如何將圖像異步加載到列表框中？

Question

使用此代碼，使用必須等到所有圖像加載完畢。我想要將這些圖像異步加載到列表框中，以便用戶不必等待。我怎麼做？

public photos() 
    { 
     InitializeComponent(); 
     refreshView(); 
    } 

    private void refreshView() 
    { 
     string[] fileNames = storage.GetFileNames(); 
     for (int i = 0; i < fileNames.Length; i++) 
     { 
      image = new Image(); 
      FileStream jpegStream = storage.OpenFile(fileNames[i], FileMode.Open, FileAccess.Read); 
      image.Source = PictureDecoder.DecodeJpeg(jpegStream, 200, 200); 
      jpegStream.Dispose(); 
      photoList.Items.Add(image); 
     } 
    } 

Answer 1

你可以使用一個BackgroundWorker。

BackgroundWorker bw = new BackgroundWorker(); 
bw.DoWork += (o, args) => 
    { 
     //now you have a choice: get all images and add when all are retrieved, 
     //or get images asynchronously here too... 
     //probably best to do the latter: 

     string[] fileNames = storage.GetFileNames(); 
     Parallell.ForEach(fileNames, file => 
     { 
      Image image = new Image(); 
      using(FileStream jpegStream = storage.OpenFile(fileNames[i], FileMode.Open, FileAccess.Read)) 
      { 
       image.Source = PictureDecoder.DecodeJpeg(jpegStream, 200, 200); 
      } 
      Dispatcher.BeginInvoke(() => photoList.Items.Add(image)); 
     } 
    }; 
bw.RunWorkerAsync();