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;;

;; CAPTURING A MOVIE

;;

;; This example captures the first 10 seconds of 

;; throbbing text to the tmp directory. each

;; frame is saved individually once every 

;; 1/10 of a second.  You can use quicktime

;; to build a movie using these individual files

;; by selecting open image sequence in quickttime

;; and selecting the first file in the image sequence then

;; selecting the frame rate (10 frames a second in this example).

;;

;; You could of course call gfx:capture-canvas directly inside

;; the throb function everytime you update the canvas. The

;; idea in this example though is to show how this can happen

;; indendently of any drawing routines. 

;;

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(define canvas (gfx:make-canvas 400 400))

(define text-style (gfx:make-text-style "Times-Roman" 72.0 (list 1.0 1.0 1.0 0.25)))

(define text-path (gfx:make-path))

; make the text into a path

(gfx:set-start-point text-path 50 150)

(gfx:add-text text-path text-style "impromptu")

; start with a clean cavas

(gfx:clear-canvas (now) canvas '(0.1 0.1 0.27 1))

(define throb

   (lambda (time path val)

      ; wipe out a bit of the previous drawing

      (gfx:clear-canvas time canvas '(0.1 0.1 0.27 0.09))

      ; display the text-path

      (gfx:draw-path (+ time 1) canvas path

                 '(0.5 0.7 0.9 0.3)

                 '(0.0 0.9 0.2 0.1) 4)

      ; shift the text-path rotation one degree

      (gfx:rotate-path (now) path 1 200 153 *degrees*)

      ; change the size of the text-path

      (gfx:scale-path (+ time 2) path val val *gfx:centre-scale*)

      ; repeat the process with slightly changed values

      (callback (+ time 1000) 'throb (+ time 3000) path

                (if (> val 1.2) 0.8 (+ val 0.025)))))

(define movie-capture

   (lambda (time inc cnt)

      (gfx:capture-canvas canvas (string-append "/tmp/throb_" (number->string cnt) ".png"))

      (if (< cnt 100) 

          (callback (+ time inc) 'movie-capture (+ time inc) inc (+ cnt 1)))))

; start

(throb (now) text-path 0.8)

; capture 10 seconds at 10 frames per second

(movie-capture (now) (* *second* 0.1) 0)