animation

From: Kumar Balachandran <kumar_at_rtp.ericsson.se>
Date: Thu, 4 Apr 1996 13:09:14 -0500

(define c (make <Canvas>))
(pack c)
(define o (make <oval> :parent c :coords '(10 10 20 20) :fill "green"))

(define-generic f)
(define-method f ((o <oval>))
        (set! (fill o) "brown")
        (display "you should now be seeing a brown oval\n")
        (update) (do ((i 0 (+ i 1))) ((= i 100000) #f) #f)
        (set! (fill o) "blue")
        (update))

works
Jonathan Berry writes:
> Many thanks to Erick for that bind-for-dragging fix. I have replaced
> the old version with the new at my site and my old problems have gone
> away. I haven't had a chance to try out the new features though.
>
> I have a new question for the stklos community. I would like to
> experiment with some animations, but I am having trouble doing so.
> I can't seem to make intermediate changes show up on the screen.
> Consider the following example:
> -------------------------------
> (require "Tk-classes")
> (define c (make <Canvas>))
> (pack c)
> (define o (make <oval> :parent c :coords '(10 10 20 20) :fill "green"))
>
> (define-generic f)
> (define-method f ((o <oval>))
> (set! (fill o) "brown")
> (display "you should now be seeing a brown oval\n")
> (do ((i 0 (+ i 1))) ((= i 100000) #f) #f)
> (set! (fill o) "blue"))
>
> (f o)
> --------------------------------
> I will never see a brown oval. It is still green during the execution
> of the loop, then turns blue at the end. I've tried "delay" and "force"
> without success. There is no difference if I use "slot-set!" instead of
> the shorthand "set!."
>
> thanks in advance for any help,
> Jon
>
>
Received on Thu Apr 04 1996 - 20:10:39 CEST