Skip mark-positioning lookups with null anchors instead of crashing#374
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lehni wants to merge 1 commit into
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Skip mark-positioning lookups with null anchors instead of crashing#374lehni wants to merge 1 commit into
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GPOS subtables (Lookup Types 4, 5, 6) may legally contain NULL anchor offsets per the OT spec — they mean "no anchor for this base/ligature/mark class in this lookup", which the layout engine should treat as a no-op rather than an error.
GPOSProcessor.applyAnchorcurrently dereferences bothbaseAnchorandmarkRecord.markAnchorwithout guarding againstnull, so any font that ships a NULL anchor crashes withTypeError: Cannot read properties of null (reading 'xCoordinate')during shaping.Add an early-return null check in
applyAnchor, matching HarfBuzz's behaviour (MarkBasePosFormat1.hhand friends silently skip the application when the anchor is null).Test
Added the hinted Noto Sans Malayalam (
NotoSansMalayalam-Hinted.ttf, SIL OFL) which ships 189 NULL anchors. Layout ofപുസ്തകംreaches the null path and used to throw; the assertion now matches HarfBuzz's output exactly.Resolves #367.