首先寫一個類用於隨機返回資料夾中的圖片全路徑

internal  class GetImageClass
    {
        public static string GetFilesWithRandom(DirectoryInfo dir)
        {
            FileSystemInfo[] fileinfo = dir.GetFileSystemInfos(); //初始化一個FileSystemInfo型別的例項

            Random random = new Random();   //生成隨機數

            int dirNum = random.Next(0
 
, fileinfo.Length - 1);

            if (fileinfo[dirNum] is DirectoryInfo)
            {
                GetFilesWithRandom(fileinfo[dirNum] as DirectoryInfo);   //如果選到了子資料夾，則進行遞迴查詢
            }
            else
            {
                if(fileinfo[dirNum].FullName.Substring(fileinfo[dirNum].FullName.Length-3
 
).ToLower()=="jap")
                {
                    if(fileinfo.Length==1)
                    {
                        return null;
                    }
                    GetFilesWithRandom(dir);
                }
                return fileinfo[dirNum].FullName;
            }
            
 
return null;
        }
    }

定義一個類，讓它繼承DependencyObject類，用來儲存返回的圖片路徑

public class FIleData:DependencyObject
    {

        public string MyProperty
        {
            get { return (string)GetValue(MyPropertyProperty); }
            set { SetValue(MyPropertyProperty, value); }
        }

        // Using a DependencyProperty as the backing store for MyProperty.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty MyPropertyProperty =
            DependencyProperty.Register("MyProperty", typeof(string), typeof(FIleData));
    }

該窗體的後臺程式碼，其中DispatcherTimer 類用於每過一秒改變依賴屬性MyProperty的值，來達到自動切換圖片的功能

public partial class MainWindow : Window
    {
        private DispatcherTimer timer;
        FIleData fIleData = new FIleData();
        public MainWindow()
        {
            InitializeComponent();
            
            this.DataContext= fIleData;   //設定該窗體的上下文
            initRect();
        }

        private void initRect()
        {
            double x1 = SystemParameters.PrimaryScreenWidth;//得到螢幕整體寬度

            double y1 = SystemParameters.PrimaryScreenHeight;//得到螢幕整體高度

            this.Width = x1;

            this.Height = y1;

            this.WindowStartupLocation =WindowStartupLocation.CenterScreen;

            timer = new DispatcherTimer();
            timer.Interval = TimeSpan.FromSeconds(1);
            timer.Tick += timer1_Tick;
            timer.Start();
        }

        private void timer1_Tick(object sender, EventArgs e)
        {
            //（你的定時處理）

            DirectoryInfo dir = new DirectoryInfo("C:\\Users\\zm962\\Pictures\\新建資料夾");
            fIleData.MyProperty = GetImageClass.GetFilesWithRandom(dir);
        }
    }

最後在前臺繫結依賴屬性MyProperty即可，每過一秒，會隨機返回一個新的路徑，介面也隨之切換