BackgroundWorker 组件 -- 进度条

代码：

 BackgroundWorker bw = new BackgroundWorker();
        public MainWindow()
        {
            InitializeComponent();

            bw.WorkerReportsProgress = true;
            bw.WorkerSupportsCancellation = true;
            bw.DoWork += bw_DoWork;
            bw.ProgressChanged += bw_ProgressChanged;
            bw.RunWorkerCompleted += bw_RunWorkerCompleted;

        }

        void bw_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            this.txtMsg.Text = "下载完成";
        }

        void bw_ProgressChanged(object sender, ProgressChangedEventArgs e)
        {
            this.mySlider.Value = (double)e.ProgressPercentage / ;
            this.txtMsg.Text = ((double)e.ProgressPercentage / ).ToString();

        }

        void bw_DoWork(object sender, DoWorkEventArgs e)
        {
            for (int i = ; i < ; i++)
            {
                if (bw.CancellationPending == true)
                {
                    e.Cancel = true;
                    return;
                }

                bw.ReportProgress(i);
                Thread.Sleep(TimeSpan.FromSeconds());

            }

        }

        private void btnStart_Click(object sender, RoutedEventArgs e)
        {
            bw.RunWorkerAsync();

        }

        private void btnCancel_Click(object sender, RoutedEventArgs e)
        {
            bw.CancelAsync();
        }