Would it be possible to change plot so that its windows always behave
like this? Could I make it not require cooperation from the program that
calls `plot-frame'?
This is going to come up every time someone wants to pop up plot windows
in a non-GUI, interactive loop.
Neil ⊥
On 04/17/2012 10:48 AM, Matthew Flatt 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
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