private void btnChooseImage_Click(object sender, RoutedEventArgs e)
        {
            StringBuilder sb = new StringBuilder();
            OpenFileDialog op = new Microsoft.Win32.OpenFileDialog();
            op.RestoreDirectory = true;

            op.Multiselect = true;

            op.Filter = " 图片文件(*.jpg)|*.jpg";
            
            op.ShowDialog();
            
            sb.Append(op.FileName);
            if (!String.IsNullOrEmpty(sb.ToString()))
            {
                tbImage.Text += sb;
                //imgMain.Source = new BitmapImage(new Uri(op.FileName));
            }           
        }