[PDFBOX-5592] Support GSUB LookupType 7 (Extension Substitution Subtable Format 1)

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 3.0.0 PDFBox
• Fix Version/s: 3.0.0 PDFBox
• Component/s: FontBox
• Labels: gsub
• Assignee: Tilman Hausherr
• Reporter: Tilman Hausherr
• Created: 30/Apr/23 13:27
• Updated: 11/Dec/23 12:54
• Resolved: 16/Sep/23 03:12

Description

I found some old non working code that tries to do latin ligatures, and one of the reasons it doesn't work is that some tables weren't read at all. Btw such empty tables result in further weirdness when not caught.

Issue Links

• is related to: PDFBOX-5730 The expected SubstFormat for ExtensionSubstFormat1 subtable is 108 but should be 1
• is related to: PDFBOX-5733 lookupType is to be replaced by extensionLookupType in type 7 lookup table