KeyPressEventArgs 类

定义

KeyPress 事件提供数据。Provides data for the KeyPress event.

public ref class KeyPressEventArgs : EventArgs
[System.Runtime.InteropServices.ComVisible(true)]
public class KeyPressEventArgs : EventArgs
type KeyPressEventArgs = class
    inherit EventArgs
Public Class KeyPressEventArgs
Inherits EventArgs
继承
KeyPressEventArgs
属性

示例

下面的示例演示如何使用KeyPressEventArgs在按下键时对键进行计数,并在每次按键后显示结果。The following example illustrates using the KeyPressEventArgs to count keys as they are pressed and to display the results after each key press. Handled然后,将设置为 true,以防止操作系统进一步处理该键。Handled is then set to true to keep the operating system from further processing the key. 该示例假设有一个TextBox放置在该窗体上的窗体。The example assumes a form with a TextBox placed on it.

public ref class myKeyPressClass
{
private:
   static long keyPressCount = 0;
   static long backspacePressed = 0;
   static long returnPressed = 0;
   static long escPressed = 0;
   TextBox^ textBox1;
   void myKeyCounter( Object^ sender, KeyPressEventArgs^ ex )
   {
      switch ( ex->KeyChar )
      {
            // Counts the backspaces.
         case '\b':
         backspacePressed = backspacePressed + 1;
         break;

            // Counts the ENTER keys.
         case '\r':
         returnPressed = returnPressed + 1;
         break;

            // Counts the ESC keys.  
         case (char)27:
         escPressed = escPressed + 1;
         break;
            
            // Counts all other keys.
         default:
         keyPressCount = keyPressCount + 1;
         break;
      }
      textBox1->Text = String::Concat( 
         backspacePressed, " backspaces pressed\r\n",
         escPressed, " escapes pressed\r\n",
         returnPressed, " returns pressed\r\n",
         keyPressCount, " other keys pressed\r\n" );
      ex->Handled = true;
   }
};
public class myKeyPressClass 
 {
     static long keyPressCount = 0 ;
     static long backspacePressed =  0;
     static long returnPressed = 0 ;
     static long escPressed = 0 ;
     private TextBox textBox1 = new TextBox();
     private void myKeyCounter(object sender, KeyPressEventArgs ex)
     {
     switch(ex.KeyChar)
     {
             // Counts the backspaces.
         case '\b':
         backspacePressed = backspacePressed + 1;
         break ;
             // Counts the ENTER keys.
         case '\r':
         returnPressed = returnPressed + 1 ;
         break ;
             // Counts the ESC keys.  
         case (char)27:
         escPressed = escPressed + 1 ;
         break ;
             // Counts all other keys.
         default:
         keyPressCount = keyPressCount + 1 ;
         break;
     }
     
     textBox1.Text = 
         backspacePressed + " backspaces pressed\r\n" + 
         escPressed + " escapes pressed\r\n" +
         returnPressed + " returns pressed\r\n" +
         keyPressCount + " other keys pressed\r\n" ;
     ex.Handled = true ;
     }
 }
Public Class myKeyPressClass
    Private Shared keyPressCount As Long = 0
    Private Shared backspacePressed As Long = 0
    Private Shared returnPressed As Long = 0
    Private Shared escPressed As Long = 0
    Private textBox1 As TextBox
    
    Private Sub myKeyCounter(sender As Object, ex As KeyPressEventArgs)
        Select Case ex.KeyChar
            ' Counts the backspaces.
            Case ControlChars.Back
                backspacePressed = backspacePressed + 1
            ' Counts the ENTER keys.
            Case ControlChars.Lf
                returnPressed = returnPressed + 1
            ' Counts the ESC keys.  
            Case Convert.ToChar(27)
                escPressed = escPressed + 1
            ' Counts all other keys.
            Case Else
                keyPressCount = keyPressCount + 1
        End Select
        
        textBox1.Text = backspacePressed & " backspaces pressed" & _
            ControlChars.Lf & ControlChars.Cr & escPressed & _
            " escapes pressed" & ControlChars.CrLf & returnPressed & _
            " returns pressed" & ControlChars.CrLf & keyPressCount & _
            " other keys pressed" & ControlChars.CrLf
        ex.Handled = True
    End Sub
End Class

必须创建此类的新实例。You must create a new instance of this class. 还必须设置事件处理程序。You must also set the event handler. 可以在类的构造函数中执行此操作。You can do this in the constructor for your class.

public:
   myKeyPressClass^ myKeyPressHandler;

   Form1()
   {
      myKeyPressHandler = gcnew myKeyPressClass;

      InitializeComponent();

      textBox1->KeyPress += gcnew KeyPressEventHandler(
         myKeyPressHandler, &myKeyPressClass::myKeyCounter );
   }
myKeyPressClass myKeyPressHandler = new myKeyPressClass();
public Form1()
{
     InitializeComponent();
 
     textBox1.KeyPress += new KeyPressEventHandler(myKeyPressHandler.myKeyCounter);
}
Private myKeyPressHandler As New myKeyPressClass()

Public Sub New()
    InitializeComponent()
    
    AddHandler textBox1.KeyPress, AddressOf myKeyPressHandler.myKeyCounter
End Sub

当在控件中引发指定的事件时,将调用附加的方法,并且应用程序可以执行代码以响应事件。When the specified event is raised in the control, the attached method is called and the application can execute code in response to the event.

注解

KeyPressEventArgs指定当用户按下某个键时构成的字符。A KeyPressEventArgs specifies the character that is composed when the user presses a key. 例如,当用户按下 SHIFT + K 时,属性KeyChar将返回一个大写的 K。For example, when the user presses SHIFT + K, the KeyChar property returns an uppercase K.

KeyPress用户按下某个键时,将发生事件。A KeyPress event occurs when the user presses a key. KeyPress事件密切相关的两个事件为KeyUpKeyDownTwo events that are closely related to the KeyPress event are KeyUp and KeyDown. KeyDown用户按下某个键时,KeyPress事件位于每个事件的前面,当用户释放某个键时,将发生事件。KeyUpThe KeyDown event precedes each KeyPress event when the user presses a key, and a KeyUp event occurs when the user releases a key. 当用户按下某个键时,重复KeyDown KeyPress ,每次重复该字符时,都会发生事件。When the user holds down a key, duplicate KeyDown and KeyPress events occur each time the character repeats. 发布KeyUp时,将生成一个事件。One KeyUp event is generated upon release.

对于每KeyPress个事件KeyPressEventArgs ,都传递。With each KeyPress event, a KeyPressEventArgs is passed. 通过每个KeyDownKeyUp事件传递。 KeyEventArgsA KeyEventArgs is passed with each KeyDown and KeyUp event. 指定KeyEventArgs是否将任何修改键(CTRL、SHIFT 或 ALT)与另一个键一起使用。A KeyEventArgs specifies whether any modifier keys (CTRL, SHIFT, or ALT) were pressed along with another key. (也可以通过ModifierKeys Control类的属性获取此修饰符信息。)(This modifier information can also be obtained through the ModifierKeys property of the Control class.)

设置Handledtrue可取消KeyPress事件。Set Handled to true to cancel the KeyPress event. 这会使控件不会按下键进行处理。This keeps the control from processing the key press.

备注

某些控件将在上KeyDown处理某些关键笔画。Some controls will process certain key strokes on KeyDown. 例如, RichTextBox在调用之前KeyPress处理 Enter 键。For example, RichTextBox processes the Enter key before KeyPress is called. 在这种情况下,不能KeyPress取消事件,而必须取消中KeyDown的键笔划。In such cases, you cannot cancel the KeyPress event, and must cancel the key stroke from KeyDown instead.

有关事件模型的信息,请参阅处理和引发事件For information about the event model, see Handling and Raising Events.

构造函数

KeyPressEventArgs(Char)

初始化 KeyPressEventArgs 类的新实例。Initializes a new instance of the KeyPressEventArgs class.

属性

Handled

获取或设置一个值,该值指示是否处理过 KeyPress 事件。Gets or sets a value indicating whether the KeyPress event was handled.

KeyChar

获取或设置与按下的键对应的字符。Gets or sets the character corresponding to the key pressed.

方法

Equals(Object)

确定指定的对象是否等于当前对象。Determines whether the specified object is equal to the current object.

(继承自 Object)
GetHashCode()

用作默认哈希函数。Serves as the default hash function.

(继承自 Object)
GetType()

获取当前实例的 TypeGets the Type of the current instance.

(继承自 Object)
MemberwiseClone()

创建当前 Object 的浅表副本。Creates a shallow copy of the current Object.

(继承自 Object)
ToString()

返回一个表示当前对象的 string。Returns a string that represents the current object.

(继承自 Object)

适用于

另请参阅