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[csswg-drafts] [css-values][css-text-decor] Relative length units for stroke widths

From: Christoph Päper via GitHub <sysbot+gh@w3.org>
Date: Tue, 27 Dec 2016 14:19:51 +0000
To: public-css-archive@w3.org
Message-ID: <issues.opened-197709379-1482848389-sysbot+gh@w3.org>
Crissov has just created a new issue for 
https://github.com/w3c/csswg-drafts:

== [css-values][css-text-decor] Relative length units for stroke 
widths ==
As 
[mentioned](https://github.com/w3c/csswg-drafts/issues/459#issuecomment-260609781)
 
[before](https://github.com/w3c/csswg-drafts/issues/239#issuecomment-265941151)
 in #459 and #239, I believe that it would be useful to have 
additional [relative length units](#font-relative-lengths) to refer to
 the nominal width or thickness of strokes in the glyphs of a font.

* The *base stroke thickness* is the width of primary stems, usually 
straight vertical strokes.  
  UAs may determine the base stroke width from the median width of a 
vertical stem in a lowercase glyph with ascender, e.g. _h_ (_1_?, `/` 
in _x_?).
  In the cases where it is impossible or impractical to determine the 
base stroke thickness, a value of `0.0625em` must be assumed. This is 
`1px` for the common default font size of `16px`.

* The *hair-line stroke thickness* is the width of secondary stems, 
often straight horizontal or diagonal strokes. In some fonts, by 
design, it does not differ from the base stroke thickness.
  UAs may determine the hair-line stroke width from the median width 
of a horizontal bar in a lowercase glyph, e.g. _e_ (_7_?, `\` in 
_x_?).
  In the cases where it is impossible or impractical to determine the 
hair-line stroke thickness, a value of `1bs` must be assumed.

The exact names, definitions and abbreviations are of course open to 
discussion. I used to favor `bs` and `hs` or `ds` and `us`, but the 
_s_ standing in for _stroke_ may be too reminiscent of the one in `s` 
‘second’ and `ms` ‘millisecond’.

Please view or discuss this issue at 
https://github.com/w3c/csswg-drafts/issues/838 using your GitHub 
account
Received on Tuesday, 27 December 2016 14:20:07 UTC

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