71 lines
1.3 KiB
Racket
71 lines
1.3 KiB
Racket
#lang planet dyoo/whalesong
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(require (planet dyoo/whalesong/js))
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(require (planet dyoo/whalesong/world))
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;; A slide is either a simple string or an image.
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(define slides
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(list "Whalesong: a Racket to JavaScript Compiler"
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"Why Whalesong?"
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"World programs on the web"
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"Reusing Racket..."
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"Hello world!"
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"What's missing?"
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"http://hashcollision.org/whalesong"))
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(define (WIDTH)
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(viewport-width))
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(define (HEIGHT)
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(viewport-height))
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(define (BACKGROUND)
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(empty-scene (WIDTH) (HEIGHT)))
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(define (key w a-key)
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(cond
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[(key=? a-key "left")
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(my-max (sub1 w) 0)]
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[(key=? a-key "right")
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(my-min (sub1 w) (length slides))]
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[else w]))
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(define (draw w)
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(let ([a-slide (list-ref slides w)]
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[bg (BACKGROUND)])
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(cond
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[(string? a-slide)
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(place-image (text a-slide 300 "black")
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(quotient (image-width bg) 2)
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(quotient (image-height bg) 2)
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bg)]
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[(image? a-slide)
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(place-image a-slide
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(quotient (image-width bg) 2)
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(quotient (image-height bg) 2)
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bg)])))
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(define (my-max x y)
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(if (> x y)
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x
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y))
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(define (my-min x y)
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(if (< x y)
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x
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y))
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(big-bang 0
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(on-key key)
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(on-draw draw)) |