- From: John Foliot <john.foliot@deque.com>
- Date: Wed, 12 Jul 2017 08:54:44 -0500
- 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>, "w3c-wai-gl@w3.org" <w3c-wai-gl@w3.org>, public-low-vision-a11y-tf <public-low-vision-a11y-tf@w3.org>
- Message-ID: <CAKdCpxyFQ_30Bk1vJxowkm1mk3DZp3zWkKJoU6r9OPS6JQc+2g@mail.gmail.com>
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: Inline 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
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Received on Wednesday, 12 July 2017 13:55:23 UTC