Control.OnKeyUp(KeyEventArgs) 方法
定义
protected:
virtual void OnKeyUp(System::Windows::Forms::KeyEventArgs ^ e);
protected virtual void OnKeyUp (System.Windows.Forms.KeyEventArgs e);
abstract member OnKeyUp : System.Windows.Forms.KeyEventArgs -> unit
override this.OnKeyUp : System.Windows.Forms.KeyEventArgs -> unit
Protected Overridable Sub OnKeyUp (e As KeyEventArgs)
参数
包含事件数据的 KeyEventArgs。A KeyEventArgs that contains the event data.
示例
下面的代码示例将 KeyUp 事件与类一起使用, Help 以便向用户显示弹出式样式帮助。The following code example uses the KeyUp event with the Help class to display pop-up style help to the user.
// This example demonstrates how to use the KeyUp event with the Help class to display
// pop-up style help to the user of the application. When the user presses F1, the Help
// class displays a pop-up window, similar to a ToolTip, near the control. This example assumes
// that a TextBox control, named textBox1, has been added to the form and its KeyUp
// event has been connected to this event handler method.
private:
void textBox1_KeyUp( Object^ /*sender*/, System::Windows::Forms::KeyEventArgs^ e )
{
// Determine whether the key entered is the F1 key. Display help if it is.
if ( e->KeyCode == Keys::F1 )
{
// Display a pop-up help topic to assist the user.
Help::ShowPopup( textBox1, "Enter your first name", Point(textBox1->Right,this->textBox1->Bottom) );
}
}
// This example demonstrates how to use the KeyUp event with the Help class to display
// pop-up style help to the user of the application. When the user presses F1, the Help
// class displays a pop-up window, similar to a ToolTip, near the control. This example assumes
// that a TextBox control, named textBox1, has been added to the form and its KeyUp
// event has been contected to this event handler method.
private void textBox1_KeyUp(object sender, System.Windows.Forms.KeyEventArgs e)
{
// Determine whether the key entered is the F1 key. Display help if it is.
if(e.KeyCode == Keys.F1)
{
// Display a pop-up help topic to assist the user.
Help.ShowPopup(textBox1, "Enter your first name", new Point(textBox1.Right, this.textBox1.Bottom));
}
}
' This example demonstrates how to use the KeyUp event with the Help class to display
' pop-up style help to the user of the application. When the user presses F1, the Help
' class displays a pop-up window, similar to a ToolTip, near the control. This example assumes
' that a TextBox control, named textBox1, has been added to the form and its KeyUp
' event has been contected to this event handler method.
Private Sub textBox1_KeyUp(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles textBox1.KeyUp
' Determine whether the key entered is the F1 key. Display help if it is.
If e.KeyCode = Keys.F1 Then
' Display a pop-up help topic to assist the user.
Help.ShowPopup(textBox1, "Enter your first name", New Point(textBox1.Right, Me.textBox1.Bottom))
End If
End Sub
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.
OnKeyUp 方法还允许派生类对事件进行处理而不必附加委托。The OnKeyUp 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 OnKeyUp(KeyEventArgs) 时,一定要调用基类的 OnKeyUp(KeyEventArgs) 方法,以便已注册的委托对事件进行接收。When overriding OnKeyUp(KeyEventArgs) in a derived class, be sure to call the base class's OnKeyUp(KeyEventArgs) method so that registered delegates receive the event.