How to get Items count from CollectionViewSource?

I am using CollectionViewSource to filter the records displayed in a ListBox. The xaml follows.

   <Window x:Class="WPFStarter.ListBoxItemsFilter.ListBoxFilterUsingCollectionViewSource"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        x:Name="userControl"
        Title="ListBoxFilterUsingCollectionViewSource" Height="300" Width="300">
        <Window.Resources>
        <CollectionViewSource Source="{Binding ElementName=userControl, Path=DataContext.Items}"
                              x:Key="cvs" Filter="CollectionViewSource_Filter"/>
        </Window.Resources>
    <StackPanel Orientation="Vertical">
        <TextBox x:Name="txtSearch" TextChanged="txtSearch_TextChanged"/>
        <TextBlock x:Name="txtSummary" Grid.Column="0" HorizontalAlignment="Right" VerticalAlignment="Bottom"  FontSize="8"></TextBlock>
        <ListBox ItemsSource="{Binding Source={StaticResource cvs}}" DisplayMemberPath="First"/>
    </StackPanel>

</Window>

And here is my code-behing ( please don;t mind this code-behind, in the real application i am using the best of MVVM for this scenario).

 public partial class ListBoxFilterUsingCollectionViewSource : Window
    {
        private string _text="";
        private readonly CollectionViewSource _viewSource;

        public ListBoxFilterUsingCollectionViewSource()
        {
            InitializeComponent();
            _viewSource = this.FindResource("cvs") as CollectionViewSource;
        }

        private void CollectionViewSource_Filter(object sender, FilterEventArgs e)
        {
            var character = e.Item as Ch开发者_如何学Pythonaracter;
            e.Accepted = character != null && character.First.ToLower().Contains(_text.ToLower());
        }

        private void txtSearch_TextChanged(object sender, TextChangedEventArgs e)
        {
            _text = txtSearch.Text;
            _viewSource.View.Refresh();

            SetSummary();
        }

        private void SetSummary()
        {                
            var initialCount = 10; //HELP????
            var filteredCount = 10; //HELP????
            txtSummary.Text = String.Format("{0} of {1}", filteredCount, initialCount);
        }
    }

QUESTION: I Need help in writing the "SetSummary" method, wherein i can get the "initialCount" and the "filteredCount" from CollectionViewSource object.

Thanks for your interest.

You could also do _viewSource.View.Cast<object>().Count() for the filtered list and _viewSource.View.SourceCollection.Cast<object>().Count() for the original.

I think the better solution is, as usual, Linq!

_viewSource.View.Cast<[your_type]>().Count();

...or...

_viewSource.View.Cast<object>().Count();

...if you don't know the items' type at runtime!

The source collection and collectionview both implements IEnumerable so you can always iterate over them and count how many are in them. But I would only recommend doing this if you have no access to the actual collection you used as source.

private void SetSummary() 
{
    int initialCount = 0;
    foreach(var item in _viewSource.View.SourceCollection)
    {
        initialCount++;
    }

    int filteredCount = 0;
    foreach (var item in _viewSource.View)
    {
        filteredCount++;
    }
}

If you're doing MVVM, you could have your VM create a collection view rather than one being created on your behalf by the CollectionViewSource. Then, you have control over what type of CVS is created, so you can create a ListCollectionViewSource, which has a Count property. It really depends on the properties of the data you're filtering.

var count = DataGrid.ItemsSource.OfType<object>().Count();

public static int Count(this ICollectionView view)
    {
        var index = 0;
        foreach (var unused in view)
        {
            index++;
        }
        return index;
    }