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;
}

}
}