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
415.624.2709 (o)
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>; Bryan Garaventa <bryan.garaventa@ssbbartgroup.com>
Cc: 'Accessible Platform Architectures Working Group' <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

[IBM Watson]

Watson Release Management and Quality