Re: [racket-users] Re: Scrolling in racket/gui

[Alex Harsanyi]

On Thursday, March 2, 2017 at 10:56:30 AM UTC+8, Philip McGrath wrote:
> Almost — thanks! (I'm sure I read over that page of the docs, but I somehow 
> missed 'vscroll.)
> 
> 
> The one thing that isn't working is scrolling with the mouse/trackpad. It 
> seems like I might need to override on-subwindow-char to listen for 'wheel-up 
> and 'wheel-down, which I can do, but I'm not finding how to change the 
> scrolling position of the panel if I do catch one of those events. (Or maybe 
> there's a way to do it without implementing it myself?)
> 

I don't think you will be able to update the scroll-bar positions.  The scroll 
functionality that is implemented for panel objects is limited to automatic 
scrolling and the racket GUI code would have to be updated to allow changing it 
programmatically.

BTW, I am looking forward to being proven wrong on this, as I could use the 
functionality myself :-)

Alex.

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Re: [racket-users] Re: Scrolling in racket/gui

[Philip McGrath]

Almost — thanks! (I'm sure I read over that page of the docs, but I somehow
missed 'vscroll.)

The one thing that isn't working is scrolling with the mouse/trackpad. It
seems like I might need to override on-subwindow-char to listen for
'wheel-up and 'wheel-down, which I can do, but I'm not finding how to
change the scrolling position of the panel if I do catch one of those
events. (Or maybe there's a way to do it without implementing it myself?)

-Philip

On Wed, Mar 1, 2017 at 5:39 PM, Alex Harsanyi 
wrote:

> On Thursday, March 2, 2017 at 4:16:47 AM UTC+8, Philip McGrath wrote:
> > This seems like it should be a simple question, but I can't figure out
> how to get a scroll bar in a gui application like this one:
> >
> >
> > #lang racket/gui
> > (define frame
> >   (new frame% [label "Example"]))
> > (for ([letter '("A" "B" "C" "D")])
> >   (define grp
> > (new group-box-panel%
> >  [parent frame]
> >  [label letter]))
> >   (for ([i (in-range 0 10)])
> > (new button%
> >  [parent grp]
> >  [label (number->string i)])))
> > (send frame show #t)
> >
> >
> > I can see something like what I have in mind in Dr. Racket's
> "Colors">"Color Schemes" preferences tab (at least on Mac OS), but I can't
> figure out how to do it.
> >
> >
> > Thanks,
> > Philip
>
> Does this do what you want?
>
> #lang racket/gui
>
> (define frame
>   (new frame% [label "Example"] [height 300]))
> (for ([letter '("A" "B" "C" "D")])
>   (define grp
> (new group-box-panel%
>  [parent frame]
>  [min-height 100]
>  [label letter]))
>   (define panel
> (new vertical-panel%
>  [parent grp]
>  [style '(vscroll)]
>  [alignment '(left top)]))
>   (for ([i (in-range 0 10)])
> (new button%
>  [parent panel]
>  [label (number->string i)])))
> (send frame show #t)
>
> Best Regards,
> Alex.
>
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