Re: [wxhaskell-users] TreeCtrl Drag and Drop

[Daan L. <daa...@xs...>]

Hi alias in space and time :-)

On Tue, 18 May 2004 23:31:00 -0500, <wxh...@al...> wrote:

> Continuing with my last example, I have been trying to get drag and drop
> working for trees.  Is this implemented yet?  The following doesn't seem
> to work with or without the "veto" line commented out.  Any guidance
> would be appreciated.  If it hasn't been implemented yet, how much work
> would be required to do so?

Well, when I tried your example, it first crashed on me! As I am using
a debug version, I quickly found out that the wxWidget code asserts that
an image list is present when dragging -- even when just using text labels :-(
I just wonder whether that might cause you trouble. When I added images (using
the filebrowse example images) everything worked -- of course, drags were vetoed
so, nothing would happen.

I hope this helps,
All the best,
    Daan.

>
> Thanks
>
> module Main where
>
> import Graphics.UI.WX
> import Graphics.UI.WXCore
>
> imageNone :: Int
> imageNone = (-1)
>
> appendChild tree parent child = treeCtrlAppendItem tree parent child
> imageNone imageNone objectNull
>
> appendList tree parent children = mapM_ (appendChild tree parent)
> children
>
> main :: IO()
> main = start test
>
> test :: IO()
> test = do f <- frame [text := "Hello!"]
>           tree <- treeCtrl f []
>           root <- treeCtrlAddRoot tree "Root" imageNone imageNone
>           objectNull
>           child1 <- treeCtrlAppendItem tree root "Child1" imageNone
>           imageNone objectNull
>           child2 <- treeCtrlAppendItem tree root "Child2" imageNone
>           imageNone objectNull
>           appendList tree child1 ["A","B","C"]
>           appendList tree child2 ["1","2","3"]
>           set tree [on treeEvent := onTreeEvent tree]
>           set f [layout := fill $ widget tree, clientSize := sz 500 300]
>
>
> onTreeEvent :: TreeCtrl a -> EventTree -> IO ()
> onTreeEvent t event
>   = case event of
>       TreeBeginDrag item point veto
>         -> do putStrLn "started dragging..."
>               veto
>               propagateEvent
>       TreeEndDrag item point
>         -> do putStrLn "stopped dragging..."
>               propagateEvent
>       other
>         -> propagateEvent
>
>
>
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