Re: SC 2.4.13 perimeter calculation inacuracy

On 15/10/2023 14:32, wolfgang.berndorfer@zweiterblick.at wrote:

> The calculation in the example does not meet the definition of the 
> perimeter:
> 
> https://www.w3.org/TR/WCAG22/#dfn-perimeter 
> <https://www.w3.org/TR/WCAG22/#dfn-perimeter>
> 
> The definition says:
> 
> „continuous line forming the boundary of a shape *not including shared 
> pixels*, […]”
> 
> But the example does not subtract the shared pixels (like it did in the 
> draft):
> 
> „The perimeter calculation for a 2 CSS pixel perimeter around a 
> rectangle is 4h+4w, where h is the height and w is the width.“
> 
> Is this inaccuracy an approximate value due to easier readability or do 
> I miss something?

Not sure if this was answered or not (just came across this email in 
isolation while clearing things out this morning), but I believe that 
yes, this was handwaved here - and also gets complicated because it 
depends on whether this perimeter is inside or outside of the component 
(if inside, there's the overlap at the four corners of the rectange; if 
outside - like a focus outline that sits around the outside of the 
rectangle - then there's now *gaps* at the corners). Still, agree that 
this inaccuracy is confusing, and should have been called out with at 
least a parenthetical that explains the above in somewhat simple terms).

P
-- 
Patrick H. Lauke

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Received on Monday, 4 December 2023 08:36:10 UTC