数据模型依赖于另一个数据模型的属性时的数据绑定

Question

我有节点（屏幕上的矩形）以及链接（矩形之间的箭头）。

在数据方面，节点和链路都有各自的数据属性。但是一个链路的坐标等于它的两个组成节点的坐标；即。

• link.x1=节点1.x
• link.y1=节点1.y
• link.x2=节点2.x
• Link.y2=Node2.y

理想情况下，每当节点的位置改变时，其所有输入和输出链路的位置也应随之改变。

他们是一个简单的方法（除了下面的）来完成这件事吗？

我的意思是，最终我所需要的只是类似LinkInstance.x1=NodeInstance1.x之类的东西。当然，我可能做错了。如果是的话，请对我大喊大叫。

class Link : ReactiveBase
{
    private int x1;
    private int y1;
    private int x2;
    private int y2;

    private Node fromNode;
    private Node toNode;

    //Just copies value, no updates.
    public int X1 { get {return this.fromNode.X;} }
    public int Y1 { get {return this.fromNode.Y;} }
    public int X2 { get {return this.toNode.X;} }
    public int Y2 { get {return this.toNode.Y;} }

    //Binding to From.X in xaml works; but don't like accessing node from  link
    public Node From { get { return this.fromNode; } }
    //...

    public Link(Node from, Node to)
    {
        this.fromNode = from;
        this.toNode = to;

        //works; but quite a lot of work
        from.PropertyChanged += test;
        //...
    }

    private void test(object sender, PropertyChangedEventArgs e)
    {
        if (e.PropertyName == "X")
        {
            this.NotifyPropertyChanged("X1");
        }
        else if (e.PropertyName == "Y")
        {
            this.NotifyPropertyChanged("Y1");
        }
    }
    //...
}

Answer 1

我认为这是一个更简单的解决方案:

class Node: ViewModelBase
{    
    private int _X;
    public int X
    {
        get => _X;
        set
        {
            _X = value;
            OnPropertyChanged(new PropertyChangedEventArgs(nameof(X)));
        }
    }

    private int _Y;
    public int Y
    {
        get => _Y;
        set
        {
            _Y = value;
            OnPropertyChanged(new PropertyChangedEventArgs(nameof(Y)));
        }
    }
}

class Link: ViewModelBase
{
    public Link(Node from, Node to)
    {
        FromNode = from;
        ToNode = to;
    }
    
    private Node _FromNode;
    public Node FromNode
    {
        get => _FromNode;
        set
        {
            _FromNode = value;
            OnPropertyChanged(new PropertyChangedEventArgs(nameof(FromNode)));
        }
    }
    private Node _ToNode;
    public Node ToNode
    {
        get => _ToNode;
        set
        {
            _ToNode = value;
            OnPropertyChanged(new PropertyChangedEventArgs(nameof(ToNode)));
        }
    }
}

其中ViewModelBase是实现InotifyPropertyChanged接口的基类。您的链接可以保存一组节点的坐标，而不是保存对节点本身的引用，这样您就不需要处理x和y属性更新，因为它们是由节点本身处理的。