How to convert COLORREF into Hex-CString and back to COLORREF

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Hey Guys,

i'm trying to convert a COLORREF to a Hex-CString and then back from Hex-CString into COLORREF and i've run into a small problem.

Here some Code for Converting from COLORREF to a CString (Hexadecimal):
This part isn't the problem.

C++

COLORREF crefColor = RGB(128,0,0);

DWORD dwR = GetRValue(crefColor);
DWORD dwG = GetGValue(crefColor);
DWORD dwB = GetBValue(crefColor);

CString sValue;
sValue.Format(_T("#%02X%02X%02X"), dwR, dwG, dwB);
ASSERT(sValue == _T("#800000")); // correct

Now the more annoying part.
Back from CString to COLORREF:

C++

CString sValue(_T("#800000"));
LPCTSTR pszTmp = sValue;
pszTmp++; // cut the #

COLORREF crefColor;
COLORREF crefColor2;
sscanf_s(pszTmp, "%x", &crefColor); // should return the same as strtol
crefColor2 = strtol(pszTmp, NULL, 16); // should return the same as sscanf_s
ASSERT(crefColor == crefColor2); // just to be sure

INT nR = GetRValue(crefColor);
ASSERT(nR == 128); // expected: 128; nR in reallity: 0

INT nG = GetGValue(crefColor);
ASSERT(nG == 0); // expected: 0; nG in reallity: 0

INT nB = GetBValue(crefColor);
ASSERT(nB == 0); // expected: 0; nB in realität: 128

Could anyone suggest me, why the RGB is reversed?
I mean, if i know this problem, i could fix it and simlpy reverse it back:

C++

crefColor = RGB(nB, nG, nR);

But i think the result should be in the right direction after sscanf_s / strtol
Hope anyone could explain me the reason for this and show me the mistake i've done with my code.

Thank you so much guys for helping me!

Posted 15-Jul-14 20:41pm

C3D1

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Comments

Sergey Alexandrovich Kryukov 16-Jul-14 2:47am

This is easy enough, but why?
—SA

C3D1 16-Jul-14 2:53am

I'm more interessted in the reason why the RGB-Value is reversed than in the solution.

Sergey Alexandrovich Kryukov 16-Jul-14 3:10am

Hm. Look, you are calling RGB(g, b, r)...
Anyway, you did not answer my question, so why would I answer yours?
—SA

Jochen Arndt 16-Jul-14 2:56am

Hint:
Have a look at the COLORREF entry in the MSDN (Windows GDI) and the implementations of the GetXValue macros.

C3D1 16-Jul-14 2:59am

*facepalm* okay now i see where is the problem!
Thanks a lot!

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This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

C3D1 · Accepted Answer · 2014-07-15T21:02:00

Big thanks to Jochen Arndt for his hint.

I updated my code for converting from Hexadecimal CString to COLORREF to this:

C++

CString sValue(_T("#800000"));
LPCTSTR pszTmp = sValue;
pszTmp++; // cut the #

LPTSTR pStop;
INT nTmp = _tcstol(pszTmp, &pStop, 16);
INT nR	= (nTmp & 0xFF0000) >> 16;
INT nG	= (nTmp & 0xFF00) >> 8;
INT nB	= (nTmp & 0xFF);

COLORREF crefColor = RGB(nR, nG, nB);

How to convert COLORREF into Hex-CString and back to COLORREF

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How to convert COLORREF into Hex-CString and back to COLORREF

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