> > evaluate (my-draw) at repl
Yes, in that case it works. Initially I ran it just from the code area in DrRacket (I added call (my-draw) at the end). But after calling this function from REPL it worked. Thanks! On 27 January 2015 at 20:20, Matthias Felleisen <[email protected]> wrote: > > My code is tested. Copy, paste, run, evaluate (my-draw) at repl. If it > doesn't work, report the exact actions you perform to get a failure. > > > > > On Jan 27, 2015, at 1:08 PM, Alexandr M wrote: > > Thanks, > > I copied your example and it seems it doesn't work .. > > If I comment the code inside [paint-callback .. it also doesn't draw > anything. > > In general I need to send 'messages' from 'outside' to the canvas object > to visualize numerical experiment performed by separate function. > > I can implement experiment itself inside [pain-callback (lambda ... > functions ) under definition of canvas, but it looks strange and clumsy. > Sometimes I need just to run computations, but sometimes I need also to do > visualization with animation. > > How could I achieve this? > > Best regards, > Alex > > On 27 January 2015 at 19:54, Matthias Felleisen <[email protected]> > wrote: > >> >> Do you want something like this: >> >> #lang racket/gui >> >> (define frame (new frame% [label ""] [width 700] [height 500])) >> (define canvas >> (new canvas% >> [parent frame] >> [paint-callback >> (lambda (c dc) >> (send dc draw-line 1 1 100 100))])) >> (send frame show #true) >> >> (define (my-draw) >> (send (send canvas get-dc) draw-line 100 100 0 200)) >> >> >> -- Matthias >> >> >> >> On Jan 27, 2015, at 12:09 PM, Alexandr M wrote: >> >> > Hello, >> > >> > How can I draw the line (for example) in the canvas object defined as: >> > >> > (define frame (new frame% [label ""] [width 700] [height 500])) >> > (define canvas (new canvas% [parent frame] >> > ;;;; - call from outside: [paint-callback (lambda (c dc) (send dc >> draw-line 1 1 10 10) )] >> > )) >> > >> > by calling a function like >> > >> > (define (MyDraw canvas-obj) .... (draw-line 1 1 10 10)) >> > >> > ? >> > >> > -- >> > Best regards, >> > Alex >> > ____________________ >> > Racket Users list: >> > http://lists.racket-lang.org/users >> >> > > > -- > Best regards, > Alexander Maslov > > > -- Best regards, Alexander Maslov
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