TriggerAction扩展----ExInvokeCommandAction

 Wp&Win8中使用命令绑定时，除了Button控件自带命令绑定，其他的时候是用Interactivity库中的InvokeCommandAction实现的(Win8 需要额外安装第三方NuGet包才可使用，我的MVFM示例博客中带有这个库),但使用过程中发现InvokeCommandAction并不能满足我们的要求，主要有以下几点：

  1 无法获取发送者；

  2 用EventTrigger触发时往往需要用到EventArg参数，但是InvokeCommandAction无法获取；

  3 有时需要传递多个参数，无法满足；

  于是我对InvokeCommandAction进行了一些改进，首先定义参数的结构体：

 

/// <summary>  
/// 扩展CommandParameter，使CommandParameter可以带事件参数  
/// </summary>  
public class ExCommandParameter
{
    /// <summary>  
    /// 事件触发源  
    /// </summary>  
    public object Sender { get; set; }
    /// <summary>  
    /// 事件参数  
    /// </summary>  
    public object EventArgs { get; set; }
    /// <summary>  
    /// 参数  
    /// </summary>  
    public object Parameter { get; set; }
    /// <summary>  
    /// 扩展参数  
    /// </summary>  
    public object Parameter2 { get; set; }
    /// <summary>  
    /// 扩展参数  
    /// </summary>  
    public object Parameter3 { get; set; }
}  

　　 然后定义处理的TriggerAction：

/// <summary>  
   /// 扩展的InvokeCommandAction  
   /// </summary>  
   public class ExInvokeCommandAction : CustomTriggerActionBase
   {
       private string commandName;
       public static readonly DependencyProperty CommandProperty = DependencyProperty.Register("Command", typeof(ICommand), typeof(ExInvokeCommandAction), null);
       public static readonly DependencyProperty CommandParameterProperty = DependencyProperty.Register("CommandParameter", typeof(object), typeof(ExInvokeCommandAction), null);
       public static readonly DependencyProperty CommandParameter2Property = DependencyProperty.Register("CommandParameter2", typeof(object), typeof(ExInvokeCommandAction), null);
       public static readonly DependencyProperty CommandParameter3Property = DependencyProperty.Register("CommandParameter3", typeof(object), typeof(ExInvokeCommandAction), null);

       /// <summary>  
       /// 获得或设置此操作应调用的命令的名称。  
       /// </summary>  
       /// <value>此操作应调用的命令的名称。</value>  
       /// <remarks>如果设置了此属性和 Command 属性，则此属性将被后者所取代。</remarks>  
       public string CommandName
       {
           get
           {
               return this.commandName;
           }
           set
           {
               if (this.commandName != value)
               {
                   this.commandName = value;
               }
           }
       }
  
       /// <summary>  
       /// 获取或设置此操作应调用的命令。这是依赖属性。  
       /// </summary>  
       /// <value>要执行的命令。</value>  
       /// <remarks>如果设置了此属性和 CommandName 属性，则此属性将优先于后者。</remarks>  
       public ICommand Command
       {
           get
           {
               return (ICommand)base.GetValue(ExInvokeCommandAction.CommandProperty);
           }
           set
           {
               base.SetValue(ExInvokeCommandAction.CommandProperty, value);
           }
       }
       /// <summary>  
       /// 获得或设置命令参数。这是依赖属性。  
       /// </summary>  
       /// <value>命令参数。</value>  
       /// <remarks>这是传递给 ICommand.CanExecute 和 ICommand.Execute 的值。</remarks>  
       public object CommandParameter
       {
           get
           {
               return base.GetValue(ExInvokeCommandAction.CommandParameterProperty);
           }
           set
           {
               base.SetValue(ExInvokeCommandAction.CommandParameterProperty, value);
           }
       }

       public object CommandParameter2
       {
           get
           {
               return base.GetValue(ExInvokeCommandAction.CommandParameter2Property);
           }
           set
           {
               base.SetValue(ExInvokeCommandAction.CommandParameter2Property, value);
           }
       }

       public object CommandParameter3
       {
           get
           {
               return base.GetValue(ExInvokeCommandAction.CommandParameter3Property);
           }
           set
           {
               base.SetValue(ExInvokeCommandAction.CommandParameter3Property, value);
           }
       }

       /// <summary>  
       /// 调用操作。  
       /// </summary>  
       /// <param name="parameter">操作的参数。如果操作不需要参数，则可以将参数设置为空引用。</param>  
       protected override void Invoke(object parameter)
       {
           ICommand command = this.ResolveCommand();

           ExCommandParameter exParameter = new ExCommandParameter
           {
               Sender = this.AssociatedObject,
               Parameter = GetValue(CommandParameterProperty),
               Parameter2 = GetValue(CommandParameter2Property),
               Parameter3 = GetValue(CommandParameter3Property),
               EventArgs = parameter

           };

           if (command != null && command.CanExecute(exParameter))
           {
               command.Execute(exParameter);
           }
       }

       //手动触发
       public void TriggerCommand()
       {
           Invoke(null);
       }

       public void TriggerCommand(object CommandParameter)
       {
           TriggerCommand(null, CommandParameter);
       }

       public void TriggerCommand(object sender = null, object commandParameter = null, object commandParameter2 = null, object commandParameter3 = null)
       {
           this.CommandParameter = commandParameter;
           this.CommandParameter2 = commandParameter2;
           this.CommandParameter3 = commandParameter3;
           Invoke(null);
       }

       protected ICommand ResolveCommand()
       {
           ICommand result = null;
           if (this.Command != null)
           {
               result = this.Command;
           }
           else
           {
               foreach (PropertyInfo propertyInfo in this.AssociatedObject.GetType().GetTypeInfo().DeclaredProperties)
               {
                   if (typeof(ICommand).GetTypeInfo().IsAssignableFrom(propertyInfo.PropertyType.GetTypeInfo()) && string.Equals(propertyInfo.Name, this.CommandName, StringComparison.Ordinal))
                   {
                       result = (ICommand)propertyInfo.GetValue((object)this.AssociatedObject, (object[])null);
                   }
               }
           }
           return result;
       }
   }

　　

  使用时和InvokeCommandAction是一样的：

 

<i:Interaction.Triggers>
    <i:EventTrigger EventName="Loaded">  
         <Behavior:ExInvokeCommandAction Command="{Binding Command,Source={StaticResource ViewModel}}" CommandParameter="1" CommandParameter2="2" CommandParameter3="3"/>
    </i:EventTrigger>
</i:Interaction.Triggers>