Win32 key translation code outputting unwanted key-presses

Question

I'm using the following code to get an unicode string of a keyboard state:

std::wstring App::DecodeMessage(KBDLLHOOKSTRUCT* kbHook) {
    // Clean up the keyboard state
    for(int i=0; i<256; ++i) keyboardMap[i] = 0;

    // Get the state of all the virtual keys
    GetKeyboardState(keyboardMap);

    // Then we get the current layout setting
    HKL kbdLayout = GetKeyboardLayout(0);

    // We create the buffer to receive the unicode chars
    std::vector<wchar_t> buffer;
    buffer.resize(257);
    buffer.assign(257, L'\0');

    // And finally we translate all this to an unicode char
    int numberOfChars = ToUnicode(kbHook->vkCode, kbHook->scanCode, keyboardMap, &buffer[0], 256, 0);

    if(numberOfChars >= -1 && numberOfChars <= 0) return std::wstring(L"");

    return std::wstring(&buffer[0], numberOfChars);
}

My keyboard layout is US-INTL, and without the app running, when i press "'" (simple quote), and on a second keystroke i press "a", i get á. However, with this function, when i press "'" (simple quote again) i actually get ANOTHER single quote in whatever app i'm focused. Also, it doesn't seem to get the encoding right, as it won't record á. I'm clueless, can anyone help?

Answer 1

So i finally sorted it out to not using ToUnicode. I ended up using the solution created by Marc-André Moreau, found available at http://keymagic.googlecode.com/svn-history/r112/trunk/KeyMagicDll/kbdext.cpp, if anyone is interested.