[wxhaskell-users] Key-event translation

[Stefan H. <st...@cs...>]

Hi all,

I've ran into a quite annoying problem...

The key events wxHaskell allows you to handle originate from so- 
called char events at the wxWidgets side. These carry 'translated'  
key codes. For instance, when the 'A'-key is pressed while the SHIFT- 
key isn't (nor is CAPS LOCK etc.), the char event will carry the  
ASCII code for 'a', i.e., 97. However, when the 'A'-key is pressed  
together with the SHIFT-key, the char event will carry the ASCII code  
for 'A' (upper case), i.e., 65. The ratio behind all this is that's  
it's cumbersome to explicitly find out whether which modifiers  
(SHIFT, ALT, etc.) come with which key press.

(wxWidgets, by the way, also offers 'untranslated' key events that  
just let you inspect the key code for the pressed key. The point here  
is that wxHaskell works with the _translated_ events.)

So far, so good.

Unfortunately, so I find out, I run an incarnation of wxWidgets,  
i.e., wxMac 2.6.2, that translates key events a bit too agressive.  
For instance, pressing the up-arrow key results in a translated event  
that carries the ASCII code for a form separator '\RS'. So, instead  
of the expected value

   KeyUp

the event carries

   KeyChar '\RS'

Besides with wxMac, I've also experienced this agressiveness with  
wxGtk 2.6.3.3 on Gentoo Linux.

Right now, I work around it by defining my own event constructors:

   module MyGUI where

   import Graphics.WX.UI hiding (upKey, downKey)

   ...

   upKey   = charKey '\RS'
   downKey = charKey '\US'

Still, it is of course quite annoying. It would suit me better if  
wxHaskell would work with untranslated key events. This boils down to  
adapting the Reactive instance for Window:

   instance Reactive (Window a) where
     ...
     keyboard = newEvent "keyboard" windowGetOnKeyDown windowOnKeyDown
     ...

I'd be more than happy to supply a patch for this.

Any thoughts?

On a related note: handlers for key events that I attach to frames do  
not seem to have any effect at all. Can someone explain to me why?

Cheers,

   Stefan