Suppose you have a Windows Forms application in which you want to see the intermediate progress and status of a time-consuming process in the GUI of the Main Form. This time-consuming process is running in a separate DLL. As the process progresses, the DLL sends current status/progress to the calling application (the Windows Forms application).

In the GUI of the Calling application, the progress and current status text of the process is displayed in a Progress Bar as shown below:

event1.gif

Let us see how we can do this in a very simple way:
So, the whole code of the class "MyClass" looks like:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;

namespace MyClassLibrary
{
// Created a public delegate in the same namespace but outside of the class "MyClass"
 // in order to raise the Status event to show the intermediate processing status on
// GUI in the Main Form
 public delegate void MyDLL_InternalStatus(int progress, string statustext);
public class MyClass
 {
// Created a public event
 public event MyDLL_InternalStatus MyClassStatusEvent;
public void TimeConsumingProcess()
{
// event firing
 MyClassStatusEvent(10, "Task-1 is started. Task-1 is in process...");
Task1();
MyClassStatusEvent(20, "Task-1 is finished. Task-2 is in process...");
Task2();
MyClassStatusEvent(40, "Task-2 is finished. Task-3 is in process...");
Task3();
MyClassStatusEvent(60, "Task-3 is finished. Task-4 is in process...");
Task4();
MyClassStatusEvent(80, "Task-4 is finished. Task-5 is in process...");
Task5();
MyClassStatusEvent(100, "Task-5 is finished. All tasks completed sucessfully!");
}
// Suppose Task1 takes 2 seconds
 private void Task1()
{
Thread.Sleep(1000);
}
// Suppose Task2 takes 2 seconds
 private void Task2()
{
Thread.Sleep(2000);
}
// Suppose Task3 takes 4 seconds
 private void Task3()
{
Thread.Sleep(4000);
}

// Suppose Task4 takes 3 seconds
 private void Task4()
{
Thread.Sleep(3000);
}

// Suppose Task5 takes 2 seconds
 private void Task5()
{
Thread.Sleep(2000);
}
}
}

And the code of the calling application's main form ("MyForm") will look like:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace EventBubblerDemo
{
public partial class MyForm : Form
 {
// Created an object of the Dll
 MyClassLibrary.MyClass oMyClass;
public MyForm()
{
InitializeComponent();

// MyClass object is created
 oMyClass = new MyClassLibrary.MyClass();

// MyClass's event is subscribed here
 oMyClass.MyClassStatusEvent += new MyClassLibrary.MyDLL_InternalStatus(oMyClass_MyClassStatusEvent);
}

// Event Handler of MyClass's event
 void oMyClass_MyClassStatusEvent(int progress, string statustext)
{
toolStripProgressBar.Value = progress; // Setting ProgreeBar Value
 toolStripStatusLabel.Text = statustext; // Setting Status Text

// To refresh the GUI simultaneously as the background process progresses
 Application.DoEvents();
}
/// <summary>
 /// Start Button Click Method
 /// </summary>
 /// <param name="sender"></param>
 /// <param name="e"></param>
 private void btn_Start_Click(object sender, EventArgs e)
{
oMyClass.TimeConsumingProcess();
}
}
}
Thank You...