omg it works!!
thank you!
although I am satisfied with this method,
do you know the better way for it?

, Richard Cleis <[email protected]>님이 작성:
Insert the two lines below to see that what you want is possible, but I doubt such a quick hack is the right way to do it.



rac



On Oct 27, 2010, at 8:48 PM, [email protected] wrote:



> hello

> I finally circle the bitmap where I point by mouse

> but there are several problem

> 1. the circle filled with white color that I can't see bitmap through the circle

> 2. the drawn circle didn't erased after I point another coordinates

>

> could somebody give me an little advice?

>

> my code looks messy and not neat but

> I paste the code for make it easier to understand

>

>

> #lang scheme

> (require 2htdp/image

> racket/gui)

> (define chipset (make-object bitmap% "town.png" 'png))

> (define (check dc m)





(send dc draw-bitmap chipset 0 0)

(send dc set-brush "blue" 'transparent)







> (define x (send m get-x))

> (define y (send m get-y))

> (send dc draw-ellipse (- x (modulo x 16)) (- y (modulo y 16)) 16 16))

> (define f (new frame% (label "map editor")))

> (define xymsg (new message% (label "nth so far") (parent f)))

> (define select%

> (class canvas%

> (override on-event on-paint)

> (define on-paint (λ () (send (send this get-dc) draw-bitmap chipset 0 0)))

> (define on-event (λ (m)

> (send xymsg set-label

> (string-append "x:"

> (number->string (send m get-x))

> " y:"

> (number->string (send m get-y))))

> (when (send m get-left-down) (check (send this get-dc) m))))

>

> (super-new )

> ))

> (new select% (parent f) (min-width (image-width chipset)) (min-height (image-height chipset)) )

> (send f show #t)_________________________________________________

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