鍵盤響應事件總結

鍵盤響應事件是在使用者按下某個鍵後觸發的事件，可以是任意操作，但不是任意鍵都可以被捕獲的。

原型：public event KeyPressEventHandler KeyPress
MSDN說明：鍵事件按以下順序發生：
1.KeyDown
2.KeyPress
3.KeyUp
KeyPress 事件不能由非字元鍵引發；但是非字元鍵能夠引發 KeyDown 和 KeyUp事件。
使用 KeyChar 屬性取樣執行時的鍵擊，以及使用或修改常用鍵擊的一個子集。
若要僅在窗體級別處理鍵盤事件而不允許其他控制元件接收鍵盤事件，請將窗體的 KeyPress 事件處理方法中的KeyPressEventArgs.Handled 屬性設定為 true。

MSDN

下面的程式碼示例使用 KeyPress事件來禁止向控制元件輸入字元。

 // 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;
            }
        }

鍵值對照表

PS：以上表格的匯入如果使用Makedown語法顯然不太合適，這裡我使用表格自動轉換HTML語法的網站，非常方便，連結如下：線上HTML格式轉換