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|
{-# LANGUAGE CPP #-}
-- -*-haskell-*-
-- GIMP Toolkit (GTK) Class TreeRowReference
--
-- Author : Duncan Coutts
--
-- Created: 14 April 2005
--
-- Copyright (C) 2005 Axel Simon, Duncan Coutts
--
-- 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)
--
-- A persistent index into a tree model.
--
module Graphics.UI.Gtk.ModelView.TreeRowReference (
-- * Detail
--
-- | A 'RowReference' is an index into a
-- 'Graphics.UI.Gtk.ModelView.TreeModel.TreeModel' that is persistent even if
-- rows are inserted, deleted or reordered.
--
-- * Types
TreeRowReference,
-- * Constructors
treeRowReferenceNew,
-- * Methods
treeRowReferenceGetPath,
treeRowReferenceValid,
) where
import Control.Monad (liftM)
import System.Glib.FFI
{#import Graphics.UI.Gtk.Types#}
{#import Graphics.UI.Gtk.ModelView.Types#}
{# context lib="gtk" prefix="gtk" #}
-- | Tree Row Reference : like a 'TreePath' it points to a subtree or node, but
-- it is persistent. It identifies the same node (so long as it exists) even
-- when items are added, removed, or reordered.
--
{#pointer * TreeRowReference foreign newtype#}
--------------------
-- Constructors
-- | Creates a row reference based on a path. This reference will keep pointing
-- to the node pointed to by the given path, so long as it exists. Returns @Nothing@ if there is no node at the given path.
--
treeRowReferenceNew :: TreeModelClass self => self
-> TreePath
-> IO (Maybe TreeRowReference)
treeRowReferenceNew self path = withTreePath path $ \path -> do
rowRefPtr <-
{#call gtk_tree_row_reference_new#} (toTreeModel self) path
if rowRefPtr==nullPtr then return Nothing else
liftM (Just . TreeRowReference) $
newForeignPtr rowRefPtr tree_row_reference_free
--------------------
-- Methods
-- | Returns a path that the row reference currently points to.
--
-- * The returned path may be the empty list if the reference was invalid.
--
treeRowReferenceGetPath :: TreeRowReference -> IO TreePath
treeRowReferenceGetPath ref =
{# call unsafe tree_row_reference_get_path #} ref
>>= fromTreePath -- path must be freed
-- | Returns True if the reference refers to a current valid path.
--
treeRowReferenceValid :: TreeRowReference -> IO Bool
treeRowReferenceValid self =
liftM toBool $
{# call unsafe tree_row_reference_valid #}
self
foreign import ccall unsafe ">k_tree_row_reference_free"
tree_row_reference_free :: FinalizerPtr TreeRowReference
|
