SUB - SC 2.5.7: Dragging Movements (Level AA) does not have a scroll bar example

[HelenBurge]

Originally raised in w3c/wcag#4329 as felt it was a missing example, but this is a question about scroll bars, dragging gestures and mobile applications that are a User Agent. Currently the UAAG (1.8.3 Provide Viewport Scrollbars) does specify a scrollbar is required, but not to make it accessible with buttons (like on desktop browsers).

Should mobile applications have more guidance for accessible scrollbars?

[JJdeGroot]

Hi @HelenBurge thanks for raising this issue, good question.

As you commented in the original issue in the wcag repository, it's important to redefine the User Agent.

We have an open issue for that: #63

The user agent mapping was also mentioned by @jamieherrera in our Issue for 2.5.7

Coincidentally, we discussed 2.5.7 in our meetings last week #53 (comment)

To apply 2.5.7, we need to clarify what a layer is in a mobile application, and who/what the user agent is in a mobile application.

The scroll bar in mobile applications, is usually not rendered by developers, but by the (native) components they are using.

A big difference between web and native Android/iOS is that browsers automatically render scroll bars when web content exceeds the viewport. On Android/iOS, scroll bars are only rendered if a ScrollView is explicitly provided as parent of the content. In most cases, the scroll bar is rendered by the framework/platform and not by the developers.

Also...

Note the difference between dragging and pointer gestures > https://tetralogical.com/blog/2023/03/17/foundations-pointer-gestures/

As I understand it, scrolling is considered a single pointer gestures, and would be part of SC 2.5.1, and not 2.5.7.

NOTE: This requirement applies to web content that interprets pointer actions (i.e., this does not apply to actions that are required to operate the user agent or assistive technology).

For 2.5.1, we also need to map the user agent to determine if the exception applies or not.

The understanding doc for 2.5.1 has some more details about scrolling, including on touch-based devices.

When testing on desktop the scroll has arrow controls at the top and bottom to reduce the need for a drag movement.

On Windows, yes. But on macOS, there are no arrow controls (by default).

Should mobile applications have more guidance for accessible scrollbars?

Perhaps, depending on the way user agent is mapped.

[HelenBurge]

Thanks for the response - 2.5.1 does have some guidance but more about how it might be used instead of the author path based gesture. Scroll bars tend to be just a drag action until the user lets go. I will check the rest out though!

[detlevhfischer]

per note

NOTE: This requirement applies to web content that interprets pointer actions (i.e., this does not apply to actions that are required to operate the user agent or assistive technology).

...it would appear that if we equate the user agent in the web space with the OS in native mobile, this would mean that if authors include containers where the OS takes care of scrolling functionality, the content would pass. If however the author evaluates scroll position and does something (e.g. lock a slider to a particular position so you have in effect "stepped scrolling" and not fluent scrolling where any end position of content in the range of the slider is possible), the behaviour would fall under the responsibility of the author and the author would need to make sure that there are elements to move / scroll content with simple tap gestures (either tapping arrow buttons or pager navigation dots, or single-tapping a position on a scrollbar if the content will then move accordingly).

It does not really matter that much if this falls under 2.5.1 or 2.5.7 since in both cases the author should supply simple alternatives (for single pointer tap or click). If a horizontal slider is in a vertically scrolling page, starting the dragging movement or pointer gesture in a vertical direction normally pans the page, which would this a gesture that falls under 2.5.1 (since there is an initial point on the horizontal axis to trigger the horizontal movement).