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Sample Code to Override an API in the Microsoft Layer for Unicode

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The following sample code demonstrates how to override the LoadCursor function in the Microsoft Layer for Unicode.

// forward declare of override
HCURSOR __stdcall UserLoadCursorW(HINSTANCE hInstance, LPCWSTR lpCursorName);

// override
extern FARPROC Unicows_LoadCursorW = (FARPROC)&UserLoadCursorW;

HCURSOR __stdcall
UserLoadCursorW(HINSTANCE hInstance, LPCWSTR lpCursorName)
{
    // Only convert real strings, not user atoms or NULLs
    if ((ULONG_PTR)(lpCursorName) > 0xffff)
    {
        // Get the size of the Unicode string 
        size_t cchCursorName = wcslen(lpCursorName);

        // Allocate enough space for the Ansi string
        LPSTR lpCursorNameA = _alloca((cchCursorName + 1) * 2);

        // Convert the string from Unicode
        WideCharToMultiByte(CP_ACP, 
                            0, 
                            lpCursorName, 
                            cchCursor, 
                            lpCursorNameA, 
                            cchCursor * 2, 
                            NULL, 
                            NULL);

        return(LoadCursorA(hInstance, lpCursorNameA);
    }
    else
    {
        // This is not actually a string, so it is okay to call 
        // straight through without converting the parameter
        return(LoadCursorA(hInstance, (LPSTR)lpCursorName);
    }
}