#2511 - Add GSUB Multiple Substitution (Type 2) and enable ccmp - #2512
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swmal wants to merge 2 commits into
Open
#2511 - Add GSUB Multiple Substitution (Type 2) and enable ccmp#2512swmal wants to merge 2 commits into
swmal wants to merge 2 commits into
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See #2511.
GSUB Lookup Type 2 (Multiple Substitution) was not implemented, so a font could not expand one glyph into several - what most real-world
ccmpdecomposition relies on.ccmpwas also unreachable: it had no flag in the publicGsubFeatureenum.Changes
MultipleSubstSubTable+ deserializer, wired intoGsubTableLoader.MultipleSubstitutionProcessor: expands a glyph into its sequence during shaping, as a new first phase inTextShaper.MultipleSubstHandler: preserves the expanded glyphs through subsetting.GsubFeature.Ccmpadded, enabled by default inShapingOptionsandPdfPageSettings, ordered first.PdfContentStream: fixed a latent bug dropping a trailing glyph withCharCount0, cutting off the tail of an expanded cluster.Behaviour change
Enabling
ccmpaffects existing output: fonts may compose decomposed sequences (Roboto renderse+U+0301 as one precomposed glyph) or swap marks for cap-height variants. Two tests now shape withoutccmpto keep testing mark positioning.