void PScreen(IStream *fStream, UINT quality)  
{  
    HDC hDCSrc = ::GetDC(NULL);  
    int nBitPerPixel = GetDeviceCaps(hDCSrc, BITSPIXEL);  
    int nWidth = GetDeviceCaps(hDCSrc, HORZRES);  
    int nHeight = GetDeviceCaps(hDCSrc, VERTRES);  
    CImage cImage;//使用CImage能省好多截图的代码  
    cImage.Create(nWidth, nHeight, nBitPerPixel);  
    BitBlt(cImage.GetDC(), 0, 0, nWidth, nHeight, hDCSrc, 0, 0, SRCCOPY);  
    ReleaseDC(NULL, hDCSrc);  
    cImage.ReleaseDC();//截图的代码到这里就结束了  
      
    COleStreamFile cImgStream;  
    cImgStream.CreateMemoryStream(NULL);  
    cImage.Save(cImgStream.GetStream(), Gdiplus::ImageFormatBMP);//将2进制数据写入流  
    Image image(cImgStream.GetStream());//从流创建Graphics::Image对象  
    cImgStream.Close();  
  
    CLSID encoderClsid;  
    GetEncoderClsid(L"image/jpeg", &encoderClsid);//获取编码CLSID  
    EncoderParameters encoderParameters;//下面这几样编码的参数我只知道一个.Value为压缩率，其他的不懂。  
    encoderParameters.Count = 1;   
    encoderParameters.Parameter[0].Guid = EncoderQuality;   
    encoderParameters.Parameter[0].Type = EncoderParameterValueTypeLong;   
    encoderParameters.Parameter[0].NumberOfValues = 1;   
    encoderParameters.Parameter[0].Value = &quality;  
  
      
    image.Save(fStream, &encoderClsid, &encoderParameters);//写入流  
  
    image.Save(L"C:\\图片.jpg", &encoderClsid, &encoderParameters); //也可直接写入图片文件  
}