[wxhaskell-users] Creating an new attribute

2012-02-28 Thread Alexander McPhail 
Hi,

Using GTK, the following works

code

-- | create a new 'Figure' plot
-- click on the window to save
plotNew :: FigureHandle - IO DrawingArea
plotNew f = do
   canvas - drawingAreaNew

   set canvas [maybeFigure := (Just f)]

   return canvas

-

-- | the figure attribute
figure :: Attr DrawingArea FigureState
figure = newAttr getFigure setFigure
   where getFigure o = do
   Just f - get o maybeFigure
   readMVar f
 setFigure o f = set o [maybeFigure :~ (\(Just h) - do
  modifyMVar_ h
(\_ - return f)
  return $ Just
h)]

-

maybeFigure :: Attr DrawingArea (Maybe FigureHandle)
maybeFigure = unsafePerformIO $ objectCreateAttribute
{-# NOINLINE maybeFigure #-}

-

/code

I am attempting to port this code to WxHaskell but can not see how to
create a new attribute for the `FigureHandle`.

This is the code I have so far

type FigureHandle = MVar FigureState

-
-- | create a new 'Figure' plot
-- click on the window to save
plot ::  Frame () - FigureHandle - IO (Panel ())
plot fr f = do
  p - panel fr [figure := f]
  set p [on paint := paintFigure p]
  return p

paintFigure :: Panel () - DC a - Rect - IO ()

-- | the figure attribute
figure :: Attr (Panel a) FigureHandle
figure = newAttr figure getFigure setFigure
   where getFigure o = do
   readMVar figureHandle
 setFigure o f = do
   modifyMVar_ figureHandle (\_ - return f)

-

I looked in the CustomControl.hs example, which uses a pre-existing
attribute and does not create a new one in the way that the call to
`objectCreateAttribute` does with GTK.

Thanks,

Vivian


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Re: [wxhaskell-users] Creating an new attribute

2012-02-28 Thread Jeremy O'Donoghue 
Hi,

On 28 February 2012 03:28, Alexander McPhail 
haskell.vivian.mcph...@gmail.com wrote:

 Hi,

 Using GTK, the following works

 code

 -- | create a new 'Figure' plot
 -- click on the window to save
 plotNew :: FigureHandle - IO DrawingArea
 plotNew f = do
canvas - drawingAreaNew

set canvas [maybeFigure := (Just f)]

return canvas


 -

 -- | the figure attribute
 figure :: Attr DrawingArea FigureState
 figure = newAttr getFigure setFigure
where getFigure o = do
Just f - get o maybeFigure
readMVar f
  setFigure o f = set o [maybeFigure :~ (\(Just h) - do
   modifyMVar_
 h (\_ - return f)
   return $
 Just h)]


 -

 maybeFigure :: Attr DrawingArea (Maybe FigureHandle)
 maybeFigure = unsafePerformIO $ objectCreateAttribute
 {-# NOINLINE maybeFigure #-}


 -

 /code

 I am attempting to port this code to WxHaskell but can not see how to
 create a new attribute for the `FigureHandle`.

 This is the code I have so far

 type FigureHandle = MVar FigureState


 -
 -- | create a new 'Figure' plot
 -- click on the window to save
 plot ::  Frame () - FigureHandle - IO (Panel ())
 plot fr f = do
   p - panel fr [figure := f]
   set p [on paint := paintFigure p]
   return p

 paintFigure :: Panel () - DC a - Rect - IO ()

 -- | the figure attribute
 figure :: Attr (Panel a) FigureHandle
 figure = newAttr figure getFigure setFigure
where getFigure o = do
readMVar figureHandle
  setFigure o f = do
modifyMVar_ figureHandle (\_ - return f)


You may find this entry from my blog helpful:
http://wewantarock.wordpress.com/2010/01/11/custom-controls-in-wxhaskell-part-3/

I think you cannot create an attribute for FigureHandle. Attributes in
wxHaskell are typed on the control to which they apply, for example (taken
from the blog) if you have a DiffViewer control, then to create a diffFiles
attribute which sets the files to be compared has the type signature below

 diffFiles :: Attr (DiffViewer a) (FilePath, FilePath)
 diffFiles = newAttr diffFiles dvGetFiles dvSetFiles
 where
 dvGetFiles win = {- Code follows... -}
 dvSetFiles win (txt1, txt2) = {- Code follows -}

You can just as easily create a new attribute for an existing control. In
this case, I think that what you need is much closer to the code you have
for GTK than what you have shown for wxHaskell.

Hope this helps - I don't have a Gtk2Hs install to let me check they types
of your working code, I'm afraid, so there is a bit of guesswork on my side.

Best regards
Jeremy
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