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Re: Color contrast principle

From: James A. <A.James@soton.ac.uk>
Date: Fri, 8 Feb 2019 07:48:28 +0000
To: Alastair Campbell <acampbell@nomensa.com>
CC: "WCAG list (w3c-wai-gl@w3.org)" <w3c-wai-gl@w3.org>
Message-ID: <F98889FF-C11C-424D-9C54-8B738EE55A4C@soton.ac.uk>
Hi Alistair

Thank you for your detailed, late night responses. I think you suggested additional text will help, particular if we can also add a visual example to the understanding document.

Best wishes


Sent from my iPhone

On 7 Feb 2019, at 22:27, Alastair Campbell <acampbell@nomensa.com<mailto:acampbell@nomensa.com>> wrote:

James wrote:
> We are looking at coloured buttons without a border and there doesn’t seem to be any examples that cover this in the understanding document.

Conceptually the ‘boundaries’ section covers this:
“This success criteria does not require that controls have a visual boundary indicating the hit area, but if the visual indicator of the control is the only way to identify the control, then that indicator must have sufficient contrast. …  If a button with text also has a colored border, since the border does not provide the only indication there is no contrast requirement beyond the text contrast”

Perhaps that should be  “If a button with text also has a colored border or background…”?

Just before publication of 2.1 there was a discussion along the lines of: Requiring links/buttons with a background seemed to be counter-productive. There were quite a few examples [1] where it was judged that requiring a flat background color to have contrast had a negative impact.

That should be represented in the understanding doc, but if it isn’t clear, we can add some examples.

So the answer to:

  *   if there is a visual indicator of the control other than through the colour of the hit area (e.g. through styling of the text as in this example), does it pass?

It depends on the control, but a hit-area isn’t required, so if it is a link/button then there is no contrast requirement beyond the ‘content’ (text or icon). Other types of control rely more on visual information though, so inputs and checkboxes (for example) would need some visual indicators with contrast.

  *   if it easier to pass this success criteria when no indication of the hit area is provided (particularly with icon buttons), would that actually be more detrimental to accessibility/usability?

That was part of the reason why we decided not to have a requirement for hit area, it would setup a negative incentive. So whilst it is desirable to have a hit-area (i.e. an affordance) for buttons, that is more from a usability point than accessibility (i.e. sucks for everyone).

There is an argument for an accessibility guideline for visual affordances, but it’s a different one from the low-vision contrast requirement that probably requires some form of personalisation.



1] https://lists.w3.org/Archives/Public/public-comments-wcag20/2018May/0001.html<https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.w3.org%2FArchives%2FPublic%2Fpublic-comments-wcag20%2F2018May%2F0001.html&data=01%7C01%7CA.James%40soton.ac.uk%7C5864352425dd4f74819608d68d4b73ed%7C4a5378f929f44d3ebe89669d03ada9d8%7C1&sdata=9QlAkfoRMKSvh4oqVZyQwLdFtmbw9cZc27FRxKultXQ%3D&reserved=0>

Received on Friday, 8 February 2019 07:48:54 UTC

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