netcore webapi 输出imges，在docker里面swagger报错

发现：service中有个webapi输出了：

public Bitmap GetLogoQRCode(string url, string logoPath, int pixel)
        {
            return QRCoderHelper.GetLogoQRCode(url, logoPath, pixel);
        }

在IIS里面正常，但是在docker里面就报错。

IIS里面swagger中显示该方法返回的是：

"System.Drawing.Bitmap"

-------------
暂时改为：

public FileResult GetPTQRCode(QRCoderDto dto)
        {
            try
            {
                var bitmap = QRCoderHelper.GetPTQRCode(dto.Url, dto.Pixel);
                MemoryStream ms = new MemoryStream();
                bitmap.Save(ms, ImageFormat.Jpeg);

                return new FileContentResult(ms.ToArray(), "image/png");
            }
            catch (Exception)
            {
                throw new UserFriendlyException("二维码生成异常,请检查");
            }
        }

然后在dockerfile中加入：

RUN  mv /etc/apt/sources.list /etc/apt/sources.list.bak
RUN  echo "deb http://mirrors.163.com/debian/ jessie main non-free contrib" >> /etc/apt/sources.list
RUN  echo "deb http://mirrors.163.com/debian/ jessie-proposed-updates main non-free contrib" >>/etc/apt/sources.list
RUN  echo "deb-src http://mirrors.163.com/debian/ jessie main non-free contrib" >>/etc/apt/sources.list
RUN  echo "deb-src http://mirrors.163.com/debian/ jessie-proposed-updates main non-free contrib" >>/etc/apt/sources.list
RUN apt-get update -y
RUN apt-get install libgdiplus