Form1.cs in Async Delegate Example

    0 using System;
    1 using System.Drawing;
    2 using System.Collections;
    3 using System.ComponentModel;
    4 using System.Windows.Forms;
    5 using System.Data;
    6 using System.Threading; // for Thread.Sleep
    7 
    8 namespace HarborMist
    9 {
   10 
   11     public class Form1 : System.Windows.Forms.Form
   12     {
   13         private System.Windows.Forms.Button button1;
   14         private System.Windows.Forms.ProgressBar progressBar1;
   15         private System.Windows.Forms.Timer timer1;
   16         private System.Windows.Forms.TextBox textBox1;
   17         private System.Windows.Forms.ProgressBar progressBar2;
   18         private System.Windows.Forms.Button buttonExit;
   19         private System.Windows.Forms.Label label1;
   20         private System.ComponentModel.IContainer components;
   21 
   22 
   23         public Form1()
   24         {
   25             // required for Windows Form Designer support
   26             InitializeComponent();
   27 
   28         }
   29 
   30 
   31 
   32         private string threadIdentity()
   33         {
   34             string myString = "";
   35             if (Thread.CurrentThread.IsThreadPoolThread)
   36                 myString = "Thread pool thread";
   37             else
   38                 myString = "Form thread";
   39             myString = myString + ", priority=";
   40             myString = myString + Thread.CurrentThread.Priority.ToString();
   41             if (Thread.CurrentThread.IsBackground)
   42                 myString = myString + " (background)";
   43             else
   44                 myString = myString + " (foreground)";
   45             return myString;
   46         }
   47 
   48 
   49 
   50         [STAThread]
   51         static void Main() 
   52         {
   53             Application.Run(new Form1());
   54         }
   55 
   56 
   57 
   58         private void button1_Click(object sender, System.EventArgs e)
   59         {
   60             try
   61             {
   62                 myDelegateForWorkerThread = new delegateForWorkerThread(workerCode);
   63                 myDelegateForWorkerThread.BeginInvoke(10, new AsyncCallback(codeForAfterWorkerCode), null);
   64             }
   65             catch
   66             {
   67                 MessageBox.Show("Failed to create worker thread.");
   68             }
   69         }
   70        
   71 
   72         private delegate string delegateForWorkerThread(int param);
   73 
   74         private delegate void delegateForFormUpdate(string myMessage, int myCount);
   75 
   76         private delegate void delegateForTextBox1Update(string theAddendum);
   77 
   78         private delegateForWorkerThread myDelegateForWorkerThread;
   79 
   80 
   81         private string workerCode(int howManyUpdates)
   82         {
   83             int count;
   84             for (count=1;count<=howManyUpdates;count++)
   85             {
   86                 if (progressBar2.InvokeRequired)
   87                 {
   88                     progressBar2.Invoke(new delegateForFormUpdate(workerGUIupdate),
   89                         new object[]{"loop count = ",count});
   90                 }
   91                 else
   92                 {
   93                     workerGUIupdate("I am not a worker thread.", count);
   94                 }
   95                 Thread.Sleep(600);
   96             }
   97             return threadIdentity() + "\r\nworker loop ran " + (count-1).ToString() + " times";
   98         }
   99 
  100 
  101         private void workerUpdateTextBox1(string myAddition)
  102         {
  103             textBox1.Text = textBox1.Text + myAddition;
  104         }
  105 
  106 
  107         // called after the asynchronous work is done
  108         private void codeForAfterWorkerCode(IAsyncResult results)
  109         {
  110             string myMessage = "\r\n" +
  111                 myDelegateForWorkerThread.EndInvoke(results) + "\r\n" +
  112                 "progress bar value = " + progressBar2.Value.ToString();
  113 
  114             if (textBox1.InvokeRequired)
  115             {
  116                 progressBar2.Invoke(new delegateForTextBox1Update(workerUpdateTextBox1),
  117                     new object[] { myMessage });
  118             }
  119             else
  120             {
  121                 workerUpdateTextBox1(myMessage);
  122             }
  123         }
  124 
  125 
  126         private void workerGUIupdate(string theMessage, int theCount)
  127         {
  128             int x = this.progressBar2.Value + 1;
  129             if (x > this.progressBar2.Maximum) x = 1;
  130             this.progressBar2.Value = x;
  131             this.textBox1.Text = theMessage + theCount.ToString();
  132             return;
  133         }
  134 
  135 
  136         private void timer1_Tick(object sender, System.EventArgs e)
  137         {
  138             timer1.Enabled = false;
  139             int x = progressBar1.Value + 10;
  140             if (x > progressBar1.Maximum) x = 0;
  141             progressBar1.Value = x;
  142             timer1.Enabled = true;
  143         }
  144 
  145 
  146         private void Form1_Load(object sender, System.EventArgs e)
  147         {
  148             timer1.Interval = 100;
  149             timer1.Enabled = true;
  150             label1.Text = threadIdentity() + " is updating this progress bar.";
  151         }
  152 
  153 
  154         private void buttonExit_Click(object sender, System.EventArgs e)
  155         {
  156             this.Close();
  157         }
  158 
  159 
  160         private void Form1_Resize(object sender, System.EventArgs e)
  161         {
  162             this.label1.Top = this.progressBar1.Top + this.progressBar1.Height;
  163         }
  164 
  165 
  166     } // end class