KeyEventArgs KeyEventArgs KeyEventArgs KeyEventArgs Class

定义

KeyDownKeyUp 事件提供数据。Provides data for the KeyDown or KeyUp event.

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

示例

下面的代码示例演示如何检测按键的状态。The following code examples demonstrate how to detect the state of a key press.

示例1Example 1

下面的代码示例演示如何将KeyDown事件Help与类一起使用来向应用程序的用户显示弹出式样式帮助。The following code example demonstrates how to use the KeyDown event with the Help class to display pop-up style Help to the user of the application. 该示例使用KeyEventArgs传递给事件处理程序方法的属性来筛选按 F1 键和修改键的所有变体。The example uses the KeyEventArgs properties passed to the event handler method to filter for all variations of pressing the F1 key with a modifier key. 当用户按下包含任何键盘修饰符的 F1 的任何变体时Help , 类将在控件附近显示一个弹出窗口, ToolTip该窗口类似于。When the user presses any variation of F1 that includes any keyboard modifier, the Help class displays a pop-up window, similar to a ToolTip, near the control. 如果用户按 ALT + F2, 将显示不同的帮助弹出窗口, 其中显示了其他信息。If the user presses ALT+F2, a different Help pop-up is displayed with additional information.

   // This example demonstrates how to use the KeyDown event with the Help class to display
   // pop-up style help to the user of the application. The example filters for all variations
   // of pressing the F1 key with a modifier key by using the KeyEventArgs properties passed
   // to the event handling method.
   // When the user presses any variation of F1 that includes any keyboard modifier, the Help
   // class displays a pop-up window, similar to a ToolTip, near the control. If the user presses
   // ALT + F2, a different Help pop-up is displayed with additional information. This example assumes
   // that a tTextBox control, named textBox1, has been added to the form and its KeyDown
   // event has been contected to this event handling method.
private:
   void textBox1_KeyDown( Object^ /*sender*/, System::Windows::Forms::KeyEventArgs^ e )
   {
      // Determine whether the key entered is the F1 key. If it is, display Help.
      if ( e->KeyCode == Keys::F1 && (e->Alt || e->Control || e->Shift) )
      {
         
         // Display a pop-up Help topic to assist the user.
         Help::ShowPopup( textBox1, "Enter your name.", Point(textBox1->Bottom,textBox1->Right) );
      }
      else
      if ( e->KeyCode == Keys::F2 && e->Modifiers == Keys::Alt )
      {
         // Display a pop-up Help topic to provide additional assistance to the user.
         Help::ShowPopup( textBox1, "Enter your first name followed by your last name. Middle name is optional.",
            Point(textBox1->Top,this->textBox1->Left) );
      }
   }
private void textBox1_KeyDown(object sender, System.Windows.Forms.KeyEventArgs e)
{
    // Determine whether the key entered is the F1 key. If it is, display Help.
    if(e.KeyCode == Keys.F1 && (e.Alt || e.Control || e.Shift))
    {
        // Display a pop-up Help topic to assist the user.
        Help.ShowPopup(textBox1, "Enter your name.", new Point(textBox1.Bottom, textBox1.Right));
    }
    else if(e.KeyCode == Keys.F2 && e.Modifiers == Keys.Alt)
    {
        // Display a pop-up Help topic to provide additional assistance to the user.
        Help.ShowPopup(textBox1, "Enter your first name followed by your last name. Middle name is optional.",
            new Point(textBox1.Top, this.textBox1.Left));
    }
}
Private Sub textBox1_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles textBox1.KeyDown
    ' Determine whether the key entered is the F1 key. If it is, display Help.
    If e.KeyCode = Keys.F1 AndAlso (e.Alt OrElse e.Control OrElse e.Shift) Then
        ' Display a pop-up Help topic to assist the user.
        Help.ShowPopup(textBox1, "Enter your name.", New Point(textBox1.Bottom, textBox1.Right))
    ElseIf e.KeyCode = Keys.F2 AndAlso e.Modifiers = Keys.Alt Then
        ' Display a pop-up Help topic to provide additional assistance to the user.
        Help.ShowPopup(textBox1, "Enter your first name followed by your last name. Middle name is optional.", _
             New Point(textBox1.Top, Me.textBox1.Left))
    End If
End Sub

示例2Example 2

下面的示例确定用户是否按下了 ALT + E, 如果鼠标指针位于TreeNode, 则允许用户对其进行TreeNode编辑。The following example determines whether the user pressed ALT+E, and if the mouse pointer is over a TreeNode, allows the user to edit that TreeNode.

private:
   void treeView1_KeyDown( Object^ /*sender*/, KeyEventArgs^ e )
   {
      /* If the 'Alt' and 'E' keys are pressed,
         * allow the user to edit the TreeNode label. */
      if ( e->Alt && e->KeyCode == Keys::E )
      {
         treeView1->LabelEdit = true;
         
         // If there is a TreeNode under the mose cursor, begin editing.
         TreeNode^ editNode = treeView1->GetNodeAt( treeView1->PointToClient( Control::MousePosition ) );
         if ( editNode != nullptr )
         {
            editNode->BeginEdit();
         }
      }
   }

   void treeView1_AfterLabelEdit( Object^ /*sender*/, NodeLabelEditEventArgs^ /*e*/ )
   {
      // Disable the ability to edit the TreeNode labels.
      treeView1->LabelEdit = false;
   }
private void treeView1_KeyDown(object sender, KeyEventArgs e)
{
   /* If the 'Alt' and 'E' keys are pressed,
      * allow the user to edit the TreeNode label. */
   if(e.Alt && e.KeyCode == Keys.E)
         
   {
      treeView1.LabelEdit = true;
      // If there is a TreeNode under the mose cursor, begin editing. 
      TreeNode editNode = treeView1.GetNodeAt(
         treeView1.PointToClient(System.Windows.Forms.Control.MousePosition));
      if(editNode != null)
      { 
         editNode.BeginEdit();
      }
   }
}

private void treeView1_AfterLabelEdit(object sender, NodeLabelEditEventArgs e)
{
   // Disable the ability to edit the TreeNode labels.
   treeView1.LabelEdit = false;
}
Private Sub treeView1_KeyDown(sender As Object, _
  e As KeyEventArgs) Handles treeView1.KeyDown
   ' If the 'Alt' and 'E' keys are pressed,
   ' allow the user to edit the TreeNode label. 
   If e.Alt And e.KeyCode = Keys.E Then
      treeView1.LabelEdit = True
      ' If there is a TreeNode under the mose cursor, begin editing. 
      Dim editNode As TreeNode = treeView1.GetNodeAt( _
        treeView1.PointToClient(System.Windows.Forms.Control.MousePosition))
      If (editNode IsNot Nothing) Then
         editNode.BeginEdit()
      End If
   End If
End Sub

Private Sub treeView1_AfterLabelEdit(sender As Object, _
  e As NodeLabelEditEventArgs) Handles treeView1.AfterLabelEdit
   ' Disable the ability to edit the TreeNode labels.
   treeView1.LabelEdit = False
End Sub

示例3Example 3

下面的示例确定用户是否按了非数值键, 如果是, 则KeyPress Handled使用属性取消事件。The following example determines whether the user pressed a non-numeric key, and if so, cancels the KeyPress event by using the Handled property.

   // Boolean flag used to determine when a character other than a number is entered.
private:
   bool nonNumberEntered;

   // Handle the KeyDown event to determine the type of character entered into the control.
   void textBox1_KeyDown( Object^ /*sender*/, System::Windows::Forms::KeyEventArgs^ e )
   {
      // Initialize the flag to false.
      nonNumberEntered = false;

      // Determine whether the keystroke is a number from the top of the keyboard.
      if ( e->KeyCode < Keys::D0 || e->KeyCode > Keys::D9 )
      {
         // Determine whether the keystroke is a number from the keypad.
         if ( e->KeyCode < Keys::NumPad0 || e->KeyCode > Keys::NumPad9 )
         {
            // Determine whether the keystroke is a backspace.
            if ( e->KeyCode != Keys::Back )
            {
               // A non-numerical keystroke was pressed.
               // Set the flag to true and evaluate in KeyPress event.
               nonNumberEntered = true;
            }
         }
      }
      //If shift key was pressed, it's not a number.
      if (Control::ModifierKeys == Keys::Shift) {
         nonNumberEntered = true;
      }
   }

   // This event occurs after the KeyDown event and can be used to prevent
   // characters from entering the control.
   void textBox1_KeyPress( Object^ /*sender*/, System::Windows::Forms::KeyPressEventArgs^ e )
   {
      // Check for the flag being set in the KeyDown event.
      if ( nonNumberEntered == true )
      {         // Stop the character from being entered into the control since it is non-numerical.
         e->Handled = true;
      }
   }
// Boolean flag used to determine when a character other than a number is entered.
private bool nonNumberEntered = false;

// Handle the KeyDown event to determine the type of character entered into the control.
private void textBox1_KeyDown(object sender, System.Windows.Forms.KeyEventArgs e)
{
    // Initialize the flag to false.
    nonNumberEntered = false;

    // Determine whether the keystroke is a number from the top of the keyboard.
    if (e.KeyCode < Keys.D0 || e.KeyCode > Keys.D9)
    {
        // Determine whether the keystroke is a number from the keypad.
        if (e.KeyCode < Keys.NumPad0 || e.KeyCode > Keys.NumPad9)
        {
            // Determine whether the keystroke is a backspace.
            if(e.KeyCode != Keys.Back)
            {
                // A non-numerical keystroke was pressed.
                // Set the flag to true and evaluate in KeyPress event.
                nonNumberEntered = true;
            }
        }
    }
    //If shift key was pressed, it's not a number.
    if (Control.ModifierKeys == Keys.Shift) {
        nonNumberEntered = true;
    }
}

// This event occurs after the KeyDown event and can be used to prevent
// characters from entering the control.
private void textBox1_KeyPress(object sender, System.Windows.Forms.KeyPressEventArgs e)
{
    // Check for the flag being set in the KeyDown event.
    if (nonNumberEntered == true)
    {
        // Stop the character from being entered into the control since it is non-numerical.
        e.Handled = true;
    }
}

' Boolean flag used to determine when a character other than a number is entered.
Private nonNumberEntered As Boolean = False


' Handle the KeyDown event to determine the type of character entered into the control.
Private Sub textBox1_KeyDown(sender As Object, e As System.Windows.Forms.KeyEventArgs) _
     Handles textBox1.KeyDown
    ' Initialize the flag to false.
    nonNumberEntered = False
  
    ' Determine whether the keystroke is a number from the top of the keyboard.
    If e.KeyCode < Keys.D0 OrElse e.KeyCode > Keys.D9 Then
        ' Determine whether the keystroke is a number from the keypad.
        If e.KeyCode < Keys.NumPad0 OrElse e.KeyCode > Keys.NumPad9 Then
            ' Determine whether the keystroke is a backspace.
            If e.KeyCode <> Keys.Back Then
                ' A non-numerical keystroke was pressed. 
                ' Set the flag to true and evaluate in KeyPress event.
                nonNumberEntered = True
            End If
        End If
    End If
    'If shift key was pressed, it's not a number.
    If Control.ModifierKeys = Keys.Shift Then
        nonNumberEntered = true
    End If
End Sub


' This event occurs after the KeyDown event and can be used 
' to prevent characters from entering the control.
Private Sub textBox1_KeyPress(sender As Object, e As System.Windows.Forms.KeyPressEventArgs) _
    Handles textBox1.KeyPress
    ' Check for the flag being set in the KeyDown event.
    If nonNumberEntered = True Then
        ' Stop the character from being entered into the control since it is non-numerical.
        e.Handled = True
    End If
End Sub

注解

一个KeyEventArgs, 它指定用户按下的键以及是否同时按下任何修改键 (CTRL、ALT 和 SHIFT), 并与每个KeyDownKeyUp事件一起传递。A KeyEventArgs, which specifies the key the user pressed and whether any modifier keys (CTRL, ALT, and SHIFT) were pressed at the same time, is passed with each KeyDown or KeyUp event.

KeyDown用户按任意键时发生此事件。The KeyDown event occurs when the user presses any key. 用户KeyUp释放密钥时发生此事件。The KeyUp event occurs when the user releases the key. 如果KeyDown键已关闭, 但在用户释放密钥时只会生成一个KeyUp事件, 则每次键重复时, 都会发生重复的事件。Duplicate KeyDown events occur each time the key repeats, if the key is held down, but only one KeyUp event is generated when the user releases the key.

KeyPress下某个键时, 也会发生该事件。The KeyPress event also occurs when a key is pressed. 随每个KeyPress事件传递, 并指定作为每个按键的结果而构成的字符。 KeyPressEventArgsA KeyPressEventArgs is passed with each KeyPress event, and specifies the character that was composed as a result of each key press.

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

KeyEventArgs(Keys) KeyEventArgs(Keys) KeyEventArgs(Keys) KeyEventArgs(Keys)

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

属性

Alt Alt Alt Alt

获取一个值,该值指示是否曾按下 Alt 键。Gets a value indicating whether the ALT key was pressed.

Control Control Control Control

获取一个值,该值指示是否曾按下 Ctrl 键。Gets a value indicating whether the CTRL key was pressed.

Handled Handled Handled Handled

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

KeyCode KeyCode KeyCode KeyCode

获取 KeyDownKeyUp 事件的键盘代码。Gets the keyboard code for a KeyDown or KeyUp event.

KeyData KeyData KeyData KeyData

获取 KeyDownKeyUp 事件的键数据。Gets the key data for a KeyDown or KeyUp event.

KeyValue KeyValue KeyValue KeyValue

获取 KeyDownKeyUp 事件的键盘值。Gets the keyboard value for a KeyDown or KeyUp event.

Modifiers Modifiers Modifiers Modifiers

获取 KeyDownKeyUp 事件的修饰符标志。Gets the modifier flags for a KeyDown or KeyUp event. 这些标志指示按下的 Ctrl、Shift 和 Alt 键的组合。The flags indicate which combination of CTRL, SHIFT, and ALT keys was pressed.

Shift Shift Shift Shift

获取一个值,该值指示是否曾按下 Shift 键。Gets a value indicating whether the SHIFT key was pressed.

SuppressKeyPress SuppressKeyPress SuppressKeyPress SuppressKeyPress

获取或设置一个值,该值指示键事件是否应传递到基础控件。Gets or sets a value indicating whether the key event should be passed on to the underlying control.

方法

Equals(Object) Equals(Object) Equals(Object) 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.

(Inherited from Object)
GetHashCode() GetHashCode() GetHashCode() GetHashCode()

作为默认哈希函数。Serves as the default hash function.

(Inherited from Object)
GetType() GetType() GetType() GetType()

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

(Inherited from Object)
MemberwiseClone() MemberwiseClone() MemberwiseClone() MemberwiseClone()

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

(Inherited from Object)
ToString() ToString() ToString() ToString()

返回表示当前对象的字符串。Returns a string that represents the current object.

(Inherited from Object)

适用于

另请参阅