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73 lines
4.7 KiB
Racket
73 lines
4.7 KiB
Racket
#lang racket/base
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(require xenomorph sugar/unstable/dict)
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(provide OS/2)
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#|
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approximates
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https://github.com/mbutterick/fontkit/blob/master/src/tables/OS2.js
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|#
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(define OS/2 (let ()
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(define type-1
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(dictify 'typoAscender int16be
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'typoDescender int16be
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'typoLineGap int16be
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'winAscent uint16be
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'winDescent uint16be
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'codePageRange (x:array #:type uint32be #:length 2)))
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(define type-2
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(dictify 'xHeight int16be
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'capHeight int16be
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'defaultChar uint16be
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'breakChar uint16be
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'maxContent uint16be))
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(define type-5
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(dictify 'usLowerOpticalPointSize uint16be
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'usUpperOpticalPointSize uint16be))
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(x:versioned-struct
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uint16be
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(dictify
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'header (dictify 'xAvgCharWidth int16be ;; average weighted advance width of lower case letters and space
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'usWeightClass uint16be ;; visual weight of stroke in glyphs
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'usWidthClass uint16be ;; relative change from the normal aspect ratio (width to height ratio)
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;; Indicates font embedding licensing rights
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'fsType (x:bitfield #:type uint16be
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#:flags '(null noEmbedding viewOnly editable null null null null noSubsetting bitmapOnly))
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'ySubscriptXSize int16be ;; recommended horizontal size in pixels for subscripts
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'ySubscriptYSize int16be ;; recommended vertical size in pixels for subscripts
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'ySubscriptXOffset int16be ;; recommended horizontal offset for subscripts
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'ySubscriptYOffset int16be ;; recommended vertical offset form the baseline for subscripts
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'ySuperscriptXSize int16be ;; recommended horizontal size in pixels for superscripts
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'ySuperscriptYSize int16be ;; recommended vertical size in pixels for superscripts
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'ySuperscriptXOffset int16be ;; recommended horizontal offset for superscripts
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'ySuperscriptYOffset int16be ;; recommended vertical offset from the baseline for superscripts
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'yStrikeoutSize int16be ;; width of the strikeout stroke
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'yStrikeoutPosition int16be ;; position of the strikeout stroke relative to the baseline
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'sFamilyClass int16be ;; classification of font-family design
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'panose (x:array #:type uint8 #:length 10) ;; describe the visual characteristics of a given typeface
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'ulCharRange (x:array #:type uint32be #:length 4)
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'vendorID (x:symbol #:length 4) ;; four character identifier for the font vendor
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;; bit field containing information about the font
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'fsSelection (x:bitfield #:type uint16
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#:flags '(italic underscore negative outlined strikeout bold regular useTypoMetrics wws oblique))
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'usFirstCharIndex uint16be ;; The minimum Unicode index in this font
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'usLastCharIndex uint16be) ;; The maximum Unicode index in this font
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0 null
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1 type-1
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2 (append type-1 type-2)
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3 (append type-1 type-2)
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4 (append type-1 type-2)
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5 (append type-1 type-2 type-5)))))
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(module+ test
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(require rackunit racket/serialize "../helper.rkt")
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(define ip (open-input-file charter-path))
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(define dir (deserialize (read (open-input-file charter-directory-path))))
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(define offset (hash-ref (hash-ref (hash-ref dir 'tables) 'OS/2) 'offset))
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(define len (hash-ref (hash-ref (hash-ref dir 'tables) 'OS/2) 'length))
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(check-equal? offset 360)
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(check-equal? len 96)) |