转载：C# 使用IP端口网络打印图片 - 如.若 - 博客园 (cnblogs.com)

 ///   <summary> 
    ///   POSPrinter的摘要说明。
    ///   此类处理网络打印,使用了IP端口.
    ///   </summary> 
    public class NetPOSPrinter
    {
        string ipPort = "192.168.1.212";

        public NetPOSPrinter()
        {

        }

        public NetPOSPrinter(string IpPort)
        {
            this.ipPort = IpPort;//打印机端口 
        }

        ///   <summary> 
        ///   输出文字到打印机 
        ///   </summary> 
        ///   <param   name= "str "> 要打印的内容 </param> 
        public void PrintLine(string str)
        {
            //建立连接
            IPAddress ipa = IPAddress.Parse(ipPort);
            IPEndPoint ipe = new IPEndPoint(ipa, 9100);//9100为小票打印机指定端口
            Socket soc = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
            soc.Connect(ipe);

            //string str= "hello,123456789,大家好! ";

            byte[] b = System.Text.Encoding.GetEncoding("GB2312").GetBytes(str);
            soc.Send(b);
            soc.Close();
        }


        public void PrintPic(Bitmap bmp)
        {
            //把ip和端口转化为IPEndPoint实例
            IPEndPoint ip_endpoint = new IPEndPoint(IPAddress.Parse(ipPort), 9100);
            //创建一个Socket
            Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
            //连接到服务器
            socket.Connect(ip_endpoint);
            //应对同步Connect超时过长的办法，猜测应该是先用异步方式建立以个连接然后，
            //确认连接是否可用，然后报错或者关闭后，重新建立一个同步连接                    
            //socket.SendTimeout = 1000;

            //初始化打印机，并打印
            Byte[] byte_send = Encoding.GetEncoding("gb18030").GetBytes("\x1b\x40");
            //发送测试信息
            socket.Send(byte_send, byte_send.Length, 0);

            byte[] data = new byte[] { 0x1B, 0x33, 0x00 };
            socket.Send(data, data.Length, 0);
            data[0] = (byte)'\x00';
            data[1] = (byte)'\x00';
            data[2] = (byte)'\x00';    // Clear to Zero.

            Color pixelColor;
            // ESC * m nL nH 点阵图
            byte[] escBmp = new byte[] { 0x1B, 0x2A, 0x00, 0x00, 0x00 };
            escBmp[2] = (byte)'\x21';
            //nL, nH
            escBmp[3] = (byte)(bmp.Width % 256);
            escBmp[4] = (byte)(bmp.Width / 256);
            // data
            for (int i = 0; i < (bmp.Height / 24) + 1; i++)
            {
                socket.Send(escBmp, escBmp.Length, 0);

                for (int j = 0; j < bmp.Width; j++)
                {
                    for (int k = 0; k < 24; k++)
                    {
                        if (((i * 24) + k) < bmp.Height)   // if within the BMP size
                        {
                            pixelColor = bmp.GetPixel(j, (i * 24) + k);
                            if (pixelColor.R == 0)
                            {
                                data[k / 8] += (byte)(128 >> (k % 8));
                            }
                        }
                    }
                    socket.Send(data, 3, 0);
                    data[0] = (byte)'\x00';
                    data[1] = (byte)'\x00';
                    data[2] = (byte)'\x00';    // Clear to Zero.
                }
                byte_send = Encoding.GetEncoding("gb18030").GetBytes("\n");
                //发送测试信息
                socket.Send(byte_send, byte_send.Length, 0);
            } // data

            byte_send = Encoding.GetEncoding("gb18030").GetBytes("\n");
            //发送测试信息
            socket.Send(byte_send, byte_send.Length, 0);
            socket.Close();
        }


        ///   <summary> 
        ///   打开钱箱 
        ///   </summary> 
        public void OpenCashBox()
        {
            IPAddress ipa = IPAddress.Parse(ipPort);
            IPEndPoint ipe = new IPEndPoint(ipa, 9100);//9100为小票打印机指定端口
            Socket soc = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
            soc.Connect(ipe);
            char[] c = { Convert.ToChar(27), 'p', Convert.ToChar(0), Convert.ToChar(60), Convert.ToChar(255) };
            byte[] b = System.Text.Encoding.GetEncoding("GB2312").GetBytes(c);
            soc.Send(b);
            soc.Close();
        }
    }