Icon 转 Bitmap

HBITMAP IconToBitmap(HICON hIcon, SIZE* pTargetSize = NULL)
{
    ICONINFO info = {0};
    if(hIcon == NULL
        || !GetIconInfo(hIcon, &info)
        || !info.fIcon)
    {
        return NULL;
    }

    INT nWidth = 0;
    INT nHeight = 0;
    if(pTargetSize != NULL)
    {
        nWidth = pTargetSize->cx;
        nHeight = pTargetSize->cy;
    }
    else
    {
        if(info.hbmColor != NULL)
        {
            BITMAP bmp = {0};
            GetObject(info.hbmColor, sizeof(bmp), &bmp);

            nWidth = bmp.bmWidth;
            nHeight = bmp.bmHeight;
        }
    }

    if(info.hbmColor != NULL)
    {
        DeleteObject(info.hbmColor);
        info.hbmColor = NULL;
    }

    if(info.hbmMask != NULL)
    {
        DeleteObject(info.hbmMask);
        info.hbmMask = NULL;
    }

    if(nWidth <= 0
        || nHeight <= 0)
    {
        return NULL;
    }

    INT nPixelCount = nWidth * nHeight;

    CDC* pDC = GetDC();
    HDC dc = pDC->GetSafeHdc();
    INT* pData = NULL;
    HDC dcMem = NULL;
    HBITMAP hBmpOld = NULL;
    bool* pOpaque = NULL;
    HBITMAP dib = NULL;
    BOOL bSuccess = FALSE;

    do
    {
        BITMAPINFOHEADER bi = {0};
        bi.biSize = sizeof(BITMAPINFOHEADER);    
        bi.biWidth = nWidth;
        bi.biHeight = -nHeight;  
        bi.biPlanes = 1;    
        bi.biBitCount = 32;    
        bi.biCompression = BI_RGB;
        dib = CreateDIBSection(dc, (BITMAPINFO*)&bi, DIB_RGB_COLORS, (VOID**)&pData, NULL, 0);
        if(dib == NULL) break;

        memset(pData, 0, nPixelCount * 4);

        dcMem = CreateCompatibleDC(dc);
        if(dcMem == NULL) break;

        hBmpOld = (HBITMAP)SelectObject(dcMem, dib);
        ::DrawIconEx(dcMem, 0, 0, hIcon, nWidth, nHeight, 0, NULL, DI_MASK);

        //pOpaque = new(std::nothrow) bool[nPixelCount];
        pOpaque = new bool[nPixelCount];
        if(pOpaque == NULL) break;
        for (INT i = 0; i < nPixelCount; ++i)
        {
            pOpaque[i] = !pData[i];
        }

        memset(pData, 0, nPixelCount * 4);
        ::DrawIconEx(dcMem, 0, 0, hIcon, nWidth, nHeight, 0, NULL, DI_NORMAL);

        BOOL bPixelHasAlpha = FALSE;
        UINT* pPixel = (UINT*)pData;
        for(INT i = 0; i<nPixelCount; ++i, ++pPixel)
        {
            if((*pPixel & 0xff000000) != 0)
            {
                bPixelHasAlpha = TRUE;
                break;
            }
        }

        if(!bPixelHasAlpha)
        {
            pPixel = (UINT*)pData;
            for(INT i=0;i <nPixelCount; ++i, ++pPixel)
            {
                if(pOpaque[i])
                {
                    *pPixel |= 0xFF000000;
                }
                else
                {
                    *pPixel &= 0x00FFFFFF;
                }
            }
        }

        bSuccess = TRUE;

    } while(FALSE);


    if(pOpaque != NULL)
    {
        delete []pOpaque;
        pOpaque = NULL;
    }

    if(dcMem != NULL)
    {
        SelectObject(dcMem, hBmpOld);
        DeleteDC(dcMem);
    }

    ReleaseDC(pDC);

    if(!bSuccess)
    {
        if(dib != NULL)
        {
            DeleteObject(dib);
            dib = NULL;
        }
    }

    return dib;
}