WPF元素事件处理程序中的UI更新 [英] UI update in WPF elements event handlers

问题描述

我有这样的代码：

  private void ButtonClick_EventHandler（object sender，RoutedEventArgs e）
 {
 Label.Visibility = Visibility.Visible; 
 TextBox.Text =处理...; 
 
 LongTimeMethod（）; //一些长操作
} 
  

问题是，直到LongTimeMethod结束（即事件处理程序结束），Label.Visibility和TextBox.Text不会更改。

我现在解决了这个问题：

  private void ButtonClick_EventHandler（object sender，RoutedEventArgs e）
 {
 Label.Visibility = Visibility.Visible; 
 TextBox.Text =处理...; 
 
 Dispatcher.BeginInvoke（new Action（LongTimeMethod），
 DispatcherPriority.Background）; 
} 
  

有没有其他解决方案没有使用调度程序调用？调用this.UpdateLayout（）没有帮助。

解决方案

使用 Dispatcher.BeginInvoke 你仍在使用UI线程 LongTimeMethod（）。如果这不是必需的（即它正在做某种后台处理），我建议使用TPL在后台线程上运行：

  private void ButtonClick_EventHandler（object sender，RoutedEventArgs e）
 {
 Label.Visibility = Visibility.Visible; 
 TextBox.Text =处理...; 
 
 Task.Factory.StartNew（（）=> LongTimeMethod（））
 .ContinueWith（t => 
 {
 Dispatcher.BeginInvoke（（Action） delegate（）
 {
 TextBox.Text =Done！; 
}）; 
}）; 
 
} 
  

使用这种方法，长时间运行的方法在背景线程（所以UI线程将可以自由地保持渲染，并且应用程序不会被冻结），并且您可以做任何改变UI（例如更新文本框文本）的任何事情在UI 调度程序当后台任务完成

There is a problem with UI update in WPF.

I have such code:

    private void ButtonClick_EventHandler(object sender, RoutedEventArgs e)
    {
        Label.Visibility = Visibility.Visible;
        TextBox.Text = "Processing...";

        LongTimeMethod(); //some long operation
    }

The problem is that until LongTimeMethod ends (that is event handler ends), Label.Visibility and TextBox.Text will not be changed.

I solved it like this so far:

    private void ButtonClick_EventHandler(object sender, RoutedEventArgs e)
    {
        Label.Visibility = Visibility.Visible;
        TextBox.Text = "Processing...";

        Dispatcher.BeginInvoke(new Action(LongTimeMethod), 
            DispatcherPriority.Background);
    }

Is there any other solution without using dispatcher invocation? Calling this.UpdateLayout() doesn't help.

解决方案

With Dispatcher.BeginInvoke you are still using the UI thread for LongTimeMethod(). If this is not required (i.e. it is doing some kind of background processing) I would suggest using the TPL to run it on a background thread:

private void ButtonClick_EventHandler(object sender, RoutedEventArgs e)
{
    Label.Visibility = Visibility.Visible;
    TextBox.Text = "Processing...";

    Task.Factory.StartNew(() => LongTimeMethod())
        .ContinueWith(t =>
        {
            Dispatcher.BeginInvoke((Action)delegate()
            {
                TextBox.Text = "Done!";
            });
        });

}

With this method, the long running method is processed on a background thread (so the UI thread will be free to keep rendering and the app won't freeze up) and you can do anything that does alter the UI (such as updating the textbox text) on the UI Dispatcher when the background task completes

这篇关于WPF元素事件处理程序中的UI更新的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！