WPF Multibinding - 需要使用 Relaycommand

Question

所以，我有一个元素，它有一个带有 2 个参数的命令要传递。

我之前用我找到的一段 sn-p 代码做到了这一点，但我终生无法记住如何做到这一点或再次找到它。

所以，这里是我之前创建的多值转换器：

public class MultiValueConverter : IMultiValueConverter
{

    public object Convert(object[] values, Type targetType,
    object parameter, CultureInfo culture)
    {
        return values.Clone();
    }

    public object[] ConvertBack(object value, Type[] targetTypes, object parameter, System.Globalization.CultureInfo culture)
    {
        return (value as string).Split(' ');
    }

}

现在，我只需在 ICommand 中分配我想要调用的函数。我通常使用类似于以下的行：

enemyPopupTooltip = new RelayCommand(param => this.EnemyPopupTooltipEx(param),null);

但是，当它的多值时，这将不起作用。如何使用我的中继命令通过多值转换器将 2 个参数传递到我的函数中？

作为参考，这里是 relaycommand 类中的所有内容：

public class RelayCommand : ICommand
{
    /// <summary>
    /// Initializes a new instance of the <see cref="RelayCommand"/> class.
    /// </summary>
    /// <param name="execute">The execute.</param>
    public RelayCommand(Action<object> execute)
        : this(execute, null)
    {
    }

    /// <summary>
    /// Initializes a new instance of the <see cref="RelayCommand"/> class.
    /// </summary>
    /// <param name="execute">The execute.</param>
    /// <param name="canExecute">The can execute.</param>
    public RelayCommand(Action<object> execute, Predicate<object> canExecute)
    {
        if (execute == null)
            throw new ArgumentNullException("execute");
        _execute = execute;
        _canExecute = canExecute;
    }

    /// <summary>
    /// Defines the method that determines whether the command can execute in its current state.
    /// </summary>
    /// <param name="parameter">Data used by the command.  If the command does not require data to be passed, this object can be set to null.</param>
    /// <returns>
    /// true if this command can be executed; otherwise, false.
    /// </returns>
    public bool CanExecute(object parameter)
    {
        return _canExecute == null ? true : _canExecute(parameter);
    }

    /// <summary>
    /// Occurs when changes occur that affect whether or not the command should execute.
    /// </summary>
    public event EventHandler CanExecuteChanged
    {
        add { CommandManager.RequerySuggested += value; }
        remove { CommandManager.RequerySuggested -= value; }
    }

    /// <summary>
    /// Defines the method to be called when the command is invoked.
    /// </summary>
    /// <param name="parameter">Data used by the command.  If the command does not require data to be passed, this object can be set to null.</param>
    public void Execute(object parameter)
    {
        _execute(parameter);
    }

    /// <summary>
    /// Action
    /// </summary>
    private readonly Action<object> _execute;


    /// <summary>
    /// Predicate
    /// </summary>
    private readonly Predicate<object> _canExecute;

Answer 1

你说：

但是，当它的多值时，这将不起作用

这个假设是错误的。它确实有效！

当您的多转换器返回值数组时，该数组将作为参数传递给 Command.Execute 方法。

new RelayCommand(EnemyPopupTooltipEx, null);

public void EnemyPopupTooltipEx(object parameter){
   var values = (object[])parameters;
}

然而，这是非常肮脏的做法。我猜您正在将一些 UIElement(s) 传递给命令参数。这违反了 viewmodel 的责任。考虑将需要引用 UIElement 的代码移动到代码隐藏中。

Answer 2

只需将您的两个参数放入一个对象中。您可以使用任何类型的集合或数组，但也许最简单的选择是在您的IMultiValueConverter 中使用Tuple<T1, T2> Class：

if (values != null && values.Length >= 2)
{
    Tuple<Type1, Type2> yourTwoValues = new Tuple<Type1, Type2>(values[0], values[1]);
    return yourTwoValues;
}

然后您可以将Tuple 作为参数传递给您的ICommand，并在另一端提取各个值。

Answer 3

尝试使用新的属性，在 CommandParameter 中执行 multibing 并在 ExecuteEnterCommand 中处理。喜欢object[] arr = (object[])obj;

 public ICommand EnemyPopupTooltip
        {
            get
            {
                if (this.enemyPopupTooltip == null)
                {
                    this.enemyPopupTooltip = new RelayCommand<object>(this.ExecuteEnterCommand, this.CanExecuteEnterCommand);
                }

                return this.enemyPopupTooltip;
            }
        }


        private ICommand enemyPopupTooltip;