Question

我有一个很长的操作，我想要显示扩展工具包忙指示符。我之前发过一篇关于此事的帖子，并修复了Wpf Extended toolkit BusyIndicator not showing during operation。但是，在该调用期间，我必须与UI元素（画布）进行交互，并且我得到一个＆＃34;调用线程必须是STA，因为许多UI组件需要这个＆＃34;。我理解（现在）后台工作者（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，无法设置为STA。所以我尝试在自己的线程中调用使用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();
        }
    }

我与canvas元素交互的地方：

      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);
            }
        }
    }

但我得到了一个＆＃34;调用线程无法访问此对象，因为另一个线程拥有它＆＃34; 我不知道如何在没有后台工作者的情况下显示BusyIndicator时调用长时间运行（LoadItemData（））函数。任何帮助表示赞赏

Answer 1

有多种方法：

1）Async binding，不推荐，但它就在那里。你可以在属性getter中运行长时间运行的任务，框架将阻止UI阻塞，当它完成时 - 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）你可以完全阻止主窗口的UI线程，没问题。但为了表明它正忙，你可以在另一个线程中创建窗口并显示忙状态（运行动画等）：

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

在STA线程上显示忙指示符

1 个答案: