Re: Changing definition of "Large text" to use px rather than pt

On 26/04/2016 18:18, Wayne Dick wrote:
> I agree that the user agent size is the base. That gives us REM.

Arguably rem aren't enough, as they only relate to the root size of the 
document, i.e. the font size defined for "html" itself, which can be 
easily overridden in CSS, e.g.

html { font-size: 10px; }

> Users
> don't care how W3 measures points or pixels.

But authors trying to follow WCAG 2, and auditors trying to determine 
whether something is or isn't "large scale (text)", do.

> To them the concept of
> perceivable font-size is defined by the dimensions of their eye. At
> present both screen physical size and eye size are imponderables for
> software. Lack of knowledge of screen size is not a necessity, but new
> hardware requirements would be needed to correct that problem.
>
> So, where do we stand.  What is large print. At present it is 24 / 16 =
> 1.5 times the REM that is usually 16px.  For now large print is 1.5xREM.
>
> The issue of matching font size to eyeballs. Is a little more tricky.
> Each individual can learn their critical print size (CPS), the minimum
> highly legible font size. The user agents will choose the average user
> CPS by trial and error, because they want normal users to use their
> browser.  Other users will need adjustments. Clearly setting the user
> agent REM should be available to users who are not average and content
> should respond to a wide range of REM.

Agreed, and certainly for WCAG.next and for any additions/definitions 
done in Low Vision TF work, this approach (making it relative to base 
font size, rather than some measure borrowed from print) should be favored.

P
-- 
Patrick H. Lauke

www.splintered.co.uk | https://github.com/patrickhlauke
http://flickr.com/photos/redux/ | http://redux.deviantart.com
twitter: @patrick_h_lauke | skype: patrick_h_lauke

Received on Tuesday, 26 April 2016 23:45:57 UTC