c# BackgroundWorker组件的作用

public partial class Form1 : Form
  {
    public Form1()
    {
      InitializeComponent();
    }

    private void button1_Click(object sender, EventArgs e)
    {
      int a = int.Parse(textBox1.Text.Trim());
      int b = int.Parse(textBox2.Text.Trim());
      Add ad = new Add(a,b);
      backgroundWorker1.RunWorkerAsync(ad);
    }

    private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
    {
       Add args=(Add)e.Argument;
       for (int i = 0; i < 11; i++)
       {
         Thread.Sleep(200);
         backgroundWorker1.ReportProgress(i*10);
       }
      
       e.Result = args.a + args.b;
    }

    private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
    {
      label1.Text = e.Result.ToString();
    }

    private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
    {
      progressBar1.Value = e.ProgressPercentage;
    }
  }
  public class Add
  {
    public int a;
    public int b;
    public Add(int a, int b)
    {
      this.a = a;
      this.b = b;
    }

  }