[meta] Comply with WCAG guideline 2.3: Seizures [#2036293]

WCAG Guideline 2.3:

Do not design content in a way that is known to cause seizures.

2.3.1 Three Flashes or Below Threshold (Level A):

Web pages do not contain anything that flashes more than three times in any one second period, or the flash is below the general flash and red flash thresholds.

Sufficient Techniques:

G19: Ensuring that no component of the content flashes more than three times in any 1-second period OR
G176: Keeping the flashing area small enough OR
G15: Using a tool to ensure that content does not violate the general flash threshold or red flash threshold

Reference:

http://www.w3.org/WAI/GL/UNDERSTANDING-WCAG20/seizure-does-not-violate.html

2.3.2 Three Flashes (Level AAA):

Web pages do not contain anything that flashes more than three times in any one second period.

Sufficient Techniques:

G19: Ensuring that no component of the content flashes more than three times in any 1-second period

Reference:

http://www.w3.org/WAI/GL/UNDERSTANDING-WCAG20/seizure-three-times.html

ATAG Guideline A.3.3:

Help authors avoid flashing that could cause seizures.

A.3.3.1 Static View Option (Level A):

If the authoring tool contains editing-views that render visual time-based content, then those editing-views can be paused and can be set to not play automatically.

Reference:

http://www.w3.org/TR/IMPLEMENTING-ATAG20/#gl_a33

Comments

Comment #1

Pancho

UTC+2 🇪🇺 EU

CreditAttribution: Pancho commented 6 July 2013 at 19:50

I actually cannot come up with anything in Drupal core that purposely uses flashing or blinking content, that may be contained in animations, videos.

All I can possibly can come up with is a batch with the individual ops running very fast and alternatingly returning long - short - long - short - long - short - long status messages. If we take this guideline very serious and want to pass AAA level, we should systematically avoid them.
For A resp. AA level it would be enough if the potential flash is less than 21,824 pixels large. I'm quite sure that batch messages are smaller but didn't measure them.

Also, we should avoid any multiple flickering of the page (larger) page elements. However, I can't come up with any functionality in Drupal core where building the screen could possibly flicker more than once.

So even meeting the higher AAA level should be possible here, but we should make sure I didn't miss some aspect.