Windows Unicode键盘钩

Question

I'm developing an application that in some point needs to capture the keyboard and mouse user input. I had no problems installing and using the mouse hook, but the keyboard is not working properly. I need to capture wide characters from multiple keyboard layouts. I found something relevant but did not solve my problem: https://stackoverflow.com/questions/15976108/keyboard-hook-not-capturing-unicode-in-other-threads

That's what I have without the not necessary stuff

WinMain:

//Set the hook, with threadId = 0
hHook = SetWindowsHookEx(WH_KEYBOARD_LL, KeyboardProc, hInstance, 0); 
HKL keyboardLayout = GetKeyboardLayout(0);
//All the window and message queue code

KeyboardProc:

WCHAR unicodeChar;
BYTE keyboardLayout[256];
KBDLLHOOKSTRUCT* keyParam = (KBDLLHOOKSTRUCT*) lParam;

if(code < 0)
    return CallNextHookEx(hHook, code, wParam, lParam);

if(wParam == WM_KEYDOWN)
{
    GetKeyboardState(keyboardState);

    int translation = ToUnicodeEx(keyParam->vkCode, keyParam->scanCode, keyboardState, &unicodeChar, 1, 0, keyboardLayout);
    translation = ToUnicodeEx(keyParam->vkCode, keyParam->scanCode, keyboardState, &unicodeChar, 1, 0, keyboardLayout);

    if(translation == 0 )//|| translation == -1)
        return 0;

    PushToBuffer(&unicodeChar);
}

//return CallNextHookEx(hHook, code, wParam, lParam);
return 0;

I left the commented code to show what I've already tried based on that post I mentioned and MSDN documentation. The push to buffer receives a wchar_t pointer and stores it in a wstring used as a buffer, that dumps in a wofstream.

What happens:

If I call ToUnicodeEx once, the user input is modified and any dead-key is shown twice for him: for example, in a International English Layout, where you press ' then a to print an á, it shows: ''a. With the application closed the user input goes back to normal.

If I call ToUnicodeEx twice, the dead-key is consumed and I simply the char is shown.

I wonder why the user input is being modified, since I do not change any of the parameters given by the callback caller. Is unicode not possible for low-level hooks?

Answer 1

ToUnicodeEx is broken when it comes to dead keys. This is what your looking for: https://code.google.com/p/jnativehook/source/browse/tags/1.1.4/src/native/windows/WinUnicodeHelper.c