C# Chat Application Over Asynchronous UDP Sockets (server and client side)

This is two article very easy written by C# a server support multi users can chat from client in a local network.

Server side:
http://www.daveoncsharp.com/2009/08/csharp-chat-application-over-asynchronous-udp-sockets-part-1/


Client side:
http://www.daveoncsharp.com/2009/08/csharp-chat-application-over-asynchronous-udp-sockets-part-2/

Single instance in c#

Today, I will share an easy way to create a single instance application in C#.

Add Microsoft.VisualBasic in references by righ click to References -> Add Reference...

Default content of Program.cs is:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    static class Program
    {
        /// <summary>
        /// The main entry point for the application.
        /// </summary>
        [STAThread]
        static void Main()
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Application.Run(new Form1());
        }
    }
}

Change to:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Windows.Forms;
using Microsoft.VisualBasic.ApplicationServices;


namespace DesktopServer
{
    static class Program
    {
        [STAThread]
        static void Main()
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            string[] args = Environment.GetCommandLineArgs();
            SingleInstanceController controller = new SingleInstanceController();
            controller.Run(args);
        }
    }

    public class SingleInstanceController : WindowsFormsApplicationBase
    {
        public SingleInstanceController()
        {
            IsSingleInstance = true;
            StartupNextInstance += this_StartupNextInstance;
        }

        void this_StartupNextInstance(object sender, StartupNextInstanceEventArgs e)
        {
            Form1 form = MainForm as Form1; //My derived form type
        }

        protected override void OnCreateMainForm()
        {
            MainForm = new Form1();
        }
    }
}

Example using android remote desktop to control mouse via wifi

I searched an easy and helpful source code an android app connect with c# server in desktop via wifi and control mouse in desktop in here. Behind is content:

After my last post about .NET – Android, I was pretty excited about the possibilities. Therefore, I decided to create a new little “useful” app for my phone.
If your mouse batteries are low and you have to finish something, you can use your phone as a mouse.

How it works on Android:
I created an app which captures the movements on the screen and sends the positions over a socket (UDP) to my PC. My “protocol” supports following commands:

D.CLICK	Sending a double click. (Not really necessary.)
CLICK	Sending a click. (2x “click” => same as d.click.)
X,Y	Sending delta x and y. 0,1 or 1,0 etc.

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@Override public boolean onTouchEvent(MotionEvent event) {     super.onTouchEvent(event);     switch(event.getAction()) {         case MotionEvent.ACTION_DOWN: {             final float x = event.getX();             final float y = event.getY();             // last position             this.lastX = x;             this.lastY = y;             // first position             this.firstX = x;             this.firstY = y;             // click time             this.clickDown = new Date();             break;         }         case MotionEvent.ACTION_MOVE: {             // new position             final float x = event.getX();             final float y = event.getY();                           //  get delta             final float deltax = x - this.lastX;             final float deltay = y - this.lastY;             // set last position             this.lastX = x;             this.lastY = y;                                           try {                 // prepare message -> x,y                 byte[] message = (deltax + "," + deltay).getBytes("UTF-8");                 // package definition. ip of pc and port.                 this.packet = new DatagramPacket(message, message.length,                         InetAddress.getByName("192.168.0.150"), 8000);                 // send package                 this.socket.send(this.packet);             } catch(Throwable e) {                 e.printStackTrace();             }             break;         }                   case MotionEvent.ACTION_UP: {             // get current position             final float x = event.getX();             final float y = event.getY();             // get delta             final float deltaX = this.firstX - x;             final float deltaY = this.firstY - y;                           Date now = new Date();             byte[] message = null;                           try {                 // when the users clicks and holds over 1 second send a double click to the pc.                 if (deltaX < this.tolerance[0] &&                     deltaX > this.tolerance[1] &&                     deltaY < this.tolerance[0] &&                     deltaY > this.tolerance[1] &&                     now.getTime() - this.clickDown.getTime() >= 1000) {                     message = ("d.click").getBytes("UTF-8");                 // When the users clicks (not holding) send a normal click to the pc.                 } else if (x == this.firstX && y == this.firstY) {                     message = ("click").getBytes("UTF-8");                 }                 if (message != null) {                     // prepare and send package -> d.click or click                     this.packet = new DatagramPacket(message, message.length, InetAddress.getByName("192.168.0.150"), 8000);                     this.socket.send(this.packet);                  }             } catch (Throwable e) {                 e.printStackTrace();             }             break;         }     }     return true; }

Application on the PC:
I created an application, which receives the packages and sets the cursor position on the PC:

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public partial class MainWindow : Window {     // Dll import. -> method mouse_move     [DllImport("user32.dll")]     static extern void mouse_event(int dwFlags, int dx, int dy, int dwData, int dwExtraInfo);     private EndPoint point;     private Socket receiveSocket;     private byte[] recBuffer;     private int speed = 2;     // Flags for mouse_event api     [Flags]     public enum MouseEventFlagsAPI     {         LEFTDOWN = 0x00000002,         LEFTUP = 0x00000004,         MIDDLEDOWN = 0x00000020,         MIDDLEUP = 0x00000040,         MOVE = 0x00000001,         ABSOLUTE = 0x00008000,         RIGHTDOWN = 0x00000008,         RIGHTUP = 0x00000010     }     public MainWindow()     {         InitializeComponent();     }     private void Window_Loaded(object sender, RoutedEventArgs e)     {         // initilization and listening         receiveSocket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);             point = new IPEndPoint(IPAddress.Any, 8000);         this.recBuffer = new byte[60];         receiveSocket.Bind(point);         receiveSocket.BeginReceiveFrom(recBuffer, 0, recBuffer.Length,             SocketFlags.None, ref point,             new AsyncCallback(MessageReceiveCallback), (object)this);                   }     private void SendClick()     {         // Send click to system         mouse_event((int)MouseEventFlagsAPI.LEFTDOWN, 0, 0, 0, 0);         mouse_event((int)MouseEventFlagsAPI.LEFTUP, 0, 0, 0, 0);     }     private void MessageReceiveCallback(IAsyncResult result)     {         EndPoint remote = new IPEndPoint(0, 0);         string pos = "";         try         {             // get received message.             pos = Encoding.UTF8.GetString(recBuffer);             // clicked?             if (pos.StartsWith("click"))                 this.SendClick();             // long click = double click             else if (pos.StartsWith("d.click"))             {                 this.SendClick();                 this.SendClick();             }             // Otherwise move             else             {                 // calculate delta                 int deltaX = (int)float.Parse(pos.Substring(0, pos.IndexOf(","))) * this.speed;                 int deltaY = (int)float.Parse(pos.Substring(pos.IndexOf(",") + 1,                     pos.IndexOf("\0") + 1 - pos.IndexOf(",") + 1)) * this.speed;                 // set new point                 System.Drawing.Point pt = System.Windows.Forms.Cursor.Position;                 System.Windows.Forms.Cursor.Position = new System.Drawing.Point(pt.X + deltaX, pt.Y + deltaY);             }         }         catch (Exception)         {             Console.Write(pos);         }         // End and "begin" for next package         this.receiveSocket.EndReceiveFrom(result, ref remote);         receiveSocket.BeginReceiveFrom(recBuffer, 0, recBuffer.Length,             SocketFlags.None, ref point,             new AsyncCallback(MessageReceiveCallback), (object)this);     } }

Watch the video! 

The C# source code is here
The Java source code is here