[csswg-drafts] [css-fonts-4] Behavior for variable fonts with 'ital' axis ambiguous / underspec'ed

drott has just created a new issue for https://github.com/w3c/csswg-drafts:

== [css-fonts-4] Behavior for variable fonts with 'ital' axis ambiguous / underspec'ed ==
@jpamental initially reported this issue discussing font matching and rendering results for a variable font that has an `ital` axis.

I do not see a clear and interoperable way to make them work described by the spec:

Assume there is a font face declaration as follows:

    @font-face { /* Font Face 1 */
    font-family: ItalAxisExampleFont;
    font-style: oblique 0deg 20deg;
    }

for a font that has an 'ital' axis ranging from 0 to 1.

And a style rule as follows:

    * {
    font-family: ItalAxisExampleFont;
    font-style: italic;
    }

The font matching algorithm describes that after no match for `italic` is found, oblique 20deg and above should be tried next, so _Font Face 1_ is matched.

However, as there is no way of specifying `font-style: italic 0 1` the `@font-face` declaration and the actual font axes mismatch. The `@font-face` declaration pretends to be able to apply a `slnt` / oblique axis varying between 0 and 20 to the font. However, the font does not have a `slnt` axis.

If we really do not want to have a way of specifying a way for italic (not oblique) to be variable, then I am missing a clarification in the spec that would say something about how `oblique <angle> <angle>` and a resulting matched instance / style like `oblique 20deg` should be applied as `ital 1` in terms of variation parameters to a font that does not have a real `ital` axis but instead is declared with `oblique <angle> <angle>`.

CC @behdad @kojii @jpamental

Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/3125 using your GitHub account

Received on Tuesday, 18 September 2018 13:44:40 UTC