Events DependencyProperties with Bools:False导致事件不激发

因此，我为我的xaml用户控件创建了一个bool依赖属性。但是，当该值在xaml中设置为false时，它不会在xaml中设置为true时触发事件。我怎样才能让它在任何情况下启动活动

public static readonly DependencyProperty AvailableProperty =
    DependencyProperty.Register("Available", typeof(bool), typeof(DetailPannel),
    new PropertyMetadata(null, onAvailablePropertyChanged));

public bool Available
{
    get { return (bool)GetValue(AvailableProperty);  }
    set { SetValue(AvailableProperty, value); }
}

private async static void onAvailablePropertyChanged(DependencyObject d,   DependencyPropertyChangedEventArgs e)
{
    var obj = d as DetailPannel;
    bool avaible = (bool.Parse(e.NewValue.ToString())); 
    if(avaible == false )
    {            
        obj.PreviewImage.Source = await ConvertToGreyscale(obj.PreviewImage);
        obj.StateRelatedImage.Source = new BitmapImage(new Uri("ms-appx:///icon.png")); 
    }
} 

---

值

null

对于bool属性无效。更改PropertyMetadata以指定

false

或

true

作为默认值：

public static readonly DependencyProperty AvailableProperty =
    DependencyProperty.Register("Available", typeof(bool), typeof(DetailPannel),
    new PropertyMetadata(false, onAvailablePropertyChanged));

此外，PropertyChanged处理程序中的代码看起来可疑。不要使用

bool.Parse

，只需将

e.NewValue

转换为

bool

：

private async static void onAvailablePropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
    var obj = d as DetailPannel;
    var available = (bool)e.NewValue; 

    if (!available)
    {
        ...
    }
}