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80 lines
2.3 KiB
Racket
80 lines
2.3 KiB
Racket
#lang fontkit/racket
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(require 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/GlyphIterator.js
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|#
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(define-subclass object%
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(GlyphIterator glyphs [flags (mhasheq)])
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(field [index #f])
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(reset flags)
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(define/public (reset flags)
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(set-field! flags this flags)
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(set-field! index this 0))
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(define/public (cur)
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(and (< (· this index) (length (· this glyphs)))
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(list-ref (· this glyphs) (· this index))))
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(define/public (shouldIgnore glyph flags)
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(or (and (· flags ignoreMarks) (· glyph isMark))
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(and (· flags ignoreBaseGlyphs) (not (· glyph isMark)))
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(and (· flags ignoreLigatures) (· glyph isLigature))))
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(define/public (move dir)
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(unless (= (abs dir) 1)
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(raise-argument-error 'GlyphIterator:move "1 or -1" dir))
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(increment-field! index this dir)
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(while (and (<= 0 (· this index))
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(< (· this index) (length (· this glyphs)))
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(send this shouldIgnore (list-ref (· this glyphs) (· this index)) (· this flags)))
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(increment-field! index this dir))
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(if (or (> 0 (· this index))
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(>= (· this index) (length (· this glyphs))))
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#f
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(list-ref (· this glyphs) (· this index))))
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(define/public (next) (move 1))
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(define/public (prev) (move -1))
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(define/public (peek [count 1])
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(define idx (· this index))
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(define res (send this increment count))
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(set-field! index this idx)
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res)
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(define/public (peekIndex [count 1])
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(define idx (· this index))
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(send this increment count)
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(define res (· this index))
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(set-field! index this idx)
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res)
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(define/public (increment [count 1])
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(for/last ([i (in-range (abs count))])
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(send this move (if (negative? count) -1 1)))))
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(test-module
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(define gi (+GlyphIterator '(a b c)))
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(check-equal? (· gi index) 0)
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(check-equal? (send gi cur) 'a)
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(check-equal? (send gi move 1) 'b)
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(check-equal? (send gi move 1) 'c)
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(check-false (send gi move 1))
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(check-false (send gi cur))
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(check-equal? (send gi increment -3) 'a)
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(check-equal? (send gi cur) 'a)
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(check-equal? (send gi peek 1) 'b)
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(check-equal? (send gi peek 2) 'c)
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(check-equal? (send gi peek 3) #f)
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(check-equal? (send gi cur) 'a)
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)
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