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27 lines
1.4 KiB
Racket
27 lines
1.4 KiB
Racket
#lang racket/base
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(provide (all-defined-out))
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;; Represents positioning information for a glyph in a GlyphRun.
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;; x-advance = The amount to move the virtual pen in the X direction after rendering this glyph.
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;; y-advance = The amount to move the virtual pen in the Y direction after rendering this glyph.
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;; x-offset = The offset from the pen position in the X direction at which to render this glyph.
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;; y-offset = The offset from the pen position in the Y direction at which to render this glyph.
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(struct glyph-position (x-advance y-advance x-offset y-offset advance-width) #:transparent #:mutable)
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(define (+glyph-position [x-advance 0] [y-advance 0] [x-offset 0] [y-offset 0] [advance-width 0])
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(glyph-position x-advance y-advance x-offset y-offset advance-width))
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(define (scale-glyph-position! gp factor)
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(set-glyph-position-x-advance! gp (* factor (glyph-position-x-advance gp)))
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(set-glyph-position-y-advance! gp (* factor (glyph-position-y-advance gp)))
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(set-glyph-position-x-offset! gp (* factor (glyph-position-x-offset gp)))
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(set-glyph-position-y-offset! gp (* factor (glyph-position-y-offset gp)))
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(set-glyph-position-advance-width! gp (* factor (glyph-position-advance-width gp)))
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gp)
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(module+ test
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(require rackunit)
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(define gp (+glyph-position 1 2 3 4))
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(check-true (glyph-position? gp))
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(check-equal? (scale-glyph-position! gp 2) (+glyph-position 2 4 6 8 0)))
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