[racket] Plot: plot-new-window never happens?

Never mind. I was calling `super-new' before the canvas instance was 
initialized, which put the canvas in the frame, so the frame forwarded 
events to the canvas.

Neil ⊥

On 05/25/2012 12:44 PM, Neil Toronto wrote:
> Looks like that mostly works. Here's a problem I ran into: it seems
> that, unless I'm careful in a way I don't understand, the children of a
> frame with a new eventspace receive callbacks before they're fully
> initialized. Here's a simple example:
>
> #lang racket
>
> (require racket/gui)
>
> (define test-editor-canvas%
> (class editor-canvas%
> (init parent)
> (super-new [parent parent])
>
> (define/override (on-size w h)
> (printf "~v~n" should-this-be-defined?))
>
> (define should-this-be-defined? #f)))
>
> (define frame
> (let ([new-es (make-eventspace)])
> (parameterize ([current-eventspace new-es])
> (define frame (new frame% [label "bob"] [width 400] [height 400]))
> (new test-editor-canvas% [parent frame])
> frame)))
>
> (send frame show #t)
>
>
> Most of the time, this prints #<undefined> instead of #f, indicating
> that the test-editor-canvas% instance isn't fully constructed before its
> `on-size' is called. If I move its construction outside the
> `current-eventspace' parameterization, it seems to always print #f as it
> should.
>
> The analogous fix in plot would be a slightly trickier, but it seems
> like I shouldn't have to do it.
>
> Neil ⊥
>
> On 04/18/2012 03:16 AM, Matthew Flatt wrote:
>> You could give each frame in its own eventspace.
>>
>> At Tue, 17 Apr 2012 11:45:20 -0600, Neil Toronto wrote:
>>> 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
>>>>>
>>>>> ____________________
>>>>> Racket Users list:
>>>>> http://lists.racket-lang.org/users
>>>>
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>