(defun test-animation (file)
  (let* ((canvas (box 0 0 256 256))
         (ds (make-data-stream :width (vectometry:width canvas)
                               :height (vectometry:height canvas)
                               :loopingp t)))
    (with-box-canvas canvas
      (loop for divisor downfrom 100
            repeat 94 do
              (set-fill-color *white*)
              (clear-canvas)
              (set-line-cap :round)
              (set-line-width 5)
              (loop for hue from 0 below 360 by 30
                    for angle from 0.0 by (/ pi divisor)
                    do
                       (set-stroke-color (hsv-color hue 1 1))
                       (move-to (centerpoint canvas))
                       (line-to (add (centerpoint canvas)
                                     (apoint angle 128)))
                       (stroke))
              (add-image (vimage-gif-image) ds)))
    (output-data-stream ds file)))