COLORREF troubles... 2

[bitbit]

Hi all,

I'm trying to separate a COLORREF into the three basic color amounts. I know the structure of COLORREF is 4 bytes set like this:

0x00bbggrr

I need to extract the blue, green and red values into separate variables. Does anyone know how to do this?

Thanks!

 

[LazyMe]

GetBValue / GetGValue / GetRValue, or just mask the COLORREF yourself....
Greetings,
Rick

 

[rbrunton]

I don't know if this is the most elegant way to do this, however, logical and bitwise operators should do the job.

COLORREF crC; // 0x00bbggrr
int nR = (crC & 0xff);
int nG = ((crC & 0x0000ff00)>>2);
int nB = ((crC & 0x00ff0000)>>4);
[\code]

HTH

Ron

 

[bitbit]

Many thanks to you both - I hadn't realized there were some API functions for this but I'm also interested in how those bitwise operations work - that's something I'm not too familiar with yet.

 

[LazyMe]

Actually those aren't API's, they're just macro's that expand to the bit masking/shifting stuff.

Be careful though; rbrunton is right with his mask, but what he probably did not realize when writing his examples is that the >> operator is a bit shifter, NOT a nibble shifter. it should be >>8 instead of >>2 and >>16 instead of >>4.
Greetings,
Rick

 

[rbrunton]

Thanks Rick. You are correct and I was too quick. :-(

Ron