Control.OnLeave(EventArgs) 方法

protected:
 virtual void OnLeave(EventArgs ^ e);

protected virtual void OnLeave (EventArgs e);

abstract member OnLeave : EventArgs -> unit
override this.OnLeave : EventArgs -> unit

Protected Overridable Sub OnLeave (e As EventArgs)

参数

示例

下面的代码示例使用 Leave 事件将控件重置为其以前的状态。The following code example uses the Leave event to reset a control to its former state.

private:
   void textBox1_Enter( Object^ /*sender*/, System::EventArgs^ /*e*/ )
   {
      // If the TextBox contains text, change its foreground and background colors.
      if ( textBox1->Text != String::Empty )
      {
         textBox1->ForeColor = Color::Red;
         textBox1->BackColor = Color::Black;

         // Move the selection pointer to the end of the text of the control.
         textBox1->Select(textBox1->Text->Length,0);
      }
   }

   void textBox1_Leave( Object^ /*sender*/, System::EventArgs^ /*e*/ )
   {
      // Reset the colors and selection of the TextBox after focus is lost.
      textBox1->ForeColor = Color::Black;
      textBox1->BackColor = Color::White;
      textBox1->Select(0,0);
   }

private void textBox1_Enter(object sender, System.EventArgs e)
{
    // If the TextBox contains text, change its foreground and background colors.
    if (!string.IsNullOrEmpty(textBox1.Text))
    {
        textBox1.ForeColor = Color.Red;
        textBox1.BackColor = Color.Black;
        // Move the selection pointer to the end of the text of the control.
        textBox1.Select(textBox1.Text.Length, 0);
    }
}

private void textBox1_Leave(object sender, System.EventArgs e)
{
    // Reset the colors and selection of the TextBox after focus is lost.
    textBox1.ForeColor = Color.Black;
    textBox1.BackColor = Color.White;
    textBox1.Select(0,0);
}

    Private Sub textBox1_Enter(sender As Object, e As System.EventArgs) Handles textBox1.Enter
        ' If the TextBox contains text, change its foreground and background colors.
        If textBox1.Text <> [String].Empty Then
            textBox1.ForeColor = Color.Red
            textBox1.BackColor = Color.Black
            ' Move the selection pointer to the end of the text of the control.
            textBox1.Select(textBox1.Text.Length, 0)
        End If
    End Sub
   
   
    Private Sub textBox1_Leave(sender As Object, e As System.EventArgs) Handles textBox1.Leave
        ' Reset the colors and selection of the TextBox after focus is lost.
        textBox1.ForeColor = Color.Black
        textBox1.BackColor = Color.White
        textBox1.Select(0, 0)
    End Sub
End Class

注解

引发事件时，将通过委托调用事件处理程序。Raising an event invokes the event handler through a delegate. 有关详细信息，请参阅 处理和引发事件。For more information, see Handling and Raising Events.

OnLeave 方法还允许派生类对事件进行处理而不必附加委托。The OnLeave method also allows derived classes to handle the event without attaching a delegate. 这是在派生类中处理事件的首选技术。This is the preferred technique for handling the event in a derived class.

继承者说明

在派生类中重写 OnLeave(EventArgs) 时，一定要调用基类的 OnLeave(EventArgs) 方法，以便已注册的委托对事件进行接收。When overriding OnLeave(EventArgs) in a derived class, be sure to call the base class's OnLeave(EventArgs) method so that registered delegates receive the event.

适用于

另请参阅

• Leave