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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
using System.Collections;
using System.ComponentModel;
namespace System.Windows.Forms;
public partial class ListBox
{
public partial class SelectedIndexCollection : IList
{
private readonly ListBox _owner;
public SelectedIndexCollection(ListBox owner)
{
_owner = owner.OrThrowIfNull();
}
/// <summary>
/// Number of current selected items.
/// </summary>
[Browsable(false)]
public int Count
{
get
{
return _owner.SelectedItems.Count;
}
}
object ICollection.SyncRoot
{
get
{
return this;
}
}
bool ICollection.IsSynchronized
{
get
{
return true;
}
}
bool IList.IsFixedSize
{
get
{
return true;
}
}
public bool IsReadOnly
{
get
{
return true;
}
}
public bool Contains(int selectedIndex)
{
return IndexOf(selectedIndex) != -1;
}
bool IList.Contains(object? selectedIndex)
{
if (selectedIndex is int selectedIndexAsInt)
{
return Contains(selectedIndexAsInt);
}
else
{
return false;
}
}
public int IndexOf(int selectedIndex)
{
// Just what does this do? The selectedIndex parameter above is the index into the
// main object collection. We look at the state of that item, and if the state indicates
// that it is selected, we get back the virtualized index into this collection. Indexes on
// this collection match those on the SelectedObjectCollection.
if (selectedIndex >= 0 &&
selectedIndex < InnerArray.Count &&
InnerArray.GetState(selectedIndex, SelectedObjectCollection.SelectedObjectMask))
{
return InnerArray.IndexOf(InnerArray.GetItem(selectedIndex), SelectedObjectCollection.SelectedObjectMask);
}
return -1;
}
int IList.IndexOf(object? selectedIndex)
{
if (selectedIndex is int selectedIndexAsInt)
{
return IndexOf(selectedIndexAsInt);
}
else
{
return -1;
}
}
int IList.Add(object? value)
{
throw new NotSupportedException(SR.ListBoxSelectedIndexCollectionIsReadOnly);
}
void IList.Clear()
{
throw new NotSupportedException(SR.ListBoxSelectedIndexCollectionIsReadOnly);
}
void IList.Insert(int index, object? value)
{
throw new NotSupportedException(SR.ListBoxSelectedIndexCollectionIsReadOnly);
}
void IList.Remove(object? value)
{
throw new NotSupportedException(SR.ListBoxSelectedIndexCollectionIsReadOnly);
}
void IList.RemoveAt(int index)
{
throw new NotSupportedException(SR.ListBoxSelectedIndexCollectionIsReadOnly);
}
/// <summary>
/// Retrieves the specified selected item.
/// </summary>
public int this[int index]
{
get
{
object identifier = InnerArray.GetEntryObject(index, SelectedObjectCollection.SelectedObjectMask);
return InnerArray.IndexOf(identifier);
}
}
object? IList.this[int index]
{
get
{
return this[index];
}
set
{
throw new NotSupportedException(SR.ListBoxSelectedIndexCollectionIsReadOnly);
}
}
/// <summary>
/// This is the item array that stores our data. We share this backing store
/// with the main object collection.
/// </summary>
private ItemArray InnerArray
{
get
{
_owner.SelectedItems.EnsureUpToDate();
return _owner.Items.InnerArray;
}
}
public void CopyTo(Array destination, int index)
{
int cnt = Count;
for (int i = 0; i < cnt; i++)
{
destination.SetValue(this[i], i + index);
}
}
public void Clear()
{
_owner?.ClearSelected();
}
public void Add(int index)
{
if (_owner is not null)
{
ObjectCollection items = _owner.Items;
if (items is not null)
{
if (index != -1 && !Contains(index))
{
_owner.SetSelected(index, true);
}
}
}
}
public void Remove(int index)
{
if (_owner is not null)
{
ObjectCollection items = _owner.Items;
if (items is not null)
{
if (index != -1 && Contains(index))
{
_owner.SetSelected(index, false);
}
}
}
}
public IEnumerator GetEnumerator()
{
return new SelectedIndexEnumerator(this);
}
}
}
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