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Re: Proposed mobile techniques for SC 3.2

From: Alastair Campbell <acampbell@nomensa.com>
Date: Mon, 13 Apr 2015 10:13:19 +0100
To: GLWAI Guidelines WG org <w3c-wai-gl@w3.org>
Message-ID: <D1514394.22E47%acampbell@nomensa.com>
Testability is difficult for this one, but I can see a couple of approaches:

 1.  Does the minimum size meet the platform guidelines. For example, I think iOS defines something like  44 points as a minimum (points being relative pixels, I.e. 88px on a 2x display), and Android & Windows have something similar. We pick the smallest of these as the minimum to work across platforms as a testable minimum.
 2.  Given that pixels are the best relative measure across platform [1], working out a minimum physical size on a small device and working out the pixels should be possible.

>From a limited experience in testing with people who have mobility impairments on mobile, they tended to pick a larger phone like a 5” Android assuming that the buttons would be bigger. (This was pre-iPhone 6 / 6+). People who needed more essentially have to use an alternative input.

I think the minimum value has to work for the mainstream, i.e. not be bigger than normal, but the SC could be used to prevent buttons being too small.

If we can’t define a minimum, then it will have to be ‘should’.

Kind regards,


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

From: Gregg Vanderheiden <gregg@raisingthefloor.org<mailto:gregg@raisingthefloor.org>>
Date: Friday, 10 April 2015 22:06
To: GLWAI Guidelines WG org <w3c-wai-gl@w3.org<mailto:w3c-wai-gl@w3.org>>
Subject: Re: Proposed mobile techniques for SC 3.2
Resent-From: <w3c-wai-gl@w3.org<mailto:w3c-wai-gl@w3.org>>
Resent-Date: Friday, 10 April 2015 22:06


I think this is important

but I wonder about testability.
And I’m not sure how we would determine what these mean.

This is for CONTENT — and target size is determined by they hardware.
e.g. the size of the button varies depending on whether it is displayed  on a    56 cm/23 inch  touch screen   or a 40cm/15.7in touchscreen   or a  10cm/4 inch screen

In fact - what will fit on one screen would not on another

If the author has no control over what size screen it would be on  —  how do they follow this provision?

If these are just  “SHOULD” guidelines (advisory) then these are fine.  I don’t see a problem/question.

but if they are SHALL  then … don’t they have to be measurable?
— and don’t they need to apply  everywhere (all content)?

We need to think about being on the receiving end of these.  If someone requires US to follow them - and will not pay our salary (fee) if we don’t.
How will we know (and prove) that we have met them?

The question/concern is about about the Target Size/Spacing provision — but also for other ones as well.


 *   Is this an advisory document (all "shoulds” )
 *   or a conformance document  (you “Shall” do these or you don’t conform).

    -  then the   “are” in the provision below needs to be changed to   “should”   or “is best if”  or something like that.

If it is a CONFORMANCE type document

 *   then we need to say exactly how large,   and say it in some measurable fashion that everyone would agree on whether it is met.
 *    “large enough” is not measurable.
    *   “large enough to touch accurately”  is different for each person.  Which person is the “certified test measure person” ?
 *   Ditto for “adequate"

Received on Monday, 13 April 2015 09:13:55 UTC

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