命令委托参数

Question

为什么我没有将参数接收到我的委托命令中？几天来我一直在关注这个问题，但仍然无法理解它，我对 .NET 框架还比较陌生。我正在使用 MVVM 和命令委托来获取单击按钮形状（如圆形）的 x 和 Y 坐标。但是，我的不断失败。如果可能的话，请帮助我。 这是我的看法

<Button Width="20" 
        Height="20" 
        Command="{Binding Path=DataContext.touchCommand,RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type Window}}}">

这是我的视图模型

public  class ViewModel :  INotifyPropertyChanged
{
    #region constructor plus member val
    public event PropertyChangedEventHandler PropertyChanged;
    public ObservableCollection<CartesianPoint> points { get; set; }
    public ObservableCollection<CartesianPoint> missPoints { get; set; }

    public DelegateCommand<CartesianPoint> SelectCommand { get; set; }
    public CartesianPoint SelectedPoint { get; set; }

    public ViewModel()
    {

        points = new ObservableCollection<CartesianPoint>();
        missPoints = new ObservableCollection<CartesianPoint>();

        this.testData();
    }

    private void InitializeCommands()
    {
        SelectCommand = new DelegateCommand<CartesianPoint>( (p) => SelectedPoint = p );

    }
    #endregion constructor plus member val


    protected void OnPropertyChanged(String propertyName)
    {
        if( PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }

        Console.WriteLine( "from on propertity change");

    }

    public ICommand touchCommand
    {
        get
        {
            if (SelectCommand == null)
            {
                SelectCommand = new DelegateCommand<CartesianPoint>(( p) => Executed( p));

            }
            return SelectCommand;
        }
    }

    public bool CanExecute()
    {
        return false;
    }

    public void Executed(object sender)
    {

        if (sender != null)
        {
            Console.WriteLine("this is a test");
            CartesianPoint  input = sender as CartesianPoint;
            Console.WriteLine("{0} {1}"input.X, input.Y);

        }
    }

Answer 1

那是因为您没有指定 CommandParameter 值。