Silverlight的跨線程UI更新問題

Question

我有這個類：

public class UploadFile : INotifyPropertyChanged { 
    private string name; 
    public string Name { 
     get { 
      return name; 
     } 
     set { 
      name = value; 
      OnPropertyChanged("Name"); 
     } 
    } 

    private FileInfo fileInfo; 
    public FileInfo FileInfo { get; set; } 

    private string length; 
    public string Length { 
     get { 
      return length; 
     } 
     set { 
      length = value; 
      OnPropertyChanged("Length"); 
     } 
    } 

    private int percentage; 
    public int Percentage { 
     get { 
      return percentage; 
     } 
     set { 
      percentage = value; 
      OnPropertyChanged("Percentage"); 
     } 
    } 

    public string ProgressValue { 
     get { return string.Format("{0}%", Percentage); } 
    } 

    private string imageSource; 
    public string ImageSource { 
     get { 
      return imageSource; 
     } 
     set { 
      imageSource = value; 
      OnPropertyChanged("ImageSource"); 
     } 
    } 


    #region INotifyPropertyChanged Members 

    public event PropertyChangedEventHandler PropertyChanged; 

    #endregion 

    private void OnPropertyChanged(string property) { 
     if (PropertyChanged != null) { 
      PropertyChanged(this, new PropertyChangedEventArgs(property)); 
     } 
    } 
} 

我試圖創建一個文件的上傳是能夠大和多文件上傳。我正在使用Web服務來做這件事。我已經在我的用戶界面中進行了雙向綁定，現在我想要上傳文件。我使用此代碼

private void DoUpload() { 
     foreach (UploadFile file in fileInfos){ 
      int BUFFERSIZE = 1024; 
      int offset = 0; //get from webservice, when partial file 
      FileStream s = file.FileInfo.OpenRead(); 
      byte[] buffer = null; 
      long remainingBytes = s.Length - offset; 
      while (remainingBytes > 0) { 
       if (remainingBytes < BUFFERSIZE) { 
        buffer = new byte[remainingBytes]; 
        BUFFERSIZE = (int)remainingBytes; 
       } 
       else if (remainingBytes > BUFFERSIZE) { 
        buffer = new byte[BUFFERSIZE]; 
       } 

       s.Read(buffer, 0, BUFFERSIZE); 
       //push to webservice 
       Thread.Sleep(20); 
       //UploadService.Service1SoapClient client = new MultiLargeFileUpload.UploadService.Service1SoapClient(); 
       //client.LargeUploadCompleted +=new EventHandler<AsyncCompletedEventArgs>(client_LargeUploadCompleted); 
       //client.LargeUploadAsync(1, buffer, file.Name); 
       offset += BUFFERSIZE; 
       int newPercentage = offset/(int)file.FileInfo.Length * 100; 
       file.Percentage = newPercentage; 
       remainingBytes = s.Length - offset;      
      } 
      //file.Percentage = 100; 
      //file.ImageSource = "accept.png"; 
     } 
    } 

的問題是，我不能更新UI，或橫紗操作這樣做。我試圖使用Dispatcher，但是我沒有成功，因爲我不知道在哪裏插入它。

Answer 1

我猜你想要做你的UI的更新中

  file.Percentage = newPercentage; 
      remainingBytes = s.Length - offset; 

你必須在一個委託來包裝這一點，並做了Dispatcher.BeginInvoke這個從另一個更新UI螺紋：

Dispatcher.BeginInvoke(()=>{ 
    file.Percentage=newPercentage; 
    remainingBytes = s.Length - offset; 
}); 

這樣你將消息發送到主線程的消息隊列，主線程可以執行委託時，他有時間。