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fontique: Fix synthesized slnt sign - #922
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tomcur
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| use parley::setting::Tag; | ||
| use parley::style::{FontFamily, FontVariation, FontVariations}; | ||
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| // Using Roboto Flex with slnt axis for italic/oblique effects | ||
| // TODO: FontStyle property doesn't automatically map to slnt axis for variable fonts, | ||
| // so, for this test, we use FontVariations directly | ||
| for (slnt_value, name) in [(0.0, "normal"), (-10.0, "italic"), (-10.0, "oblique")] { | ||
| let variations = FontVariations::List(Cow::Borrowed(&[FontVariation { | ||
| tag: Tag::new(b"slnt"), | ||
| value: slnt_value, | ||
| }])); | ||
| use parley::FontStyle; | ||
| use parley::style::FontFamily; | ||
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| // Note Roboto Flex has a `slnt` axis but no `ital` axis, so italic and oblique get a `slnt` | ||
| // variation. | ||
| for (style, name) in [ | ||
| (FontStyle::Normal, "normal"), | ||
| (FontStyle::Italic, "italic"), | ||
| (FontStyle::Oblique(None), "oblique"), | ||
| ] { | ||
| let mut builder = env.ranged_builder(text); | ||
| builder.push_default(StyleProperty::FontFamily(FontFamily::named("Roboto Flex"))); | ||
| builder.push_default(StyleProperty::FontVariations(variations)); | ||
| builder.push_default(StyleProperty::FontStyle(style)); |
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With just this test change and without the fix, the snapshots render as follows (upright, as Roboto Flex's slnt has range [-10, 0]).
style_font_style_values-italic
style_font_style_values-oblique
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LLM Contributions: Flagged it, review.
Similar to linebender#922. The OpenType angle is counter-clockwise in the positive
direction, whereas our `FontStyle::Oblique` follows CSS and is
clockwise, i.e., we need to negate.
I think this went unnoticed because, as with linebender#922, this appears to be a
relatively cold path: no fonts on my system seem to hit this branch.
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**Changelog**
> ### Fixed
> #### Fontique
>
> - `FontInfo::style` now reports oblique angles with the correct sign.
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Similarly, I don't think this is too impactful for me, but getting it out of open PRs is good.
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LLM Contributions: Review, updated test.
On top of #921 due to conflicts.
slntis counter-clockwise for a positive slant. That means we currently are trying to synthesize italics (ifitalis missing) with a counter-clockwise slant. We should pass in a negative angle to get a clockwise slant. CSS's oblique is clockwise in the positive direction, so its sign also needs to be inverted. Roboto Flex clamps at 0, so it simply keeps glyphs upright when given the old values.I think this wasn't caught because we normally match a font that is declared italic or oblique, so don't go through synthesis. The italic issue also only hits for fonts with
slntand withoutital. (When the test updated here was written, I think the fact that Roboto Flex stayed upright was assumed to be an indicator that we don't synthesize; but we were attempting to synthesize in the wrong direction.)Changelog