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BackgroundWorker and ProgressBar demo

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4.70/5 (44 votes)

May 23, 2010

CPOL
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A simple demonstration of how to use a BackgroundWorker with a ProgressBar

This gets asked almost daily so I've written this short demonstration code to demonstrate how to use a System.ComponentModel.BackgroundWorker in combination with a System.Windows.Forms.ProgressBar. All the code is commented so the flow/steps should be easy to understand. Just drop a ProgressBar (progressBar1) and a BackgroundWorker (backgroundWorker1) onto your form and copy and paste this code to see it in action.
public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
        Shown += new EventHandler(Form1_Shown);

        // To report progress from the background worker we need to set this property
        backgroundWorker1.WorkerReportsProgress = true;
        // This event will be raised on the worker thread when the worker starts
        backgroundWorker1.DoWork += new DoWorkEventHandler(backgroundWorker1_DoWork);
        // This event will be raised when we call ReportProgress
        backgroundWorker1.ProgressChanged += new ProgressChangedEventHandler(backgroundWorker1_ProgressChanged);
    }
    void Form1_Shown(object sender, EventArgs e)
    {
        // Start the background worker
        backgroundWorker1.RunWorkerAsync();
    }
    // On worker thread so do our thing!
    void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
    {
        // Your background task goes here
        for (int i = 0; i <= 100; i++)
        {
            // Report progress to 'UI' thread
            backgroundWorker1.ReportProgress(i);
            // Simulate long task
            System.Threading.Thread.Sleep(100);
        }
    }
    // Back on the 'UI' thread so we can update the progress bar
    void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
    {
        // The progress percentage is a property of e
        progressBar1.Value = e.ProgressPercentage;
    }
}