WPF在单独的UI线程上加载动画？ （C＃）
好的，我有一个加载动画，在填充大型DataTable时运行，让用户知道程序没有冻结。 我有动画工作正常，但它也冻结了DataTable也在更新。 有没有办法拥有多个UI线程，以便在DataTable加载信息时动画将继续运行？
编辑：当前代码如下。
private void CreateFileTable() { file_data = new DataSet(); data_table = new DataTable(); file_data.Tables.Add(data_table); DataColumn tempCol = new DataColumn("File Name", typeof(string)); data_table.Columns.Add(tempCol); tempCol = new DataColumn("Ext", typeof(string)); data_table.Columns.Add(tempCol); tempCol = new DataColumn("Size", typeof(string)); data_table.Columns.Add(tempCol); tempCol = new DataColumn("Created", typeof(Label)); data_table.Columns.Add(tempCol); tempCol = new DataColumn("Modified", typeof(Label)); data_table.Columns.Add(tempCol); tempCol = new DataColumn("Accessed", typeof(Label)); data_table.Columns.Add(tempCol); tempCol = new DataColumn("Location", typeof(string)); data_table.Columns.Add(tempCol); File_List.ItemsSource = file_data.Tables[0].DefaultView; } private void PopulateDirectories(string[] directories) { for (int i = 0; i < directories.Length; i++) { DirectoryInfo tempDirInfo = new DirectoryInfo(directories[i]); bool isSystem = ((tempDirInfo.Attributes & FileAttributes.System) == FileAttributes.System); if (!isSystem) { DataRow tempRow = data_table.NewRow(); tempRow["File Name"] = tempDirInfo.Name; tempRow["Ext"] = ""; tempRow["Size"] = ""; tempLabel = new Label(); tempLabel.Padding = new Thickness(2, 0, 2, 0); tempLabel.Content = tempDirInfo.CreationTime.ToLongDateString() + ", " + tempDirInfo.CreationTime.ToLongTimeString(); tempRow["Created"] = tempLabel; tempLabel = new Label(); tempLabel.Padding = new Thickness(2, 0, 2, 0); tempLabel.Content = tempDirInfo.LastWriteTime.ToLongDateString() + ", " + tempDirInfo.LastWriteTime.ToLongTimeString(); tempRow["Modified"] = tempLabel; tempLabel = new Label(); tempLabel.Padding = new Thickness(2, 0, 2, 0); tempLabel.Content = tempDirInfo.LastAccessTime.ToLongDateString() + ", " + tempDirInfo.LastAccessTime.ToLongTimeString(); tempRow["Accessed"] = tempLabel; tempRow["Location"] = tempDirInfo.FullName; data_table.Rows.Add(tempRow); } } } private void PopulateFiles(string[] files) { for (int i = 0; i 1048576) { tempRow["Size"] = "" + fileSize / 1048576 + " MB"; } else if (fileSize > 1024) { tempRow["Size"] = "" + fileSize / 1024 + " KB"; } else { tempRow["Size"] = "" + fileSize + " B"; } tempLabel = new Label(); tempLabel.Padding = new Thickness(2, 0, 2, 0); tempLabel.Content = tempFileInfo.CreationTime.ToLongDateString() + ", " + tempFileInfo.CreationTime.ToLongTimeString(); tempRow["Created"] = tempLabel; tempLabel = new Label(); tempLabel.Padding = new Thickness(2, 0, 2, 0); tempLabel.Content = tempFileInfo.LastWriteTime.ToLongDateString() + ", " + tempFileInfo.LastWriteTime.ToLongTimeString(); tempRow["Modified"] = tempLabel; tempLabel = new Label(); tempLabel.Padding = new Thickness(2, 0, 2, 0); tempLabel.Content = tempFileInfo.LastAccessTime.ToLongDateString() + ", " + tempFileInfo.LastAccessTime.ToLongTimeString(); tempRow["Accessed"] = tempLabel; tempRow["Location"] = tempFileInfo.DirectoryName; data_table.Rows.Add(tempRow); } } } private string GetSelectedPath(TreeViewItem selectedNode) { return selectedNode.Tag as string; } private void PopulateFileList() { PopulateDirectories(Directory.GetDirectories(GetSelectedPath((TreeViewItem)Dir_Tree.SelectedItem))); PopulateFiles(Directory.GetFiles(GetSelectedPath((TreeViewItem)Dir_Tree.SelectedItem))); } private void UpdateFileList() { LoadingWheel.Visibility = System.Windows.Visibility.Visible; CreateFileTable(); PopulateFileList(); TxtFoundCount.Text = "Files/Folders Found: " + File_List.Items.Count; LoadingWheel.Visibility = System.Windows.Visibility.Hidden; } 我已经尝试使用BackgroundWorker并在其中调用UpdateFileList（）方法，但我没有运气。
编辑：下面是我的BackgroundWorker代码。
private BackgroundWorker bgWorker1; private void InitializeBackgroundWorker() { bgWorker1 = new BackgroundWorker(); bgWorker1.DoWork += new DoWorkEventHandler(bgWorker1_DoWork); bgWorker1.RunWorkerCompleted += new RunWorkerCompletedEventHandler(bgWorker1_RunWorkerCompleted); } private void bgWorker1_DoWork(object sender, DoWorkEventArgs e) { if (Dispatcher.CheckAccess()) { PopulateFileList(); } else { Dispatcher.Invoke(new Action(() => PopulateFileList())); } } private void bgWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e) { TxtFoundCount.Text = "Files/Folders Found: " + File_List.Items.Count; LoadingWheel.Visibility = System.Windows.Visibility.Hidden; } private void UpdateFileList() { LoadingWheel.Visibility = System.Windows.Visibility.Visible; CreateFileTable(); bgWorker1.RunWorkerAsync(); }
我在TreeView上有一个SelectionChanged事件，它调用InitializeBackgroundWorker（）和UpdateFileList（）。 列表仍然加载，我没有错误，但加载动画永远不会显示。
任何帮助将不胜感激。
谢谢。
只有一个UI线程。 您需要做的是在不同的线程上加载DataTable中的数据。
如果要在整个过程中（直接或通过ProgressBar或其他某种机制）显示DataTable加载的进度， BackgroundWorker是一种相当直接的方法。
更新：非常简单的后台工作者示例
这是一个相当简单的例子。 它为一个集合添加了100个随机数，在每个集合之间暂停一段时间以模拟一个长时间加载过程。 您可以简单地将其剪切并粘贴到您自己的测试项目中，以使其工作。
需要注意的是，繁重的工作（需要一段时间的工作）是在DoWork中完成的，而所有UI更新都在ProgressChanged和RunWorkerCompleted中完成。 实际上，在DoWork处理程序中创建了一个单独的列表（数字），因为全局mNumbers集合位于UI线程上，并且无法在DoWork处理程序中进行交互。
XAML
C＃Code-Behind
BackgroundWorker bgWorker = new BackgroundWorker(); ObservableCollection mNumbers = new ObservableCollection (); public Window1() { InitializeComponent(); bgWorker.DoWork += new DoWorkEventHandler(bgWorker_DoWork); bgWorker.ProgressChanged += new ProgressChangedEventHandler(bgWorker_ProgressChanged); bgWorker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(bgWorker_RunWorkerCompleted); bgWorker.WorkerReportsProgress = true; btnGenerateNumbers.Click += (s, e) => UpdateNumbers(); this.DataContext = this; } void bgWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e) { progress.Visibility = Visibility.Collapsed; lstItems.Opacity = 1d; btnGenerateNumbers.IsEnabled = true; } void bgWorker_ProgressChanged(object sender, ProgressChangedEventArgs e) { List numbers = (List )e.UserState; foreach (int number in numbers) { mNumbers.Add(number); } progress.Value = e.ProgressPercentage; } void bgWorker_DoWork(object sender, DoWorkEventArgs e) { Random rnd = new Random(); List numbers = new List (10); for (int i = 1; i <= 100; i++) { // Add a random number numbers.Add(rnd.Next()); // Sleep from 1/8 of a second to 1 second Thread.Sleep(rnd.Next(125, 1000)); // Every 10 iterations, report progress if ((i % 10) == 0) { bgWorker.ReportProgress(i, numbers.ToList ()); numbers.Clear(); } } } public ObservableCollection NumberItems { get { return mNumbers; } } private void UpdateNumbers() { btnGenerateNumbers.IsEnabled = false; mNumbers.Clear(); progress.Value = 0; progress.Visibility = Visibility.Visible; lstItems.Opacity = 0.5; bgWorker.RunWorkerAsync(); }
我写了一个小测试程序，它显示了Dispatcher类的用法。 它只需要一个WPF-Window和一个名为“listBox”的ListBox。 应该很容易将此解决方案应用于您的问题。
public void Populate() { // for comparison, freezing the ui thread for (int i = 0; i < 1000000; i++) { listBox.Items.Add(i); } } private delegate void AddItemDelegate(int item); public void PopulateAsync() { // create a new thread which is iterating the elements new System.Threading.Thread(new System.Threading.ThreadStart(delegate() { // inside the new thread: iterate the elements for (int i = 0; i < 1000000; i++) { // use the dispatcher to "queue" the insertion of elements into the UI-Thread // DispatcherPriority.Background ensures Animations have a higher Priority and the UI does not freeze // possible enhancement: group the "jobs" to small units to enhance the performance listBox.Dispatcher.Invoke(new AddItemDelegate(delegate(int item) { listBox.Items.Add(item); }), System.Windows.Threading.DispatcherPriority.Background, i); } })).Start(); }