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

A couple of quick comments:

‘Large text’ is in the glossary, which is labelled as normative.

Note 3 within the definition indicates that the measure is based on the user-agents calculation, not a physical size:
"The point size should be obtained from the user agent, or calculated based on font metrics as the user agent does, when evaluating this success criterion.”

I think there are two useful steps from here:

1. In the near future, use the ‘understanding’ doc to explicitly say that 1pt = 1.33px, so use 18/24px. I have been confused by the use of PT before (assuming it was equivalent to px), as have many (probably most?) people I’ve talked to. 

2. For WCAG.next, drop the explicit sizes and work from the user-agents' default text-size.  

I maintain that pixels are the best relative unit[1], as the device maker / browser has to decide the base size for a CSS pixel based on intended usage [2], which they do already quite effectively.

Being aware that authors can over-ride the ‘base’ text-size by setting it on the HTML/Body elements, we could refer to proportions of the default size, e.g. 120% & 150% of the default text-size of the user-agent (although that might ban setting a size on HTML/body elements in practice?).

Cheers,

-Alastair

1] https://alastairc.ac/2012/04/relative-pixels/

2] https://alastairc.ac/2013/02/how-to-hold-your-ipad/

Received on Tuesday, 26 April 2016 08:28:49 UTC