Limit number of displayed items in WPF ListView

Question

So I have a ListView control backed by an ObservableCollection<> which periodically gets items added to it. However I would only like to display at most the first 10 items; ie if there are at most 10 items it displays them all, while resizing accordingly, and if there are more than 10 it stops displaying them at the 10th item.

I was wondering if there was a reasonable way to do this as my current intuition is to have a second collection which mirrors the top 10 items of the ItemsSource, updating accordingly.

Answer 1

You could do something like this (i haven't tested it, but you may get the idea):

_defaultView = CollectionViewSource.GetDefaultView(YourCollection);
_defaultView.SortDescriptions.Add(new System.ComponentModel.SortDescription(".", System.ComponentModel.ListSortDirection.Ascending));
_defaultView.Filter = o =>
{
    int index = YourCollection.OrderBy(s => s).ToList().IndexOf(o as string);
    return index >= 0 && index < 10;
};
_defaultView.Refresh();

Answer 2

I prefer using a converter for this rather than adding new model value or other extra collections as that often interferes with the change tracking.

The following filter sets the list to a fixed size of 10:

<ItemsControl ItemsSource="{Binding Configuration.RecentDocuments,Converter={StaticResource ItemSourceCountFilterConverter},ConverterParameter=10}" 

This converter basically takes the original IEnumerable and filters it down to the desired count of items and returns it:

public  class ItemSourceCountFilterConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        var val = value as IEnumerable;
        if (val == null)
            return value;

        int take = 10;
        if (parameter != null)
            int.TryParse(parameter as string, out take);


        if (take < 1)
            return value;
        var list = new List<object>();

        int count = 0;
        foreach (var li in val)
        {
            count++;
            if(count > take)
                break;
            list.Add(li);
        }
        return list;
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}