CreateGrayscaleIcon()

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Environment: VC++ 6.0, XP, Win2k, NT 4.0, Win9x/ME

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(m_hWnd);
  hMemDC1 = ::CreateCompatibleDC(hMainDC);
  hMemDC2 = ::CreateCompatibleDC(hMainDC);
  if (hMainDC == NULL ||
    hMemDC1 == NULL ||
    hMemDC2 == NULL)
      return NULL;

  if (::GetObject(csII.hbmColor,
                sizeof(BITMAP), &
                amp;bmp))
  {
    csGrayII.hbmColor =
         ::CreateBitmap(csII.xHotspot*2,
                        csII.yHotspot*2,
                        bmp.bmPlanes,
                        bmp.bmBitsPixel,
                        NULL);
    if (csGrayII.hbmColor)
    {
      hOldBmp1 =
         (HBITMAP)::SelectObject(hMemDC1,
                                 csII.hbmColor);
      hOldBmp2 =
         (HBITMAP)::SelectObject(hMemDC2,
                                 csGrayII.hbmColor);

      ::BitBlt(hMemDC2, 0, 0, csII.xHotspot*2,
               csII.yHotspot*2, hMemDC1, 0, 0,
               SRCCOPY);

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

      for (dwLoopY = 0; dwLoopY < csII.yHotspot*2; dwLoopY++)
      {
        for (dwLoopX = 0; dwLoopX < csII.xHotspot*2; dwLoopX++)
        {
          crPixel = ::GetPixel(hMemDC2, 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(m_hWnd, hMainDC);

  return hGrayIcon;
} // End of CreateGrayscaleIcon

• Date Published: April 23, 2002
  First release (4/16)

Downloads

Download source code & demo project – 123 Kb