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Check request: verify font.sfntVersion against the presence of glyf and CFF/CFF2 #3388

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justvanrossum opened this issue Jul 23, 2021 · 6 comments
Closed

Check request: verify font.sfntVersion against the presence of glyf and CFF/CFF2 #3388

justvanrossum opened this issue Jul 23, 2021 · 6 comments
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New check proposal We expect new check proposals to include a detailed rationale description and a suggested check-id Severity 5 (Highest) Font problems that must be addressed urgently!
Milestone
0.8.9

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@justvanrossum
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It's possible to build fonts that have the wrong sfntVersion field, say a TTF with a glyf table, yet with an sfntVersion of "OTTO". Such fonts are rejected by FreeType.

See also: fonttools/fonttools#2370

(I just saw that ots already warns about this, so perhaps it's redundant for fontbakery.)
@justvanrossum
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Although: ots only warns for it, for fontbakery it should be a FAIL IMO, as FreeType rejects such fonts.

@felipesanches felipesanches added the New check proposal We expect new check proposals to include a detailed rationale description and a suggested check-id label Jul 23, 2021
@felipesanches
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I just saw that ots already warns about this, so perhaps it's redundant for fontbakery.

In general we're happy to substitute 3rd party checks with our own fontbakery checks, specially if we're able to document them with more detailed rationale metadata.

@felipesanches felipesanches added this to the 0.8.x series milestone Jul 23, 2021
@felipesanches felipesanches added the Severity 5 (Highest) Font problems that must be addressed urgently! label Jul 23, 2021
@felipesanches
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Correct me if I'm wrong, please. I'm proposing to classify this as a maximum severity check as it seems the font is completely broken if it does not pass this check, right?

@justvanrossum
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justvanrossum commented Jul 23, 2021 •
edited

It depends: FreeType rejects a font with sfntVersion="OTTO" and a glyf table, but doesn't have a CFF or CFF2 table, but other font consumers may not have problems with it. I can't really judge, I'm not familiar enough with fontbakery's severity gradations.

@felipesanches
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I'm not familiar enough with fontbakery's severity gradations.

At this point they're still experimental. We're gradually coming up with a way to categorize checks by perceived severity, but this is still very much subjective.

@miguelsousa
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@felipesanches please assign this to me, and add it to the 0.8.9 queue.

@miguelsousa miguelsousa mentioned this issue Jun 1, 2022
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felipesanches pushed a commit that referenced this issue Jun 1, 2022
@miguelsousa @felipesanches
New check: com.adobe.fonts/check/sfnt_version
708a0d8 
Added to the Universal profile.
Ensures the font has the proper sfntVersion value.
(issue #3388)
@felipesanches felipesanches modified the milestones: 0.8.x series, 0.8.9 Jun 1, 2022
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New check proposal We expect new check proposals to include a detailed rationale description and a suggested check-id Severity 5 (Highest) Font problems that must be addressed urgently!
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0.8.9
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