zone-pgm-rainbow

;; zone-pgm-rainbow

(require 'zone)
(defvar zone-programs)
(defvar zpr-hue-factor 50)
(defvar zpr-sat 1.0)
(defvar zpr-light 0.5)

(defun zone-pgm-rainbow ()
  (require 'color nil)
  (cl-loop
   while (not (input-pending-p))
   with k = 0
   do (cl-loop
       for i from (window-start) to (1- (window-end))
       do (add-text-properties
           i (1+ i)
           `(face ((foreground-color
                    . ,(apply 'color-rgb-to-hex
                              (color-hsl-to-rgb
                                 (/ (* (% (+ i k) zpr-hue-factor) 1.0) zpr-hue-factor)
                                 zpr-sat zpr-light)))))))
   (sit-for 0.2)
   (setq k (1+ k))))

(defun zone-choose (pgm)
  "Choose a PGM to run for `zone'."
  (interactive
   (list
    (completing-read
     "Program: "
     (mapcar 'symbol-name zone-programs))))
  (let ((zone-programs (list (intern pgm))))
    (zone)))

(defun zone-rainbow () (interactive)
    (zone-choose "zone-pgm-rainbow"))

(run-with-idle-timer 90 nil 'zone-rainbow)