[racket] Possible bug with init-auto-scrollbars

On Wed, Sep 10, 2014 at 7:46 PM, Matthew Flatt <mflatt at cs.utah.edu> wrote:

> That's a bug in v6.1 and earlier (on platforms other than Mac OS X).
>
> The bug has been fixed for the next version, so you could try a
> snapshot from
>  http://pre.racket-lang.org/
>
> If you need to stick with a different version, I think you can work
> around the bug by creating a `canvas%` subclass that calls
> `init-auto-scrollbars` on each `on-resize`:
>

Thanks, the workaround works great for my program.
Sincerely, Campbell Stahlman

>
>  #lang racket
>  (require racket/gui)
>
>  (define frame (new frame%
>                     [label "Example"]
>                     [width 300]
>                     [height 300]))
>
>  (define workaround-canvas%
>    (class canvas%
>      (super-new)
>      (inherit init-auto-scrollbars)
>      (define/override (on-size w h)
>        (init-auto-scrollbars 500 500 0.0 0.0))))
>
>  (define canv (new workaround-canvas%
>                    [parent frame]
>                    [style '(vscroll hscroll)]
>                    [paint-callback
>                     (lambda (canvas dc)
>                       (send dc draw-ellipse 0 0 500 500))]))
>
>  (send frame show #t)
>
> At Wed, 10 Sep 2014 19:29:53 -0500, Amy Stahlman wrote:
> > I've been working on a program that uses "init-auto-scrollbars" and I
> > noticed that when the window is resized it actually changes the size of
> the
> > virtual canvas along with the literal canvas instead of just resizing the
> > scrollbar and changing the size of the literal canvas.
> >
> > Here's an example that shows this:
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > *(require racket/gui)(define frame (new frame%                  [label
> > "Example"]                  [width 300]                  [height
> > 300]))(define canv (new canvas% [parent frame]    [style '(vscroll
> > hscroll)]            [paint-callback             (lambda (canvas dc)(send
> > dc draw-ellipse 0 0 500 500))]))(send frame show #t)(send canv
> > init-auto-scrollbars 500 500 0.0 0.0)*
> >
> > Resize the window, making it large enough to show the entire ellipse;
> > notice how the scrollbar's relative size doesn't change, and there is
> blank
> > space at the bottom.
> > Is this by design or some kind of bug?
> > ____________________
> >   Racket Users list:
> >   http://lists.racket-lang.org/users
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.racket-lang.org/users/archive/attachments/20140910/673a6017/attachment.html>