Chat Application

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/*
Professional Windows GUI Programming Using C#
by Jay Glynn, Csaba Torok, Richard Conway, Wahid Choudhury, 
   Zach Greenvoss, Shripad Kulkarni, Neil Whitlow

Publisher: Peer Information
ISBN: 1861007663
*/
using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
using System.Net;
using System.IO;
using System.Net.Sockets;
using System.Threading;

namespace Wrox.WindowsGUIProgramming.Chapter9
{
    /// <summary>
    /// Summary description for Form1.
    /// </summary>
    public class ChatApplication : System.Windows.Forms.Form
    {
        internal System.Windows.Forms.ListBox listBox1;
        private System.Windows.Forms.TextBox txtMessage;
        private System.Windows.Forms.Button btSend;
        /// <summary>
        /// Required designer variable.
        /// </summary>
        private System.ComponentModel.Container components = null;
        private System.Windows.Forms.ComboBox cmdHost;
        private System.Windows.Forms.CheckBox chkSuspendClient;

        private PeerConnection p = null;

        public ChatApplication()
        {
            //
            // Required for Windows Form Designer support
            //
            InitializeComponent();

            //
            // TODO: Add any constructor code after InitializeComponent call
            //
            p = new PeerConnection(4048, listBox1, cmdHost);
        }

        /// <summary>
        /// Clean up any resources being used.
        /// </summary>
        protected override void Dispose( bool disposing )
        {
            if( disposing )
            {
                if (components != null) 
                {
                    components.Dispose();
                }
            }
            base.Dispose( disposing );
        }

        #region Windows Form Designer generated code
        /// <summary>
        /// Required method for Designer support - do not modify
        /// the contents of this method with the code editor.
        /// </summary>
        private void InitializeComponent()
        {
            this.listBox1 = new System.Windows.Forms.ListBox();
            this.txtMessage = new System.Windows.Forms.TextBox();
            this.btSend = new System.Windows.Forms.Button();
            this.cmdHost = new System.Windows.Forms.ComboBox();
            this.chkSuspendClient = new System.Windows.Forms.CheckBox();
            this.SuspendLayout();
            // 
            // listBox1
            // 
            this.listBox1.Name = "listBox1";
            this.listBox1.Size = new System.Drawing.Size(688, 394);
            this.listBox1.TabIndex = 0;
            // 
            // txtMessage
            // 
            this.txtMessage.Location = new System.Drawing.Point(8, 408);
            this.txtMessage.Name = "txtMessage";
            this.txtMessage.Size = new System.Drawing.Size(576, 20);
            this.txtMessage.TabIndex = 1;
            this.txtMessage.Text = "";
            // 
            // btSend
            // 
            this.btSend.Location = new System.Drawing.Point(608, 408);
            this.btSend.Name = "btSend";
            this.btSend.TabIndex = 2;
            this.btSend.Text = "Send";
            this.btSend.Click += new System.EventHandler(this.btSend_Click);
            // 
            // cmdHost
            // 
            this.cmdHost.Location = new System.Drawing.Point(8, 432);
            this.cmdHost.Name = "cmdHost";
            this.cmdHost.Size = new System.Drawing.Size(520, 21);
            this.cmdHost.TabIndex = 3;
            this.cmdHost.Text = "localhost";
            // 
            // chkSuspendClient
            // 
            this.chkSuspendClient.Location = new System.Drawing.Point(544, 432);
            this.chkSuspendClient.Name = "chkSuspendClient";
            this.chkSuspendClient.Size = new System.Drawing.Size(152, 24);
            this.chkSuspendClient.TabIndex = 4;
            this.chkSuspendClient.Text = "Suspend Client";
            this.chkSuspendClient.CheckedChanged += new System.EventHandler(this.chkSuspendClient_CheckedChanged);
            // 
            // ChatApplication
            // 
            this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
            this.ClientSize = new System.Drawing.Size(688, 462);
            this.Controls.AddRange(new System.Windows.Forms.Control[] {
                                                                          this.chkSuspendClient,
                                                                          this.cmdHost,
                                                                          this.btSend,
                                                                          this.txtMessage,
                                                                          this.listBox1});
            this.MaximizeBox = false;
            this.Name = "ChatApplication";
            this.Text = "Chat!";
            this.ResumeLayout(false);

        }
        #endregion

        /// <summary>
        /// The main entry point for the application.
        /// </summary>
        [STAThread]
        static void Main() 
        {
            Application.Run(new ChatApplication());
        }

        private void btSend_Click(object sender, System.EventArgs e)
        {
            p.Write(txtMessage.Text);
        }

        private void chkSuspendClient_CheckedChanged(object sender, System.EventArgs e)
        {
            if(chkSuspendClient.Checked==true)
            {
                p.Enabled = true;
            }
            else
            {
                p.Enabled = false;
            }
        }
    }


    public class PeerConnection
    {
        private System.Net.Sockets.TcpListener peerListener = null;
        private System.Net.Sockets.TcpClient peerClient = null;
        private System.Net.Sockets.NetworkStream netStream = null;
        private Thread t1 = null;
        private IntPtr formHandle;
        private int port = 0;
        private bool clientEnabled = true;
        private ListBox lb;
        private ComboBox cmb;

        public PeerConnection(int port, ListBox formHandle, ComboBox cmdHost)
        {
            this.port = port;
            this.lb = formHandle;
            this.cmb = cmdHost;
            t1 = new Thread(new ThreadStart(CreateListener));
            t1.Name = "Listener Thread";
            t1.Priority = ThreadPriority.AboveNormal;
            t1.Start();
        }

        delegate void CallbackListbox(string message);

        void SetListboxString(string item)
        {
            lb.Items.Add(item);
        }

        private void CreateListener()
        {
            Socket tc = null;

            peerListener = new TcpListener(port);
            peerListener.Start();

            CallbackListbox clb = new CallbackListbox(SetListboxString);
            while(true)
            {
                tc = peerListener.AcceptSocket();
                byte[] byMessage = new byte[256];
                Thread.Sleep(500);
                int iLength = tc.Receive(byMessage, 0, byMessage.Length, SocketFlags.None); 
                if(iLength>0)
                {
                    string message = System.Text.Encoding.Default.GetString(byMessage);
                    try
                    {
                        if(lb.InvokeRequired) lb.Invoke(clb, new object[]{message});
                    }
                    catch(Exception e)
                    {
                        message = e.Message;
                    }
                    finally
                    {
                        System.Diagnostics.Debug.WriteLine(message);
                    }
                }
            }
        }

        private void CreateClient(object message)
        {
            peerClient = new TcpClient();
            peerClient.Connect(cmb.SelectedText, port);

            netStream = peerClient.GetStream();

            StreamWriter sw = new StreamWriter(netStream);
            sw.Write((string)message);
            sw.Flush();

            peerClient.Close();
        }

        internal void Write(string message)
        {
            ThreadPool.QueueUserWorkItem(new WaitCallback(CreateClient), message);
        }

        internal bool Enabled
        {
            set
            {
                if(t1.ThreadState==ThreadState.Suspended&amp;&amp;value==true)
                {
                    t1.Resume();
                }
                else if(t1.ThreadState!=ThreadState.Suspended&amp;&amp;value==false)
                {
                    t1.Suspend();
                }
                clientEnabled = value;
            }
            get
            {
                return clientEnabled;
            }   
        }
    }
}


           
          


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