如何通过 ViewModel 中的另一个属性捕捉模型中属性的变化？

Question

我对模型的扩展有疑问。我需要在 Station 类中更新 AngleNegative 属性的同时更新 AngleNegative 属性。 AngleNegative 属性数据基于来自 Angle 的数据，如您在示例中所见。我无法修改 Station 模型，因为它在另一个 VM 中使用并且有相同的问题但具有其他属性。有什么办法可以解决？

  public class Station : BindableBase, IStation
     {
        //some properties
        .
        .
        .

        private int _angle;

        public int Angle
        {
            get => _angle;
            set => SetProperty(ref _angle, value);
        }
     }


public class ViewModel : BindableBase
    {
        private Station _station;
        public Station Station
        {
            get => _station;
            set => SetProperty(ref _station, value);
        }

        //delete this property duplicate and base on Station.Angle
        private int _angle;
        public int Angle
        {
            get => _angle;
            set
            {
                SetProperty(ref _angle, value);
                AngleNegative = value - 180;
            }
        }

        private int _angleNegative;

        public int AngleNegative
        {
            get => _angleNegative;
            set => SetProperty(ref _angleNegative, value);
        }
    }

我认为我可以从 IStation 继承 VM，但之后有很多代码重复。

Answer 1

我会通过在 ViewModel 上设置一个方法来侦听其 Station 上的 PropertyChanged 事件，如下所示：

public class ViewModel : BindableBase
{
    private Station _station;
    public Station Station
    {
        get => _station;
        set => SetProperty(ref _station, value);
    }

    private int _angleNegative;
    public int AngleNegative
    {
        get => _angleNegative;
        set => SetProperty(ref _angleNegative, value);
    }

    public ViewModel()
    {
        Station.PropertyChanged += Station_PropertyChanged;
    }

    private void Station_PropertyChanged(object sender, PropertyChangedEventArgs e)
    {
        if (e.PropertyName == "Angle")
        {
            AngleNegative = Station.Angle - 180;
        }
    }
}