;; The first three lines of this file were inserted by DrRacket. They record metadata ;; about the language level of this file in a form that our tools can easily process. #reader(lib "htdp-advanced-reader.ss" "lang")((modname jpr-bug) (read-case-sensitive #t) (teachpacks ()) (htdp-settings #(#t constructor repeating-decimal #t #t none #f ()))) ;; This program demonstrated that the idea of using default handlers (K) for ;; absent mouse and key handlers was a horrible idea. The balls on his cannvas ;; just started jumping around when the mouse moved in. (require 2htdp/universe) (require 2htdp/image) (define (animation2) (local [(define SIZE 300) (define SCENE (rectangle SIZE SIZE 'outline "black")) (define dM 1) (define INIT 0) (define (suivant m) (+ m dM)) (define (dessiner m) (place-image (circle m 'solid "red") (random SIZE) (random SIZE) SCENE))] (big-bang INIT (on-tick suivant 1) (on-draw dessiner SIZE SIZE)))) (animation2)