Make a BackgroundWorker do several operations sequentially without freezing the form

Question

I have already asked a somwhat similar question here but I now have a follow-up question.

I need to launch the external program several times in a row, but I have se

Answer 1

So nobugz give you already the right direction, but for completeness here is some sample code:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Threading;
using System.Windows.Forms;

namespace Threading
{
    public partial class FormMain : Form
    {
        private BackgroundWorker _BackgroundWorker;
        private Queue> _Commands;
        private Random _Random;

        public FormMain()
        {
            InitializeComponent();

            _Random = new Random();
            _Commands = new Queue>();
            _BackgroundWorker = new BackgroundWorker();

            _BackgroundWorker.WorkerReportsProgress = true;
            _BackgroundWorker.WorkerSupportsCancellation = true;
            _BackgroundWorker.DoWork += backgroundWorker_DoWork;
            _BackgroundWorker.ProgressChanged += backgroundWorker_ProgressChanged;
            _BackgroundWorker.RunWorkerCompleted += backgroundWorker_RunWorkerCompleted;

            _BackgroundWorker.RunWorkerAsync();
        }

        private void backgroundWorker_DoWork(object sender, DoWorkEventArgs e)
        {
            while (!_BackgroundWorker.CancellationPending)
            {
                if (_Commands.Count > 0)
                {
                    AddMessage("Starting waiting job...");
                    AddMessage(_Commands.Dequeue().Invoke());
                }
                Thread.Sleep(1);
            }
        }

        void backgroundWorker_ProgressChanged(object sender, ProgressChangedEventArgs e)
        {
            progressBar.Value = e.ProgressPercentage;
        }

        private void backgroundWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            AddMessage("BackgroundWorker doesn't make any further jobs.");
        }

        private void buttonStart_Click(object sender, EventArgs e)
        {
            _Commands.Enqueue(DoSomething);
            //or maybe with a lambda
            //_Commands.Enqueue(new Func(() =>
            //{
            //    string message;
            //    message = DoSomething();
            //    return message;
            //}));
        }

        private string DoSomething()
        {
            int max = 10;
            for (int i = 1; i <= max; i++)
            {
                Thread.Sleep(_Random.Next(10, 1000));

                if (_BackgroundWorker.CancellationPending)
                {
                    return "Job aborted!";
                }

                AddMessage(String.Format("Currently working on item {0} of {1}", i, max));
                _BackgroundWorker.ReportProgress((i*100)/max);
            }

            return "Job is done.";
        }

        private void AddMessage(string message)
        {
            if (textBoxOutput.InvokeRequired)
            {
                textBoxOutput.BeginInvoke(new Action(AddMessageInternal), message);
            }
            else
            {
                AddMessageInternal(message);
            }
        }

        private void AddMessageInternal(string message)
        {
            textBoxOutput.AppendText(String.Format("{0:G}   {1}{2}", DateTime.Now, message, Environment.NewLine));

            textBoxOutput.SelectionStart = textBoxOutput.Text.Length;
            textBoxOutput.ScrollToCaret();
        }

        private void FormMain_FormClosing(object sender, FormClosingEventArgs e)
        {
            if (_BackgroundWorker.IsBusy)
            {
                _BackgroundWorker.CancelAsync();
                e.Cancel = true;

                AddMessage("Please close only if all jobs are done...");
            }
        }
    }
}