alert.

So sanity wins by 3-2, the effect should not be specified, and Safari
and BB have a bug. At least, that's my opinion.

ppk, mobile platform strategist
Received on Tuesday, 15 February 2011 21:35:53 UTC

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