KeyEventArgs.KeyCode 屬性

定義

命名空間:

System.Windows.Forms

組件:

System.Windows.Forms.dll

取得 KeyDown 或 KeyUp 事件的鍵盤程式碼。

C#

public System.Windows.Forms.Keys KeyCode { get; }

屬性值

Keys

Keys 值是事件的按鍵碼。

範例

下列程式碼範例示範如何使用 KeyCode 屬性來判斷按下的按鍵。

範例 1

下列程式碼範例示範如何使用 KeyDown 事件搭配 Help 類別來顯示應用程式的快顯樣式說明。 此範例會 KeyEventArgs 使用傳遞至事件處理常式方法的屬性，篩選使用修飾詞按鍵按下 F1 鍵的所有變化。 當使用者按下包含任何鍵盤修飾詞的任何 F1 變化時， Help 類別會顯示類似 ToolTip 控制項附近的快顯視窗。 如果使用者按下 ALT+F2，則會顯示其他 [說明] 快顯視窗並顯示其他資訊。

C#

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));
    }
}

範例 2

下列範例會判斷使用者是否按下 ALT+E，以及滑鼠指標是否位於 上方 TreeNode ，允許使用者編輯該 TreeNode 。

C#

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 mouse 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;
}

範例 3

下列範例會判斷使用者是否按下非數值索引鍵，如果是，則使用 Handled 屬性取消 KeyPress 事件。

C#

// 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;
    }
}

適用於

另請參閱

• KeyData
• KeyValue