Question

我有一个USB键盘，有一些特殊的键，如＆＃34; FN＆＃34;，PLAY，MUTE和一个改变键盘灯的键。我试图得到这个关键字＆＃34; name＆＃34;执行逻辑以定期更改颜色。

private void textBox1_TextChanged(object sender, EventArgs e)
    {
        var key = sender as TextBox;

        var result = key.Text;
    }

但关键不是要识别的字符串。我怎样才能做到这一点？谢谢！

Answer 1

我建议您使用OnKeyPress和OnKeyDown事件来检查被按下的内容。 MSDN Link。
例如：

// 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;
    }
}

如何使用C＃从键盘检测自定义键

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