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RE: CFC: Target Size and Target Size (no exception) SC

From: Repsher, Stephen J <stephen.j.repsher@boeing.com>
Date: Wed, 24 May 2017 13:11:29 +0000
To: "Patrick H. Lauke" <redux@splintered.co.uk>, "w3c-wai-gl@w3.org" <w3c-wai-gl@w3.org>
Message-ID: <c31712af2f3341ed889da52e8d68f795@XCH15-08-08.nw.nos.boeing.com>
> Why do websites need to define a specific minimum color contrast when users can just use high contrast mode on their device?
Let's not get carried away here.  If you're talking about OS high contrast modes, those have no effect on web content.  If you're talking about color inversion, that has mathematically zero effect on contrast ratio.

Steve

-----Original Message-----
From: Patrick H. Lauke [mailto:redux@splintered.co.uk] 
Sent: Wednesday, May 24, 2017 5:22 AM
To: w3c-wai-gl@w3.org
Subject: Re: CFC: Target Size and Target Size (no exception) SC

On 24/05/2017 02:58, Gregg C Vanderheiden wrote:
> I still continue to have concerns about this.     40px is a non-defined 
> size.   on ever device it is a different size 
 > — yet we are saying it
 > MUST be this big or larger —  when  THIS   is some arbitrary size on
 > different screens.
 >

Note that it's not completely arbitrary, just the best that can currently be defined.
On devices/UAs where a CSS pixel approximately matches the definition of the reference pixel https://www.w3.org/TR/css3-values/#reference-pixel a size defined in CSS pixels shakes out to roughly (with varying degrees of "rough") the same size at the same viewing/use distance.

Indeed, on mobile/touch devices there's certainly variance, but a size defined in CSS pixels (when the ideal viewport is set on the page using the appropriate meta element) comes to roughly the same size as rendered on the screen. (regardless of whether it's a high-dpi/"retina" display or not, since we're talking CSS pixels and not actual physical pixels).

See
https://www.w3.org/WAI/GL/mobile-a11y-tf/wiki/Summary_of_Research_on_Touch/Pointer_Target_Size#Comparison_of_web_content_sized_in_px_and_physical_size_of_rendered_content_on_common_device_screens


[...]
> Finally — why do controls need to be large for everyone when a person 
> who needs them to be larger can zoom to make them larger — as large as 
> they need them to be.

Why do websites need to define a specific minimum color contrast when users can just use high contrast mode on their device?

Zooming (in most/all user agents on phone/tablet devices) leads to horizontal and vertical scrolling. Yes, a user can zoom to make targets more easily "tap-able", but at the expense of then having to scroll in both directions around the page.

Having said all that, I'm still personally leaning more towards turning this into a best practice piece of advice (in Silver), rather than a hard SC in WCAG 2.1.

P
-- 
Patrick H. Lauke

www.splintered.co.uk | https://github.com/patrickhlauke

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Received on Wednesday, 24 May 2017 13:12:08 UTC

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