c# - 在STA线程上显示忙碌指示器

Question

我要进行长时间的操作，希望显示“扩展工具包”的繁忙状态指示器。我之前对此发表过一篇文章，它是固定的Wpf Extended toolkit BusyIndicator not showing during operation。但是，在该调用期间，我必须与UI元素( Canvas )进行交互，并且得到一个“调用线程必须是STA，因为许多UI组件都需要STA”。我了解(现在)有后台工作人员(请参见代码):

     private void CboItemId_SelectionChanged(object sender, SelectionChangedEventArgs e)
    {
        
        BackgroundWorker _backgroundWorker = new BackgroundWorker();
        _backgroundWorker.DoWork += new DoWorkEventHandler(backgroundWorker_DoWork);
        _backgroundWorker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(_backgroundWorker_RunWorkerCompleted);
        ItemSearchBusyIndicator.IsBusy = true;
      
       // Mouse.OverrideCursor = System.Windows.Input.Cursors.Wait;
        if (RdoItemSearch.IsChecked == false) return;
        ///backgroundWorker_DoWork(null, null);
        
        if (CboItemId.SelectedValue == null) return;
        if (CboItemId.SelectedValue.ToString() != string.Empty)
        {
            selectedItem = CboItemId.SelectedValue.ToString();
            _backgroundWorker.RunWorkerAsync();
        }
       // Mouse.OverrideCursor = System.Windows.Input.Cursors.Arrow;
    }

    public void backgroundWorker_DoWork(object sender, DoWorkEventArgs e)
    {
        
            LoadItemData(selectedItem);
    }

使用MTA，并且不能设置为STA。因此，我尝试调用在其自己的线程中使用UI元素的内部函数:

       public void LoadItemData(string itemId)
    {
        
        Axapta ax = new Axapta();
        files.Clear();
        try
        {
            ax.Logon(Settings.Default.Server, null, Settings.Default.Test, null);
            AxaptaContainer path = (AxaptaContainer)ax.CallStaticClassMethod(Settings.Default.ClassName, Settings.Default.ItemData, itemId);
            for (int i = 1; i <= path.Count; i++)
            {
                AxaptaContainer somestring = (AxaptaContainer)path.get_Item(i);
                for (int j = 1; j <= somestring.Count; j += 2)
                {
                    string extension = Path.GetExtension(somestring.get_Item(j + 1).ToString().ToLower());
                    if (extension == ".jpg"
                        || extension == ".jpeg"
                        || extension == ".gif"
                        || extension == ".png"
                        || extension == ".bmp"
                        || extension == ".pdf")
                        /* key=path - value=description */
                        files.Add(somestring.get_Item(j + 1).ToString(), somestring.get_Item(j).ToString());
                }
            }
            
           // _canvas.Children.Clear();
            Thread t = new Thread(new ThreadStart(LoadPictures));
            t.SetApartmentState(ApartmentState.STA);
            t.Start();
           
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message);
        }
        finally
        {
            ax.Logoff();
        }
    }

这是我与canvas元素进行交互的地方:

      private void LoadPictures()
    {

        foreach (DictionaryEntry filePath in files)
        {

            try
            {

                Picture p = new Picture();
                ToolTip t = new ToolTip();
                t.Content = filePath.Value;
                p.ToolTip = t;
                TextBlock tb = new TextBlock();
                tb.Text = filePath.Value.ToString();
                Canvas.SetTop(tb, y);
                Canvas.SetLeft(tb, x);

                    p.ImagePath = filePath.Key.ToString();
                    p.OriginalImagePath = filePath.Key.ToString();
                    p.ImageName = filePath.Value.ToString();
                    _canvas.Children.Add(p); //<-------This is where i seem to error
            }
            catch (Exception ex)
            {
                MessageBox.Show("Error:" + ex.Message,"File Load Error",MessageBoxButton.OK,MessageBoxImage.Error);
            }
        }
    }

但我收到“调用线程无法访问该对象，因为其他线程拥有它”
我不知道在没有背景工作人员的情况下显示BusyIndi​​cator时如何调用长时间运行的(LoadItemData())函数。任何帮助表示赞赏

Answer 1

有多种方法:

1)Async binding，不建议使用，但它在那里。您可以在属性getter中运行长时间运行的任务，完成后，框架将阻止UI阻塞-UI将得到更新。

2)使用BackgroundWorker或Task/Thread运行代码，但将其调用到UI线程中。在您的示例中:

Dispatcher.InvokeAsync(() => _canvas.Children.Add(p));

3)您可以完全阻止主窗口的UI线程，没有问题。但是要表明它正忙，可以在另一个线程中创建一个窗口，并在其中显示忙状态(运行动画等):

        var thread = new Thread(() =>
        {
            var window = new SomeWindow();
            window.ShowDialog();
        });
        thread.SetApartmentState(ApartmentState.STA);
        thread.IsBackground = true;
        thread.Start();