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66 lines
2.6 KiB
Racket
66 lines
2.6 KiB
Racket
#lang fontkit/racket
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(require restructure "tables.rkt")
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(provide (all-defined-out))
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#|
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https://github.com/mbutterick/fontkit/blob/master/src/tables/directory.js
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|#
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(define TableEntry (+Struct
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(dictify 'tag (+String 4)
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'checkSum uint32be
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'offset (+Pointer uint32be 'void (mhash 'type 'global))
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'length uint32be)))
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;; for stupid tags like 'cvt '
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(define (symbol-replace sym this that)
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(string->symbol (string-replace (if (string? sym) sym (symbol->string sym)) this that)))
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(define (escape-tag tag) (symbol-replace tag " " "_"))
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(define (unescape-tag tag) (symbol-replace tag "_" " "))
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(define-subclass Struct (RDirectory)
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(define/augride (process this-res stream ctx)
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(define new-tables-val (mhash))
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(for ([table (in-list (· this-res tables))])
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(hash-set! new-tables-val (escape-tag (· table tag)) table))
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(dict-set! this-res 'tables new-tables-val)
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this-res)
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(define/override (preEncode this-val stream)
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(define tables (for/list ([(tag table) (in-hash (· this-val tables))])
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(mhash 'tag (unescape-tag tag)
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'checkSum 0
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'offset (+VoidPointer (hash-ref table-codecs tag) table)
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'length (send (hash-ref table-codecs tag) size table))))
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(define numTables (length tables))
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(define searchRange (* (floor (log numTables 2)) 16))
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(hash-set*! this-val
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'tag "true"
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'numTables numTables
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'tables tables
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'searchRange searchRange
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'entrySelector (floor (/ searchRange (log 2)))
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'rangeShift (- (* numTables 16) searchRange))))
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(define Directory (+RDirectory (dictify 'tag (+String 4)
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'numTables uint16be
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'searchRange uint16be
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'entrySelector uint16be
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'rangeShift uint16be
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'tables (+Array TableEntry 'numTables))))
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(define (directory-decode ip [options (mhash)])
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(send Directory decode (+DecodeStream (port->bytes ip))))
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(define (file-directory-decode ps)
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(directory-decode (open-input-file ps)))
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#;(test-module
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(define ip (open-input-file charter-path))
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(define decoded-dir (deserialize (read (open-input-file charter-directory-path))))
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(check-equal? (directory-decode ip) decoded-dir)) |