此函式建立了1080p高清圖片，即解析度為：1920 x  1080

如果想建立不同的解析度圖片，可以修改函式中的 nWidth 和 nHeight.

此文僅供參考，如有不妥之處，請多多指教。

void Create1080p()

{
    int nWidth = 1920;
    int nHeight = 1080;
    int size = nWidth*nHeight;
    HDC hdc = ::GetDC(GetDesktopWindow());//獲取螢幕DC
    HDC hdcmem = ::CreateCompatibleDC(hdc);//建立相容dC
    HBITMAP hbitmap = ::CreateCompatibleBitmap(hdc, nWidth, nHeight);
    HBITMAP holdmap = (HBITMAP)::SelectObject(hdcmem, hbitmap);
    ::BitBlt(hdcmem, 0, 0, nWidth, nHeight, hdc, 0, 0, SRCCOPY);

    BITMAPINFO* bMapInfo = (BITMAPINFO*)::LocalAlloc(LPTR, sizeof(BITMAPINFO));
    bMapInfo->bmiHeader.biBitCount = 24;
    bMapInfo->bmiHeader.biClrImportant = 0;
    bMapInfo->bmiHeader.biCompression = 0;
    bMapInfo->bmiHeader.biHeight = nHeight;
    bMapInfo->bmiHeader.biPlanes = 1;
    bMapInfo->bmiHeader.biSize = sizeof(BITMAPINFO);
    bMapInfo->bmiHeader.biSizeImage = size*3;
    bMapInfo->bmiHeader.biWidth = nWidth;
    bMapInfo->bmiHeader.biXPelsPerMeter = 0;
    bMapInfo->bmiHeader.biYPelsPerMeter = 0;

    BITMAPFILEHEADER bmfh;
    bmfh.bfOffBits = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER);
    bmfh.bfReserved1 = 0;
    bmfh.bfReserved2 = 0;
    bmfh.bfSize = sizeof(BITMAPFILEHEADER);
    bmfh.bfType = 0x4D42;

    RGBTRIPLE *rgb = new RGBTRIPLE[size];
    ZeroMemory(rgb, sizeof(byte)*size*3);
    ::GetDIBits(hdc, hbitmap, 0, nHeight, rgb, bMapInfo, DIB_RGB_COLORS);
    
    CString bmpfile = _T("..\\top.bmp");
    CFile file(bmpfile, CFile::modeCreate|CFile::modeWrite);
    file.Write(&bmfh, sizeof(BITMAPFILEHEADER));
    file.Write(&bMapInfo->bmiHeader, sizeof(BITMAPINFOHEADER));
    file.Write(rgb, bMapInfo->bmiHeader.biSizeImage);
    file.Close();
    
    ::LocalFree(bMapInfo);
    delete rgb;
    ::SelectObject(hdcmem, holdmap);
    ::DeleteObject(hbitmap);
    ::DeleteDC(hdcmem);
    ::DeleteObject(hdc);
}