[racket] draw circle over bitmap and erase old circle

thank you for your replying
maybe I have not enough experience to understand your advice easily
now I got it what the transparent option is.
I tried several change but nothing changed
could you be more specify?
I was thought I need to set a style option on circle but draw-bitmap  
doesn't have such a transparent option.
and I tried following modification but does nothing

(new select% (parent f) (min-width (image-width chipset)) (min-height  
(image-height chipset)) )
to
(new select% (parent f) (min-width (image-width chipset)) (min-height  
(image-height chipset)) (style '(transparent)))

thanks in advanced




, Mathew Kurian <bluejamesbond at gmail.com>님이 작성:
> Greetings,

> According to Racket Docs:


> ----Just set style-----


> 'transparent - the canvas is automatically "erased" before an update  
> using it's parent window's background; the result is undefined if this  
> flag is combined with 'no-autoclear



> Hopefully that helps.

> Sincerely,


> Mathew Kurian
> --
> Mathew Kurian
> Seven Lakes High School

> Cell: 8324932862 | Home: 2814929526
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