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38 lines
1.1 KiB
Racket
38 lines
1.1 KiB
Racket
#lang racket/base
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(require "glyph-position.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/layout/GlyphRun.js
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|#
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;; Represents a run of Glyph and GlyphPosition objects.
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;; Returned by the font layout method.
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; An array of Glyph objects in the run
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; An array of GlyphPosition objects for each glyph in the run
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(struct glyphrun (glyphs positions) #:transparent)
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(define (+glyphrun [glyphs null] [positions null])
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(glyphrun glyphs positions))
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(define (glyphrun-advance-width gr)
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(for/sum ([pos (in-list (glyphrun-positions gr))])
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(glyph-position-x-advance pos)))
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(define (append-glyphruns . grs)
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(for/fold ([glyphss null]
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[positionss null]
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#:result (glyphrun
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(apply append (reverse glyphss))
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(apply append (reverse positionss))))
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([gr (in-list grs)])
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(values (cons (glyphrun-glyphs gr) glyphss)
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(cons (glyphrun-positions gr) positionss))))
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(module+ test
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(require rackunit)
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(define gr (+glyphrun))
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(check-true (glyphrun? gr))
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(check-equal? (append-glyphruns gr gr) gr))
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