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Re: First Draft, Touch Interface Spec

From: Olli Pettay <Olli.Pettay@helsinki.fi>
Date: Tue, 01 Feb 2011 15:20:31 +0200
Message-ID: <4D48089F.9070105@helsinki.fi>
To: Doug Schepers <schepers@w3.org>
CC: "public-webevents@w3.org" <public-webevents@w3.org>
On 01/25/2011 04:41 PM, Doug Schepers wrote:
> Hi, folks-
>
> Rather later than promised, but here is a first draft of the Touch
> Interface spec:
> http://dvcs.w3.org/hg/webevents/raw-file/tip/touchevents.html
>
> As mentioned before, I modeled this on the WebKit implementation, with a
> few suggested enhancements. I don't know how close I got it, but at
> least we now have a starting point to build on...
>
> Comments welcome!
>
> Regards-
> -Doug Schepers
> W3C Team Contact, SVG, WebApps, and Web Events WGs
>
>


Some questions, comments


What is .identifier? Each TouchPoint get their own id? Why couldn't 
scripts just use the objects as identifiers?
Or, is it expected that implementation creates a new TouchPoint object
whenever something in it changes (like, user moves a finger a bit so 
that coordinates change), but the identifier stays the same?
In that case .identifier would be closer to event stream id.

.target in TouchPoint. What should happen if the target is moved to 
another document? Again, this problem depends on the case whether
implementation is expected to create new TouchPoint objects all the time
or just update the existing ones.

How does event targeting work. If I use two fingers and move them 
somewhat simultaneously, I do get two touchmove events, right?
.touches contain them both, but what is in .changedTouches?
What is .targetTouches? Apple's documentation has exactly the
same description for .touches and .targetTouches.


In general, do we need TouchLists, especially now that browsers
are starting to implement things like requestAnimationFrame and 
beforePaint[1]? One could just capture all the touch events
between beforePaint events and collect the events as a list, if
it really needs to, and then possibly update the layout based on the 
events in the beforePaint event listener.



-Olli


[1] 
http://hacks.mozilla.org/2010/08/more-efficient-javascript-animations-with-mozrequestanimationframe/
Received on Tuesday, 1 February 2011 13:21:00 GMT

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