GSUB: resume in spurious ligature lookup
parent
5cfd6ae98a
commit
c1bc246b19
@ -0,0 +1,7 @@
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fontkit = require '../pdfkit/node_modules/fontkit'
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fira_path = "../pitfall/test/assets/fira.ttf"
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f = fontkit.openSync(fira_path)
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console.log "*************************** start decode"
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thing = f.GSUB.lookupList.get(19)
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console.log thing
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@ -0,0 +1,89 @@
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#lang fontkit/racket
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(require xenomorph br/cond "opentype.rkt")
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(provide (all-defined-out))
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#|
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approximates
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https://github.com/mbutterick/fontkit/blob/master/src/tables/GSUB.js
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|#
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(define Sequence (+Array uint16be uint16be))
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(define AlternateSet Sequence)
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(define Ligature (+Struct
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(dictify
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'glyph uint16be
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'compCount uint16be
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'components (+Array uint16be (λ (t) (sub1 (· t compCount)))))))
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(define LigatureSet (+Array (+Pointer uint16be Ligature) uint16be))
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(define-subclass VersionedStruct (GSUBLookup-VersionedStruct))
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(define GSUBLookup
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(+GSUBLookup-VersionedStruct
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'lookupType
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(dictify
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;; Single Substitution
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1 (+VersionedStruct uint16be
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(dictify
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1 (dictify
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'coverage (+Pointer uint16be Coverage)
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'deltaGlyphID int16be)
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2 (dictify
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'coverage (+Pointer uint16be Coverage)
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'glyphCount uint16be
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'substitute (+LazyArray uint16be 'glyphCount))))
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2 ;; Multiple Substitution
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(dictify
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'substFormat uint16be
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'coverage (+Pointer uint16be Coverage)
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'count uint16be
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'sequences (+LazyArray (+Pointer uint16be Sequence) 'count))
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3 ;; Alternate Substitution
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(dictify
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'substFormat uint16be
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'coverage (+Pointer uint16be Coverage)
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'count uint16be
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'alternateSet (+LazyArray (+Pointer uint16be AlternateSet) 'count))
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4 ;; Ligature Substitution
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(dictify
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'substFormat uint16be
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'coverage (+Pointer uint16be Coverage)
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'count uint16be
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'ligatureSets (+LazyArray (+Pointer uint16be LigatureSet) 'count))
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5 Context ;; Contextual Substitution
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6 ChainingContext ;; Chaining Contextual Substitution
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7 ;; Extension Substitution
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(dictify
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'substFormat uint16be
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'lookupType uint16be ; cannot also be 7
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'extension (+Pointer uint32be (λ () (error 'circular-reference-unfixed))))
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8 ;; Reverse Chaining Contextual Single Substitution
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(dictify
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'substFormat uint16be
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'coverage (+Pointer uint16be Coverage)
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'backTrackCoverage (+Array (+Pointer uint16be Coverage) 'backtrackGlyphCount)
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'lookaheadGlyphCount uint16be
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'lookaheadCoverage (+Array (+Pointer uint16be Coverage) 'lookaheadGlyphCount)
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'glyphCount uint16be
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'substitute (+Array uint16be 'glyphCount)))))
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;; Fix circular reference
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(ref*-set! GSUBLookup 'versions 7 'extension 'type GSUBLookup)
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(define-subclass VersionedStruct (GSUB-MainVersionedStruct))
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(define GSUB (+GSUB-MainVersionedStruct uint32be
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(dictify
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'header (dictify 'scriptList (+Pointer uint16be ScriptList)
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'featureList (+Pointer uint16be FeatureList)
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'lookupList (+Pointer uint16be (LookupList GSUBLookup))
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)
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#x00010000 (dictify)
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#;#x00010001 #;(+Pointer uint32be FeatureVariations))))
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(test-module)
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@ -0,0 +1,160 @@
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#lang fontkit/racket
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(require "ot-processor.rkt" "glyphinfo.rkt" br/cond)
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(provide (all-defined-out))
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#|
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approximates
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https://github.com/mbutterick/fontkit/blob/master/src/opentype/GSUBProcessor.js
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|#
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(define-subclass OTProcessor (GSUBProcessor)
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(define/override (applyLookup lookupType table)
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(report/file 'GSUBProcessor:applyLookup)
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(case lookupType
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[(1) ;; Single Substitution
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(report 'single-substitution)
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(define index (send this coverageIndex (· table coverage)))
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(cond
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[(= index -1) #f]
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[else (define glyph (· this glyphIterator cur))
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(set-field! id glyph
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(case (· table version)
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[(1) (bitwise-and (+ (· glyph id) (· table deltaGlyphID)) #xffff)]
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[(2) (send (· table substitute) get index)]))
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#t])]
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[(2) ;; Multiple Substitution
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(report 'multiple-substitution)
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(define index (send this coverageIndex (· table coverage)))
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(cond
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[(= index -1) #f]
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[else (define sequence (send (· table sequences) get index))
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(set-field! id (· this glyphIterator cur) (list-ref sequence 0))
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(set-field! ligatureComponent (· this glyphIterator cur) 0)
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(define features (· this glyphIterator cur features))
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(define curGlyph (· this glyphIterator cur))
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(define replacement (for/list ([(gid i) (in-indexed (cdr sequence))])
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(define glyph (+GlyphInfo (· this font) gid #f features))
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(set-field! shaperInfo glyph (· curGlyph shaperInfo))
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(set-field! isLigated glyph (· curGlyph isLigated))
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(set-field! ligatureComponent glyph (add1 i))
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(set-field! substituted glyph #t)
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glyph))
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(set-field! glyphs this (let-values ([(head tail) (split-at (· this glyphs) (add1 (· this glyphIterator index)))])
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(append head replacement tail)))
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#t])]
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[(3) ;; Alternate substitution
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(report 'altnernate-substitution)
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(define index (send this coverageIndex (· table coverage)))
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(cond
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[(= index -1) #f]
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[else (define USER_INDEX 0)
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(set-field! id (· this glyphIterator cur) (list-ref (send (· table alternateSet) get index) USER_INDEX))
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#t])]
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[(4) ;; Ligature substitution
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(report 'ligature-substitution)
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(define index (report* (· table coverage) (send this coverageIndex (· table coverage))))
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(cond
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[(= index -1) #f]
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[(for* ([ligature (in-list (send (· table ligatureSets) get index))]
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[matched (in-value (send this sequenceMatchIndices 1 (report* ligature (· ligature components))))]
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#:when matched)
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(report*/file matched (· this glyphs) index)
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(define curGlyph (· this glyphIterator cur))
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;; Concatenate all of the characters the new ligature will represent
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(define characters
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(append (· curGlyph codePoints)
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(append* (for/list ([index (in-list matched)])
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(get-field codePoints (list-ref (· this glyphs) index))))))
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;; Create the replacement ligature glyph
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(define ligatureGlyph (+GlyphInfo (· this font) (· ligature glyph) characters (· curGlyph features)))
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(set-field! shaperInfo ligatureGlyph (· curGlyph shaperInfo))
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(set-field! ligated ligatureGlyph #t)
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(set-field! substituted ligatureGlyph #t)
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(report 'from-harfbuzz)
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;; From Harfbuzz:
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;; - If it *is* a mark ligature, we don't allocate a new ligature id, and leave
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;; the ligature to keep its old ligature id. This will allow it to attach to
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;; a base ligature in GPOS. Eg. if the sequence is: LAM,LAM,SHADDA,FATHA,HEH,
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;; and LAM,LAM,HEH for a ligature, they will leave SHADDA and FATHA with a
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;; ligature id and component value of 2. Then if SHADDA,FATHA form a ligature
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;; later, we don't want them to lose their ligature id/component, otherwise
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;; GPOS will fail to correctly position the mark ligature on top of the
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;; LAM,LAM,HEH ligature. See https://bugzilla.gnome.org/show_bug.cgi?id=676343
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;;
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;; - If a ligature is formed of components that some of which are also ligatures
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;; themselves, and those ligature components had marks attached to *their*
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;; components, we have to attach the marks to the new ligature component
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;; positions! Now *that*'s tricky! And these marks may be following the
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;; last component of the whole sequence, so we should loop forward looking
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;; for them and update them.
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;;
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;; Eg. the sequence is LAM,LAM,SHADDA,FATHA,HEH, and the font first forms a
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;; 'calt' ligature of LAM,HEH, leaving the SHADDA and FATHA with a ligature
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;; id and component == 1. Now, during 'liga', the LAM and the LAM-HEH ligature
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;; form a LAM-LAM-HEH ligature. We need to reassign the SHADDA and FATHA to
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;; the new ligature with a component value of 2.
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;;
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;; This in fact happened to a font... See
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;; https://bugzilla.gnome.org/show_bug.cgi?id=437633
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(define isMarkLigature
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(and (· curGlyph isMark)
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(for/and ([match-idx (in-list matched)])
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(· (list-ref (· this glyphs) match-idx) isMark))))
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(report isMarkLigature)
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(set-field! ligatureID ligatureGlyph (cond
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[isMarkLigature #f]
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[else (define id (· this ligatureID))
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(increment-field! ligatureID this)
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id]))
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(define lastLigID (· curGlyph ligatureID))
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(define lastNumComps (length (· curGlyph codePoints)))
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(define curComps lastNumComps)
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(define idx (add1 (· this glyphIterator index)))
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(report/file 'set-ligature-id)
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;; Set ligatureID and ligatureComponent on glyphs that were skipped in the matched sequence.
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;; This allows GPOS to attach marks to the correct ligature components.
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(for ([matchIndex (in-list matched)])
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(report/file matchIndex)
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;; Don't assign new ligature components for mark ligatures (see above)
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(cond
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[isMarkLigature (set! idx matchIndex)]
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[else (while (< idx matchIndex)
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(define ligatureComponent (+ curComps (- lastNumComps) (min (or (get-field ligatureComponent (list-ref (· this glyphs) idx)) 1) lastNumComps)))
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(set-field! ligatureID (list-ref (· this glyphs) idx) (· ligatureGlyph ligatureID))
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(set-field! ligatureComponent (list-ref (· this glyphs) idx) ligatureComponent)
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(increment! idx))])
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(define lastLigID (· (list-ref (· this glyphs) idx) ligatureID))
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(define lastNumComps (length (· (list-ref (· this glyphs) idx) codePoints)))
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(increment! curComps lastNumComps)
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(increment! idx)) ;; skip base glyph
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;; Adjust ligature components for any marks following
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(when (and lastLigID (not isMarkLigature))
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(for ([i (in-range idx (length (· this glyphs)))]
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#:when (= (· (list-ref (· this glyphs) idx) ligatureID) lastLigID))
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(define ligatureComponent (+ curComps (- lastNumComps) (min (or (get-field ligatureComponent (list-ref (· this glyphs) i)) 1) lastNumComps)))
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(set-field! ligatureComponent (list-ref (· this glyphs) i) ligatureComponent)))
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;; Delete the matched glyphs, and replace the current glyph with the ligature glyph
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(set-field! glyphs this (drop-right (· this glyphs) (length matched)))
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(set-field! glyphs this (list-set (· this glyphs) (· this glyphIterator index) ligatureGlyph))
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#t)]
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[else #f])])))
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@ -0,0 +1,60 @@
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#lang fontkit/racket
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(require fontkit "gsub-processor.rkt" rackunit xenomorph racket/serialize describe)
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(define fira-path "../pitfall/test/assets/fira.ttf")
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(define f (openSync fira-path))
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(define gsub (· f GSUB))
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(define proc (+GSUBProcessor f gsub))
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;; liga lookupList
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(car (· (get (· gsub lookupList) 30) subTables)) ; f gid = 450
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(send (· (car (· (get (· gsub lookupList) 30) subTables)) ligatureSets) to-list) ; i gid = 480, l gid = 514
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;; fi glyph = 731 fl glyph = 732
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(check-equal? (dump (· proc features))
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'((c2sc (lookupCount . 1) (lookupListIndexes 26) (featureParams . 0))
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(pnum (lookupCount . 1) (lookupListIndexes 23) (featureParams . 0))
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(liga (lookupCount . 1) (lookupListIndexes 30) (featureParams . 0))
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(tnum (lookupCount . 1) (lookupListIndexes 24) (featureParams . 0))
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(onum (lookupCount . 1) (lookupListIndexes 25) (featureParams . 0))
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(ss01 (lookupCount . 1) (lookupListIndexes 33) (featureParams . 0))
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(dlig (lookupCount . 1) (lookupListIndexes 29) (featureParams . 0))
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(lnum (lookupCount . 1) (lookupListIndexes 22) (featureParams . 0))
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(sups (lookupCount . 1) (lookupListIndexes 14) (featureParams . 0))
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(zero (lookupCount . 1) (lookupListIndexes 31) (featureParams . 0))
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(ss02 (lookupCount . 1) (lookupListIndexes 34) (featureParams . 0))
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(aalt (lookupCount . 2) (lookupListIndexes 0 1) (featureParams . 0))
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(subs (lookupCount . 1) (lookupListIndexes 13) (featureParams . 0))
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(ss03 (lookupCount . 1) (lookupListIndexes 35) (featureParams . 0))
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(ordn (lookupCount . 2) (lookupListIndexes 20 21) (featureParams . 0))
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(calt (lookupCount . 4) (lookupListIndexes 36 37 38 39) (featureParams . 0))
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(dnom (lookupCount . 1) (lookupListIndexes 16) (featureParams . 0))
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(smcp (lookupCount . 1) (lookupListIndexes 27) (featureParams . 0))
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(salt (lookupCount . 1) (lookupListIndexes 32) (featureParams . 0))
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(case (lookupCount . 1) (lookupListIndexes 28) (featureParams . 0))
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(numr (lookupCount . 1) (lookupListIndexes 15) (featureParams . 0))
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(frac (lookupCount . 3) (lookupListIndexes 17 18 19) (featureParams . 0))
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(mgrk (lookupCount . 1) (lookupListIndexes 12) (featureParams . 0))))
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(check-equal? (dump (· proc script))
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'((count . 0)
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(defaultLangSys
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(featureIndexes 0 14 28 42 56 70 84 98 112 136 150 164 178 192 206 220 234 248 262 276 290 304 318)
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(reserved . 0)
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(reqFeatureIndex . 65535)
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(featureCount . 23))
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(langSysRecords)))
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(check-equal? (dump (· proc scriptTag)) 'DFLT)
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(check-equal? (dump (· proc language))
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'((featureIndexes 0 14 28 42 56 70 84 98 112 136 150 164 178 192 206 220 234 248 262 276 290 304 318)
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(reserved . 0)
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(reqFeatureIndex . 65535)
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(featureCount . 23)))
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(check-equal? (dump (· proc languageTag)) #f)
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(check-equal? (dump (· proc lookups)) empty)
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(check-equal? (dump (· proc direction)) 'ltr)
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@ -1,11 +1,158 @@
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#lang fontkit/racket
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(require "ot-processor.rkt")
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(require "ot-processor.rkt" "glyphinfo.rkt" br/cond)
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(provide (all-defined-out))
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#|
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approximates
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https://github.com/mbutterick/fontkit/blob/master/src/opentype/GSUBProcessor.js
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|#
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(define-subclass OTProcessor (GSUBProcessor)
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)
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(define/override (applyLookup lookupType table)
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(report* 'GSUBProcessor:applyLookup lookupType)
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(case lookupType
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[(1) ;; Single Substitution
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(report 'single-substitution)
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(define index (send this coverageIndex (· table coverage)))
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(cond
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[(= index -1) #f]
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[else (define glyph (· this glyphIterator cur))
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(set-field! id glyph
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(case (· table version)
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[(1) (bitwise-and (+ (· glyph id) (· table deltaGlyphID)) #xffff)]
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[(2) (send (· table substitute) get index)]))
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#t])]
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[(2) ;; Multiple Substitution
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(report 'multiple-substitution)
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(define index (send this coverageIndex (· table coverage)))
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(cond
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[(= index -1) #f]
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[else (define sequence (send (· table sequences) get index))
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(set-field! id (· this glyphIterator cur) (list-ref sequence 0))
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(set-field! ligatureComponent (· this glyphIterator cur) 0)
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(define features (· this glyphIterator cur features))
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(define curGlyph (· this glyphIterator cur))
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(define replacement (for/list ([(gid i) (in-indexed (cdr sequence))])
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(define glyph (+GlyphInfo (· this font) gid #f features))
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(set-field! shaperInfo glyph (· curGlyph shaperInfo))
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(set-field! isLigated glyph (· curGlyph isLigated))
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(set-field! ligatureComponent glyph (add1 i))
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(set-field! substituted glyph #t)
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glyph))
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(set-field! glyphs this (let-values ([(head tail) (split-at (· this glyphs) (add1 (· this glyphIterator index)))])
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(append head replacement tail)))
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#t])]
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[(3) ;; Alternate substitution
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(report 'alternate-substitution)
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(define index (send this coverageIndex (· table coverage)))
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(cond
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[(= index -1) #f]
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[else (define USER_INDEX 0)
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(set-field! id (· this glyphIterator cur) (list-ref (send (· table alternateSet) get index) USER_INDEX))
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#t])]
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[(4) ;; Ligature substitution
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(report '---------------------------)
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(report 'ligature-substitution)
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(report* lookupType (· table coverage glyphs))
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(define index (send this coverageIndex (· table coverage)))
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(report index 'forker)
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(cond
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[(= index -1) #f]
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[(for*/or ([ligature (in-list (report (send (· table ligatureSets) get (report index 'starting-index))))]
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[matched (in-value (send this sequenceMatchIndices 1 (report (· ligature components))))]
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#:when (report matched))
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(define curGlyph (· this glyphIterator cur))
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;; Concatenate all of the characters the new ligature will represent
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(define characters
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(append (· curGlyph codePoints)
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(append* (for/list ([index (in-list matched)])
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(report index)
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(get-field codePoints (list-ref (· this glyphs) index))))))
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(report characters)
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;; Create the replacement ligature glyph
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(define ligatureGlyph (+GlyphInfo (· this font) (· ligature glyph) characters (· curGlyph features)))
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(report (· ligatureGlyph id))
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(set-field! shaperInfo ligatureGlyph (· curGlyph shaperInfo))
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(set-field! isLigated ligatureGlyph #t)
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(set-field! substituted ligatureGlyph #t)
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;; From Harfbuzz:
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;; - If it *is* a mark ligature, we don't allocate a new ligature id, and leave
|
||||
;; the ligature to keep its old ligature id. This will allow it to attach to
|
||||
;; a base ligature in GPOS. Eg. if the sequence is: LAM,LAM,SHADDA,FATHA,HEH,
|
||||
;; and LAM,LAM,HEH for a ligature, they will leave SHADDA and FATHA with a
|
||||
;; ligature id and component value of 2. Then if SHADDA,FATHA form a ligature
|
||||
;; later, we don't want them to lose their ligature id/component, otherwise
|
||||
;; GPOS will fail to correctly position the mark ligature on top of the
|
||||
;; LAM,LAM,HEH ligature. See https://bugzilla.gnome.org/show_bug.cgi?id=676343
|
||||
;;
|
||||
;; - If a ligature is formed of components that some of which are also ligatures
|
||||
;; themselves, and those ligature components had marks attached to *their*
|
||||
;; components, we have to attach the marks to the new ligature component
|
||||
;; positions! Now *that*'s tricky! And these marks may be following the
|
||||
;; last component of the whole sequence, so we should loop forward looking
|
||||
;; for them and update them.
|
||||
;;
|
||||
;; Eg. the sequence is LAM,LAM,SHADDA,FATHA,HEH, and the font first forms a
|
||||
;; 'calt' ligature of LAM,HEH, leaving the SHADDA and FATHA with a ligature
|
||||
;; id and component == 1. Now, during 'liga', the LAM and the LAM-HEH ligature
|
||||
;; form a LAM-LAM-HEH ligature. We need to reassign the SHADDA and FATHA to
|
||||
;; the new ligature with a component value of 2.
|
||||
;;
|
||||
;; This in fact happened to a font... See
|
||||
;; https://bugzilla.gnome.org/show_bug.cgi?id=437633
|
||||
|
||||
|
||||
(define isMarkLigature
|
||||
(and (· curGlyph isMark)
|
||||
(for/and ([match-idx (in-list matched)])
|
||||
(· (list-ref (· this glyphs) match-idx) isMark))))
|
||||
|
||||
(set-field! ligatureID ligatureGlyph (cond
|
||||
[isMarkLigature #f]
|
||||
[else (define id (· this ligatureID))
|
||||
(increment-field! ligatureID this)
|
||||
id]))
|
||||
|
||||
(define lastLigID (· curGlyph ligatureID))
|
||||
(define lastNumComps (length (· curGlyph codePoints)))
|
||||
(define curComps lastNumComps)
|
||||
(define idx (add1 (· this glyphIterator index)))
|
||||
|
||||
;; Set ligatureID and ligatureComponent on glyphs that were skipped in the matched sequence.
|
||||
;; This allows GPOS to attach marks to the correct ligature components.
|
||||
(for ([matchIndex (in-list matched)])
|
||||
;; Don't assign new ligature components for mark ligatures (see above)
|
||||
(cond
|
||||
[isMarkLigature (set! idx matchIndex)]
|
||||
[else (while (< idx matchIndex)
|
||||
(define ligatureComponent (+ curComps (- lastNumComps) (min (or (get-field ligatureComponent (list-ref (· this glyphs) idx)) 1) lastNumComps)))
|
||||
(set-field! ligatureID (list-ref (· this glyphs) idx) (· ligatureGlyph ligatureID))
|
||||
(set-field! ligatureComponent (list-ref (· this glyphs) idx) ligatureComponent)
|
||||
(increment! idx))])
|
||||
|
||||
(define lastLigID (· (list-ref (· this glyphs) idx) ligatureID))
|
||||
(define lastNumComps (length (· (list-ref (· this glyphs) idx) codePoints)))
|
||||
(increment! curComps lastNumComps)
|
||||
(increment! idx)) ;; skip base glyph
|
||||
|
||||
;; Adjust ligature components for any marks following
|
||||
(when (and lastLigID (not isMarkLigature))
|
||||
(for ([i (in-range idx (length (· this glyphs)))]
|
||||
#:when (= (· (list-ref (· this glyphs) idx) ligatureID) lastLigID))
|
||||
(define ligatureComponent (+ curComps (- lastNumComps) (min (or (get-field ligatureComponent (list-ref (· this glyphs) i)) 1) lastNumComps)))
|
||||
(set-field! ligatureComponent (list-ref (· this glyphs) i) ligatureComponent)))
|
||||
|
||||
;; Delete the matched glyphs, and replace the current glyph with the ligature glyph
|
||||
(set-field! glyphs this (drop-right (· this glyphs) (length matched)))
|
||||
(set-field! glyphs this (list-set (· this glyphs) (· this glyphIterator index) ligatureGlyph))
|
||||
#t)]
|
||||
[else #f])])))
|
||||
|
||||
|
||||
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Reference in New Issue