WPF: Data Virtualization

using System;
using System.Collections.Generic;
using System.Windows;
using System.Windows.Threading;

namespace DataVirtualization
{
    /// <summary>
    /// Interaction logic for DemoWindow.xaml
    /// </summary>
    public partial class DemoWindow
    {
        /// <summary>
        /// Initializes a new instance of the <see cref="DemoWindow"/> class.
        /// </summary>
        public DemoWindow()
        {
            InitializeComponent();
            
            // use a timer to periodically update the memory usage
            DispatcherTimer timer = new DispatcherTimer();
            timer.Interval = new TimeSpan(0, 0, 1);
            timer.Tick += timer_Tick;
            timer.Start();
        }

        private void timer_Tick(object sender, EventArgs e)
        {
            tbMemory.Text = string.Format("{0:0.00} MB", GC.GetTotalMemory(true)/1024.0/1024.0);
        }

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            // create the demo items provider according to specified parameters
            int numItems = int.Parse(tbNumItems.Text);
            int fetchDelay = int.Parse(tbFetchDelay.Text);
            DemoCustomerProvider customerProvider = new DemoCustomerProvider(numItems, fetchDelay);

            // create the collection according to specified parameters
            int pageSize = int.Parse(tbPageSize.Text);
            int pageTimeout = int.Parse(tbPageTimeout.Text);

            if ( rbNormal.IsChecked.Value )
            {
                DataContext = new List<Customer>(customerProvider.FetchRange(0, customerProvider.FetchCount()));
            }
            else if ( rbVirtualizing.IsChecked.Value )
            {
                DataContext = new VirtualizingCollection<Customer>(customerProvider, pageSize);
            }
            else if ( rbAsync.IsChecked.Value )
            {
                DataContext = new AsyncVirtualizingCollection<Customer>(customerProvider, pageSize, pageTimeout*1000);
            }
        }
    }
}