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88 lines
3.4 KiB
Racket
88 lines
3.4 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 uint32be
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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/override (process this-res stream)
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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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(hash-set! this-res 'tables new-tables-val))
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(define/override (preEncode this-val stream)
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(define preamble-length 12)
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(define table-header-size (+ preamble-length
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(* (length (hash-keys (· this-val tables))) (send TableEntry size))))
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(define-values (table-headers table-datas _)
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(for/lists (ths tds lens)
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([(tag table) (in-hash (· this-val tables))])
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(define table-data
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(let ([es (+EncodeStream)])
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(send (hash-ref table-codecs tag) encode es table)
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(send es dump)))
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(define table-header (mhash
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'tag (unescape-tag tag)
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'checkSum 0
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'offset (apply + (cons table-header-size lens))
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'length (bytes-length table-data)))
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(values table-header table-data (bytes-length table-data))))
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(define numTables (length table-headers))
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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 table-headers
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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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'data table-datas)))
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(define directory-common-dict (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 (+RDirectory directory-common-dict))
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;; we don't know what tables we might get
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;; so we represent as generic Buffer type,
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;; and convert the tables to bytes manually in preEncode
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(define EncodableDirectory (+RDirectory (append directory-common-dict (list (cons 'data (+Array (+Buffer)))))))
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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)) |