WPF 视图导航

<Window x:Class="ViewExam.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525" Loaded="Window_Loaded_1">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition></RowDefinition>
            <RowDefinition Height="Auto"></RowDefinition>
        </Grid.RowDefinitions>
        <Grid Grid.Row="0">
            <Grid.RowDefinitions>
                <RowDefinition Height="Auto"></RowDefinition>
                <RowDefinition Height="Auto"></RowDefinition>
                <RowDefinition Height="Auto"></RowDefinition>
                <RowDefinition Height="Auto"></RowDefinition>             
                <RowDefinition Height="*"></RowDefinition>
            </Grid.RowDefinitions>
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="Auto"></ColumnDefinition>
                <ColumnDefinition></ColumnDefinition>
            </Grid.ColumnDefinitions>
            <TextBlock>Model Number</TextBlock>
            <TextBox Text="{Binding Path=ModelNumber}" Grid.Column="1"></TextBox>
            <TextBlock Grid.Row="1">Model Name</TextBlock>
            <TextBox Text="{Binding Path=ModelName}" Grid.Column="1" Grid.Row="1"></TextBox>
            <TextBlock Grid.Row="2">Unit Cost</TextBlock>
            <TextBox Text="{Binding Path=UnitCost}" Grid.Column="1" Grid.Row="2"></TextBox>
            <TextBlock Grid.Row="3">Description</TextBlock>
            <TextBox Text="{Binding Path=Description}" TextWrapping="Wrap"  Grid.Row="5" Grid.ColumnSpan="2"></TextBox>
        </Grid>
        <StackPanel Grid.Row="1" Orientation="Horizontal">
            <Button Name="btnPrevious" Click="btnPrevious_Click_1">previous</Button>
            <Label x:Name="lblPosition" Width="400"></Label>
            <Button Name="btnNext" Click="btnNext_Click_1">Next</Button>
        </StackPanel>
    </Grid>
</Window>

using DBAccess;

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace ViewExam
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }

        private ListCollectionView view;

        private void Window_Loaded_1(object sender, RoutedEventArgs e)
        {
            ICollection<Product> products = StoreDB.GetProducts();
            this.DataContext = products;
            view = (ListCollectionView)CollectionViewSource.GetDefaultView(products);

            view.CurrentChanged += view_CurrentChanged;
            view_CurrentChanged(this, null);
            
        }

        void view_CurrentChanged(object sender, EventArgs e)
        {
            lblPosition.Content = "Record " + (view.CurrentPosition + 1).ToString() + " of " + view.Count.ToString();
            btnPrevious.IsEnabled = view.CurrentPosition > 0;
            btnNext.IsEnabled = view.CurrentPosition < view.Count - 1;
        }

        private void btnPrevious_Click_1(object sender, RoutedEventArgs e)
        {
            view.MoveCurrentToPrevious();
        }

        private void btnNext_Click_1(object sender, RoutedEventArgs e)
        {
            view.MoveCurrentToNext();
        }
    }
}