UI 在大量计算时冻结

Question

我正在将巨大的文件加载到内存中，但在此计算中我的应用程序冻结了。

知道我的代码有什么问题吗？

public void Drop(DragEventArgs args)
{
  BackgroundWorker worker = new BackgroundWorker();
  string fileName = IsSingleTextFile(args);
  if (fileName == null) return;
  worker.DoWork += (o, ea) =>
  {
    try
    {
      StreamReader fileToLoad = new StreamReader(fileName);
      string filecontent = fileToLoad.ReadToEnd();
      fileToLoad.Close();
      // providing the information to the UI thread

      Application.Current.Dispatcher.BeginInvoke(DispatcherPriority.Background,
        new Action(() => SfmLogFile = filecontent));
    }
    catch (Exception)
    {
      throw;
    }
  };

  worker.RunWorkerCompleted += (o, ea) =>
  {
    args.Handled = true;
    IsBusy = false;
  };

  // Mark the event as handled, so TextBox's native Drop handler is not called.

  IsBusy = true;
  worker.RunWorkerAsync();

}

Answer 1

我会将您的示例转换为如下所示：

public void Drop(DragEventArgs args)
{
  string fileName = IsSingleTextFile(args);
  if (fileName == null) return;
  // It is better to create worker after check for file name.
  BackgroundWorker worker = new BackgroundWorker();
  worker.DoWork += (o, ea) =>
  {
    try
    {
      string filecontent = ReadAllText(fileName);    
      ea.Result = fileContent;
    }
    catch (Exception)
    {
      throw;
    }
  };

  worker.RunWorkerCompleted += (o, ea) =>
  {
    var fileContent = ea.Result as string;
    Application.Current.Dispatcher.BeginInvoke(DispatcherPriority.Background,
        new Action(() => SfmLogFile = filecontent));

    // if IsBusy propery is not on the UI thread, then you may leave it here
    // otherwise it should be set using the dispatcher too.
    IsBusy = false;
  };

  IsBusy = true;
  worker.RunWorkerAsync();
  // Mark the event as handled, so TextBox's native Drop handler is not called.    
  args.Handled = true;
}

Answer 2

我不确定这是否是问题的原因，但您正在后台工作人员的回调中设置 args.Handled ，因此它将在 drop 事件处理程序返回后被调用。它不会达到预期的效果，因为设置得太晚，并且可能会扰乱事件处理中的某些内容。