UIElement.AddHandler（）VS .Event + =定义 [英] UIElement.AddHandler() vs .Event += Definition

问题描述

在quesion的 1.st部分：
是什么这两个事件注册的区别

  _popUp.AddHandler（PreviewMouseLeftButtonDownEvent，新MouseButtonEventHandler（PopUp_PreviewMouseLeftButtonDown））; 
 
 _popUp.PreviewMouseLeftButtonDown + =新MouseButtonEventHandler（_popUp_PreviewMouseLeftButtonDown）; 
  

的问题2.nd部分：
或最终与

  popUp.Opened + = PopUp_Opened; 
  

解决方案

据的Redgate's反射，没有任何区别。这两种方法最终调用内部方法 EventHandlerStore.AddRoutedEventHandler 。这是添加访问的的PreviewMouseLeftButtonDown 事件（在类 UIElement的反射输出）：

 公共无效add_PreviewMouseLeftButtonDown（MouseButtonEventHandler值）
 {
本.AddHandler（PreviewMouseLeftButtonDownEvent，价值，FALSE）; 
} 
  

正如你可以看到它调用 UIElement.AddHandler 为您服务。

在你编辑你的问题你问的打开事件弹出。在这种情况下，是有区别的：首先，打开事件不作为路由事件，但作为一个简单的事件，所以你甚至不能使用的AddHandler 就可以了电话。其次，反射器显示一个不同的方法是所谓的 EventHandlerStore 它增加了处理程序，以一个简单的委托集合。

1.st part of the quesion: What is the difference between these 2 event registrations ?

_popUp.AddHandler(PreviewMouseLeftButtonDownEvent, new MouseButtonEventHandler(PopUp_PreviewMouseLeftButtonDown));

_popUp.PreviewMouseLeftButtonDown += new MouseButtonEventHandler(_popUp_PreviewMouseLeftButtonDown);

2.nd part of the question: or eventually versus

popUp.Opened += PopUp_Opened;

解决方案

According to Redgate's Reflector, there is no difference. Both methods eventually call the internal method EventHandlerStore.AddRoutedEventHandler. This is the reflector output of the add accessor for the PreviewMouseLeftButtonDown event (in the class UIElement):

public void add_PreviewMouseLeftButtonDown(MouseButtonEventHandler value)
{
    this.AddHandler(PreviewMouseLeftButtonDownEvent, value, false);
}

As you can see it calls UIElement.AddHandler for you.

Before you edited your question you were asking about the Opened event of the popup. In that case, there is a difference: First, the Opened event is not implemented as a routed event but as a simple event, so you can't even use the AddHandler call on it. Secondly, the reflector shows that a different method is called in the EventHandlerStore which adds the handler to a simple delegate collection.

这篇关于UIElement.AddHandler（）VS .Event + =定义的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！