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Re: Several event types are too discrete to be useful for touchscreen input

From: Rick Byers <rbyers@chromium.org>
Date: Mon, 5 Nov 2012 15:44:30 -0500
Message-ID: <CAFUtAY8o1A4qxZG3Whm0LE1vs1uWPsYQEEcydAxOeDzaKi8VAg@mail.gmail.com>
To: James Craig <jcraig@apple.com>
Cc: Robert Kroeger <rjkroege@chromium.org>, public-indie-ui <public-indie-ui@w3.org>
Great, thanks!  Sorry I'm not up-to-date on the minutes of this group (I
actually can't find the specific minutes you're referring to -
http://www.w3.org/WAI/IndieUI/wiki/Meetings/TPAC2012#Minutes says they're
TBD).

Is there a good reason to prefer polar co-ordinates to
cartesian co-ordinates?  If the goal is to enable apps to use these events
instead of mousewheel, it would help in adoption to have the co-ordinate
system be the same (and seems like most real use cases would end up having
to convert to delta-X and delta-Y values anyway).

Ok, so how about UIValueChangeRequestEvent then?  The spec mentions
"gestures on touch-enabled interfaces" as one of the scenarios.  Should it
also change to use some sort of continuous value instead of the four
different delta amounts specified by the enum?

Rick

On Mon, Nov 5, 2012 at 3:21 PM, James Craig <jcraig@apple.com> wrote:

> This came up during one of the F2F meetings last week. I'd encourage you
> to read the minutes, but the general end result for those was to make
> scroll request a 2-dimensional direction and distance. Likewise a second
> event, panRequest, would be a variant of scrollRequest to the primary
> difference being that the limit values (e.g. home/end) apply to general
> scroll views but not on pan views.
>
> ACTION-23: Add panRequest with pan direction (360) and distance
> ACTION-27: Consider moveRequest in the context of scrollRequest and
> panRequest
>
> On Nov 5, 2012, at 8:24 AM, Rick Byers <rbyers@chromium.org> wrote:
>
> > Hi,
> > I know there was originally a desire that Indie UI events would be rich
> enough to be useful for common touch screen interactions (eg. see
> http://www.w3.org/WAI/IndieUI/wiki/Use_Cases_and_Requirements#Scenario_1:_Manipulating_a_map).
>  To what extent is this still a goal?
> >
> > I took a quick look at the work-in-progress spec (
> https://dvcs.w3.org/hg/IndieUI/raw-file/7f84811c9874/src/events.html) and
> see that a common theme is to make the events fairly discrete, eg. with an
> enum of possible values.  For example, the UIScrollRequestEvent takes an
> enum for one of 4 directions.  I'd love to be able to use UIScrollRequest
> to, eg., pan a map with a touch screen, but for that it would need
> _at_least_ some measure of distance connected to the screen (eg. scrolled
> 10 pixels up and 2 pixels to the right).  Even for the more common scenario
> of triggering these events from a track pad, you'd need a measure of
> distance.  Do you intend for UIScrollRequest to replace the use of
> mousewheel (http://www.w3.org/TR/DOM-Level-3-Events/#events-WheelEvent)
> events, or would apps always need to listen to both?
> >
> > The overall impression I get is that these events are really designed to
> be triggered by discrete operations like pressing of buttons.  I think the
> approach would need to be modified (eg. to take arbitrary precision values
> in place of enums) to really ever get used for any sort of continuous input
> like a touch screen or track pad.  But perhaps that's no longer a goal?
> >
> > Thanks,
> >    Rick
> >
> >
>
>
Received on Monday, 5 November 2012 20:45:18 GMT

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