- From: John Foliot <john.foliot@deque.com>
- Date: Wed, 12 Jul 2017 10:01:19 -0500
- To: Alastair Campbell <acampbell@nomensa.com>
- Cc: Laura Carlson <laura.lee.carlson@gmail.com>, 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: <CAKdCpxxOEcskrRspob3PzO6V0NPGOG-wZq3cH5Qkbv73wTafXg@mail.gmail.com>
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
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Received on Wednesday, 12 July 2017 15:01:55 UTC