wxhaskell-users

[wxhaskell-users] problems on Windows

[Dean H. <her...@mi...>]

I'm using wxhaskell 0.10.3 with ghc 6.8.2 on Windows XP Pro.  I'm 
trying to figure out how to change the content of a frame 
dynamically.  The program shown below has several problems:
   * The initial text is garbled (a combination of "Screen 1" and "Screen 2").
   * The button label doesn't change when first clicked.
   * Nothing changes on subsequent button presses.
Any ideas?

>  module Main where
>
>  import Graphics.UI.WX
>
>  main = start gui
>
>  gui = do
>    f    <- frame [text := "Test 1"]
>    p    <- panel f []
>    t1   <- staticText p [text := "Screen 1"]
>    b1   <- button p [text := "switch to 2"]
>    t2   <- staticText p [text := "Screen 2"]
>    b2   <- button p [text := "switch to 1"]
>    set b1 [on command := switch f p t2 b2]
>    set b2 [on command := switch f p t1 b1]
>    switch f p t1 b1
>
>  switch f p t b = set f [layout := fill $ container p $ margin 10 $ 
>column 5 [widget t, widget b]]

Re: [wxhaskell-users] problems on Windows

[Dean H. <her...@mi...>]

Is anyone out there???

I reread Daan's original paper and found a hint that layouts need to 
mention each widget exactly once (though I can't find anything 
definitive in documentation for either wxhaskell or wxwidgets). 
Obeying that "rule" avoids the garbling, but I'm still not able 
successfully to change the layout repeatedly.  Even if I could, how 
then would I show different subsets of widgets at different times?

Is there any hope of getting a decent description of wxhaskell's 
(intended) semantics?  I'm getting exasperated.

At 12:08 AM -0400 5/9/08, Dean Herington wrote:
>I'm using wxhaskell 0.10.3 with ghc 6.8.2 on Windows XP Pro.  I'm
>trying to figure out how to change the content of a frame
>dynamically.  The program shown below has several problems:
>    * The initial text is garbled (a combination of "Screen 1" and "Screen 2").
>    * The button label doesn't change when first clicked.
>    * Nothing changes on subsequent button presses.
>Any ideas?
>
>>   module Main where
>>
>>   import Graphics.UI.WX
>>
>>   main = start gui
>>
>>   gui = do
>>     f    <- frame [text := "Test 1"]
>>     p    <- panel f []
>>     t1   <- staticText p [text := "Screen 1"]
>>     b1   <- button p [text := "switch to 2"]
>>     t2   <- staticText p [text := "Screen 2"]
>>     b2   <- button p [text := "switch to 1"]
>>     set b1 [on command := switch f p t2 b2]
>>     set b2 [on command := switch f p t1 b1]
>>     switch f p t1 b1
>>
>>   switch f p t b = set f [layout := fill $ container p $ margin 10 $
>  >column 5 [widget t, widget b]]

Re: [wxhaskell-users] problems on Windows

[Eric Y. K. <eri...@gm...>]

Hi Dean,

I'm very sorry nobody got back to you.  Personally, I filed your message
away in my pending queue and marked it 'reread'.

By the way, it might help to attach your examples in an easy
compile-and-run format, as I have hopefully done.  It just smooths
out these discussions a little bit! :-)

On Thu, May 15, 2008 at 01:10:58 -0400, Dean Herington wrote:
> I reread Daan's original paper and found a hint that layouts need to 
> mention each widget exactly once (though I can't find anything 
> definitive in documentation for either wxhaskell or wxwidgets). 
> Obeying that "rule" avoids the garbling, but I'm still not able 
> successfully to change the layout repeatedly.

Could you attach your modified code?  My experience with wxhaskell is
that once you create a widget, it's going to be displayed, so you might
as well lay it out somewhere.

> Even if I could, how 
> then would I show different subsets of widgets at different times?

You could set the visible attribute.
See attachment.

I do not claim that this is the right way to go about things.  Maybe
somebody like Mads or Shelarcy would have a better idea.

-- 
Eric Kow <http://www.nltg.brighton.ac.uk/home/Eric.Kow>
PGP Key ID: 08AC04F9

Re: [wxhaskell-users] problems on Windows

[Dean H. <her...@mi...>]

Hi, Eric,

(I wish I could have replied earlier, but this past weekend was very busy.)

Thanks to replies from you and Mads I'm back in business.

At 9:13 AM +0100 5/15/08, Eric Y. Kow wrote:
>Hi Dean,
>
>I'm very sorry nobody got back to you.  Personally, I filed your message
>away in my pending queue and marked it 'reread'.
>
>By the way, it might help to attach your examples in an easy
>compile-and-run format, as I have hopefully done.  It just smooths
>out these discussions a little bit! :-)

Good idea.  Will do next time.

>
>On Thu, May 15, 2008 at 01:10:58 -0400, Dean Herington wrote:
>>  I reread Daan's original paper and found a hint that layouts need to
>>  mention each widget exactly once (though I can't find anything
>>  definitive in documentation for either wxhaskell or wxwidgets).
>>  Obeying that "rule" avoids the garbling, but I'm still not able
>>  successfully to change the layout repeatedly.
>
>Could you attach your modified code?  My experience with wxhaskell is
>that once you create a widget, it's going to be displayed, so you might
>as well lay it out somewhere.

Yes, you and Mads helped me figure that out.  I believe I now 
understand all the anomalies I saw.

>
>>  Even if I could, how
>>  then would I show different subsets of widgets at different times?
>
>You could set the visible attribute.
>See attachment.

Ah, thanks for the tip.

>
>I do not claim that this is the right way to go about things.  Maybe
>somebody like Mads or Shelarcy would have a better idea.

In fact, Mads's suggestion does work better for my application.  (See 
my upcoming reply to him.)

>
>Eric Kow <http://www.nltg.brighton.ac.uk/home/Eric.Kow>

Thanks again.  And sorry I overreacted at my earlier frustration.

Dean

Re: [wxhaskell-users] problems on Windows

[Mads L. <mad...@ya...>]

Hi Dean

Dean Herington wrote:
> Is anyone out there???
Yes.

> 
> I reread Daan's original paper and found a hint that layouts need to 
> mention each widget exactly once (though I can't find anything 
> definitive in documentation for either wxhaskell or wxwidgets). 
> Obeying that "rule" avoids the garbling, but I'm still not able 
> successfully to change the layout repeatedly.  Even if I could, how 
> then would I show different subsets of widgets at different times?
Every widget which is created must be used once and only once. That is
the rule.

In your action (the "on command := do" -stuff) to change the panel
content do:

1) delete your old widgets like:

get p children >>= mapM_ objectDelete

2) create new widgets

3) do "set p [ layout := ... ].

4) finally it might be good to do "refit p".

Also have a look at dynamic
http://wxhaskell.sourceforge.net/doc/Graphics-UI-WXCore-Layout.html#v%
3Adynamic . I am no quite sure when it is necessary to use this
function.


Greetings,

Mads

> 
> Is there any hope of getting a decent description of wxhaskell's 
> (intended) semantics?  I'm getting exasperated.
> 
> At 12:08 AM -0400 5/9/08, Dean Herington wrote:
> >I'm using wxhaskell 0.10.3 with ghc 6.8.2 on Windows XP Pro.  I'm
> >trying to figure out how to change the content of a frame
> >dynamically.  The program shown below has several problems:
> >    * The initial text is garbled (a combination of "Screen 1" and "Screen 2").
> >    * The button label doesn't change when first clicked.
> >    * Nothing changes on subsequent button presses.
> >Any ideas?
> >
> >>   module Main where
> >>
> >>   import Graphics.UI.WX
> >>
> >>   main = start gui
> >>
> >>   gui = do
> >>     f    <- frame [text := "Test 1"]
> >>     p    <- panel f []
> >>     t1   <- staticText p [text := "Screen 1"]
> >>     b1   <- button p [text := "switch to 2"]
> >>     t2   <- staticText p [text := "Screen 2"]
> >>     b2   <- button p [text := "switch to 1"]
> >>     set b1 [on command := switch f p t2 b2]
> >>     set b2 [on command := switch f p t1 b1]
> >>     switch f p t1 b1
> >>
> >>   switch f p t b = set f [layout := fill $ container p $ margin 10 $
> >  >column 5 [widget t, widget b]]
> 
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Re: [wxhaskell-users] problems on Windows

[Dean H. <her...@mi...>]

Hi, Mads,

Thanks for your very helpful reply.  I'm back in business.

At 4:33 PM +0200 5/15/08, Mads Lindstrøm wrote:
>Hi Dean
>
>Dean Herington wrote:
>>  Is anyone out there???
>Yes.
>
>>
>>  I reread Daan's original paper and found a hint that layouts need to
>>  mention each widget exactly once (though I can't find anything
>>  definitive in documentation for either wxhaskell or wxwidgets).
>>  Obeying that "rule" avoids the garbling, but I'm still not able
>>  successfully to change the layout repeatedly.  Even if I could, how
>>  then would I show different subsets of widgets at different times?
>Every widget which is created must be used once and only once. That is
>the rule.

Does the documentation for either wxHaskell or 
wxWidgets explain this rule?  I couldn't find it.

>
>In your action (the "on command := do" -stuff) to change the panel
>content do:
>
>1) delete your old widgets like:
>
>get p children >>= mapM_ objectDelete
>
>2) create new widgets
>
>3) do "set p [ layout := ... ].
>
>4) finally it might be good to do "refit p".

The above approach works for me.  Thanks a lot for the explanation!

Dean

>
>Also have a look at dynamic
>http://wxhaskell.sourceforge.net/doc/Graphics-UI-WXCore-Layout.html#v%
>3Adynamic . I am no quite sure when it is necessary to use this
>function.
>
>
>Greetings,
>
>Mads
>
>>
>>  Is there any hope of getting a decent description of wxhaskell's
>>  (intended) semantics?  I'm getting exasperated.
>>
>>  At 12:08 AM -0400 5/9/08, Dean Herington wrote:
>>  >I'm using wxhaskell 0.10.3 with ghc 6.8.2 on Windows XP Pro.  I'm
>>  >trying to figure out how to change the content of a frame
>>  >dynamically.  The program shown below has several problems:
>>  >    * The initial text is garbled (a 
>>combination of "Screen 1" and "Screen 2").
>>  >    * The button label doesn't change when first clicked.
>>  >    * Nothing changes on subsequent button presses.
>>  >Any ideas?
>>  >
>>  >>   module Main where
>>  >>
>>  >>   import Graphics.UI.WX
>>  >>
>>  >>   main = start gui
>>  >>
>>  >>   gui = do
>>  >>     f    <- frame [text := "Test 1"]
>>  >>     p    <- panel f []
>>  >>     t1   <- staticText p [text := "Screen 1"]
>>  >>     b1   <- button p [text := "switch to 2"]
>>  >>     t2   <- staticText p [text := "Screen 2"]
>>  >>     b2   <- button p [text := "switch to 1"]
>>  >>     set b1 [on command := switch f p t2 b2]
>>  >>     set b2 [on command := switch f p t1 b1]
>>  >>     switch f p t1 b1
>>  >>
>>  >>   switch f p t b = set f [layout := fill $ container p $ margin 10 $
>  > >  >column 5 [widget t, widget b]]

Re: [wxhaskell-users] problems on Windows

[Mads L. <mad...@ya...>]

Hi,

Dean Herington wrote:

> >>  I reread Daan's original paper and found a hint that layouts need to
> >>  mention each widget exactly once (though I can't find anything
> >>  definitive in documentation for either wxhaskell or wxwidgets).
> >>  Obeying that "rule" avoids the garbling, but I'm still not able
> >>  successfully to change the layout repeatedly.  Even if I could, how
> >>  then would I show different subsets of widgets at different times?
> >Every widget which is created must be used once and only once. That is
> >the rule.
> 
> Does the documentation for either wxHaskell or 
> wxWidgets explain this rule?  I couldn't find it.

I looked a bit and could not find the rule except in the paper
"wxHaskell – A portable and concise GUI library for Haskell" (see 
http://legacy.cs.uu.nl/daan/pubs.html#wxhaskell ), which I guess is the
one you refers to.

It would be good if we added the use-only-once rule somewhere. Do you
have a suggestion? Can you name a place where would you would have found
it?


Greetings,

Mads Lindstrøm