BackGroundWorker usage example

// This is an example of BackGroundWorker usage.
// To test it, create a Windows Forms Application project, and replace the code in Form1.cs with the following.
// Once you run the application, click the button and the 2 datagridviews will be filled from the worker thread.

using System;
using System.ComponentModel;
using System.Data;
using System.Windows.Forms;
using System.Threading;

namespace Forms
{
    public partial class Form1 : Form
    {
        #region Helper classes

        class NewDataSource
        {
            public int Grid { get; set; } // is the data source for grid 1 or 2
            public DataTable DataSource { get; set; }
        }
        class NewLabel
        {
            public int Label { get; set; } // is the text for label 1 or 2
            public string Text { get; set; }
        }

        #endregion

        #region Fields

        SplitContainer splitContainer;
        DataGridView dataGridView1;
        DataGridView dataGridView2;
        TextBox textBox1;
        TextBox textBox2;
        Button button;

        BackgroundWorker bkgWorker;

        static Random rand = new Random(123);

        #endregion

        #region CTOR

        public Form1()
        {
            InitializeComponent();
            this.InitControls();
            this.InitBackGroundWorker();
        }

        #endregion

        #region Initializations

        private void InitControls()
        {
            this.textBox1 = new TextBox();
            this.textBox1.Dock = DockStyle.Top;
            this.textBox1.ReadOnly = true;
            this.textBox1.Text = " ---- empty ---- ";
            this.textBox2 = new TextBox();
            this.textBox2.Dock = DockStyle.Top;
            this.textBox2.ReadOnly = true;
            this.textBox2.Text = " ---- empty ---- ";
            this.dataGridView1 = new DataGridView();
            this.dataGridView1.Dock = DockStyle.Fill;
            this.dataGridView2 = new DataGridView();
            this.dataGridView2.Dock = DockStyle.Fill;

            this.splitContainer = new SplitContainer();
            this.splitContainer.Dock = DockStyle.Fill;

            this.splitContainer.Panel1.Controls.Add(this.textBox1);
            this.splitContainer.Panel1.Controls.Add(this.dataGridView1);

            this.splitContainer.Panel2.Controls.Add(this.textBox2);
            this.splitContainer.Panel2.Controls.Add(this.dataGridView2);

            this.button = new Button();
            this.button.Dock = DockStyle.Bottom;
            this.button.Text = "Start Elaboration";
            this.button.Click += new EventHandler(button_Click);

            this.Controls.Add(this.splitContainer);
            this.Controls.Add(this.button);

            this.splitContainer.SplitterDistance = (this.splitContainer.Width - this.splitContainer.SplitterWidth) / 2;
        }

        private void InitBackGroundWorker()
        {
            this.bkgWorker = new BackgroundWorker();
            this.bkgWorker.WorkerReportsProgress = true;
            this.bkgWorker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(worker_RunWorkerCompleted);
            this.bkgWorker.ProgressChanged += new ProgressChangedEventHandler(worker_ProgressChanged);
            this.bkgWorker.DoWork += new DoWorkEventHandler(worker_DoWork);
        }

        #endregion

        #region Event Handlers

        void button_Click(object sender, EventArgs e)
        {
            this.button.Enabled = false; // disable the button to avoid multiple elaborations

            this.bkgWorker.RunWorkerAsync();
        }

        void worker_ProgressChanged(object sender, ProgressChangedEventArgs e)
        {
            if (e.UserState is NewLabel)
            {
                var newLabel = (NewLabel)e.UserState;
                if (newLabel.Label == 0)
                    this.textBox1.Text = newLabel.Text;
                else if (newLabel.Label == 1)
                    this.textBox2.Text = newLabel.Text;
            }
            else if (e.UserState is NewDataSource)
            {
                var newDataSource = (NewDataSource)e.UserState;
                if (newDataSource.Grid == 0)
                    this.dataGridView1.DataSource = newDataSource.DataSource;
                else if (newDataSource.Grid == 1)
                    this.dataGridView2.DataSource = newDataSource.DataSource;
            }
        }

        void worker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            this.button.Enabled = true; // enable the button again
        }

        void worker_DoWork(object sender, DoWorkEventArgs e)
        {
            // we're on another thread (not the UI thread)
            // so we can perform the elaboration here
            var worker = (BackgroundWorker)sender;

            // get data for GRID and LABEL 1
            var data1 = GetDataFromDB();
            worker.ReportProgress(0, new NewLabel() { Label = 0, Text = "Grid has: " + data1.Rows.Count + " rows" });
            Thread.Sleep(1000); // simulate another delay of 1 sec
            worker.ReportProgress(0, new NewDataSource() { Grid = 0, DataSource = data1 });


            // get data for GRID and LABEL 2
            var data2 = GetDataFromDB();
            worker.ReportProgress(0, new NewLabel() { Label = 1, Text = "Grid has: " + data2.Rows.Count + " rows" });
            Thread.Sleep(1000); // simulate another delay of 1 sec
            worker.ReportProgress(0, new NewDataSource() { Grid = 1, DataSource = data2 });

            // N.B. here we're updating the datagridview whenever we get the data.
            // another approach could be collecting all the datasources and set them to e.Result = datasources
            // then update the datagridviews after the finish of the elaboration in RunWorkerCompleted event handler
        }

        #endregion

        #region Elaboration Methods

        private DataTable GetDataFromDB()
        {
            var dt = new DataTable();
            dt.Columns.Add("ID", typeof(int));
            dt.Columns.Add("Name", typeof(string));
            int nRows = rand.Next(20, 300);
            for (int i = 0; i < nRows; i++)
            {
                int id = rand.Next(1, 100000);
                dt.Rows.Add(id, "Name of id: " + id);
            }
            Thread.Sleep(2000); // to simulate DB delay (2 seconds)
            return dt;
        }

        #endregion
    }
}