code from class 2011-10-21 morning section

two-sliders.rkt

(require rsound)
(require 2htdp/universe)
(require 2htdp/image)

(define SR 44100)
(define (s sec) (* sec SR))
(define beat-frames (round (/ (* SR 60) 128)))
(define (beat b) (* beat-frames b))

(define LEAD-FRAMES (beat 0.5))
(define TICK-INTERVAL 1/28)
(define TICK-FRAMES (s TICK-INTERVAL))

(define samp (rs-read/clip "/tmp/weasel-heart.wav" (s 0) (s 20)))

;(play samp)

;; a loop is (make-loop sound frame frame)
(define-struct loop (sound start end))

(define LOOP1 (make-loop samp (s 7) (s 8)))
(define LOOP2 (make-loop samp (beat 4) (beat 8)))
(define TEST-PSTREAM (make-pstream))

(check-expect (loop-start LOOP1) (s 7))

;; plays a loop
;; loop -> "played sound"
(define (play-loop-times n loop)
  (play
   (times 
    n
    (loop->sound loop))))

;; loop -> sound
;; extract the looped portion of the sound
(define (loop->sound loop)
  (clip
   (loop-sound loop)
   (loop-start loop)
   (loop-end loop)))

;; loop -> number
;; return the length of the loop in frames
(define (loop-len l)
  (- (loop-end l) (loop-start l)))

(check-expect (loop-len (make-loop samp 340 410)) 70)

;; should play sound, as well:
#;(check-expect (play-loop-times
               4 
               (make-loop samp
                          (beat 4)
                          (beat 8)))
              "played sound")



(define WIDTH 400)
(define HEIGHT 300)
(define LEFT-PAD 40)
(define RIGHT-PAD 40)
(define LINE-HEIGHT 50)


(define START-IMG (star 40 "solid" "red"))
(define STOP-IMG (triangle 40 "solid" "tan"))

;; a world is (make-world pct pct)
(define-struct world (start end))

;; world -> scene
;; draw a slider world
(define (draw-world w)
  (place-image
   STOP-IMG
   (+ LEFT-PAD
      (* (/ (world-end w) 100)
         (- WIDTH LEFT-PAD RIGHT-PAD)))
   LINE-HEIGHT
   (place-image
    START-IMG
    (+ LEFT-PAD
      (* (/ (world-start w) 100)
         (- WIDTH LEFT-PAD RIGHT-PAD)))
    LINE-HEIGHT
    (scene+line
     (empty-scene WIDTH HEIGHT)
     LEFT-PAD LINE-HEIGHT (- WIDTH RIGHT-PAD) LINE-HEIGHT
     (make-pen "lightblue" 15 "solid" "round" "round"))))
  )



(check-expect
 (draw-world (make-world 50 75))
 (place-image
  STOP-IMG
  (+ LEFT-PAD
     (* 0.75 (- WIDTH LEFT-PAD RIGHT-PAD)))
  LINE-HEIGHT
  (place-image
   START-IMG
   200
   LINE-HEIGHT
   (scene+line
    (empty-scene WIDTH HEIGHT)
    LEFT-PAD LINE-HEIGHT (- WIDTH RIGHT-PAD) LINE-HEIGHT
    (make-pen "lightblue" 15 "solid" "round" "round")))))




(draw-world (make-world 25 50))

;; world number number string -> world
(define (mouse-handler w x y evt)
  (make-world (* 100 (/ x WIDTH))
              (world-end w))
  )

(big-bang (make-world 25 50)
          [to-draw draw-world]
          [on-mouse mouse-handler])


(check-expect (mouse-handler (make-world 25 50)
                             200 30 "mouse-down")
              (make-world 50 50))