Processing the WM_IME_COMPOSITION Message

An IME-aware application that processes the WM_IME_COMPOSITION message tests the bits in lParam parameter and calls the ImmGetCompositionString function to retrieve the indicated string or data. The following example checks for the result string, allocates sufficient memory for the string, and retrieves the result string from the IME.

HIMC hIMC;
DWORD dwSize;
HGLOBAL hstr;
LPSTR lpstr;

case WM_IME_COMPOSITION:
    if (lParam & GCS_RESULTSTR) 
    {
        hIMC = ImmGetContext(hWnd);

        if (!hIMC)
            MyError(ERROR_NULLCONTEXT);

        // Get the size of the result string. 
        dwSize = ImmGetCompositionString(hIMC, GCS_RESULTSTR, NULL, 0);

        // increase buffer size for terminating null character,  
        //   maybe it is in UNICODE 
        dwSize += sizeof(WCHAR);

        hstr = GlobalAlloc(GHND,dwSize);
        if (hstr == NULL)
             MyError(ERROR_GLOBALALLOC);

        lpstr = (LPSTR)GlobalLock(hstr);
        if (lpstr == NULL)
             MyError(ERROR_GLOBALLOCK);

        // Get the result strings that is generated by IME into lpstr. 
        ImmGetCompositionString(hIMC, GCS_RESULTSTR, lpstr, dwSize);
        ImmReleaseContext(hWnd, hIMC);

        // add this string into text buffer of application 

        GlobalUnlock(hstr);
        GlobalFree(hstr);
    }

Using Input Method Manager