RE: [Mingw-users] wingdi.h - buggy RGB macro ???

[Rob L. <Rob...@no...>]

Hi,

> > I believe it should be:
> >
> > RGB(r,g,b)
((DWORD)(((BYTE)(r)|((WORD)(BYTE)(g)<<8))|(((DWORD)(BYTE)(b))<<16)))

> I agree,
> 
> Actually this should be sufficient:
> 
> #define RGB(r,g,b) ((COLORREF) ((BYTE)(r) | ((BYTE)(g) << 8) | ((BYTE)(b)
<< 16)))

I think shifting a byte 8 bits to the left leaves you with a byt containing
only 0's, and the
original value disappearing because it does not fit into a byte anymore.
The same
holds for the 16 bit shift.   It may depend on the compiler what actually
happens, but
I think the cast to WORD or DWORD are probably best left in.
(Personally I'd use DWORD for everything)


Rob Lievaart.