Vertical Metrics consistency

[vv-monsalve]

The fonts currently published to Google Fonts don't follow the vertical metrics specifications, resulting in inconsistency across platforms, and appearing too wide on Windows.

In preparation for the new fonts update, they should follow the spec. However, due to the significant difference, we can't apply the strategy of inheriting the Win metrics, in which case, an overall regression must be accepted and a new compromise between platforms should be made.

Please find the current and proposed values below, with comparative images between them.

Current values

Metrics	Bungee	Hairline	Inline	Outline	Shade	Spice
sTypoAscender	860	860	860	860	860	860
sTypoDescender	-140	-140	-140	-140	-140	-140
sTypoLinegap	200	200	200	200	200	200
hhea Ascender	860	860	860	860	860	860
hhea Descender	-140	-140	-140	-140	-140	-140
hhea Linegap	200	200	200	200	200	200
winAscent	1634	1614	1634	1644	1634	1138
winDescent	914	894	914	924	914	362

Requirements and new values proposed

• Changing the Typo and hhea values, and keeping the win metrics for each family (to avoid clipping)
• Linegaps == 0
• Use of Typo Metrics must be enabled

Metrics	Bungee	Hairline	Inline	Outline	Shade	Spice
sTypoAscender	1020	1020	1020	1020	1020	1020
sTypoDescender	-300	-300	-300	-300	-300	-300
sTypoLinegap	0	0	0	0	0	0
hhea Ascender	1020	1020	1020	1020	1020	1020
hhea Descender	-300	-300	-300	-300	-300	-300
hhea Linegap	0	0	0	0	0	0
winAscent	1634	1614	1634	1644	1634	1138
winDescent	914	894	914	924	914	362

Comparative images

Old = GF distributed / New = proposed values

Windows

Mac

[justvanrossum]

We'll implement this very soon, thanks for the suggested new values!

[vv-monsalve]

Excellent news! The values were calculated as an average between the current values for both Windows and Mac, and also to give a prudent space for stacked diacritics. Considering this is an all-caps display font, the leading has been kept tight while also making a compromise for the Vietnamese accents.

You can test the suggestions and make further tweaks if needed, as long as they fall within our recommended range of 120% to 130% for the leading :)

[justvanrossum]

I'd be happy to stick to your recommendations.

The only thing I'm worried about is what fontbakery will say: there are a couple of "oversized" glyphs that go way over or under. I think the following are the most extreme: uni21AB.arrow and uni21AC.arrow:

[justvanrossum]

The winAscent and winDescent values for the COLR fonts may be different than the suggestions, as they have a larger glyph set now than the released versions had.

[vv-monsalve]

The only thing I'm worried about is what fontbakery will say: there are a couple of "oversized" glyphs that go way over or under. I think the following are the most extreme: uni21AB.arrow and uni21AC.arrow:

Yes, I saw those oversized glyphs but prioritized the text and did not consider them in the VM calculations. Otherwise, the leading would end up being too loose for the text.

The winAscent and winDescent values for the COLR fonts may be different than the suggestions, as they have a larger glyph set now than the released versions had.

Sure!