Re: Testability of Animation from interactions Issue 18

Apologies, I see that you agreed with "1/3 of the web page" as being 
baffling in my original email, while I also included (and more so) "33% 
of any 10 degree visual field on the screen" as a source of bafflement.

Taken a step back then, does "visual field on the screen" as in the 
current WCAG 2.0 definition actually mean, in essence, the overall size 
of the screen? If so, the suggestion below still stands (referring to 
"viewport size" rather than "web page")

On 10/01/2017 23:46, Patrick H. Lauke wrote:

> not 1/3 of the *web page*, but 1/3 of the viewport size (e.g. on most
> smartphones, for a page that sets a mobile-friendly ideal viewport with
> a width=device-width meta viewport directive, around 320 x 600 density
> independent CSS pixels).
>
>>>> 2. and you can’t use 1/3 of screen for the same reason as #2 above.
>
> You could if you take at least the assumption that a user will position
> themselves in a way that they can comfortably see the entirety of the
> screen/viewport, so that it takes up their field of vision. That won't
> be true everywhere, of course, but without any form of base assumption
> like that, I don't think we can have ANY anchor points (this echoes
> pretty much the discussion about not being able to determine physical
> size of something rendered on a screen, combined now with a further
> unknown variable of viewer distance)
>
>>>> 4)  I THINK — Doing it in CSS pixels (aka David) is the best bet but
>>>> remember that a large blinking “O" only changes a relatively small
>>>> number of pixels -- so you might look at pixel area rather than pixels.
>>>
>>> What about simply percentage of overall screen/viewport size? It's
>>> still an approximation, as some users will be closer/further away
>>> from their screen so even the full screen/viewport will in fact
>>> occupy different angle of their full field of view, but it's at least
>>> something that can be consistently queried and tested (though in
>>> context of responsive design, it'll need to be tested for each
>>> breakpoint/common device screen resolution). for instance, simply
>>> saying "more than 1/4 of the viewport" or similar?
>>
>>
>> Same problem as above.  You have absolutely no idea how large that is
>> without knowing a bunch of things about the screen (see #2 above)
>>
>> however — you might do something like base it on a typical screen size
>> and resolution and scaling etc — and then set your threshold
>> there.      This was done for Flash.
>
> There is no single "typical screen size". At best, we can hope to define
> 10 or so "typical screen sizes" for small smartphones, medium
> smartphones, large smartphones, small tablets, medium tablets, large
> tablets, small laptop/desktop screen, etc.
>
> 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 Wednesday, 11 January 2017 00:00:30 UTC