6

简而言之，我可以在 WPF 控件中创建 2 个依赖属性，并在每个属性更改通知中放置代码以更改其他属性（即PropA更改集PropB和PropB更改集PropA）。

我希望这会消失在它自己的背面，但 WPF 似乎可以很好地处理它。对于我的目的来说，这实际上非常方便，但我在任何地方都找不到这种行为记录。

发生什么了？WPF 依赖属性更改通知系统是否可以防止重入？

代表代码如下：

XAML：

<Window x:Class="WPFReentrancy1.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">
    <Grid>
        <TextBox Text="{Binding PropB, UpdateSourceTrigger=PropertyChanged}"/>

    </Grid>
</Window>

后面的代码：

 public partial class MainWindow : Window
    {

        public string PropA
        {
            get { return (string)GetValue(PropAProperty); }
            set { SetValue(PropAProperty, value); }
        }
        public static readonly DependencyProperty PropAProperty =
                        DependencyProperty.Register("PropA", typeof (string), typeof (MainWindow),new UIPropertyMetadata("0", PropAChanged));


        public string PropB
        {
            get { return (string)GetValue(PropBProperty); }
            set { SetValue(PropBProperty, value); }
        }

        public static readonly DependencyProperty PropBProperty =
            DependencyProperty.Register("PropB", typeof (string), typeof (MainWindow), new UIPropertyMetadata("", PropBChanged));

        private static void PropBChanged(DependencyObject lDependencyObject, DependencyPropertyChangedEventArgs lDependencyPropertyChangedEventArgs)
        {
            ((MainWindow) lDependencyObject).PropA = (string) lDependencyPropertyChangedEventArgs.NewValue;
        }


        private static void PropAChanged(DependencyObject lDependencyObject, DependencyPropertyChangedEventArgs lDependencyPropertyChangedEventArgs)
        {
            ((MainWindow) lDependencyObject).PropB =
                double.Parse((string) lDependencyPropertyChangedEventArgs.NewValue).ToString("0.000");
        }


        public MainWindow()
        {
            InitializeComponent();
            DataContext = this;
            PropA = "1.123";
        }
    }
4

1 回答 1

4

只有在属性发生更改时才会触发这些回调，您的代码不会创建不同值的无限循环。

试试这个，你会得到一个 SO 异常：

private static readonly Random _random = new Random();
private static void PropBChanged(DependencyObject lDependencyObject, DependencyPropertyChangedEventArgs lDependencyPropertyChangedEventArgs)
{
    ((MainWindow)lDependencyObject).PropA = _random.Next().ToString();
}
private static void PropAChanged(DependencyObject lDependencyObject, DependencyPropertyChangedEventArgs lDependencyPropertyChangedEventArgs)
{
    ((MainWindow)lDependencyObject).PropB = _random.Next().ToString();
}
于 2012-05-14T12:41:14.833 回答