Form.MdiChildActivate 事件

定义

在多文档界面 (MDI) 应用程序内激活或关闭 MDI 子窗体时发生。Occurs when a multiple-document interface (MDI) child form is activated or closed within an MDI application.

public:
 event EventHandler ^ MdiChildActivate;
public event EventHandler MdiChildActivate;
member this.MdiChildActivate : EventHandler 
Public Custom Event MdiChildActivate As EventHandler 

示例

下面的示例演示如何使用此成员。The following example demonstrates the use of this member. 在此示例中,事件处理程序报告 MdiChildActivate 事件的发生。In the example, an event handler reports on the occurrence of the MdiChildActivate event. 此报表可帮助你了解何时发生事件,并可帮助你进行调试。This report helps you to learn when the event occurs and can assist you in debugging. 若要报告多个事件或频繁发生的事件,请考虑将 MessageBox.Show 替换为 Console.WriteLine 或将消息附加到多行 TextBox中。To report on multiple events or on events that occur frequently, consider replacing MessageBox.Show with Console.WriteLine or appending the message to a multiline TextBox.

若要运行示例代码,请将其粘贴到包含名为 Form1Form 类型实例的项目中。To run the example code, paste it into a project that contains an instance of type Form named Form1. 然后,确保事件处理程序与 MdiChildActivate 事件关联。Then ensure that the event handler is associated with the MdiChildActivate event.

private void Form1_MdiChildActivate(Object sender, EventArgs e) {

   MessageBox.Show("You are in the Form.MdiChildActivate event.");

}
Private Sub Form1_MdiChildActivate(sender as Object, e as EventArgs) _ 
     Handles Form1.MdiChildActivate

   MessageBox.Show("You are in the Form.MdiChildActivate event.")

End Sub

注解

您可以使用此事件来执行任务,例如更新 MDI 子窗体的内容,并基于所激活的 MDI 子窗体的状态更改 MDI 父窗体中可用的菜单选项。You can use this event to perform tasks such as updating the contents of the MDI child form and changing the menu options available in the MDI parent form based on the status of the MDI child form that is activated.

有关处理事件的详细信息,请参阅处理和引发事件For more information about handling events, see Handling and Raising Events.

适用于

另请参阅