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81 lines
4.7 KiB
Racket
81 lines
4.7 KiB
Racket
7 years ago
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#lang fontkit/racket
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(require restructure)
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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/tables/OS2.js
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|#
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(define-subclass VersionedStruct (ROS/2))
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(define OS/2 (let ()
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(define header-fields
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(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 (+Bitfield uint16be '(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 (+Array uint8 10) ;; describe the visual characteristics of a given typeface
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'ulCharRange (+Array uint32be 4)
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'vendorID (+String 4) ;; four character identifier for the font vendor
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;; bit field containing information about the font
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'fsSelection (+Bitfield uint16 '(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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))
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(define type-1-extra
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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 (+Array uint32be 2)))
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(define type-2-extra
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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-extra
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(dictify 'usLowerOpticalPointSize uint16be
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'usUpperOpticalPointSize uint16be))
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(make-object ROS/2
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uint16be
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(dictify
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0 (append header-fields null)
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1 (append header-fields type-1-extra)
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2 (append header-fields type-1-extra type-2-extra)
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3 (append header-fields type-1-extra type-2-extra)
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4 (append header-fields type-1-extra type-2-extra)
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5 (append header-fields type-1-extra type-2-extra type-5-extra)))))
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(test-module
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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 (· dir tables OS/2 offset))
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(define len (· dir tables OS/2 length))
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(check-equal? offset 360)
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(check-equal? len 96)
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(define ds (+DecodeStream (peek-bytes len offset ip)))
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(define version (send uint16be decode ds))
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(send OS/2 force-version! version)
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(define table-data (send OS/2 decode ds))
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(check-equal? (· table-data panose) '(2 0 5 3 6 0 0 2 0 4))
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(check-equal? (· table-data sFamilyClass) 0))
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