W3C home > Mailing lists > Public > w3c-wai-eo@w3.org > October to December 2018

Note from the weeds

From: Wayne Dick <wayneedick@gmail.com>
Date: Mon, 17 Dec 2018 15:11:45 -0800
Message-ID: <CAJeQ8SAxg7CxydL9LnGfmuYK5hfBGaVAoQzVdDLZLvX76_+CFw@mail.gmail.com>
To: GLWAI Guidelines WG org <w3c-wai-gl@w3.org>, public-low-vision-a11y-tf <public-low-vision-a11y-tf@w3.org>, "EOWG (E-mail)" <w3c-wai-eo@w3.org>, W3C WAI ig <w3c-wai-ig@w3.org>
Observations on Using Stylesheets to Implement Assistive Technology using
WCAG 2.1: Notes from the weeds

1.  Using Stylesheets as Assistive Technology
It may come as a surprise, but stylesheets are an effective assistive
technology for low vision. If you want to see how to generate them without
expertise take a look at http://nosetothepage.org/newN2tP/. This only
generates generic sheets at this time. They may or may not work depending
on the pages at hand. The spacing sheet works well most of the time. The
font sheet also works well in most cases. Color is a problem because so
much semantic information is conveyed using generated content. Color
changes often kill these semantics.

The output of the newN2tP app is input to Stylus. So, if you have Stylus
loaded in your browser, just import the output JSON file.

2. Font Size
Implementing font size is now relegated to the browser. This reduces
adjustments to font size to small changes to improve the look of pages. For
example: a user with 1600x900 outer resolution can enlarge to 500% before
meeting the 320 CSS px boundary. The jump in font size between 400% and
500% may be too much. Maybe 450% would be perfect. Recuding font size to .9
the original would give 450% enlargement with 500% zoom.

3. Spacing
Spacing works on most pages given the following exceptions. A. Fixed width
non wrapping fields and B. Fixed height regions.

Ofter the theraputically optimal spacing is too big to fit in fixed witdth
fields and the spacing must be normalized down. That is not best but it is
a compromise that is necessary.

Increased line height will often cause fixed height fields to truncate
information. These fields are common in shopping applications.

3. Font Family
The ability to change font family is not recogized by any version of WCAG.
However, to write an effective assistive technology for low vision one must
be able to change font family. As it turns out, rather than using a
uinversal selector, one can create a selector that incudes all HTML
elements that may include text, except for “span” and “i” and “math” which
may include icons or special symbols. Sometimes a long “span” will be
missed, but with size and spacing support most users can read a long “span”
here and there.

4. Why Stylesheets and not an Extension
This is the first cut of the N2tP assistive technology so Stylus input
(stylebot format) was easiest. However, there are several one sound reason
to prefer stylesheets. Stylesheets are less invasive. Stylus only inserts
stylesheets, it does not change the actual “body” code. Thus the integrity
of the page is left in tact. I believe this is important and, in the end,
will engender more support from developers and browsers.

The JSON for Stylus input allows multi-section stylesheets that are
discriminated by the URL information that triggers them. Thus when I must
change color for a page that uses generated content, I must use a very
gentle stylesheet, but if a page has no generated content that conflicts
with color change a very gross style sheet that uses universal selectors is
in order.

Good News:
WCAG 2.1 conformant pages work extremely well. Only color is a problem.


Best, Wayne
Received on Monday, 17 December 2018 23:12:46 UTC

This archive was generated by hypermail 2.4.0 : Friday, 17 January 2020 20:29:55 UTC