RE: scrolling and scroll bars

Very good point Bryan!

 

To make this accessible on mobile without rendering it noisy on desktop, it
seems we need 2 things:

1.       An author-provided delineation of the scrollable areas using an
appropriate semantic structure, such as a list, table or labeled region.
This part is simple and something that can be done today.

2.       Something in the AX tree that indicates the semantic structure is
scrollable and which portion is currently visible. Desktop screen readers
could ignore this. But mobile screen readers and other assistive
technologies could use this information to describe the container as
scrollable. And, for example, a VoiceOver for IOS 3-finger tap when the
reading cursor is inside that container could announce information about
which page of the scroll view is displayed and how many there are.
Similarly, 3-finger swipes up/down could scroll it a page at a time.

 

This is a perfect example of how user agents could, and possibly should, use
CSS to inform AX APIs of information that is critical to accessibility. Good
thing a CSS AX mapping spec is starting to form.

 

Matt

 

From: Bryan Garaventa [mailto:bryan.garaventa@ssbbartgroup.com] 
Sent: Wednesday, June 8, 2016 3:51 PM
To: Matt King <a11ythinker@gmail.com>; 'Fred Esch' <fesch@us.ibm.com>
Cc: 'Accessible Platform Architectures Working Group' <public-apa@w3.org>
Subject: RE: scrolling and scroll bars

 

To clarify an important point, this is true on platforms such as Windows in
related browsers that support virtual offscreen models, but not on platforms
such as iOS that don't, or at least not in the same way.

 

E.G If using touch by holding your finger down on the screen and moving it
around to explore the rendered objects there, any offscreen content that is
scrolled out of view within a scrollable container will not be detected, nor
is the container conveyed as being scrollable, which I think it should be.

 

I'm not referring to regular page content that is scrolled offscreen as part
of the same static page, but rather the situation when you have two
scrollable divs side by side, which both include content that is
independantly scrollable. 

 

I've seen this within online shopping apps where in the left pane is a
scrollable container that includes the available isles for browsing, and in
the right container is the products associated with the selected isle for
review.

 

In the case of iOS using VoiceOver, while holding down one finger and
sliding it around the screen, all offscreen content is clipped, and there is
no indication that the container is directly scrollable. 

 

However when swiping from Left to Right or Right to Left using one finger,
the offscreen content will be scrolled into view as VoiceOver moves focus to
it. Nevertheless, the container is still not conveyed as being scrollable.

 

Bryan Garaventa

Accessibility Fellow

SSB BART Group, Inc.

bryan.garaventa@ssbbartgroup.com <mailto:bryan.garaventa@ssbbartgroup.com> 

415.624.2709 (o)

www.SSBBartGroup.com <http://www.SSBBartGroup.com> 

 

From: Matt King [mailto:a11ythinker@gmail.com] 
Sent: Wednesday, June 08, 2016 3:34 PM
To: 'Fred Esch' <fesch@us.ibm.com <mailto:fesch@us.ibm.com> >; Bryan
Garaventa <bryan.garaventa@ssbbartgroup.com
<mailto:bryan.garaventa@ssbbartgroup.com> >
Cc: 'Accessible Platform Architectures Working Group' <public-apa@w3.org
<mailto:public-apa@w3.org> >
Subject: RE: scrolling and scroll bars

 

Screen readers read all content that is in the DOM but not explicitly hidden
from the AX tree, i.e., display:none, visibility:hidden, aria-hidden=true.

 

Screen readers (unlike magnifiers) do not care about visual scrolling as
long as scrolling is not adding to or removing from the DOM or changing
whether content is explicitly hidden. 

 

Matt

 

From: Fred Esch [mailto:fesch@us.ibm.com] 
Sent: Tuesday, June 7, 2016 11:06 AM
To: Matthew King <mattking@us.ibm.com <mailto:mattking@us.ibm.com> >; Bryan
Garaventa <bryan.garaventa@ssbbartgroup.com
<mailto:bryan.garaventa@ssbbartgroup.com> >
Cc: Accessible Platform Architectures Working Group <public-apa@w3.org
<mailto:public-apa@w3.org> >
Subject: scrolling and scroll bars

 

Matt and Bryan,

For APA I have a task to review CSS Overflow Module Level 3
<https://www.w3.org/TR/css-overflow-3/> . A main feature of this doc is
defining and handling of scrollable areas. How does AT report scrollbars and
is it important for a non-sighted user to know whether an area is scrollable
or not? Another issue is do AT's report info that is visually clipped, that
is does the AT read the data as if it weren't visually clipped or does it
somehow try to represent only what is visible?




Regards, 

Fred Esch 
Watson, IBM, W3C Accessibility




Watson Release Management and Quality