namespace BackgroundWorkerExample
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            backgroundWorker1.WorkerReportsProgress = true;
            backgroundWorker1.WorkerSupportsCancellation = true;
            btn_Stop.Enabled = false;
        }

        private void btn_Start_Click(object sender, EventArgs e)
        {
            txt_Text.Text = "開始產生10000以內的隨機數(shù)……\n\n";
            btn_Start.Enabled = false;
            btn_Stop.Enabled = true;
            //在后臺線程開始操作
            backgroundWorker1.RunWorkerAsync();
        }

        private void btn_Stop_Click(object sender, EventArgs e)
        {
            backgroundWorker1.CancelAsync();
            btn_Stop.Enabled = false;
            btn_Start.Enabled = true;
        }

        private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
        {
            //不要直接使用組件實例名稱（backgroundWorker1),因為有多個BackgroundWorker時，
            //直接使用會產生耦合問題，應該通過下面的轉換使用它
            BackgroundWorker worker = sender as BackgroundWorker;
            //下面的內容相當于線程要處理的內容。//注意：不要在此事件中和界面控件打交道
            Random r = new Random();
            int numCount = 0;
            while (worker.CancellationPending == false)
            {
                int num = r.Next(0, 10000);
                if (num % 5 == 0)
                {
                    numCount++;
                    worker.ReportProgress(0, num);
                    Thread.Sleep(1000);
                }
            }
            e.Result = numCount;
        }

        private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
        {
            int num = (int)e.UserState;
            txt_Text.Text += num + " ";
        }

        private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            if (e.Error == null)
                txt_Text.Text += "\n\n操作停止，共生產" + e.Result + "個能被5整除的隨機數(shù)";
            else
                txt_Text.Text += "\n操作過程中產生錯誤：" + e.Error;

        }
    }
}