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Matthew Butterick 7 years ago
parent 46211de41c
commit cbab5b34bd
2 changed files with 108 additions and 62 deletions
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33
pitfall/fontkit/gsub-processor.rkt
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@ -83,33 +83,6 @@ https://github.com/mbutterick/fontkit/blob/master/src/opentype/GSUBProcessor.js
(set-field! isLigated ligatureGlyph #t)
(set-field! substituted ligatureGlyph #t)
;; From Harfbuzz:
;; - 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)])
@ -158,5 +131,11 @@ https://github.com/mbutterick/fontkit/blob/master/src/opentype/GSUBProcessor.js
(report* (for/list ([g (· this glyphs)]) (· g id)) (· this glyphIterator index))
#t)]
[else #f])]
[(5) ;; Contextual Substitution
(send this applyContext table)]
[(6) ;; Chaining Contextual Substitution
(send this applyChainingContext table)]
[(7) ;; Extension Substitution
(send this applyLookup (· table lookupType) (· table extension))]
[else (error 'unimplemented-gsub-lookup)])))

137
pitfall/fontkit/ot-processor.rkt
Unescape Escape View File

@ -33,7 +33,7 @@ https://github.com/mbutterick/fontkit/blob/master/src/opentype/OTProcessor.js
(for*/first ([entry (in-list (· this table scriptList))]
[s (in-list scripts)]
#:when (eq? (· entry tag) s))
entry))))
entry))))
(define/public (selectScript [script #f] [language #f])
@ -57,9 +57,9 @@ https://github.com/mbutterick/fontkit/blob/master/src/opentype/OTProcessor.js
(when (and (not language) (not (equal? language (· this languageTag))))
(for/first ([lang (in-list (· this script langSysRecords))]
#:when (equal? (· lang tag) language))
(set-field! language this (· lang langSys))
(set-field! languageTag this (· lang tag))
(set! changed #t)))
(set-field! language this (· lang langSys))
(set-field! languageTag this (· lang tag))
(set! changed #t)))
(when (not (· this language))
(set-field! language this (· this script defaultLangSys)))
@ -69,8 +69,8 @@ https://github.com/mbutterick/fontkit/blob/master/src/opentype/OTProcessor.js
(set-field! features this (mhash))
(when (· this language)
(for ([featureIndex (in-list (· this language featureIndexes))])
(define record (list-ref (· this table featureList) featureIndex))
(dict-set! (· this features) (· record tag) (· record feature)))))))
(define record (list-ref (· this table featureList) featureIndex))
(dict-set! (· this features) (· record tag) (· record feature)))))))
(define/public (lookupsForFeatures [userFeatures empty] [exclude #f])
@ -80,10 +80,10 @@ https://github.com/mbutterick/fontkit/blob/master/src/opentype/OTProcessor.js
#:when feature
[lookupIndex (in-list (· feature lookupListIndexes))]
#:unless (and exclude (index-of exclude lookupIndex)))
#;(report*/file tag lookupIndex)
(mhasheq 'feature tag
'index lookupIndex
'lookup (send (· this table lookupList) get lookupIndex)))
#;(report*/file tag lookupIndex)
(mhasheq 'feature tag
'index lookupIndex
'lookup (send (· this table lookupList) get lookupIndex)))
< #:key (λ (i) (· i index))))
@ -103,29 +103,29 @@ https://github.com/mbutterick/fontkit/blob/master/src/opentype/OTProcessor.js
(set-field! glyphIterator this (+GlyphIterator glyphs))
(for* ([lookup-entry (in-list lookups)])
(define feature (· lookup-entry feature))
(define lookup (· lookup-entry lookup))
(define feature (· lookup-entry feature))
(define lookup (· lookup-entry lookup))
(report 'resetting-iterator)
(send (· this glyphIterator) reset (· lookup flags))
(send (· this glyphIterator) reset (· lookup flags))
(while (< (or (· this glyphIterator index) 0) (length (· this glyphs)))
(report 'start-while++++++++++++++++++)
(report (length (· this glyphs)) 'glyphs-length-top)
(report (for/list ([g (· this glyphs)]) (· g id)) 'gids-top)
(report (· this glyphIterator index) giterator-idx-top)
(report* feature (· this glyphIterator cur id) (· this glyphIterator cur features))
(report (dict-has-key? (· this glyphIterator cur features) feature))
(cond
[(not (dict-has-key? (· this glyphIterator cur features) feature))
(send (· this glyphIterator) next)]
[else
(report/file 'start-lookup-branch=================)
(report* (for/list ([g (· this glyphs)]) (· g id)) (for/list ([g (· this glyphIterator glyphs)]) (· g id)) (for/list ([g glyphs]) (· g id)) (· this glyphIterator index) (· this glyphIterator cur id) (· this glyphIterator peekIndex))
(for/or ([table (in-list (· lookup subTables))])
(send this applyLookup (· lookup lookupType) table))
(report 'incrementing-iterator-at-bottom)
(send (· this glyphIterator) next)
(report* (· this glyphIterator cur) (· this glyphIterator index))]))))
(while (< (or (· this glyphIterator index) 0) (length (· this glyphs)))
(report 'start-while++++++++++++++++++)
(report (length (· this glyphs)) 'glyphs-length-top)
(report (for/list ([g (· this glyphs)]) (· g id)) 'gids-top)
(report (· this glyphIterator index) giterator-idx-top)
(report* feature (· this glyphIterator cur id) (· this glyphIterator cur features))
(report (dict-has-key? (· this glyphIterator cur features) feature))
(cond
[(not (dict-has-key? (· this glyphIterator cur features) feature))
(send (· this glyphIterator) next)]
[else
(report/file 'start-lookup-branch=================)
(report* (for/list ([g (· this glyphs)]) (· g id)) (for/list ([g (· this glyphIterator glyphs)]) (· g id)) (for/list ([g glyphs]) (· g id)) (· this glyphIterator index) (· this glyphIterator cur id) (· this glyphIterator peekIndex))
(for/or ([table (in-list (· lookup subTables))])
(send this applyLookup (· lookup lookupType) table))
(report 'incrementing-iterator-at-bottom)
(send (· this glyphIterator) next)
(report* (· this glyphIterator cur) (· this glyphIterator index))]))))
(abstract applyLookup)
@ -139,14 +139,14 @@ https://github.com/mbutterick/fontkit/blob/master/src/opentype/OTProcessor.js
[(1) (index-of (· coverage glyphs) glyph)]
[(2) (for/first ([range (in-list (· coverage rangeRecords))]
#:when (<= (· range start) glyph (· range end)))
(+ (· range startCoverageIndex) glyph (- (· range start))))]
(+ (· range startCoverageIndex) glyph (- (· range start))))]
[else #f]) -1))
(define/public (match sequenceIndex sequence fn [matched #f])
(define pos (· this glyphIterator index))
(define glyph (send (· this glyphIterator) increment sequenceIndex))
(define idx 0)
(report* (list-ref sequence idx) (· glyph id))
(report*/file (list-ref sequence idx) glyph (· glyph id))
(while (and (< idx (length sequence)) glyph (fn (list-ref sequence idx) (· glyph id)))
(report* 'in-match-loop idx (· glyph id))
@ -163,6 +163,9 @@ https://github.com/mbutterick/fontkit/blob/master/src/opentype/OTProcessor.js
(define/public (sequenceMatchIndices sequenceIndex sequence)
(send this match sequenceIndex sequence (λ (component glyph) (= component glyph)) empty))
(define/public (coverageSequenceMatches sequenceIndex sequence)
(send this match sequenceIndex sequence (λ (coverage glyph) (>= (send this coverageIndex coverage glyph) 0))))
(define/public (getClassID glyph classDef)
(or
(case (· classDef version)
@ -174,6 +177,70 @@ https://github.com/mbutterick/fontkit/blob/master/src/opentype/OTProcessor.js
[(2)
(for/first ([range (in-list (· classDef classRangeRecord))]
#:when (<= (· range start) glyph (· range end)))
(· range class))])
0)))
(· range class))])
0))
(define/public (applyContext table)
(report/file 'otproc:applyContext)
(case (· table version)
[(1) (define index (send this coverageIndex (· table coverage)))
(cond
[(= index -1) #f]
[else (define set (list-ref (· table ruleSets) index))
(for/first ([rule (in-list set)]
#:when (send this sequenceMatches 1 (· rule input)))
(send this applyLookupList (· rule lookupRecords)))])]
[(2) (cond
[(= (send this coverageIndex (· table coverage)) -1) #f]
[else (define index
(send this getClassID (· this glyphIterator cur id) (· table classDef)))
(cond
[(- index -1) #f]
[else (define set (list-ref (· table classSet) index))
(for/first ([rule (in-list set)]
#:when (send this sequenceMatches 1 (· rule classes) (· table classDef)))
(send this applyLookupList (· rule lookupRecords)))])])]
[(3) (and (send this coverageSequenceMatches 0 (· table coverages))
(send this applyLookupList (· table lookupRecords)))]
[else #f]))
(define/public (applyChainingContext table)
(report/file 'otproc:applyChainingContext)
(case (· table version)
[(1)
(report 'case-1)
(define index (send this coverageIndex (· table coverage)))
(cond
[(= index -1) #f]
[else (define set (list-ref (· table chainRuleSets) index))
(for/first ([rule (in-list set)]
#:when (and (send this sequenceMatches (- (length (· rule backtrack)) (· rule backtrack)))
(send this sequenceMatches 1 (· rule input))
(send this sequenceMatches (add1 (length (· rule input))) (· rule lookahead))))
(send this applyLookupList (· rule lookupRecords)))])]
[(2)
(report 'case-2)
(cond
[(= -1 (send this coverageIndex (· table coverage))) #f]
[else (define index (send this getClassID (· this glyphIterator cur id) (· table inputClassDef)))
(define rules (list-ref (· table chainClassSet) index))
(cond
[(not rules) #f]
[else (for/first ([rule (in-list rules)]
#:when (and (send this classSequenceMatches (- (length (· rule backtrack)) (· rule backtrack) (· table backtrackClassDef)))
(send this classSequenceMatches 1 (· rule input) (· table inputClassDef))
(send this classSequenceMatches (add1 (length (· rule input))) (· rule lookahead) (· table lookaheadClassDef))))
(send this applyLookupList (· rule lookupRecords)))])])]
[(3)
(report 'case-3)
(and
(send this coverageSequenceMatches (- (· table backtrackGlyphCount)) (· table backtrackCoverage))
(send this coverageSequenceMatches 0 (· table inputCoverage))
(send this coverageSequenceMatches (· table inputGlyphCount) (· table lookaheadCoverage))
(send this applyLookupList (· table lookupRecords)))]
[else #f]))
)
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