please disregard the previous code. this si the correct code
```
#lang racket/gui
(define (maybe-set-box! b v)
(when b
(set-box! b v)))
(define rect-snip-class%
(class snip-class%
(inherit set-classname)
(super-new)
(set-classname "rect-snip-class%")
))
(define rect-snip-class (new rect-snip-class%))
(define rect-snip%
(class snip%
(inherit set-snipclass
set-flags get-flags
get-admin)
(init w h)
(super-new)
(set-snipclass rect-snip-class)
(define height h)
(define width w)
(define/override (get-extent dc x y [w #f] [h #f] . _)
(maybe-set-box! w width)
(maybe-set-box! h height))
(define/override (draw dc x y left top right bottom . _)
(send dc draw-rectangle x y width height))
))
(define pb
(new
(class pasteboard%
(super-new)
(inherit insert)
(define start-pos #f)
(define/override (on-default-event event)
(super on-default-event event)
(define x (send event get-x))
(define y (send event get-y))
(cond
[(and (equal? (send event get-event-type) 'left-down)
(send event button-down? 'left)
(not (send event dragging?)))
(set! start-pos (cons x y))]
[(and (equal? (send event get-event-type) 'left-up)
start-pos)
(let ([dx (- (car start-pos) x)]
[dy (- (cdr start-pos) y)])
(define-values (nx nw)
(if (> dx 0)
(values x dx)
(values (+ x dx) (abs dx))))
(define-values (ny nh)
(if (> dy 0)
(values y dy)
(values (+ y dy) (abs dy))))
(define sn (new rect-snip%
[w nw]
[h nh]))
(insert sn nx ny)
(set! start-pos #f))]))
)))
(define f-main (new frame% [label "wireframe"]))
(define cnv-main (new editor-canvas%
[editor pb]
[parent f-main]))
(send f-main show #t)
```
On Mon, Nov 23, 2020 at 9:43 AM KOKOU AFIDEGNON <kokou.afideg...@gmail.com>
wrote:
> I can click to drag in order to draw a rectangle, but when i drag the
> created rectangle (for position adjustment), a new rectangle is created
> from the said position. How do i constrain/fix the issue? i have been
> trying to use key-combination to draw a new rectangle on demand. can you
> please give a hint?
> ```
> #lang racket
> (require racket/gui racket/draw pict)
>
>
>
>
> (define my-pasteboard (class* pasteboard% ()
> (init)
> (super-new)
> (define/override (on-default-event evt)
> (new-rect evt))))
>
>
>
> (define board (new pasteboard%))
> (define toplevel (new frame%
> [label "My board"]
> [width 500]
> [height 500]))
>
> (define canvas (new editor-canvas%
> [parent toplevel]
> [editor board]))
> (send toplevel show #t)
>
> (define my-snip-class
> (new (class snip-class%
> (super-new)
> (send this set-classname "my-snip"))))
>
> (send (get-the-snip-class-list) add my-snip-class)
>
> (define rectangle-snip%
> (class snip%
> (init-field w h)
> (super-new)
> (send this set-snipclass my-snip-class)
> (define/override (get-extent dc x y width height . other)
> (when width (set-box! width w))
> (when height (set-box! height h)))
> (define/override (draw dc x y . other)
> (draw-pict (rectangle w h) dc x y))))
>
>
> (define (new-rect) (send my-pasteboard insert (new rectangle-snip% [w 30]
> [h 80]) 100 300))
> ```
>
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