var files = System.IO.Directory.EnumerateFiles(desPath);
            if(formatStr.Length == 0) {
                formatStr = "{0}.jpg";
            }
            int count = 1;
            foreach(String fileName in files) {
                if (new System.IO.FileInfo(fileName).Length > 1024 * 75) {
                    System.IO.File.Move(fileName, System.IO.Path.Combine(desPath, String.Format(formatStr, count)));//对文件进行重命名
                    count++;
                }
            }

        bool IsWindows10() {
            var reg = Registry.LocalMachine.OpenSubKey(@"SOFTWARE\Microsoft\Windows NT\CurrentVersion");
            string productName = (string)reg.GetValue("ProductName");
            return productName.StartsWith("Windows 10");
        }

        String GetDesktopDirectory() {
            return Environment.GetFolderPath(Environment.SpecialFolder.Desktop);
        }

        void NewDirectory(String path) {
            if(!System.IO.Directory.Exists(path)) {
                System.IO.Directory.CreateDirectory(path);
            }
        }

        String GetBase64String() {
            return Convert.ToBase64String(System.Text.Encoding.Default.GetBytes(DateTime.Now.ToString()));
        }

        public String GetWallPaperDirectory() {
            String desPath = "";
            String doc = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);
            doc = doc.Substring(0, doc.LastIndexOf("\\"));
            String desTemp = System.IO.Path.Combine(doc, "AppData\\Local\\Packages");
            var files = System.IO.Directory.EnumerateDirectories(desTemp);
            foreach(String t in files) {
                if(t.Contains("Microsoft.Windows.ContentDeliveryManager")) {
                    desPath = t;
                    break;
                }
            }
            if(desPath.Length > 0) {
                desPath = System.IO.Path.Combine(desPath, "LocalState\\Assets");
                return desPath;
            }
            return "";
        }

System.IO.File.Copy(fileName, System.IO.Path.Combine(newPath, String.Format(formatStr, count)));