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#lang debug racket/base
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(require sugar/unstable/dict
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"unsafe/freetype.rkt"
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"table-stream.rkt"
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"struct.rkt"
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"helper.rkt")
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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/glyph/Glyph.js
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|#
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; Glyph objects represent a glyph in the font. They have various properties for accessing metrics and
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; the actual vector path the glyph represents, and methods for rendering the glyph to a graphics context.
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;
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; You do not create glyph objects directly. They are created by various methods on the font object.
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; There are several subclasses of the base Glyph class internally that may be returned depending
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; on the font format, but they all inherit from this class.
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(define (is-mark? codepoint)
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;; mark classes = Mn Me Mc
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(regexp-match #px"\\p{Mn}|\\p{Me}|\\p{Mc}" (string (integer->char codepoint))))
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(define (+glyph id codepoints font
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[is-mark? (andmap is-mark? codepoints)]
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[is-ligature? (> (length codepoints) 1)]
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[metrics #f]
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#:constructor [constructor glyph])
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(constructor id codepoints font is-mark? is-ligature? metrics))
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(define (glyph-advance-width g)
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(hash-ref (get-glyph-metrics g) 'advanceWidth))
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(define (get-glyph-metrics g)
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(unless (glyph-metrics g)
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(define face (ft-face (glyph-font g)))
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(FT_Load_Glyph face (glyph-id g))
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(define glyph (FT_FaceRec-glyph face))
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(define ft-glyph-metrics (FT_GlyphSlotRec-metrics glyph))
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(set-glyph-metrics! g (mhash))
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;; todo: get vertical metrics
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(hash-set*! (glyph-metrics g)
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'advanceWidth (FT_Glyph_Metrics-horiAdvance ft-glyph-metrics)
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'leftBearing (FT_Glyph_Metrics-horiBearingX ft-glyph-metrics)
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'advanceHeight 'unfinished
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'topBearing 'unfinished))
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(glyph-metrics g))
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(define (+ttf-glyph . args)
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(apply +glyph #:constructor ttf-glyph args))
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(define (+cff-glyph . args)
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(apply +glyph #:constructor make-cff-glyph args))
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#|
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approximates
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https://github.com/mbutterick/fontkit/blob/master/src/glyph/TTFFont.js
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|#
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;; Returns a glyph object for the given glyph id.
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;; You can pass the array of code points this glyph represents for
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;; your use later, and it will be stored in the glyph object.
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(define (get-glyph font gid [codepoints null])
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((if (has-table? font #"CFF_")
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+cff-glyph
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+ttf-glyph) gid codepoints font)) |