;;;; animate.stk -- A simple image animation (Demo)
;;;;
;;;; Copyright © 1998 Erick Gallesio - I3S-CNRS/ESSI <eg@unice.fr>
;;;; 
;;;; Permission to use, copy, and/or distribute this software and its
;;;; documentation for any purpose and without fee is hereby granted, provided
;;;; that both the above copyright notice and this permission notice appear in
;;;; all copies and derived works.  Fees for distribution or use of this
;;;; software or derived works may only be charged with express written
;;;; permission of the copyright holder.  
;;;; This software is provided ``as is'' without express or implied warranty.
;;;;
;;;; $Id: animate.stk 1.1 Tue, 10 Mar 1998 20:43:37 +0000 eg $
;;;;
;;;;          Author: Erick Gallesio [eg@unice.fr]
;;;;   Creation date:  9-Mar-1998 18:51
;;;;Last file update:  9-Mar-1998 21:07

(define *img* #f)

(define (make-animation pattern parent delay)
  (let* ((files  (sort (glob pattern) string<?)) 
	 (size   (length files)) 
	 (images (make-vector size)) 
	 (name   (gensym (& (if (eq? parent *root*) "" parent) ".l"))) 
	 (widget (label name :bd 0 :relief "flat" :background "white"
			:env (the-environment))))
    ;; Store in the image vector all the components of the animation
    (dotimes (i size)
      (let ((key (list-ref files i)))
	(vector-set! images 
		     i 
		     (make-image key :file key))))
    
    ;; Display the first image of the animation
    (tk-set! widget :image (vector-ref images 0))

    ;; Animate the image 
    (letrec ((anim (let ((i 0))
		     (lambda () 
		       (if (>= delay 0) 
			   (when (winfo (quote exists) widget)
			     (if (>= i size) (set! i 0))
			     (tk-set! widget :image (vector-ref images i))
			     (set! i (+ i 1))
			     (update)
			     (after (abs delay) anim))
			   (after 100 anim))))))
      (after 'idle anim))
    widget))


(define (change-animation-delay w delay)
  (let ((env (tk-get w :env)))
    (eval `(set! delay ,delay) env)))