RE: WCAG 1.4.4 and resolution/DPI

Thanks very much folks!  Yes we have a wide range of monitors we support all the way up to even 4k or 8k desktop monitors and even larger when you take into account Surface Hubs 3840x2160.  We are hoping to find a minimum baseline resolution that can be set in the browsers and operating system to properly test the resize text requirement.  As you said, there is some impact since the breakpoints may be invoked earlier and I suspect in some cases, reflow will occur earlier with less pixels to use.

It seems the spirit of 1.4.4 is to be able to double the text size on whatever the "default".  A good baseline could be 1280 x 768 pixels roughly in the user agent.


From: Alastair Campbell <acampbell@nomensa.com>
Sent: Wednesday, September 5, 2018 2:27 PM
To: Jonathan Avila <jon.avila@levelaccess.com>; Jason Grieves <Jason.Grieves@microsoft.com>
Cc: public-low-vision-a11y-tf <public-low-vision-a11y-tf@w3.org>
Subject: RE: WCAG 1.4.4 and resolution/DPI

Ah, I had taken resolution as meaning the density of the pixels in the display, I see what you mean.

Indeed, the procedure from reflow is more specific about this now, example here:
https://rawgit.com/w3c/wcag/tech-flexbox-reflow/techniques/css/C31.html<https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Frawgit.com%2Fw3c%2Fwcag%2Ftech-flexbox-reflow%2Ftechniques%2Fcss%2FC31.html&data=02%7C01%7CJason.Grieves%40microsoft.com%7Ccd774005dd93420a0e9408d6137656c0%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636717796322543693&sdata=MYoa8oSFJg7W2FewVotfi4lMFhWdmIrXyc7lzEdej8o%3D&reserved=0>

Technically if there is way of getting text to be twice as large (or from a different starting point, twice as small!), it can pass Resize Text. However, in practice if you want it to be 'normal' on desktop and mobile, the text size will vary by at least 200% between those screen sizes.

The ways to fail would be to fix the size to the viewport, or use media queries to vary the size with the viewport. E.g:
https://rawgit.com/w3c/wcag/tech-failure-viewport-units/techniques/failures/F94.html<https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Frawgit.com%2Fw3c%2Fwcag%2Ftech-failure-viewport-units%2Ftechniques%2Ffailures%2FF94.html&data=02%7C01%7CJason.Grieves%40microsoft.com%7Ccd774005dd93420a0e9408d6137656c0%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636717796322543693&sdata=r7NGMhX5Bek%2B8pxhOg9%2FAAygyWGP4UXVFxN5s9V3Vto%3D&reserved=0>

Cheers,

-Alastair