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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