在 KeyDown 事件中检测单引号键

Question

我希望 TextBox 通过使用 KeyDown 事件只接受一些特定的字符。我已经让它工作了，除了一个字符，单引号。为了获得将要写入的字符，我使用 (char)e.KeyValue 它适用于除引号之外的所有字符（它给出 Û）。我知道我可以只使用 e.KeyCode 但它的值是 Keys.Oem4，AFAIK 可能因系统而异。

有什么方法可以持续检测单引号按键吗？

代码片段：

char c = (char)e.KeyValue;
char[] moves = { 'r', 'u', ..., '\'' };

if (!(moves.Contains(c) || e.KeyCode == Keys.Back || e.KeyCode == Keys.Space))
{
    e.SuppressKeyPress = true;
}

Answer 1

正如@EdPlunkett 所建议的，this answer 对我有用：

[DllImport("user32.dll")]
static extern bool GetKeyboardState(byte[] lpKeyState);

[DllImport("user32.dll")]
static extern uint MapVirtualKey(uint uCode, uint uMapType);

[DllImport("user32.dll")]
static extern IntPtr GetKeyboardLayout(uint idThread);

[DllImport("user32.dll")]
static extern int ToUnicodeEx(uint wVirtKey, uint wScanCode, byte[] lpKeyState, [Out, MarshalAs(UnmanagedType.LPWStr)] StringBuilder pwszBuff, int cchBuff, uint wFlags, IntPtr dwhkl);


public static string KeyCodeToUnicode(System.Windows.Forms.Keys key)
{
    byte[] keyboardState = new byte[255];
    bool keyboardStateStatus = GetKeyboardState(keyboardState);

    if (!keyboardStateStatus)
    {
        return "";
    }

    uint virtualKeyCode = (uint)key;
    uint scanCode = MapVirtualKey(virtualKeyCode, 0);
    IntPtr inputLocaleIdentifier = GetKeyboardLayout(0);

    StringBuilder result = new StringBuilder();
    ToUnicodeEx(virtualKeyCode, scanCode, keyboardState, result, (int)5, (uint)0, inputLocaleIdentifier);

    return result.ToString();
}

Answer 2

我已经用了很长时间了。它可以很好地处理单引号。 e.KeyChar == 39 '\'' 和 e.Handled = true 的行为完全符合您的预期。我用 KeyPress 事件测试了它并且也在那里工作。

    protected override void OnKeyPress(KeyPressEventArgs e)
    {
        base.OnKeyPress(e);
        if (e.KeyChar == (char)8) // backspace
            return;
        if (e.KeyChar == (char)3) // ctrl + c
            return;
        if (e.KeyChar == (char)22) // ctrl + v
            return;
        typedkey = true;
        if (_allowedCharacters.Count > 0) // if the string of allowed characters is not empty, skip test if empty
        {
            if (!_allowedCharacters.Contains(e.KeyChar)) // if the new character is not in allowed set,
            {
                e.Handled = true; // ignoring it
                return;
            }
        }
        if (_disallowedCharacters.Count > 0) // if the string of allowed characters is not empty, skip test if empty
        { 
            if (_disallowedCharacters.Contains(e.KeyChar)) // if the new character is in disallowed set,
            {
                e.Handled = true; // ignoring it
                return;
            }
        }
    }

在 KeyDown 事件中检测单引号键

Detect single quote key on KeyDown event

c#

keypress

winforms

single-quotes