Re: Adapting Text Units: Spaces, paragraphs, and ems

Hi Alastair,

A bit more fine-tuning... how about:

* line-height (spacing) to at least 1.5 *em* (space *line*-and-a-half)
* spacing between paragraphs to at least 2 em (2 lines)

* letter spacing (tracking) to at least 0.12 em
* word spacing to at least 0.16 em

???

JF

On Wed, Jul 12, 2017 at 9:25 AM, Alastair Campbell <acampbell@nomensa.com>
wrote:

> Hi John,
>
>
>
> The testing on HTML based sites should be fairly easy, use styles and/or
> scripts to override the values to those in the bullets.
>
>
>
> That’s what the bookmarklet [1] did (NB: needs updating to the newer
> values), so you apply that script and see what breaks or gets hidden.
>
>
>
> VIP reader (for PDFs) takes a linearization approach, and you then add
> whatever font-adjustment you like. Testing there is pretty quick to, PDFs
> tend to either reflow ok, or implode fairly badly.
>
>
>
> I’d suggest this:
>
>
>
> * line-height (spacing) to at least 1.5 (space-and-a-half)
> * spacing between paragraphs to at least 2 em (2 lines)
> * letter spacing (tracking) to at least 0.12 em
> * word spacing to at least 0.16 em
>
>
>
> In HTML/CSS, line-height is the term, line-spacing elsewhere. If that is
> still confusing, then call it “1.5 em” which is then tied to the definition
> of font-size, and the same thing in practice.
>
>
>
> For the paragraph spacing, browsers have their own padding/margin values
> which can vary, so it would be best to have a straight measurement (based
> on font-size) rather than adding to a default.
>
>
>
> The original SC from COGA included: “Line spacing (leading) is at least
> space-and-a-half within paragraphs; and paragraph spacing is at least 1.5
> times larger than the line spacing.”
>
>
>
> I’m not clear what that means because it is relative unit multiplied by a
> relative unit?!
>
>
>
> line height of 1.5 * 2 = 2.25 em?
>
>
>
> I suggest we just round that off to “2 lines”, or “2 em”. If the
> requirement is for more, we can increase it but let’s do it clearly!
>
>
>
> Cheers,
>
>
>
> -Alastair
>
>
>
> PS. Wayne has done some great work on how letter/word spacing, font-size,
> and font-family interact. It looks to me like we could combine the two
> width bullets into:
>
> * letter spacing (tracking) to at least 0.05 em
>
>
>
> 1] https://github.com/w3c/wcag21/issues/78#issuecomment-277743607
>
>
>
>
>
> *From: *John Foliot <john.foliot@deque.com>
> *Date: *Wednesday, 12 July 2017 at 14:54
> *To: *Laura Carlson <laura.lee.carlson@gmail.com>
> *Cc: *Greg Lowney <gcl-0039@access-research.org>, Jason White <
> jjwhite@ets.org>, Detlev Fischer <detlev.fischer@testkreis.de>, WCAG <
> w3c-wai-gl@w3.org>, LVTF - low-vision-a11y <public-low-vision-a11y-tf@w3.
> org>
> *Subject: *Re: Adapting Text Units: Spaces, paragraphs, and ems
> *Resent-From: *LVTF - low-vision-a11y <public-low-vision-a11y-tf@w3.org>
> *Resent-Date: *Wednesday, 12 July 2017 at 14:55
>
>
>
> Hi Laura,
>
>
>
> Thanks for this, it is indeed very nuanced.
>
>
>
> Currently, we have a technique that also refers to 'spacing' but then
> provides examples using the CSS line-height property (see:
> https://www.w3.org/TR/WCAG20-TECHS/C21.html), which ultimately is what I
> believe we are looking for here.
>
>
>
> As long as we can accurately convey the intent of this aspect of the
> requirement (it is a vertical measure we are seeking, not a horizontal one
> when it comes to spaces between lines and paragraph blocks) then I will be
> agreeable with a unitless measurement in the actual SC language (per
> existing convention), while at the same time noting that applications such
> as MS Word measure this unit as "lines":
>
>
>
> [image: nline image 1]
>
>
>
> Perhaps something like:
>
>
>
> Heights:
>
> * line spacing (leading) to at least 1.5 lines (space-and-a-half)
> * spacing between paragraphs to at least 2 lines (two spaces) larger than
> the default line spacing
>
>
>
> Widths:
> * letter spacing (tracking) to at least 0.12 em
> * word spacing to at least 0.16 em
>
>
>
> ... (?)
>
>
>
> From a testing perspective, I would envision something like first checking
> a page's CSS for the line-height property
> <https://www.w3.org/TR/CSS21/visudet.html#propdef-line-height> (which
> according to the spec can be expressed unitlessly, as an EM value, or as a
> percentage). At the opposite end of the scale, I could physically measure
> the actual height of the font / font-face in question and then, using that
> value multiply it by 1.5 to arrive at the second measure I need to test for
> (I don't advocate for this manual a test, but when push comes to shove...)
>
>
>
> JF
>
>
>
> On Wed, Jul 12, 2017 at 7:25 AM, Laura Carlson <
> laura.lee.carlson@gmail.com> wrote:
>
> Hello John, Greg, Detlev, Jason, and everyone,
>
> Based on Wayne's research and analysis, I previously suggest the
> following for the Adapting text SC.
>
> * line spacing (leading) to at least 1.5 (space-and-a-half)
> * spacing between paragraphs to at least 2 (two spaces) larger than
> the line spacing
> * letter spacing (tracking) to at least 0.12 em
> * word spacing to at least 0.16 em
>
> On the call yesterday [1], some folks brought up that they felt the
> use of "spaces" to measure leading for the Adapting Text SC is
> untestable. At one point line-height was suggested.
>
> Detlev, you were absolutely correct when you said, "if memory serves
> line-height needs no unit". In CSS line-height is unitless. Eric Meyer
> explained that in "Unitless line-heights". [2] It inherits from the
> font size. This was discussed on in the Adapting text GitHub Issue
> last March [3].
>
> Moreover, WCAG 2.0 1.4.8 Visual Presentation [4] uses the "spaces" and
> "paragraphs" for units. It states:
>
> "...Line spacing (leading) is at least space-and-a-half within
> paragraphs, and paragraph spacing is at least 1.5 times larger than
> the line spacing..."
>
> Is that currently untestable? If not, why not re-purpose that terminology?
>
> As for using ems as a unit perhaps we need a definition because that
> is a new concept for WCAG. How about something like:
>
> em: A length unit relative to the font-size that is used. e.g., letter
> spacing of 0.12 em means 0.12 spacing in addition to the default space
> between letters of the font size in use.
>
> Ideas for improvement? Other thoughts?
>
> Thanks everyone.
>
> Kindest regards,
> Laura
>
> [1] https://www.w3.org/2017/07/11-ag-minutes.html#item02
> [2] http://meyerweb.com/eric/thoughts/2006/02/08/unitless-line-heights/
> [3] https://github.com/w3c/wcag21/issues/78#issuecomment-288755938
> [4] http://www.w3.org/TR/WCAG20#visual-audio-contrast-visual-presentation
>
> --
> Laura L. Carlson
>
>
>
>
>
> --
>
> John Foliot
>
> Principal Accessibility Strategist
>
> Deque Systems Inc.
>
> john.foliot@deque.com
>
>
>
> Advancing the mission of digital accessibility and inclusion
>



-- 
John Foliot
Principal Accessibility Strategist
Deque Systems Inc.
john.foliot@deque.com

Advancing the mission of digital accessibility and inclusion