Silverlight searcher

I'm trying to do something similar to a searcher in Windows Phone 7, and what I've done is the following, I've got a TextBox with a TextChanged event and a Listbox of HyperlinkButtons. What I try it's this:

private void searchFriend_TextChanged(object sender, Tex开发者_开发技巧tChangedEventArgs e)
{
  int index = 0;
  foreach (Person person in lbFriends.Items)
  {
    ListBoxItem lbi = lbFriends.ItemContainerGenerator.ContainerFromItem(index) as ListBoxItem;
    lbi.Visibility = Visibility.Visible;

    if (!person.fullName.Contains((sender as TextBox).Text))
    {
      lbi.Background = new SolidColorBrush(Colors.Black);
    }
    index++;
  }
}

And here is the xaml:

<TextBox x:Name="searchFriend" TextChanged="searchFriend_TextChanged" />
<ListBox x:Name="lbFriends" Height="535" Margin="0,0,0,20">
  <ListBox.ItemTemplate>
    <DataTemplate>
      <StackPanel>
        <HyperlinkButton x:Name="{Binding id}" Content="{Binding fullName}" FontSize="24" Click="NavigateToFriend_Click" />
      </StackPanel>
    </DataTemplate>
  </ListBox.ItemTemplate>
</ListBox>

The problem here is when I've 68 or more elements, the ContainerFromItem just returns null ListBoxItems...

Any idea?

Thank you all

---

if the point is to filter the elements in the listbox then use a CollectionViewSource :

System.Windows.Data.CollectionViewSource cvs;
private void SetSource(IEnumerable<string> source)
{
     cvs = new System.Windows.Data.CollectionViewSource();
     cvs.Source=source;
     listBox1.ItemsSource = cvs.View;
}
private void TextBox_TextChanged(object sender, TextChangedEventArgs e)
{
     var box = (TextBox)sender;
     if (!string.IsNullOrEmpty(box.Text))
        cvs.View.Filter = o => ((string)o).Contains(box.Text);
     else
        cvs.View.Filter = null;
}

the problem using ItemContainer is that they are created only when the item has to be shown, that's why you have a null value.

---

Why don't you use Color Data Binding? It should be a simpler way.

<HyperlinkButton x:Name="{Binding id}" Content="{Binding fullName}" Background="{Binding BackgroundColor}" FontSize="24"    Click="NavigateToFriend_Click" />


private SolidColorBrush _backgroundColor;

public SolidColorBrush BackgroundColor{
    get {

        return _backgroundColor;
    }
    set { _backgroundColor= value; }
}

private void searchFriend_TextChanged(object sender, TextChangedEventArgs e)
{
 int index = 0;
 foreach (Person person in lbFriends.Items)
 {
   if (!person.fullName.Contains((sender as TextBox).Text))
   {
     person.BackgroundColor= new SolidColorBrush(Colors.Black);
   }
   index++;
  }
 }