下面的函數,GetCharFromKey(Key key)會做的。
它採用了一系列的Win32調用來解碼按下的鍵:
得到virtual key from WPF key
得到scan code from the virtual key
得到your unicode character
這old post更詳細地描述了它。
public enum MapType : uint
{
MAPVK_VK_TO_VSC = 0x0,
MAPVK_VSC_TO_VK = 0x1,
MAPVK_VK_TO_CHAR = 0x2,
MAPVK_VSC_TO_VK_EX = 0x3,
}
[DllImport("user32.dll")]
public static extern int ToUnicode(
uint wVirtKey,
uint wScanCode,
byte[] lpKeyState,
[Out, MarshalAs(UnmanagedType.LPWStr, SizeParamIndex = 4)]
StringBuilder pwszBuff,
int cchBuff,
uint wFlags);
[DllImport("user32.dll")]
public static extern bool GetKeyboardState(byte[] lpKeyState);
[DllImport("user32.dll")]
public static extern uint MapVirtualKey(uint uCode, MapType uMapType);
public static char GetCharFromKey(Key key)
{
char ch = ' ';
int virtualKey = KeyInterop.VirtualKeyFromKey(key);
byte[] keyboardState = new byte[256];
GetKeyboardState(keyboardState);
uint scanCode = MapVirtualKey((uint)virtualKey, MapType.MAPVK_VK_TO_VSC);
StringBuilder stringBuilder = new StringBuilder(2);
int result = ToUnicode((uint)virtualKey, scanCode, keyboardState, stringBuilder, stringBuilder.Capacity, 0);
switch (result)
{
case -1:
break;
case 0:
break;
case 1:
{
ch = stringBuilder[0];
break;
}
default:
{
ch = stringBuilder[0];
break;
}
}
return ch;
}
我一直在使用這一段時間,並注意到一個錯誤。兩個鍵從GetCharFromKey返回相同的結果。要驗證,只需簡單地爲TextBox創建子類,重寫PreiewKeyDown,敲擊空格鍵(它是32個字符),然後觸擊Delete鍵,同時返回32個字符。有沒有人看到這個? – gcadmes 2013-06-04 13:40:48
那真是令人h噓...... GetCharFromKey中的第一條語句是char ch ='';。因此,對於落入'0'或'1'的情況,返回字符總是空格(char)32。 (前額一巴掌) – gcadmes 2013-06-04 15:48:32
對於不生成文本字符的鍵或者((char?)null),它確實應該返回''\ 0''。 – jnm2 2014-05-19 13:37:06