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|
{-# LANGUAGE CPP #-}
-- -*-haskell-*-
-- GIMP Toolkit (GTK) Object
--
-- Author : Axel Simon
--
-- Created: 9 April 2001
--
-- Copyright (C) 2001-2005 Axel Simon
--
-- This library is free software; you can redistribute it and/or
-- modify it under the terms of the GNU Lesser General Public
-- License as published by the Free Software Foundation; either
-- version 2.1 of the License, or (at your option) any later version.
--
-- This library is distributed in the hope that it will be useful,
-- but WITHOUT ANY WARRANTY; without even the implied warranty of
-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
-- Lesser General Public License for more details.
--
-- |
-- Maintainer : gtk2hs-users@lists.sourceforge.net
-- Stability : provisional
-- Portability : portable (depends on GHC)
--
-- The base class of the Gtk+ type hierarchy.
--
-- * Each widget is a represented as a purely abstract data type. It can only
-- be accessed through and the special access functions that are defined
-- in each widget file.
--
module Graphics.UI.Gtk.Abstract.Object (
-- * Detail
--
-- | 'Object' is the base class for all widgets, and for a few non-widget
-- objects such as 'Adjustment'. 'Object' predates 'GObject'; non-widgets that
-- derive from 'Object' rather than 'GObject' do so for backward compatibility
-- reasons.
--
-- * Class Hierarchy
-- |
-- @
-- | 'GObject'
-- | +----Object
-- | +----'Widget'
-- | +----'Adjustment'
-- | +----'CellRenderer'
-- | +----'FileFilter'
-- | +----'ItemFactory'
-- | +----'Tooltips'
-- | +----'TreeViewColumn'
-- @
-- * Types
Object,
ObjectClass,
castToObject, gTypeObject,
toObject,
-- * Methods
makeNewObject,
-- * Weak references
GWeakNotify,
objectWeakref,
objectWeakunref,
-- * Signals
objectDestroy
) where
import Control.Monad (when)
import System.Glib.FFI
import System.Glib.GObject (objectUnref)
#if GLIB_CHECK_VERSION(2,10,0)
import System.Glib.GObject (objectRefSink)
#else
import System.Glib.GObject (objectRef)
#endif
{#import Graphics.UI.Gtk.Types#}
{#import Graphics.UI.Gtk.Signals#}
import Data.IORef
{# context lib="gtk" prefix="gtk" #}
--------------------
-- Methods
-- turn the initial floating state to sunk
--
-- * The floating\/sunk concept of a GTK object is not very useful to us.
-- The following procedure circumvents the whole subject and ensures
-- proper cleanup:
-- on creation: objectRef, objectSink
-- on finalization: objectUnref
--
-- * This function cannot be bound by c2hs because it is not possible to
-- override the pointer hook.
#if !GLIB_CHECK_VERSION(2,10,0)
foreign import ccall unsafe "gtk_object_sink"
objectSink :: Ptr obj -> IO ()
#endif
-- This is a convenience function to generate a new widget. It adds the
-- finalizer with the method described under objectSink.
--
-- * The constr argument is the contructor of the specific object.
--
makeNewObject :: ObjectClass obj =>
(ForeignPtr obj -> obj, FinalizerPtr obj) -> IO (Ptr obj) -> IO obj
makeNewObject (constr, objectUnref) generator = do
objPtr <- generator
when (objPtr == nullPtr) (fail "makeNewObject: object is NULL")
#if GLIB_CHECK_VERSION(2,10,0)
objectRefSink objPtr
#else
objectRef objPtr
objectSink objPtr
#endif
obj <- newForeignPtr objPtr objectUnref
return $! constr obj
{#pointer GWeakNotify#}
foreign import ccall "wrapper" mkDestructor :: IO () -> IO GWeakNotify
-- | Attach a callback that will be called after the
-- destroy hooks have been called
--
objectWeakref :: ObjectClass o => o -> IO () -> IO GWeakNotify
objectWeakref obj uFun = do
funPtrContainer <- newIORef nullFunPtr
uFunPtr <- mkDestructor $ do
uFun
funPtr <- readIORef funPtrContainer
freeHaskellFunPtr funPtr
writeIORef funPtrContainer uFunPtr
{#call unsafe g_object_weak_ref#} (toGObject obj) uFunPtr nullPtr
return uFunPtr
-- | Detach a weak destroy callback function
--
objectWeakunref :: ObjectClass o => o -> GWeakNotify -> IO ()
objectWeakunref obj fun =
{#call unsafe g_object_weak_unref#} (toGObject obj) fun nullPtr
--------------------
-- Signals
-- | Signals that all holders of a reference to the 'Object' should release
-- the reference that they hold. May result in finalization of the object if
-- all references are released.
--
objectDestroy :: ObjectClass self => Signal self (IO ())
objectDestroy = Signal (connect_NONE__NONE "destroy")
|
