TabControl.Deselecting 事件


在取消选择某个选项卡之前发生,使处理程序能够取消选项卡更改。Occurs before a tab is deselected, enabling a handler to cancel the tab change.

 event System::Windows::Forms::TabControlCancelEventHandler ^ Deselecting;
public event System.Windows.Forms.TabControlCancelEventHandler Deselecting;
member this.Deselecting : System.Windows.Forms.TabControlCancelEventHandler 
Public Custom Event Deselecting As TabControlCancelEventHandler 


下面的代码示例演示如何使用此成员。The following code example demonstrates the use of this member. 在此示例中,事件处理程序报告 Deselecting 事件的发生。In the example, an event handler reports on the occurrence of the Deselecting 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 TabControl1TabControl 类型实例的项目中。To run the example code, paste it into a project that contains an instance of type TabControl named TabControl1. 然后,确保事件处理程序与 Deselecting 事件关联。Then ensure that the event handler is associated with the Deselecting event.

private void TabControl1_Deselecting(Object sender, TabControlCancelEventArgs e) {

System.Text.StringBuilder messageBoxCS = new System.Text.StringBuilder();
messageBoxCS.AppendFormat("{0} = {1}", "TabPage", e.TabPage );
messageBoxCS.AppendFormat("{0} = {1}", "TabPageIndex", e.TabPageIndex );
messageBoxCS.AppendFormat("{0} = {1}", "Action", e.Action );
messageBoxCS.AppendFormat("{0} = {1}", "Cancel", e.Cancel );
MessageBox.Show(messageBoxCS.ToString(), "Deselecting Event" );
Private Sub TabControl1_Deselecting(sender as Object, e as TabControlCancelEventArgs) _ 
     Handles TabControl1.Deselecting

    Dim messageBoxVB as New System.Text.StringBuilder()
    messageBoxVB.AppendFormat("{0} = {1}", "TabPage", e.TabPage)
    messageBoxVB.AppendFormat("{0} = {1}", "TabPageIndex", e.TabPageIndex)
    messageBoxVB.AppendFormat("{0} = {1}", "Action", e.Action)
    messageBoxVB.AppendFormat("{0} = {1}", "Cancel", e.Cancel)
    MessageBox.Show(messageBoxVB.ToString(),"Deselecting Event")

End Sub


当当前选项卡在 TabControl中更改时,以下事件将按以下顺序发生。When the current tab changes in a TabControl, the following events occur in the following order.

通过这些事件,您可以在 TabPage 处于无效状态或更新新显示 TabPage的状态时,执行取消选项卡更改等任务。These events let you perform tasks such as canceling a tab change if a TabPage is in an invalid state or updating the state of a newly displayed TabPage.

当用户单击某个选项卡、调用 DeselectTabSelectTab 方法时,或者当你更改 SelectedIndexSelectedTab 属性的值时,当前选项卡会发生更改。The current tab changes when the user clicks a tab, when you call the DeselectTab or SelectTab method, or when you change the value of the SelectedIndex or SelectedTab property.