Fix non-standard usWeightClass on interpolated instances (#57) - #78
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Fix non-standard usWeightClass on interpolated instances (#57)#78srijavuppala wants to merge 1 commit into
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…ial#57) The 'Axis Mappings' custom parameter had its userspace/design pairs inverted. glyphsLib reads each 'A = B;' entry as userspace=A, design=B, so '547 = 500' meant userspace 547 -> design 500. Because the instances sit at design coordinates (Medium = 547) that are not mapping outputs, the build interpolated their userspace positions to non-standard values, which flowed into OS/2.usWeightClass: Display: Medium 596, SemiBold 707, Bold 799, ExtraBold 849 Text/Mono: Medium 565, SemiBold 632 Adobe apps group a family by usWeightClass and expect standard values (300/400/500/600/700/800/900), so the weights were not recognized correctly (issue RedHatOfficial#57). Swapping each pair to 'user = design' (e.g. '500 = 547') makes the named instances resolve to the intended userspace weights. Verified with a fontmake rebuild of all three families: - static usWeightClass now 300/400/500/600/700/800/900 - static glyf outlines and hmtx advance widths are byte-identical to the previous build (design coordinates unchanged) - variable fonts: glyf/gvar/hmtx/HVAR/MVAR byte-identical; only avar and the fvar named-instance positions change Fonts binaries should be regenerated from these sources on the next release build. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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Summary
Fixes #57 — the Medium/SemiBold/Bold/ExtraBold static instances ship with a non-standard
OS/2.usWeightClass, so Adobe apps (Photoshop 25+) don't recognize the weights.Root cause: the
"Axis Mappings"custom parameter has its userspace/design pairs inverted. glyphsLib reads eachA = B;entry as userspace A → design B, so547 = 500meant userspace 547 → design 500. Because the instances sit at design coordinates (e.g. Display Medium = 547) that aren't mapping outputs, the build interpolates their userspace position to non-standard values, which flow intousWeightClass:Adobe groups a family by
usWeightClassand expects standard values (300/400/500/600/700/800/900), so the weights aren't recognized correctly. (Details in my comment on #57.)Fix: swap each pair to
user = design(e.g.500 = 547) in all six sources, so the named instances resolve to the intended userspace weights. This does not move any instance in design space.Verification
Rebuilt all three families with fontmake (3.12.1 / fontTools 4.61.1) before and after the change:
usWeightClassis now 300/400/500/600/700/800/900 across Display, Text, and Mono.glyfoutlines andhmtxadvance widths are byte-identical to the pre-fix build for every style (design coordinates are unchanged).glyf,gvar,hmtx,HVAR,MVARare byte-identical; the only tables that change areavar(the mapping) andfvar(named-instance positions now land on 300/400/500/600/700/800/900).headdiffers only in the timestamp.So this corrects the userspace weight labeling with no change to any glyph outline.
This PR touches sources only; the font binaries should be regenerated from these sources on the next release build.