INotifyPropertyChanged 仅在方法存在时更新 UI

Question

我需要更新 Button_Click 方法中的 UI。

当我在 Test = "sss" 之后放置一个 break stop 时； ui 不会更新，但是当我继续直到方法完成时，它会更新 UI.

这是一个仅用于演示的简单场景，但在另一个示例中，我有一个 for 循环正在评估一长串对象，因此在整个 for 循环的评估过程中有多个更新。

如何在方法内更新ui而不是等到结束....

xaml

<Window x:Class="WpfApp1.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:WpfApp1"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    <Grid>
        <StackPanel>
            <TextBox Text="{Binding Path=Test}"></TextBox>
            <Button Click="Button_Click">Click</Button>
        </StackPanel>
    </Grid>
</Window>

MainWindow.xaml.cs

public partial class MainWindow : Window, INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler PropertyChanged;

        private void OnPropertyChanged(string propertyName)
        {
            if (PropertyChanged != null)
                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }


        private string test;
        public string Test { get { return test; } set { test = value; OnPropertyChanged("Test"); } }


        public MainWindow()
        {
            InitializeComponent();
            this.DataContext = this;
            Test = "aaa";
        }

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            Test = "sss";
            //do other stuff here
        }
    }

Answer 1

让我们使用异步方法，参见示例：

private async void Button_Click(object sender, RoutedEventArgs e)
{

  Test = "sss";
  // text box updated immediately via property Test

  await Task.Delay(5000); // wait 5 sec.

  Test = "ttt";
  // after 5 sec. updated again
}

INotifyPropertyChanged 仅在方法存在时更新 UI

INotifyPropertyChanged only updates UI when method exists

c#

wpf

inotifypropertychanged