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using System;
using System.Windows;
using System.Windows.Controls;
using System.Collections;
namespace SDKSample
{
//<SnippetSingletonPanel>
public class SingletonPanel : StackPanel
{
//private UIElementCollection _children;
private FrameworkElement _child;
public SingletonPanel() {
}
public FrameworkElement SingleChild
{
get { return _child;}
set
{
if (value==null) {
RemoveLogicalChild(_child);
} else {
if (_child==null) {
_child = value;
} else {
// raise an exception?
MessageBox.Show("Needs to be a single element");
}
}
}
}
public void SetSingleChild(object child)
{
this.AddLogicalChild(child);
}
public new void AddLogicalChild(object child)
{
_child = (FrameworkElement)child;
if (this.Children.Count == 1)
{
this.RemoveLogicalChild(this.Children[0]);
this.Children.Add((UIElement)child);
}
else
{
this.Children.Add((UIElement)child);
}
}
public new void RemoveLogicalChild(object child)
{
_child = null;
this.Children.Clear();
}
protected override IEnumerator LogicalChildren
{
get {
// cheat, make a list with one member and return the enumerator
ArrayList _list = new ArrayList();
_list.Add(_child);
return (IEnumerator) _list.GetEnumerator();}
}
}
//</SnippetSingletonPanel>
}