WPF设置图片Source时不占用图片的方法

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Controls;
using System.Windows.Media.Imaging;
using System.IO;
using System.Windows.Media;

namespace MyApp
{
    public class ImageSourceHelper
    {
        /// <summary>
        /// 获取图片的Source
        /// </summary>
        /// <param name="FilePath">图片地址</param>
        /// <returns></returns>
        public static BitmapSource GetSource(string FilePath)
        {
            try
            {
                if (!File.Exists(FilePath))
                {
                    BitmapImage bmp = new BitmapImage();
                    bmp.BeginInit();
                    bmp.UriSource = new Uri(@"pack://application:,,,/images/nothingfound.png");
                    bmp.EndInit();
                    return bmp as BitmapSource;
                }