DoWork事件的WPF后台调用方法

Question

我的WPF UserControl上有一个UserControl。

        private readonly BackgroundWorker worker = new BackgroundWorker();

        public ucCustomer()
        {
          InitializeComponent();
          worker.DoWork += worker_DoWork;
          worker.RunWorkerCompleted += worker_RunWorkerCompleted;
        }
        private void worker_DoWork(object sender, DoWorkEventArgs e)
        {
            // run all background tasks here
            System.Threading.Thread.Sleep(10000);
        }

        private void worker_RunWorkerCompleted(object sender,  RunWorkerCompletedEventArgs e)
        {
            //update ui once worker complete his work
        }
        private void UserControl_Loaded(object sender, RoutedEventArgs e)
        {
            worker.RunWorkerAsync();
        }

上面的代码是工作的，UI是任务工作时的响应，但是如果我将worker_DoWork()更改为

private void worker_DoWork(object sender, DoWorkEventArgs e)
{
    // run all background tasks here
   Dispatcher.Invoke(System.Windows.Threading.DispatcherPriority.Background, 
        new Action(() => {
        gridDataBind(); //A long data-mining task,using Dispatcher.Invoke() to access UI.
    }));
} 

private void gridDataBind()
{
    SnEntities sn = new SnEntities();
    var customers = from c in sn.Customer select c;
    dgCustomer.ItemsSource = customers.ToList();
}

UI被冻结，直到任务结束。

有什么解决办法吗？谢谢你。

Answer 1

尝试按下面的代码设置ItemsSource：

private void worker_DoWork(object sender, DoWorkEventArgs e)
{
    // run all background tasks here
    e.Result = gridDataBind(); //A long data-mining task.
}

private IList<Customer> gridDataBind()
{
    SnEntities sn = new SnEntities();
    var customers = from c in sn.Customer select c;
    return customers.ToList();
}

private void worker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
    {
        var customers = e.Result as IList<Customer>;

        ObservableCollection<Customer> gridItemsSource = new ObservableCollection<Customer>();
        Dispatcher.Invoke(System.Windows.Threading.DispatcherPriority.Background,
                             new Action(() =>
                             {
                                 dgCustomer.ItemsSource = gridItemsSource;
                             }));

        foreach(var customer in customers)
        {
            Dispatcher.Invoke(System.Windows.Threading.DispatcherPriority.Background,
                                 new Action(() =>
                                 {
                                     gridItemsSource.Add(customer);
                                 }));
        }

    }

Answer 2

将数据存储在e.result中的worker_DoWork中，并在worker_RunWorkerCompleted中更新UI。在这种情况下，当数据来自数据库时，UI将是免费的。

Answer 3

试试这个，它会帮你的

Application.Current.Dispatcher.BeginInvoke(
  DispatcherPriority.Background,
  new Action(() => gridDataBind();));