Control.KeyUp 事件

定义

命名空间:

System.Windows.Forms

程序集:

System.Windows.Forms.dll

Source:

Control.cs

在控件有焦点的情况下释放键时发生。

C#

public event System.Windows.Forms.KeyEventHandler? KeyUp;

事件类型

KeyEventHandler

示例

下面的代码示例将 事件与 类一 KeyUp 起使用 Help ，向用户显示弹出样式帮助。

C#

// 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));
    }
}

下面的代码示例演示了 、 KeyUp 和 KeyPress 事件的上升KeyDown顺序，以及如何在它们上注册事件处理程序。

C#

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");
    }
}

注解

关键事件按以下顺序发生：

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，请将窗体的事件KeyPress处理方法中的 属性设置为 。KeyPressEventArgs.Handledtrue 某些键（如 TAB、RETURN、ESC 和箭头键）由控件自动处理。 若要让这些键引发 KeyUp 事件，必须重写 IsInputKey 窗体上每个控件中的 方法。 重写 IsInputKey 的代码需要确定是否按下了一个特殊键并返回值 true。

有关处理事件的详细信息，请参阅 处理和引发事件。

适用于

另请参阅

• OnKeyUp(KeyEventArgs)
• KeyDown
• KeyPress