Page up / page down – select to item on previous / next page WPF C# listbox)

<Window
    x:Class="PagingVirtualListView.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

    Title="Paging Virtualized ListView"
    Height="300" Width="500" WindowStartupLocation="CenterScreen">

    <Grid>
        <Grid.ColumnDefinitions>
            <ColumnDefinition/>
            <ColumnDefinition Width="Auto"/>
        </Grid.ColumnDefinitions>

        <ListView x:Name="PeopleList" ItemsSource="{Binding Persons}" >
            <ListView.View>
                <GridView>
                    <GridViewColumn Header="Avatar" Width="100">
                        <GridViewColumn.CellTemplate>
                            <DataTemplate>
                                <Image Source="{Binding AvatarUrl}" Margin="10" />
                            </DataTemplate>
                        </GridViewColumn.CellTemplate>
                    </GridViewColumn>
                    <GridViewColumn Header="Name" Width="200" DisplayMemberBinding="{Binding Name}" />
                    <GridViewColumn Header="Age" Width="50" DisplayMemberBinding="{Binding Age}" />
                </GridView>
            </ListView.View>
        </ListView>

        <StackPanel Grid.Column="1" Margin="10" VerticalAlignment="Center">
            <Button Content="PGUP" Click="OnPgUpClick" Padding="10 5" Margin="10"/>
            <Button Content="PGDn" Click="OnPgDnClick" Padding="10 5" Margin="10"/>
        </StackPanel>
    </Grid>

</Window>

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
        PeopleList.Loaded += PeopleList_Loaded;

        DataContext = this;
        Mock();
    }

    ScrollViewer lvScrollViewer;

    public ObservableCollection<Person> Persons { get; set; }
        = new ObservableCollection<Person>();

    private Random rand = new Random();

    private void Mock()
    {
        for (int i = 0; i < 100000; i++)
        {
            Persons.Add(new Person
            {
                AvatarUrl = "http://www.freepngimg.com/download/happy_person/2-2-happy-person-free-download-png.png",
                Name = $"Person {i}",
                Age = rand.Next(20, 60)
            });
        }
    }

    private void PeopleList_Loaded(object sender, RoutedEventArgs e)
    {
        PeopleList.Loaded -= PeopleList_Loaded;

        // remember the ListView's Scrollviewer
        lvScrollViewer = PeopleList.GetVisualChild<ScrollViewer>();
    }

    private void OnPgUpClick(object sender, RoutedEventArgs e)
    {
        lvScrollViewer.ScrollToVerticalOffset(
            Math.Max(0, lvScrollViewer.VerticalOffset - lvScrollViewer.ViewportHeight));
    }
    private void OnPgDnClick(object sender, RoutedEventArgs e)
    {
        lvScrollViewer.ScrollToVerticalOffset(
            Math.Min(lvScrollViewer.VerticalOffset + lvScrollViewer.ViewportHeight, Persons.Count - 1));
    }
}

public static class HelperExtension
{
    public static T GetVisualChild<T>(this Visual referenceVisual) where T : Visual
    {
        Visual child = null;
        for (Int32 i = 0; i < VisualTreeHelper.GetChildrenCount(referenceVisual); i++)
        {
            child = VisualTreeHelper.GetChild(referenceVisual, i) as Visual;
            if (child != null && (child.GetType() == typeof(T)))
                break;
            else if (child != null)
            {
                child = GetVisualChild<T>(child);
                if (child != null && (child.GetType() == typeof(T)))
                    break;
            }
        }
        return child as T;
    }
}

public class Person
{
    public string AvatarUrl { get; set; }
    public string Name { get; set; }
    public int Age { get; set; }
}