从后台工作程序或事件更新GUI [英] Update GUI from background worker or event

问题描述

我想了解如何定期用简单的文本字符串更新GUI. 本质上，我正在编写一个twitter应用程序，该应用程序定期轮询twitter以获取更新.我希望将更新的内容显示在一个文本块中，在一个恒定的循环中一个接一个地显示.

I want to understand how I can update my GUI with a simple text string on a regular basis. Essentially, I'm writing a twitter application which regularly polls twitter for updates. I want the contents of the update to be shown in a text block, one by one on a constant loop.

为了保持GUI的响应速度，我需要在后台工作线程中执行查询，但是无法从该线程更新GUI.作为一名学习者，我正在努力实现一种通过使用事件来更新GUI的方法.

In order to keep the GUI responsive I need to perform the query in a background worker thread, however updating the GUI from this thread is not possible. As a learner, I'm struggling implement a way of updating the GUI by using events.

在下面的代码中，我很欣赏'MainWindowGoUpdate'将位于'错误的线程'上，但是如何获取GUI线程来监听事件呢?

In my code below, I appreciated 'MainWindowGoUpdate' is going to be on the 'wrong thread' but how can I get the GUI thread to listen for the event?

赞赏指针.

public partial class MainWindow : Window
{
  public MainWindow()
  {
    public static event UpdateTimeLineEvent _goUpdate;

    public static string TheTimeLine;
    UpdateTimeLine();
  }

  private void UpdateTimeLine()
  {        
   txtb_timeline.Text = "Updating...";

   BackgroundWorker startTimelineUpdater = new BackgroundWorker();
   startTimelineUpdater.DoWork += new DoWorkEventHandler(startTimelineUpdater_DoWork);
   startTimelineUpdater.RunWorkerCompleted += new RunWorkerCompletedEventHandler(startTimelineUpdater_RunWorkerCompleted);
   startTimelineUpdater.RunWorkerAsync();        
  }

  void startTimelineUpdater_DoWork(object sender, DoWorkEventArgs e)
  {
    while (true)
    {
      Xtweet getSQL = new Xtweet();
      var sqlset = getSQL.CollectLocalTimelineSql();

      int i = 0;
      while (i < 10)
      {
        foreach (var stringse in sqlset)
        {
          StringBuilder sb = new StringBuilder();

          sb.Append(stringse[0] + ": ");
          sb.Append(stringse[1] + " @ ");
          sb.Append(stringse[2]);

          sb.Append("\n");

          TheTimeLine = sb.ToString();

          _goUpdate += new UpdateTimeLineEvent(MainWindowGoUpdate);
          _goUpdate.Invoke();

          Thread.Sleep(10000);
          i++;
        } 
      } 
    }        
  }
  void MainWindowGoUpdate()
  {
    txtb_timeline.Text = TheTimeLine;
  }
  void startTimelineUpdater_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
  {
    txtb_timeline.Text = "should not see this";
  }  
 }

推荐答案

我将尝试以下更改:
在您的UpdateTimeLine中添加

I will try these change:
In your UpdateTimeLine add

 startTimelineUpdater.WorkerReportsProgress = true;
 startTimelineUpdater.ProgressChanged += new ProgressChangedEventHandler
                                      (startTimelineUpdater_ProgressChanged);

在startTimelineUpdater_DoWork中删除这些行

In startTimelineUpdater_DoWork remove these lines

TheTimeLine = sb.ToString();  
_goUpdate += new UpdateTimeLineEvent(MainWindowGoUpdate);  
_goUpdate.Invoke();  

并插入以下内容:

BackgroundWorker bkgwk = sender as BackgroundWorker;
bkgwk.ReportProgress(0, sb.ToString());

最后添加进度事件

private void startTimelineUpdater_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
   txtb_timeline.Text = e.ObjectState.ToString();
}

现在，您只能保留对UpdateTimeLine的调用，并删除MainWindowGoUpdate方法

Now you can leave only the call to UpdateTimeLine and remove the MainWindowGoUpdate method

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