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//---------------------------------------------------------------------------
//
// <copyright file="SelectedItemCollection.cs" company="Microsoft">
// Copyright (C) 2008 by Microsoft Corporation. All rights reserved.
// </copyright>
//
//
// Description: SelectedItemCollection holds the list of selected items of a Selector.
//
//
// History:
// 10/01/2008 : atanask - Created
//
//---------------------------------------------------------------------------
using System;
using System.Collections;
using System.Collections.ObjectModel;
using System.Windows.Controls.Primitives;
namespace System.Windows.Controls
{
/// <summary>
/// This class represent the collection of SelectedItems in Selector. It extends the ObservableCollection by providing methods for bulk selection.
/// </summary>
internal class SelectedItemCollection : ObservableCollection<object>
{
#region Contructors
/// <summary>
/// Create a new SelectedItemCollection object which keeps a reference to the corresponding Selector
/// </summary>
/// <param name="selector"></param>
public SelectedItemCollection(Selector selector)
{
_selector = selector;
_changer = new Changer(this);
}
#endregion
#region Protected Methods
/// <summary>
/// Clear all items from the selection. This method modifies the behavior of IList.Clear()
/// </summary>
protected override void ClearItems()
{
if (_updatingSelectedItems)
{
foreach (ItemsControl.ItemInfo current in _selector._selectedItems)
{
_selector.SelectionChange.Unselect(current);
}
}
else
{
using (ChangeSelectedItems())
{
base.ClearItems();
}
}
}
/// <summary>
/// Removes an item from the selection. This method modifies the behavior of IList.Remove() and IList.RemoveAt()
/// </summary>
protected override void RemoveItem(int index)
{
if (_updatingSelectedItems)
{
_selector.SelectionChange.Unselect(_selector.NewItemInfo(this[index]));
}
else
{
using (ChangeSelectedItems())
{
base.RemoveItem(index);
}
}
}
/// <summary>
/// Inserts an item in the selection
/// </summary>
protected override void InsertItem(int index, object item)
{
if (_updatingSelectedItems)
{
// For defered selection we should allow only Add method
if (index == Count)
{
_selector.SelectionChange.Select(_selector.NewItemInfo(item), true /* assumeInItemsCollection */);
}
else
{
throw new InvalidOperationException(SR.Get(SRID.InsertInDeferSelectionActive));
}
}
else
{
using (ChangeSelectedItems())
{
base.InsertItem(index, item);
}
}
}
/// <summary>
/// Sets an item on specified index
/// </summary>
protected override void SetItem(int index, object item)
{
if (_updatingSelectedItems)
{
throw new InvalidOperationException(SR.Get(SRID.SetInDeferSelectionActive));
}
else
{
using (ChangeSelectedItems())
{
base.SetItem(index, item);
}
}
}
/// <summary>
/// Movea an item from one position to another
/// </summary>
/// <param name="oldIndex">index of the column which is being moved</param>
/// <param name="newIndex">index of the column to be move to</param>
protected override void MoveItem(int oldIndex, int newIndex)
{
if (oldIndex != newIndex)
{
if (_updatingSelectedItems)
{
throw new InvalidOperationException(SR.Get(SRID.MoveInDeferSelectionActive));
}
else
{
using (ChangeSelectedItems())
{
base.MoveItem(oldIndex, newIndex);
}
}
}
}
#endregion
#region Reentrant changes
internal bool IsChanging { get { return (_changeCount > 0); } }
private IDisposable ChangeSelectedItems()
{
++_changeCount;
return _changer;
}
private void FinishChange()
{
if (--_changeCount == 0)
{
_selector.FinishSelectedItemsChange();
}
}
private class Changer : IDisposable
{
public Changer(SelectedItemCollection owner)
{
_owner = owner;
}
public void Dispose()
{
_owner.FinishChange();
}
SelectedItemCollection _owner;
}
int _changeCount;
Changer _changer;
#endregion Reentrant changes
#region MultiSelector methods
/// <summary>
/// Begin tracking selection changes. SelectedItems.Add/Remove will queue up the changes but not commit them until EndUpdateSelecteditems is called.
/// </summary>
internal void BeginUpdateSelectedItems()
{
if (_selector.SelectionChange.IsActive || _updatingSelectedItems)
{
throw new InvalidOperationException(SR.Get(SRID.DeferSelectionActive));
}
_updatingSelectedItems = true;
_selector.SelectionChange.Begin();
}
/// <summary>
/// Commit selection changes.
/// </summary>
internal void EndUpdateSelectedItems()
{
if (!_selector.SelectionChange.IsActive || !_updatingSelectedItems)
{
throw new InvalidOperationException(SR.Get(SRID.DeferSelectionNotActive));
}
_updatingSelectedItems = false;
_selector.SelectionChange.End();
}
/// <summary>
/// Returns true after BeginUpdateSelectedItems is called
/// </summary>
internal bool IsUpdatingSelectedItems
{
get
{
return _selector.SelectionChange.IsActive || _updatingSelectedItems;
}
}
/// <summary>
/// Add an ItemInfo to the deferred selection
/// </summary>
internal void Add(ItemsControl.ItemInfo info)
{
if (!_selector.SelectionChange.IsActive || !_updatingSelectedItems)
{
throw new InvalidOperationException(SR.Get(SRID.DeferSelectionNotActive));
}
_selector.SelectionChange.Select(info, true /* assumeInItemsCollection */);
}
/// <summary>
/// Remove an ItemInfo from the deferred selection
/// </summary>
internal void Remove(ItemsControl.ItemInfo info)
{
if (!_selector.SelectionChange.IsActive || !_updatingSelectedItems)
{
throw new InvalidOperationException(SR.Get(SRID.DeferSelectionNotActive));
}
_selector.SelectionChange.Unselect(info);
}
#endregion
#region Private data
// Keep a reference for Selector owner
private Selector _selector;
// We need a flag for indicating user bulk selection mode. We cannot re-use SelectionChange.IsActive because there are cases when SelectionChange.IsActive==true and SelectedItems.Add is called internally (End()) to update the collection
// When EndUpdateSelectedItems() is called we first reset this flag to allow SelectedItems.Add to change the collection
private bool _updatingSelectedItems;
#endregion
}
}
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