[racket] how to stop canvas% from refreshing after on-event

From: Robby Findler (robby at eecs.northwestern.edu)
Date: Mon Feb 11 16:39:16 EST 2013

I don't think it does that. The program below, at least for me, doesn't do
crazy colors when I move the mouse around (it does when resizing, tho).


#lang racket/gui

(define c%
  (class canvas%
    (inherit get-client-size get-dc)
    (define/override (on-paint)
      (define-values (w h) (get-client-size))
      (define dc (get-dc))
      (define c (make-object color% (random 255) (random 255) (random 255)))
      (send dc set-brush c 'solid)
      (send dc set-pen "black" 1 'transparent)
      (send dc draw-ellipse 0 0 w h))

(define f (new frame% [label ""] [width 100] [height 100]))
(define c (new c% [parent f]))
(send f show #t)

On Mon, Feb 11, 2013 at 9:41 AM, Philipp Dikmann <philipp at dikmann.de> wrote:

> It appears that the GUI canvas% refreshes itself whenever it receives a
> mouse-event%.
> I intend to refresh the canvas at a steady pace (using a timer%) and
> independently of any mouse-events instead.
> Is there a reasonable way to suppress the default behavior?
> Thanks for your time,
> Philipp
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