Re: Rough draft of some success criteria for a extension guideline "Touch accessible"

On 18/08/2015 02:25, David MacDonald wrote:
 > Furthermore Detlev has a good start on the modified gesture issue
 >
 > 2.5.3 Modified Touch: When touch input behavior is modified by built-in
 > assistive technology, all functionality of the content is still operable
 > through touch gestures. (Level A)

I'm still not sure if this is actually within the power of a web content 
developer to control.

Let's take a concrete example: say I implement a swipe gesture detection 
on a page. For instance, this rough and ready 
http://patrickhlauke.github.io/touch/swipe/ - ignore the fact that 
currently this is completely inaccessible in many other ways, it's just 
something I've made up ages ago to explore gesture detection principles 
- let's assume the gesture detection is tied to a focusable control, and 
that swiping left, right, up, down triggers some form of behavior.

Once AT is running on the touchscreen device, swipes are intercepted by 
the AT. No touchstart/touchmove/touchend JavaScript events are fired 
when the user swipes, as those gestures are now handled by the AT.

For me as the web content developer, there is no mechanism to say to the 
AT that I do want to handle gestures (whereas on desktop, for 
keyboard-based interactions, I can add role="application").

For the user, on iOS/VO there's a pass-through gesture (double-tap and 
hold, perform the actual gesture that will be passed to the page). When 
this is used, the page's JavaScript does receive 
touchstart/touchmove/touchend events as normal. However, there is no 
announcement, hint, or anything else that would lead a user to even 
think there's a possible extra gesture in the page, and that they should 
use the pass-through. On Android/TalkBack, Windows Phone/Narrator, there 
is no - to my knowledge - pass-through gesture or equivalent, so both 
the developer and the user can't do anything with gestures at all, and 
they're all intercepted by the AT.

So, as a developer, I have no way to actually meeting this proposed SC, 
unless there's some very clear clarification that custom gestures are 
excluded somehow, which then defeats the intended purpose of the SC I think.

The only realistic option, from a developer's point of view, is to keep 
my gestures (for non-AT touchscreen users), but to complement them / 
provide equivalent functionality with more traditional means (controls, 
buttons, etc that react to click events).

P
-- 
Patrick H. Lauke

www.splintered.co.uk | https://github.com/patrickhlauke
http://flickr.com/photos/redux/ | http://redux.deviantart.com
twitter: @patrick_h_lauke | skype: patrick_h_lauke

Received on Tuesday, 18 August 2015 09:00:34 UTC