BackgroundWorker report progress from external Class?

Question

I have a working solution that reports progress & text to a progress bar and a label on the applications's main form. I have now moved my worker methods to a class to they are accessible across multiple forms etc.

Within the worker methods are BW.ReportProgress() statements that push back the progress and text to the BackgroundWorker in the main form.

To give a better idea here is the file layout:

MainScreen.cs

List repSelected = new List();
XMLandRar xXMLandRar = new XMLandRar();

private void Rarbtn_Click(object sender, EventArgs e)
        {
            GetReps();

            //Run worker
            if (!CreateRarBW.IsBusy)
            {
                CreateRarBW.RunWorkerAsync();
            }
        }

//Worker
private void CreateRarBW_DoWork(object sender, DoWorkEventArgs e)
{
    xXMLandRar.RarFiles(repSelected);
}

//Progress reporting
private void CreateRarBW_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
    progBar.Value = e.ProgressPercentage;
    Statuslbl.Text = e.UserState.ToString();
}

Then my newly created Class that encompasses all of the worker methods and is to push progress to the main form.

XMLandRar.cs

public class XMLandRar
{
    public void RarFiles(List repSelected)
    {
        int step = 100 / repSelected.Count();
        int i = 0;
        //Iterate through list and run rar for each
        foreach (string rep in repSelected)
        {
            CreateRarBW.ReportProgress(i, "Raring files for " + rep);
            DirectoryExists(rep);
            ProcessRunner(rep);
            i += step;
            CreateRarBW.ReportProgress(i, "Raring files for " + rep);
        }
    }
}

The problem I am having is that in the XMLandRar class the CreateRarBW is not recognised (obviously) - how can I make a ReportProgress call to the BW in the main screen of the application?

Answer 1

Create an event in your XMLandRar class which you could subscribe to.

This way the XMLandRar class doesn't need to know or care about the UI or progressbar, it only cares about sending a message if anyone would listen. And there can also be more than one subscriber (let's say if you want to report to the background worker and a log, maybe)

Example:

private void Rarbtn_Click(object sender, EventArgs e)
{
    GetReps();

    //Run worker
    if (!CreateRarBW.IsBusy)
    {
        // This should be done once, maybe in the contructor. Bind to new event.
        xXMLandRar.ReportProgress += new EventHandler<XMLandRar.ProgressArgs>(xXMLandRar_ReportProgress);

        CreateRarBW.RunWorkerAsync();
    }
}

protected void xXMLandRar_ReportProgress(object sender, XMLandRar.ProgressArgs e)
{
    // Call the UI backgroundworker
    CreateRarBW.ReportProgress(e.Percentage, e.Message);
}

public class XMLandRar
{
    // Event handler to bind to for reporting progress
    public EventHandler<ProgressArgs> ReportProgress;

    // Eventargs to contain information to send to the subscriber
    public class ProgressArgs : EventArgs
    {
        public int Percentage { get; set; }
        public string Message { get; set; }
    }

    public void RarFiles(List repSelected)
    {
        int step = 100 / repSelected.Count();
        int i = 0;
        //Iterate through list and run rar for each
        foreach (string rep in repSelected)
        {
            // Report progress if somebody is listening (subscribed)
            if (ReportProgress != null)
            {
                ReportProgress(this, new ProgressArgs { Percentage = i, Message = "Raring files for " + rep });
            }

            DirectoryExists(rep);
            ProcessRunner(rep);
            i += step;

            // Report progress if somebody is listening (subscribed)
            if (ReportProgress != null)
            {
                ReportProgress(this, new ProgressArgs { Percentage = i, Message = "Raring files for " + rep });
            }
        }
    }
}

Answer 2

The sender object in the DoWork callback is the BackgroundWorker instance which is calling this callback.

This enables to use the instance and add it to your new XMLandRar class.

private void CreateRarBW_DoWork(object sender, DoWorkEventArgs e)
{
    var worker = sender as BackgroundWorker.
    xXMLandRar.RarFiles(repSelected, worker);
}

XMLandRar.cs

public class XMLandRar
{
    public void RarFiles(List repSelected, BackgroundWorker worker)
    {
    // ...
    }
}

Or you set the BackgroundWorkerinstance as a class property to the XMLandRar.

public class XMLandRar
{
    protected BackgroundWorker mWorker;

    public XMLandRar(BackgroundWorker worker) {
        mWorker = BackgroundWorker;
    }


    public void RarFiles(List repSelected)
    {
        // Do something with {mWorker}
    }
}

Or as mentioned in the comments, using events in the XMLandRar class.

XMLandRar.cs

public class XmlandRarCompletedEventArgs : EventArgs
{
    public readonly bool Finished;
    public readonly bool Canceled;

    public XmlandRarCompletedEventArgs(bool finished)
    {
        Finished = finished;
        Canceled = !finished;
    }    

}public class OnXmlandRarUpdateEventArgs : EventArgs
{
    public readonly int Percentage;
    public readonly string Message;

    public XmlandRarCompletedEventArgs(int perc) :
        this(perc, "") {
    }   

    public XmlandRarCompletedEventArgs(int perc, string message)
    {
        Percentage = perc;
        Message = message;
    }    

}

public delegate void OnXmlandRarDoWorkHandler(object o);
public delegate void OnXmlandRarUpdateHandler(object o, OnXmlandRarUpdateEventArgs args);
public delegate void OnXmlandRarCompleteHandler(object o, XmlandRarCompletedEventArgs args);

public class XMLandRar
{
    public event OnXmlandRarDoWorkHandler OnDoWork;
    public event OnXmlandRarUpdateHandler OnUpdate;
    public event OnXmlandRarCompletedHandler OnComplete;

    public void RarFiles(List repSelected)
    {
        TriggerDoWork();

        int step = 100 / repSelected.Count();
        int i = 0;
        //Iterate through list and run rar for each
        foreach (string rep in repSelected)
        {
            TriggerUpdate(i, "Raring files for " + rep);
            DirectoryExists(rep);
            ProcessRunner(rep);
            i += step;
            TriggerUpdate(i, "Raring files for " + rep);
        }

        TriggerComplete(true);
    }


    private void TriggerDoWork() 
    {
        if (OnDoWork != null) {
            OnDoWork(this);
        }
    }

    private void TriggerUpdate(perc) {
    }
        if (OnUpdate != null) {
            OnUpdate(this, new OnXmlandRarUpdateEventArgs(perc));
        }

    private void TriggerUpdate(perc, string message) 
    {
        if (OnUpdate != null) {
            OnUpdate(this, new OnXmlandRarUpdateEventArgs(perc, message));
        }
    }

    private void TriggerComplete(bool finished)
    {
        if (OnComplete != null) {
            OnComplete(this, new XmlandRarCompletedEventArgs(finished));
        }
    }
}

Usage:

private void CreateRarBW_DoWork(object sender, DoWorkEventArgs e)
{
    var worker = sender as BackgroundWorker;
    // Attach events to class
    xXMLandRar.OnDoWork += delegate(object o) {
        // ...
    };
    xXMLandRar.OnUpdate += delegate(object o, OnXmlandRarUpdateEventArgs args) {
        // ...
    };
    xXMLandRar.OnComplete += delegate(object o, XmlandRarCompletedEventArgs args) {
        // ...
    };
    xXMLandRar.RarFiles(repSelected, worker);
}

Hopefully without typos 'cause I'm in the office.

Answer 3

I have fixed errors in the code submitted and cleaned it up... This is a working sample that will help those that maybe couldn't understand the code since it was broken as it was... Although I would like to say that the intent and functionality of the code after it was cleaned up and enhanced is excellent.

This is working code that can get you started in your project for using a backGroundWorker thread for whatever you need.

Just modify this method -

    public void RarFiles(List<string> repSelected)

To do whatever work you need. You will also have to modify the arguments you plan on using.. i.e. you may need a DataTable or some custom object... You can modify the

     public class OnXmlandRarUpdateEventArgs : EventArgs

For your needs.. that way when you get a callback.. you can update your main UI form with the changes made to those items..

You may need to do some tweaking.. but you see what i mean..

This is the Form Code.. Don't forget to create a button on the form...

    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 ThreadSample
    {
        public partial class Form1 : Form
        {
            List<string> repSelected = new List<string>();
            XMLandRar xXMLandRar = new XMLandRar();
            BackgroundWorker CreateRarBW = new BackgroundWorker();
            public Form1()
            {
                InitializeComponent();
                repSelected = new List<string> { "asdf", "asdfsd", "h;ljj" };
                CreateRarBW.DoWork += new DoWorkEventHandler(CreateRarBW_DoWork);
            }

            private void Rarbtn_Click(object sender, EventArgs e)
            {
                //GetReps();

                //Run worker
                if (!CreateRarBW.IsBusy)
                {
                    // This should be done once, maybe in the contructor. Bind to new event.
                    xXMLandRar.ReportProgress += new EventHandler<XMLandRar.ProgressArgs>(xXMLandRar_ReportProgress);

                    CreateRarBW.RunWorkerAsync();
                }
            }

            protected void xXMLandRar_ReportProgress(object sender, XMLandRar.ProgressArgs e)
            {
                // Call the UI backgroundworker
                CreateRarBW.ReportProgress(e.Percentage, e.Message);
            }

            //private void CreateRarBW_DoWork(object sender, DoWorkEventArgs e)
            //{
            //    var worker = sender as BackgroundWorker;
            //    xXMLandRar.RarFiles(repSelected, worker);
            //}


            private void CreateRarBW_DoWork(object sender, DoWorkEventArgs e)
            {
                var worker = sender as BackgroundWorker;
                // Attach events to class
                xXMLandRar.OnDoWork += delegate(object o)
                {
                    // ...
                    MessageBox.Show("Hey ... Something is going on over there in the classLib .. " + o);
                };
                xXMLandRar.OnUpdate += delegate(object o, OnXmlandRarUpdateEventArgs args)
                {
                    // ...
                    //foreach (object oo in args)
                    {
                        MessageBox.Show("Hey ... Something is going on over there in the classLib .. Message is " + args.Message + " and Percentage is " + args.Percentage);
                    }
                };
                xXMLandRar.OnComplete += delegate(object o, XmlandRarCompletedEventArgs args)
                {
                    MessageBox.Show("Hey ... Something is going on over there in the classLib .. Canceled is " + args.Canceled + " and Finished is " + args.Finished);
                    // ...
                };
                xXMLandRar.RarFiles(repSelected);//, worker);
            }
        }
    }

This is the class code. You can just create a class in your current project... Keep in mind that the CreateRarBW object is a BackGroundWorker instance... (Wasn't included above..)

    using System;
    using System.Collections.Generic;
    using System.Data;
    using System.Drawing;
    using System.Linq;
    using System.Text;
    using System.IO;
    using System.Diagnostics;
    using System.Threading;

    namespace ThreadSample
    {
        public class XmlandRarCompletedEventArgs : EventArgs
        {
            public readonly bool Finished;
            public readonly bool Canceled;

            public XmlandRarCompletedEventArgs(bool finished)
            {
                Finished = finished;
                Canceled = !finished;
            }
        }

        public class OnXmlandRarUpdateEventArgs : EventArgs
        {
            public readonly int Percentage;
            public readonly string Message;


            public OnXmlandRarUpdateEventArgs(int perc) : this(perc, "")
            {

            }   

            public OnXmlandRarUpdateEventArgs(int perc, string message)
            {
                Percentage = perc;
                Message = message;
            }

        }

        public delegate void OnXmlandRarDoWorkHandler(object o);
        public delegate void OnXmlandRarUpdateHandler(object o, OnXmlandRarUpdateEventArgs args);
        public delegate void OnXmlandRarCompleteHandler(object o, XmlandRarCompletedEventArgs args);

        public class XMLandRar      // : BackgroundWorker
        {

            // Event handler to bind to for reporting progress
            public EventHandler<ProgressArgs> ReportProgress;

            // Eventargs to contain information to send to the subscriber
            public class ProgressArgs : EventArgs
            {
                public int Percentage { get; set; }
                public string Message { get; set; }
            }

            public event OnXmlandRarDoWorkHandler OnDoWork;
            public event OnXmlandRarUpdateHandler OnUpdate;
            public event OnXmlandRarCompleteHandler OnComplete;

            public void RarFiles(List<string> repSelected)
            {
                TriggerDoWork();

                int step = 100 / repSelected.Count();
                int i = 0;
                //Iterate through list and run rar for each
                foreach (string rep in repSelected)
                {
                    TriggerUpdate(i, "Raring files for " + rep);
                    //DirectoryExists(rep);
                    //ProcessRunner(rep);
                    i += step;
                    TriggerUpdate(i, "Raring files for " + rep);
                }

                TriggerComplete(true);
            }


            private void TriggerDoWork()
            {
                if (OnDoWork != null)
                {
                    OnDoWork(this);
                }
            }

            private void TriggerUpdate(int perc)
            {

                if (OnUpdate != null)
                {
                    OnUpdate(this, new OnXmlandRarUpdateEventArgs(perc));
                }
            }

            private void TriggerUpdate(int perc, string message)
            {
                if (OnUpdate != null)
                {
                    OnUpdate(this, new OnXmlandRarUpdateEventArgs(perc, message));
                }
            }

            private void TriggerComplete(bool finished)
            {
                if (OnComplete != null)
                {
                    OnComplete(this, new XmlandRarCompletedEventArgs(finished));
                }
            }
        }

    }