WPF ListBox UserControl ShowPicture AutoScroll

//usercontrol
//xaml
<UserControl x:Class="WpfApp44.ImgTbk"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             xmlns:local="clr-namespace:WpfApp44"
             mc:Ignorable="d" 
             d:DesignHeight="450" d:DesignWidth="800">
    <UserControl.Resources>
        <local:SizeHalfConverter x:Key="sizeHalfConverter"/>
    </UserControl.Resources>
    <Border BorderBrush="Blue"
            BorderThickness="5"
            Width="{Binding ActualWidth,RelativeSource={RelativeSource Mode=FindAncestor,AncestorType={x:Type Window}}}"
            Height="{Binding ActualHeight,RelativeSource={RelativeSource Mode=FindAncestor,AncestorType={x:Type Window}}}">
        <Border.Background>
            <ImageBrush ImageSource="{Binding BgImgBrush,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}"
                        Stretch="Uniform"
                        RenderOptions.BitmapScalingMode="Fant"/>
        </Border.Background>
        <TextBlock FontSize="100" 
                   Text="{Binding TbkStr,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}"
                   Foreground="Red"
                   VerticalAlignment="Center"
                   HorizontalAlignment="Center"/>
    </Border>
</UserControl>



//cs
using System;
using System.Collections.Generic;
using System.Globalization;
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 WpfApp44
{
    /// <summary>
    /// Interaction logic for ImgTbk.xaml
    /// </summary>
    public partial class ImgTbk : UserControl
    {
        public ImgTbk()
        {
            InitializeComponent();
            this.DataContext = this;
        }



        public ImageSource BgImgBrush
        {
            get { return (ImageSource)GetValue(BgImgBrushProperty); }
            set { SetValue(BgImgBrushProperty, value); }
        }

        // Using a DependencyProperty as the backing store for BgImgBrush.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty BgImgBrushProperty =
            DependencyProperty.Register("BgImgBrush", typeof(ImageSource), 
                typeof(ImgTbk), new PropertyMetadata(null));




        public string TbkStr
        {
            get { return (string)GetValue(TbkStrProperty); }
            set { SetValue(TbkStrProperty, value); }
        }

        // Using a DependencyProperty as the backing store for TbkStr.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty TbkStrProperty =
            DependencyProperty.Register("TbkStr", typeof(string), 
                typeof(ImgTbk), new PropertyMetadata(""));



    }

    public class SizeHalfConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            double d = 0;
            if(double.TryParse(value?.ToString(),out d))
            {
                return d / 2;
            }
            return 0;
        }

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



//mainwindow.xaml
<Window x:Class="WpfApp44.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:behavior="http://schemas.microsoft.com/xaml/behaviors"
        WindowState="Maximized"
        xmlns:local="clr-namespace:WpfApp44"
        mc:Ignorable="d"
        Title="{Binding SelectedItem.Id,ElementName=lbx}"
        Height="450" Width="800">
    <behavior:Interaction.Triggers>
        <behavior:EventTrigger EventName="KeyDown">
            <behavior:InvokeCommandAction Command="{Binding KeyDownCommand}"
                                          PassEventArgsToCommand="True"/>
        </behavior:EventTrigger>
        <!--<behavior:EventTrigger EventName="KeyDown">
            <behavior:CallMethodAction MethodName="Window_KeyDown" TargetObject="{Binding}"/>
        </behavior:EventTrigger>-->
    </behavior:Interaction.Triggers>
    <Window.DataContext>
        <local:BookVM/>
    </Window.DataContext>
    <Grid>
        <ListBox x:Name="lbx" 
                 ItemsSource="{Binding BooksCollection,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}"
                 SelectedItem="{Binding SelectedBk,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}"
                 SelectedIndex="{Binding SelectedIdx,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}"
                 VirtualizingPanel.IsVirtualizing="True"
                 VirtualizingPanel.IsContainerVirtualizable="True"
                 VirtualizingPanel.VirtualizationMode="Recycling"
                 VirtualizingPanel.CacheLength="1"
                 VirtualizingPanel.CacheLengthUnit="Item">
            <behavior:Interaction.Behaviors>
                <local:LbxBehavior/>
            </behavior:Interaction.Behaviors>
            <behavior:Interaction.Triggers>
                <behavior:EventTrigger EventName="MouseEnter">
                    <behavior:InvokeCommandAction Command="{Binding ShowBigPictureCommand}"
                                                  PassEventArgsToCommand="True"/>
                </behavior:EventTrigger>
            </behavior:Interaction.Triggers>
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <local:ImgTbk BgImgBrush="{Binding DataContext.ImgSource,
                        RelativeSource={RelativeSource Mode=FindAncestor,AncestorType={x:Type ListBoxItem}}}"
                           TbkStr="{Binding DataContext.ISBN,RelativeSource={RelativeSource Mode=FindAncestor,
                        AncestorType={x:Type ListBoxItem}}}"/>                    
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>
    </Grid>
</Window>


//cs
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
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;
using System.IO;
using Microsoft.Xaml.Behaviors;
using System.Diagnostics;

namespace WpfApp44
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }
    }

    public class BookVM : INotifyPropertyChanged
    {
        public BookVM()
        {
            InitData();
            InitTimer();
            InitCommands();
        }

        private void InitCommands()
        {
            ShowBigPictureCommand = new DelCommand(ShowBigPictureCommandExecuted);
            KeyDownCommand = new DelCommand(KeyDownCommandExecuted);
        }

        private void KeyDownCommandExecuted(object obj)
        {
            var keyArgs = obj as KeyEventArgs;
            if (keyArgs != null && keyArgs.Key == Key.Space)
            {
                isPaused = !isPaused;
            }
        }

        private void ShowBigPictureCommandExecuted(object obj)
        {
            //if(!isPaused)
            //{
            //    return;
            //}

            var procs = Process.GetProcesses().Where(x => x.ProcessName.Contains("Photo"));
            if (procs!=null && procs.Any())
            {
                foreach(var pc in procs)
                {
                    pc.Kill();
                }
            }        

            if(proc==null)
            {
                proc = new Process();
            }
            
            proc.StartInfo = new ProcessStartInfo(SelectedBk.ImgUrl);
            proc.Start();
        }

        private void InitTimer()
        {
            System.Timers.Timer tmr = new System.Timers.Timer();
            tmr.Elapsed += Tmr_Elapsed;
            tmr.Interval = 1000;
            tmr.Start();
        }

        private void Tmr_Elapsed(object sender, System.Timers.ElapsedEventArgs e)
        {
            if(isPaused)
            {
                return;
            }
            if (++SelectedIdx >= imgsCount)
            {
                SelectedIdx = 0;
            }
        }

        private void InitData()
        {
            imgsList = new List<string>(System.IO.Directory.GetFiles(@"../../Images"));
            if (imgsList != null && imgsList.Any())
            {
                imgsCount = imgsList.Count;
                BooksCollection = new ObservableCollection<Book>();
                for (int i = 0; i < 1000; i++)
                {
                    BooksCollection.Add(new Book()
                    {
                        Id = i + 1,
                        ISBN = $"ISBN_{i + 1}",
                        ImgUrl = imgsList[i % imgsCount],
                        ImgSource = GetImgSourceFromUrl(imgsList[i % imgsCount])
                    });
                }
            }
        }

        private ImageSource GetImgSourceFromUrl(string imgUrl)
        {

            BitmapImage bmi = new BitmapImage();
            if (!File.Exists(imgUrl))
            {
                return bmi;
            }
            bmi.BeginInit();
            bmi.UriSource = new Uri(imgUrl, UriKind.RelativeOrAbsolute);
            bmi.CacheOption = BitmapCacheOption.OnLoad;
            bmi.EndInit();
            if (bmi.CanFreeze)
            {
                bmi.Freeze();
            }
            return bmi;
        }

        public event PropertyChangedEventHandler PropertyChanged;
        private void OnPropertyChanged(string propertyName)
        {
            var handler = PropertyChanged;
            if (handler != null)
            {
                handler?.Invoke(this, new PropertyChangedEventArgs(propertyName));
            }
        }

        private ObservableCollection<Book> booksCollection;
        public ObservableCollection<Book> BooksCollection
        {
            get
            {
                return booksCollection;
            }
            set
            {
                if (value != booksCollection)
                {
                    booksCollection = value;
                    OnPropertyChanged(nameof(BooksCollection));
                }
            }
        }

        private List<string> imgsList { get; set; }
        private int imgsCount { get; set; }
        private bool isPaused { get; set; }

        private Book selectedBk;
        public Book SelectedBk
        {
            get
            {
                return selectedBk;
            }
            set
            {
                if (value != selectedBk)
                {
                    selectedBk = value;
                    OnPropertyChanged(nameof(SelectedBk));
                }
            }
        }

        private int selectedIdx;
        public int SelectedIdx
        {
            get
            {
                return selectedIdx;
            }
            set
            {
                if (value != selectedIdx)
                {
                    selectedIdx = value;
                    OnPropertyChanged(nameof(SelectedIdx));
                }
            }
        }

        public DelCommand ShowBigPictureCommand { get; set; }

        private Process proc;
        public DelCommand KeyDownCommand { get; set; }
    }

    public class LbxBehavior : Behavior<ListBox>
    {
        protected override void OnAttached()
        {
            base.OnAttached();
            AssociatedObject.SelectionChanged += AssociatedObject_SelectionChanged;
        }

        private void AssociatedObject_SelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            var listBx = sender as ListBox;
            if (listBx != null && listBx.SelectedItem != null)
            {
                listBx.ScrollIntoView(listBx.SelectedItem);
            }
        }

        protected override void OnDetaching()
        {
            base.OnDetaching();
            AssociatedObject.SelectionChanged -= AssociatedObject_SelectionChanged;
        }
    }

    public class Book
    {
        public int Id { get; set; }

        public string ISBN { get; set; }

        public string ImgUrl { get; set; }

        public ImageSource ImgSource { get; set; }
    }

    public class DelCommand : ICommand
    {
        public event EventHandler CanExecuteChanged
        {
            add
            {
                CommandManager.RequerySuggested += value;
            }
            remove
            {
                CommandManager.RequerySuggested -= value;
            }
        }

        private Action<object> execute;
        private Predicate<object> canExecute;
        public DelCommand(Action<object> executeValue, Predicate<object> canExecuteValue = null)
        {
            execute = executeValue;
            canExecute = canExecuteValue;
        }

        public bool CanExecute(object parameter)
        {
            if (canExecute == null)
            {
                return true;
            }
            return canExecute(parameter);
        }

        public void Execute(object parameter)
        {
            execute(parameter);
        }
    }
}