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[GSUB/GPOS] Main struct >64k expansion #58

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behdad opened this issue Jul 4, 2022 · 1 comment
Closed

[GSUB/GPOS] Main struct >64k expansion #58

behdad opened this issue Jul 4, 2022 · 1 comment
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Implemented Implemented in HarfBuzz or doesn't need to Layout >64k expansion

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@behdad
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behdad commented Jul 4, 2022 •
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Currently the tables cannot support more than ~3k lookups before the LookupList offsets themselves overflow. I hit this limit when trying to merge all 180 Noto Sans fonts. To address this, the main GSUB/GPOS structs need to be bumped to version 0x00020000.

struct GSUBGPOSVersion2 {
  Version version; // 0x00020000
  Offset24To<ScriptList> scripts;
  Offset24To<FeatureList> features;
  Offset24To<LookupList24> lookups;
  Offset32To<FeatureVariations> featureVars;
};

Note that the last item is a 32bit offset, for compatibility with version 0x00010001 tables.

were LookupList24 is a list16 of offset24 to Lookup structures:

using LookupList24 = List16OfOffsetTo<Lookup, uint24>;
behdad added a commit to fonttools/fonttools that referenced this issue Jul 4, 2022
@behdad
[>64k:layout] Add GSUB/GPOS version 2.0
eb283bf 
To fix offset overflows of LookupList itself.

Implements harfbuzz/boring-expansion-spec#58
behdad added a commit to fonttools/fonttools that referenced this issue Jul 4, 2022
@behdad
[>64k:layout] Add GSUB/GPOS version 2.0
d535b43 
To fix offset overflows of LookupList itself.

Implements harfbuzz/boring-expansion-spec#58
behdad added a commit to fonttools/fonttools that referenced this issue Jul 8, 2022
@behdad
[>64k:layout] Add GSUB/GPOS version 2.0
7b8ca63 
To fix offset overflows of LookupList itself.

Implements harfbuzz/boring-expansion-spec#58
behdad added a commit to fonttools/fonttools that referenced this issue Jul 9, 2022
@behdad
[>64k:layout] Upgrade main GSUB/GPOS structure offsets to 24bit
cdfd465 
Spec updated: harfbuzz/boring-expansion-spec#58
@behdad behdad mentioned this issue Jul 10, 2022
Closed
@behdad behdad removed the WIP label Jul 10, 2022
behdad added a commit to harfbuzz/harfbuzz that referenced this issue Jul 11, 2022
@behdad
[>64k:layout:GSUBGPOS] Implement format 2
b3fdf03 
Implements harfbuzz/boring-expansion-spec#58

Subset does NOT lower format.
behdad added a commit to harfbuzz/harfbuzz that referenced this issue Jul 11, 2022
@behdad
[>64k:layout:GSUBGPOS] Implement format 2
b6e7551 
Implements harfbuzz/boring-expansion-spec#58

Subset does NOT lower format.
behdad added a commit to harfbuzz/harfbuzz that referenced this issue Jul 11, 2022
@behdad
[>64k:layout:GSUBGPOS] Implement format 2
6b3c58d 
Implements harfbuzz/boring-expansion-spec#58

Subset does NOT lower format.
behdad added a commit to harfbuzz/harfbuzz that referenced this issue Jul 11, 2022
@behdad
[>64k:layout:GSUBGPOS] Implement format 2
e5c3942 
Implements harfbuzz/boring-expansion-spec#58

Subset does NOT lower format.
behdad added a commit to harfbuzz/harfbuzz that referenced this issue Jul 12, 2022
@behdad
[>64k:layout:GSUBGPOS] Implement format 2
ea0812a 
Implements harfbuzz/boring-expansion-spec#58

Subset does NOT lower format.
@behdad behdad added the Implemented Implemented in HarfBuzz or doesn't need to label Jul 12, 2022
behdad added a commit to harfbuzz/harfbuzz that referenced this issue Jul 12, 2022
@behdad
[>64k:layout:GSUBGPOS] Implement format 2
99f017f 
Implements harfbuzz/boring-expansion-spec#58

Subset does NOT lower format.
behdad added a commit to fonttools/fonttools that referenced this issue Jul 12, 2022
@behdad
[>64k:layout] Add GSUB/GPOS version 2.0
2089239 
To fix offset overflows of LookupList itself.

Implements harfbuzz/boring-expansion-spec#58
behdad added a commit to fonttools/fonttools that referenced this issue Jul 12, 2022
@behdad
[>64k:layout] Upgrade main GSUB/GPOS structure offsets to 24bit
dc1ee8d 
Spec updated: harfbuzz/boring-expansion-spec#58
This was referenced Jul 26, 2022
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@behdad
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behdad commented Mar 6, 2023

Speced: https://github.com/harfbuzz/boring-expansion-spec/blob/main/beyond-64k.md
Implemented in HarfBuzz.

@behdad behdad closed this as completed Mar 6, 2023
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