WPF中使用Free解决访问非UI线程创建的对象抛出的Thread异常

using System;using System.Collections.Generic;using System.Linq;using System.Text;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.Threading;using System.Windows.Threading;namespace WpfMultiThread{    /// <summary>    /// MainWindow.xaml 的交互逻辑    /// </summary>    public partial class MainWindow : Window    {        class WasImage        {            public BitmapSource bmp = null;        }        public MainWindow()        {            InitializeComponent();        }        private double BoodWidth = 0;        private void Window_Loaded(object sender, RoutedEventArgs e)        {            BoodWidth = m_rectBood.Width;        }        private double counter = 1;        private delegate void NormalDelegate();        private WasImage Cal()        {            WasImage wasImg = new WasImage();            wasImg.bmp = new BitmapImage(new Uri(System.Environment.CurrentDirectory + "\\zz.jpg"));            wasImg.bmp.Freeze();//如果没有此步则在UI线程中调用会失败            return wasImg;        }        private void UpdateUI()        {            m_rectBood.Width = counter * BoodWidth;            //m_tblCounter.Text = counter.ToString();        }        private void m_btnStart_Click(object sender, RoutedEventArgs e)        {            //异步任务封装在一个delegate中, 此delegate将运行在后台线程             Func<WasImage> asyncAction = this.Cal;            //在UI线程中得到异步任务的返回值，并更新UI            //必须在UI线程中执行             Action<IAsyncResult> resultHandler = delegate(IAsyncResult asyncResult)            {                    WasImage wasImage = asyncAction.EndInvoke(asyncResult);                            m_imgtest.Source = wasImage.bmp;            };            //异步任务执行完毕后的callback, 此callback运行在后台线程上.             //此callback会异步调用resultHandler来处理异步任务的返回值.            AsyncCallback asyncActionCallback = delegate(IAsyncResult asyncResult)            {                this.Dispatcher.BeginInvoke(DispatcherPriority.Background, resultHandler, asyncResult);            };            //在UI线程中开始异步任务,             //asyncAction(后台线程), asyncActionCallback(后台线程)和resultHandler(UI线程)            //将被依次执行            asyncAction.BeginInvoke(asyncActionCallback, null);            //NormalDelegate calDele = new NormalDelegate(Cal);            //calDele.BeginInvoke(null, null);           }        private void m_btnInvoke_Click(object sender, RoutedEventArgs e)        {            //m_imgtest.Source = (this.Tag as WasImage).bmp;        }    }}