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Re: Color contrast principle

From: Alastair Campbell <acampbell@nomensa.com>
Date: Fri, 8 Feb 2019 09:46:37 +0000
To: Joshue O Connor - InterAccess <josh@interaccess.ie>
CC: "WCAG list (w3c-wai-gl@w3.org)" <w3c-wai-gl@w3.org>
Message-ID: <00288E4D-D89C-4F74-8DEB-F9B1C2CA5A5C@nomensa.com>
Hi Josh,

There is a paragraph on that in the understanding:
“In combination with 2.4.7 Focus Visible<https://www.w3.org/WAI/WCAG21/20/focus-visible.html>, the visual focus indicator for a component must have sufficient contrast against the adjacent background when the component is focused, except where the appearance of the component is determined by the user agent and not modified by the author. If the focus state relies on a change of color (e.g., changing only the background color of a button), then changing from one color to another that has at least a 3:1 contrast ratio with the previous state of the control is a method for meeting the Focus visible criteria.“

What we haven’t said is that the requirement for focus visible hasn’t really changed with 2.1.

After going through all the issues and doing the understanding update, there was basically a choice. Use the SC language to mean either:

  1.  The component (visual indicators of it) needs to maintain contrast across states, OR
  2.  The states of the component have contrast with itself.

Given the use of ‘adjacent colors’ as the measurement, the second didn’t really fit in practice. Also, it would have left out things like check-marks and other functional indicators. So we decided to include the functional indicators, and encourage good contrast on focus indicators.

It’s one of the potential 2.2 criteria – an SC that focuses on changes of state and essentially defines the ‘visible’ in focus visible.

Cheers,

-Alastair
Received on Friday, 8 February 2019 09:47:02 UTC

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