[Gtk2hs-commit] (main branch): Forgot to add the file with helper functions for tree DND.

[Axel S. <A....@ke...>]

Sun Dec  9 00:11:48 PST 2007  A....@ke...
  * Forgot to add the file with helper functions for tree DND.

    addfile ./gtk/Graphics/UI/Gtk/ModelView/TreeDrag.chs
    hunk ./gtk/Graphics/UI/Gtk/ModelView/TreeDrag.chs 1
    +-- -*-haskell-*-
    +--  GIMP Toolkit (GTK) Interface DragSource and DragDest
    +--
    +--  Author : Axel Simon
    +--
    +--  Created: 24 July 2007
    +--
    +--  Copyright (C) 2007 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  : gtk...@li...
    +-- Stability   : provisional
    +-- Portability : portable (depends on GHC)
    +--
    +-- Interfaces for drag-and-drop support in 'Graphics.UI.Gtk.ModelView.TreeView'.
    +--
    +module Graphics.UI.Gtk.ModelView.TreeDrag (
    +
    +-- * Detail
    +--
    +-- | 'Graphics.UI.Gtk.ModelView.TreeView's provide special support for
    +-- Drag-and-Drop such as hover-to-open-rows or autoscrolling. This module
    +-- implements two utility functions that set and get a path and a model in a
    +-- 'Graphics.UI.Gtk.General.Selection.Selection' structure. These functions
    +-- are thus useful to implement drag-and-drop functionality in a
    +-- 'Graphics.UI.Gtk.ModelView.TreeModel'. In fact, they are used as part of
    +-- the default drag-and-drop interfaces of
    +-- 'Graphics.UI.Gtk.ModelView.ListStore' and
    +-- 'Graphics.UI.Gtk.ModelView.TreeStore' that allows to permute rows and move
    +-- them between hierarchy levels.
    +
    +-- * Utility functions
    +  treeModelEqual,
    +  treeGetRowDragData,
    +  treeSetRowDragData
    +
    +  ) where
    +
    +-- I've decided not to bind the DragSource and DragDest interfaces. They seem
    +-- to be useful if you (a) write your own 'TreeView' widget or (b) if you
    +-- can't be bothered to implement a special variant of these interfaces in
    +-- ListStore and TreeStore. In the latter case the interfaces are useful to
    +-- "simulate" a drag-and-drop that looks like a row-permutation which is the
    +-- interface that Gtk's ListStore and TreeStore support by default. Since
    +-- overriding or augmenting the dnd interfaces for ListStore and TreeStore is
    +-- so easy in Gtk2Hs, I think we can do without the cheat way.
    +
    +import System.Glib.FFI
    +import System.Glib.GObject
    +{#import Graphics.UI.Gtk.Types#}
    +{#import Graphics.UI.Gtk.ModelView.Types#}      (TreePath, fromTreePath, withTreePath,
    +                                                 NativeTreePath(..))
    +import Graphics.UI.Gtk.General.DNDTypes         (SelectionDataM, SelectionData)
    +import Control.Monad                            (liftM)
    +import Control.Monad.Trans                      (liftIO)
    +import Control.Monad.Reader                     (ask)
    +
    +{# context lib="gtk" prefix="gtk" #}
    +
    +-- | Compare two tree model for equality.
    +treeModelEqual :: (TreeModelClass tm1, TreeModelClass tm2) => tm1 -> tm2 -> Bool
    +treeModelEqual tm1 tm2 = unTreeModel (toTreeModel tm1) == unTreeModel (toTreeModel tm2)
    +
    +-- %hash c:8dcb d:af3f
    +-- | Obtains a 'TreeModel' and a path from 'SelectionDataM' whenever the target name is
    +-- "GTK_TREE_MODEL_ROW". Normally called from a 'treeDragDestDragDataReceived' handler.
    +--
    +treeGetRowDragData :: SelectionDataM (Maybe (TreeModel, TreePath))
    +treeGetRowDragData = ask >>= \selPtr -> liftIO $ alloca $ \tmPtrPtr -> alloca $ \pathPtrPtr -> do
    +  isValid <- liftM toBool $
    +    {# call unsafe gtk_tree_get_row_drag_data #} selPtr (castPtr tmPtrPtr) (castPtr pathPtrPtr)
    +  if isValid then do
    +        tmPtr <- peek tmPtrPtr
    +        pathPtr <- peek pathPtrPtr
    +        tm <- makeNewGObject mkTreeModel (return tmPtr)
    +        path <- fromTreePath pathPtr
    +        return (Just (tm, path))
    +    else return Nothing
    +
    +-- %hash c:e3e3 d:af3f
    +-- | Sets selection data with the target name "GTK_TREE_MODEL_ROW", consisting
    +-- of a 'TreeModel' and a 'TreePath'. Normally used in a
    +-- 'treeDragSourceDragDataGet' handler.
    +--
    +-- * Returns @True@ if setting the data was successful.
    +--
    +treeSetRowDragData :: TreeModelClass treeModel => treeModel -> TreePath -> SelectionDataM Bool
    +treeSetRowDragData treeModel path = do
    +  selPtr <- ask
    +  liftM toBool $ liftIO $ withTreePath path $ \path ->
    +    {# call unsafe gtk_tree_set_row_drag_data #} selPtr [_$_]
    +    (toTreeModel treeModel)
    +    path