Bubbling up events example in winform c#

Suppose you have application (WinForm) in which you like to see the intermediate progress and status of a time taking process on the GUI of the Main Form. This Time taking process is running in a separate DLL. As the process progresses, the DLL sends current status/progress to Calling App (i.e. WinForm app).

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

Let us see how we can do this in a very simple way:

• Create a Main Application (WinForm app) as above with a “Start Process” button that is used for starting the process in my DLL. Add “StatusStrip” control too in the form. In StatusStrip, add ProgressBar (inbuilt) and StatusLable controls (inbuilt)
• Create a DLL (Class Library project) with a class named “MyClass”. Add the reference of this DLL into your Main Application.
• Now create a public delegate to raise the Status event to show the intermediate processing status on  GUI in the Main Form as:

public delegate void MyDLL_InternalStatus(int progress, string statustext);

In this delegate, we are specifying the parameters:

progress variable is used for storing current percentage progress of the process.

Statustext variable is used for storing the current status message related to process.

• In “MyClass” class, Add a method TimeConsumingProcess() that simulates a process taking a lot of time. TimeConsumingProcess() is built up with smaller several tasks such as Task-1, task-2 etc. Assume each task takes some significant amount of time (to simulate the time consumption, I used Thread.Sleep() method)

Now we want to send current status to calling application. In order to do this, we call MyClassStatusEvent() after the ending of each task.

e.g. MyClassStatusEvent(10, "Task-1 is started. Task-1 is in process...");

• Now add a reference to your DLL into your Main Application project.  Then create an object of the “MyClass” and subscribe its event as:

// MyClass object is created

oMyClass = new MyClassLibrary.MyClass();

// MyClass's event is subscribed here

oMyClass.MyClassStatusEvent +=

new MyClassLibrary.MyDLL_InternalStatus (oMyClass_MyClassStatusEvent);

                This subscription will require an event handler, which we specify like this:

// 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();                      

        }

So, the whole code of 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();

        }

    }

}