Re: [wxhaskell-users] trouble with event handlers

[<da...@cs...>]

Hi Fabian,

It might be that the frame is not receiving any key events ???
In my experience it might work better to put in some kind
of control, like a "panel". I guess this has to do how more
with the native platform (windows, gtk, etc) than with wxHaskell
as such.

I hope this helps,
-- Daan.

> hey!
> I'm currently writing my first program with wxhaskell, in fact, it's th=
e
> first time I'm using haskell to write a program that goes beyond basic
> data-structures and sorting algorithms so I hope this question doesn't
> turn out to be non-wxhaskell specific.
>
> Basically, what I want to do is react on key-presses just like in the
> bouncing balls example or in this tutorial:
> http://www.cs.uu.nl/~daan/download/papers/wxhaskell.pdf.
>
> So I wrote the following:
>
> mainFrame =3D  do
>   cs <- variable [ value :=3D (CSys (Rt start_ul start_lr))]
>   f <- frame []
>
>   set f[
>         layout :=3D space fwidth fheight
>        , on paint :=3D drawCoordSys cs fwidth fheight
>        , text:=3D "Coordinate System"
>        , on leftKey :=3D do set cs [value :~ \x -> (csys_shift_x x
> (-(fac_x_p2t fwidth x))) ]
>                           repaint f
>        ]
>
>
>   return ()
>   where
>     start_ul =3D (Pt (-4) 2)
>     start_lr =3D (Pt 2 (-2))
>     fwidth =3D 800
>     fheight =3D 600
>
> When leftKey is pressed, this is supposed to set the mutable variable c=
s
> and repaint f. This doesn't work for some reason. However, if I try the
> same with a timer, it works:
>
> t <- timer f [interval :=3D 50
>              , on command :=3D do set cs [value :~ \x -> (csys_shift_x =
x
> (-(fac_x_p2t fwidth x))) ]
>                                 repaint f
>              ]
>
>
> Any ideas?
> Thanks,
>
> - Fabian Yamaguchi
>
>
>
>
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