TargetPair.hs


{- |
Copyright  : Will Thompson, Iñaki García Etxebarria and Jonas Platte
License    : LGPL-2.1
Maintainer : Iñaki García Etxebarria (garetxe@gmail.com)

A #GtkTargetPair is used to represent the same
information as a table of #GtkTargetEntry, but in
an efficient form.
-}

module GI.Gtk.Structs.TargetPair
    ( 

-- * Exported types
    TargetPair(..)                          ,
    newZeroTargetPair                       ,
    noTargetPair                            ,


 -- * Properties
-- ** Flags
    targetPairReadFlags                     ,


-- ** Info
    targetPairReadInfo                      ,


-- ** Target
    targetPairReadTarget                    ,




    ) where

import Prelude ()
import Data.GI.Base.ShortPrelude

import qualified Data.Text as T
import qualified Data.ByteString.Char8 as B
import qualified Data.Map as Map

import GI.Gtk.Types
import GI.Gtk.Callbacks
import qualified GI.Gdk as Gdk

newtype TargetPair = TargetPair (ForeignPtr TargetPair)
-- | Construct a `TargetPair` struct initialized to zero.
newZeroTargetPair :: MonadIO m => m TargetPair
newZeroTargetPair = liftIO $ callocBytes 16 >>= wrapPtr TargetPair

noTargetPair :: Maybe TargetPair
noTargetPair = Nothing

targetPairReadTarget :: TargetPair -> IO Gdk.Atom
targetPairReadTarget s = withManagedPtr s $ \ptr -> do
    val <- peek (ptr `plusPtr` 0) :: IO (Ptr Gdk.Atom)
    -- XXX Wrapping a foreign struct/union with no known destructor, leak?
    val' <- (\x -> Gdk.Atom <$> newForeignPtr_ x) val
    return val'

targetPairReadFlags :: TargetPair -> IO Word32
targetPairReadFlags s = withManagedPtr s $ \ptr -> do
    val <- peek (ptr `plusPtr` 8) :: IO Word32
    return val

targetPairReadInfo :: TargetPair -> IO Word32
targetPairReadInfo s = withManagedPtr s $ \ptr -> do
    val <- peek (ptr `plusPtr` 12) :: IO Word32
    return val

type family ResolveTargetPairMethod (t :: Symbol) (o :: *) :: * where
    ResolveTargetPairMethod l o = MethodResolutionFailed l o

instance (info ~ ResolveTargetPairMethod t TargetPair, MethodInfo info TargetPair p) => IsLabelProxy t (TargetPair -> p) where
    fromLabelProxy _ = overloadedMethod (MethodProxy :: MethodProxy info)

#if MIN_VERSION_base(4,9,0)
instance (info ~ ResolveTargetPairMethod t TargetPair, MethodInfo info TargetPair p) => IsLabel t (TargetPair -> p) where
    fromLabel _ = overloadedMethod (MethodProxy :: MethodProxy info)
#endif