使用BackgroundWorker更新GUI中的两个(单个操作/总操作)进度条

Question

好吧，我一整天都在为此头疼。我对编程还相当陌生，很可能我在这里的整个方法都被误导了。但无论如何。。。所以我有一个简单的gui应用程序，它有一个装满文件夹的列表框，我正在依次对每个文件夹中的每个文件执行操作。这是一个非常长的操作，所以我有两个进度条——每个文件一个，每个文件夹一个。

private void buttonApplySelected_Click(object sender, EventArgs e)
{
    backgroundWorker1.RunWorkerAsync();
}
private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
     double percentToIncrement = 100.0 / Convert.ToDouble(selectedDirList.Count);
     double percentComplete = percentToIncrement;
     folderProgressBar.Value = 0;
     foreach (string dir in selectedDirList)
     {
             engine = new OEngine.OEngine(dir, backgroundWorker1);
             engine.ProcessSelected(processType);
             int percentCompleteInt = Convert.ToInt32(percentComplete);
             folderProgressBar.Value = percentCompleteInt;
             percentComplete += percentToIncrement;
     }         
}
private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
     fileProgressBar.Value = e.ProgressPercentage;
}

BackgroundWorker本身被传递给引擎，它在引擎处理该文件夹的代码中更新进度。（这可能是我的第一个错误。）UI捕获ProgressChanged事件，并在自己的线程中更新fileProgressBar。

但是folderProgressBar需要在每次通过for循环时更新一次，但它给了我Cross-thread operation not valid: Control 'folderProgressBar' accessed from a thread other than the thread it was created on.

如果我把它移出for循环，它不会在每个文件夹后更新。如果我将所有的UI更新从DoWork函数中移出，并在for循环中调用DoWork函数，它显然不会等待每个文件夹完成，我会得到"工作人员仍然很忙"的异常。

有什么想法吗？

Answer 1

windows窗体的通用解决方案：使用

WindowsFormsSynchronizationContext syncContext = new WindowsFormsSynchronizationContext();

//in the background work or any non UI Thread
//Trigger an update in the GUI thread; one can also use syncContext.Send (depending on the need for syncrhonous or async operation)
syncContext.Post(UpdateGUI, userData);
...
void UpdateGUI(object userData)
{
  //update your progress bar 
}

If using wpf, declare a variable syncContex.

SynchronizationContext syncContext;
//And when in the UI thread, set the variable's value as
syncContext = SynchronizationContext.Current;
//Then from the non-UI thread, 
syncContext.Post(UpdateGUI, userData);