在BackgroundWorker运行时显示模态窗口，而不会出现STA / MTA问题
我正在研究WPF应用程序。 我有一个耗时的方法，我想通过BackgroundWorker运行异步。 当该方法运行时，我想显示一个模态“Please Wait …”对话框窗口，该窗口必须在BackgroundWorker完成时自动关闭。
我目前对BackgroundWorker或任何multithreading编程的经验很少。
下面的代码当前导致InvalidOperationException ，消息“调用线程必须是STA，因为许多UI组件需要这个”。
请告诉我如何实现我想要实现的目标，以及额外的布朗尼点，如果你能帮我理解出了什么问题。
非常感谢！
编辑只是澄清 – 想法是主线程启动BackgroundWorker ，然后显示modal dialog。 当工人完成时，它会关闭modal dialog。 当模式对话框关闭时，主线程继续。
public class ImageResizer { private BackgroundWorker worker; private MemoryStream ImageData { get; set; } // incoming data private public MemoryStream ResizedImageData { get; private set; } // resulting data private Dialogs.WorkInProgressDialog ProgressDialog; // Public interface, called by using class: public MemoryStream ReduceImageSize(MemoryStream imageData) { // injected data: this.ImageData = imageData; // init progress dialog window: ProgressDialog = new Dialogs.WorkInProgressDialog(); // Start background worker that asyncronously does work worker = new BackgroundWorker(); worker.DoWork += new DoWorkEventHandler(worker_DoWork); worker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(worker_RunWorkerCompleted); worker.RunWorkerAsync(); // Show progress dialog. Dialog is MODAL, and must only be closed when resizing is complete ProgressDialog.ShowDialog(); // THIS LINE CAUSES THE INVALID OPERATION EXCEPTION // This thread will only continue when ProgressDialog is closed. // Return result return ResizedImageData; } private void worker_DoWork(object sender, DoWorkEventArgs e) { // Call time consuming method ResizedImageData = ReduceImageSize_ActualWork(); } // The actual work method, called by worker_DoWork private MemoryStream ReduceImageSize_ActualWork() { // Lots of code that resizes this.ImageData and assigns it to this.ResizedImageData } private void worker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e) { // Async work completed - close progress dialog ProgressDialog.Close(); } }
您无法从BackgroundWorker调用ShowDialog。 您必须使用Dispatcher来请求UI线程执行它：
this.Dispatcher.BeginInvoke(new Action(() => ProgressDialog.ShowDialog()));
BackgroundWorker的“Completed”事件在UI线程中执行，因此这部分应该没问题。