Avalonia GetObservable for WPF

GetObservable.cs

extension(DependencyObject obj)
{
    public Observable<T> GetObservable<T>(DependencyProperty property)
    {
        var descriptor = DependencyPropertyDescriptor.FromProperty(property, obj.GetType());
        return Observable
            .FromEventHandler(
                h => descriptor.AddValueChanged(obj, h),
                h => descriptor.RemoveValueChanged(obj, h))
            .Select(_ => (T)obj.GetValue(property))
            .Prepend((T)obj.GetValue(property));
    }
}

注意 DependencyProperty 是个静态的东西，一定需要释放。