CreateGrayscaleIcon

• Download demo project - 126 Kb

Abstract

CreateGrayscaleIcon is a Win32 function that creates a grayscale icon starting from a given icon.
The resulting icon will have the same size of the original one. This function is written using only Win32 APIs
to make possible to be used either in MFC and pure Win32 applications.

Function description

Just add in your project a function like the following:

// This function creates a grayscale icon starting from a given icon.
// The resulting icon will have the same size of the original one.
//
// Parameters:
//      [IN]    hIcon
//              Handle to the original icon.
//
// Return value:
//      If the function succeeds, the return value is the handle to 
//      the newly created grayscale icon.
//      If the function fails, the return value is NULL.
//
HICON CreateGrayscaleIcon(HICON hIcon)
{
    HICON       hGrayIcon = NULL;
    HDC         hMainDC = NULL, hMemDC1 = NULL, hMemDC2 = NULL;
    BITMAP      bmp;
    HBITMAP     hOldBmp1 = NULL, hOldBmp2 = NULL;
    ICONINFO    csII, csGrayII;
    BOOL        bRetValue = FALSE;

    bRetValue = ::GetIconInfo(hIcon, &csII);
    if (bRetValue == FALSE) return NULL;

    hMainDC = ::GetDC(NULL);
    hMemDC1 = ::CreateCompatibleDC(hMainDC);
    hMemDC2 = ::CreateCompatibleDC(hMainDC);
    if (hMainDC == NULL || hMemDC1 == NULL || hMemDC2 == NULL) return NULL;
  
    if (::GetObject(csII.hbmColor, sizeof(BITMAP), &bmp))
    {
        DWORD   dwWidth = csII.xHotspot*2;
        DWORD   dwHeight = csII.yHotspot*2;

        csGrayII.hbmColor = ::CreateBitmap(dwWidth, dwHeight, bmp.bmPlanes, 
                                           bmp.bmBitsPixel, NULL);
        if (csGrayII.hbmColor)
        {
            hOldBmp1 = (HBITMAP)::SelectObject(hMemDC1, csII.hbmColor);
            hOldBmp2 = (HBITMAP)::SelectObject(hMemDC2, csGrayII.hbmColor);

            //::BitBlt(hMemDC2, 0, 0, dwWidth, dwHeight, hMemDC1, 0, 0, 
            //         SRCCOPY);

            DWORD    dwLoopY = 0, dwLoopX = 0;
            COLORREF crPixel = 0;
            BYTE     byNewPixel = 0;

            for (dwLoopY = 0; dwLoopY < dwHeight; dwLoopY++)
            {
                for (dwLoopX = 0; dwLoopX < dwWidth; dwLoopX++)
                {
                    crPixel = ::GetPixel(hMemDC1, dwLoopX, dwLoopY);

                    byNewPixel = (BYTE)((GetRValue(crPixel) * 0.299) + 
                                        (GetGValue(crPixel) * 0.587) + 
                                        (GetBValue(crPixel) * 0.114));
                    if (crPixel) ::SetPixel(hMemDC2, dwLoopX, dwLoopY, 
                                            RGB(byNewPixel, byNewPixel, 
                                            byNewPixel));
                } // for
            } // for

            ::SelectObject(hMemDC1, hOldBmp1);
            ::SelectObject(hMemDC2, hOldBmp2);

            csGrayII.hbmMask = csII.hbmMask;

            csGrayII.fIcon = TRUE;
            hGrayIcon = ::CreateIconIndirect(&csGrayII);
        } // if

        ::DeleteObject(csGrayII.hbmColor);
        //::DeleteObject(csGrayII.hbmMask);
    } // if

    ::DeleteObject(csII.hbmColor);
    ::DeleteObject(csII.hbmMask);
    ::DeleteDC(hMemDC1);
    ::DeleteDC(hMemDC2);
    ::ReleaseDC(NULL, hMainDC);

    return hGrayIcon;
} // End of CreateGrayscaleIcon

History

• 03/May/2002
  Removed dependancy from m_hWnd
  Removed 1 BitBlt operation
• 16/April/2002
  First release

Disclaimer

THE SOFTWARE AND THE ACCOMPANYING FILES ARE DISTRIBUTED "AS IS" AND WITHOUT ANY WARRANTIES WHETHER EXPRESSED OR IMPLIED. NO RESPONSIBILITIES FOR POSSIBLE DAMAGES OR EVEN FUNCTIONALITY CAN BE TAKEN. THE USER MUST ASSUME THE ENTIRE RISK OF USING THIS SOFTWARE.

Terms of use

THIS SOFTWARE IS FREE FOR PERSONAL USE OR FREEWARE APPLICATIONS.

This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

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