That's extremely helpful, thank you. Deren
On Tue, Apr 17, 2012 at 12:48 PM, Matthew Flatt <[email protected]> wrote: > All GUI activity like window drawing happens only in the main thread of > an eventspace. Your program also starts out in the main thread. So, > yes, drawing has to wait until your loop completes. > > One solution is to put your loop in a separate thread. The example > below creates a thread and passes it to `yield' to wait until the > thread is done. The `yield' function is special in that it lets other > GUI activity happen while it waits: > > #lang at-exp racket > (require plot > racket/gui/base) > (plot-new-window? #t) > (yield > (thread > (lambda () > (let loop () > (let ((dummy (read))) > (if (and (number? dummy) (zero? dummy)) > (void) > (begin > (plot (function (λ(x) (* x x)) -2 2)) > (loop)))))))) > > Although the above should work, it's not really a good idea to perform > GUI actions outside of the main thread. So, here's an improved version > that uses `queue-callback' to send the `plot' call back to the main > thread: > > #lang at-exp racket > (require plot > racket/gui/base) > (plot-new-window? #t) > (yield > (thread > (lambda () > (let loop () > (let ((dummy (read))) > (if (and (number? dummy) (zero? dummy)) > (void) > (begin > ;; queue a callback instead of `plot' directly: > (queue-callback > (lambda () > (plot (function (λ(x) (* x x)) -2 2)))) > (loop)))))))) > > For more information, see > > http://docs.racket-lang.org/gui/windowing-overview.html#(part._eventspaceinfo) > > > At Tue, 17 Apr 2012 10:40:55 -0400, Deren Dohoda wrote: >> I was messing around with a spline utility last night and was using >> the plot-new-window? setting to get a plot. The goal was to share an >> exe with a coworker who doesn't have Racket. Just a command-line app >> but to get the plot to display I needed a window and this seemed >> awesome. The problem is I couldn't get the plot to display when the >> thread was in a procedure. The window would appear but it was like the >> plot backend wasn't free to draw to it. Here's a way to reproduce it >> on v5.2: >> >> #lang at-exp racket >> (require plot) >> (plot-new-window? #t) >> (let loop () >> (let ((dummy (read))) >> (if (and (number? dummy) (zero? dummy)) >> (void) >> (begin >> (plot (function (λ(x) (* x x)) -2 2)) >> (loop))))) >> >> So long as you are looping, new windows will appear without plot >> contents. When you finally quit (here by entering the number zero) all >> the plots are drawn in those windows. Any help? Did I do something >> horribly dumb? >> >> Thanks, >> Deren >> >> ____________________ >> Racket Users list: >> http://lists.racket-lang.org/users ____________________ Racket Users list: http://lists.racket-lang.org/users
