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

I don't recall our including distance.

Rich


Rich Schwerdtfeger



From:	James Craig <jcraig@apple.com>
To:	Rick Byers <rbyers@chromium.org>, Robert Kroeger
            <rjkroege@chromium.org>,
Cc:	public-indie-ui <public-indie-ui@w3.org>
Date:	11/05/2012 02:24 PM
Subject:	Re: Several event types are too discrete to be useful for
            touchscreen  input



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
>
>