Control.KeyUp Control.KeyUp Control.KeyUp Control.KeyUp Event

定义

在控件有焦点的情况下释放键时发生。Occurs when a key is released while the control has focus.

public:
 event System::Windows::Forms::KeyEventHandler ^ KeyUp;
public event System.Windows.Forms.KeyEventHandler KeyUp;
member this.KeyUp : System.Windows.Forms.KeyEventHandler 
Public Custom Event KeyUp As KeyEventHandler 

示例

下面的代码示例将KeyUp事件Help与类一起使用,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

下面的代码示例演示了KeyDown KeyUpKeyPress事件的增长顺序,以及如何在这些事件上注册事件处理程序。The following code example demonstrates the order of rising the KeyDown, KeyUp and KeyPress events, also how to register event handlers on them.

public partial class Form2 : Form
{
    public Form2()
    {
        InitializeComponent();
        textBox2.Multiline = true;
        textBox2.ScrollBars = ScrollBars.Both;

        //Setup events that listens on keypress
        textBox1.KeyDown += TextBox1_KeyDown;
        textBox1.KeyPress += TextBox1_KeyPress;
        textBox1.KeyUp += TextBox1_KeyUp;
    }

    // Handle the KeyUp event to print the type of character entered into the control.
    private void TextBox1_KeyUp(object sender, KeyEventArgs e)
    {
        textBox2.AppendText( $"KeyUp code: {e.KeyCode}, value: {e.KeyValue}, modifiers: {e.Modifiers}" + "\r\n");
    }

    // Handle the KeyPress event to print the type of character entered into the control.
    private void TextBox1_KeyPress(object sender, KeyPressEventArgs e)
    {
        textBox2.AppendText( $"KeyPress keychar: {e.KeyChar}" + "\r\n");
    }

    // Handle the KeyDown event to print the type of character entered into the control.
    private void TextBox1_KeyDown(object sender, KeyEventArgs e)
    {
        textBox2.AppendText( $"KeyDown code: {e.KeyCode}, value: {e.KeyValue}, modifiers: {e.Modifiers}" + "\r\n");
    }
}
Public Class Form2

    ' Handle the KeyDown event to print the type of character entered into the control.
    Private Sub TextBox1_KeyDown(sender As Object, e As KeyEventArgs) Handles TextBox1.KeyDown
        TextBox2.AppendText($"KeyDown code: {e.KeyCode}, value: {e.KeyValue}, modifiers: {e.Modifiers}" + vbCrLf)
    End Sub

    ' Handle the KeyPress event to print the type of character entered into the control.
    Private Sub TextBox1_KeyPress(sender As Object, e As KeyPressEventArgs) Handles TextBox1.KeyPress
        TextBox2.AppendText($"KeyPress keychar: {e.KeyChar}" + vbCrLf)
    End Sub

    ' Handle the KeyUp event to print the type of character entered into the control.
    Private Sub TextBox1_KeyUp(sender As Object, e As KeyEventArgs) Handles TextBox1.KeyUp
        TextBox2.AppendText($"KeyUp code: {e.KeyCode}, value: {e.KeyValue}, modifiers: {e.Modifiers}" + vbCrLf)
    End Sub

End Class

注解

键事件按以下顺序发生:Key events occur in the following order:

  1. KeyDown

  2. KeyPress

  3. KeyUp

若要仅在窗体级别处理键盘事件,而不允许其他控件接收键盘事件,请KeyPressEventArgs.Handled将窗体的KeyPress事件处理方法中的属性true设置为。To handle keyboard events only at the form level and not enable other controls to receive keyboard events, set the KeyPressEventArgs.Handled property in your form's KeyPress event-handling method to true. 某些键(如 TAB、RETURN、ESC 和箭头键)会自动由控件处理。Certain keys, such as the TAB, RETURN, ESC, and arrow keys are handled by controls automatically. 若要使这些键引发KeyUp事件,必须重写窗IsInputKey体上每个控件中的方法。To have these keys raise the KeyUp event, you must override the IsInputKey method in each control on your form. 重写的IsInputKey代码需要确定是否按下了一个特殊键并返回true值。The code for the override of IsInputKey would need to determine if one of the special keys is pressed and return a value of true.

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