using System;
using System.Collections.Generic;
using System.ComponentModel;////
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Threading;
namespace BackgroundWorkerSample
{
public partial class CalculateAddForm : Form
{
protected BackgroundWorker backgroundWorker1 = new BackgroundWorker();
//private int numberToCompute = 0;
//private int highestPercentageReached = 0;
public CalculateAddForm()
{
InitializeComponent();
InitializeBackgoundWorker();
}
// Set up the BackgroundWorker object by
// attaching event handlers.
private void InitializeBackgoundWorker()
{
this.backgroundWorker1.WorkerReportsProgress = true;
this.backgroundWorker1.WorkerSupportsCancellation = true;
this.backgroundWorker1.DoWork += new DoWorkEventHandler(backgroundWorker1_DoWork);
this.backgroundWorker1.ProgressChanged += new ProgressChangedEventHandler(backgroundWorker1_ProgressChanged);
this.backgroundWorker1.RunWorkerCompleted += new RunWorkerCompletedEventHandler(backgroundWorker1_RunWorkerCompleted);
}
private long ComputeAdd(int n, BackgroundWorker worker, DoWorkEventArgs e)
{
long result = 0;
// Abort the operation if the user has canceled.
// Note that a call to CancelAsync may have set
// CancellationPending to true just after the
// last invocation of this method exits, so this
// code will not have the opportunity to set the
// DoWorkEventArgs.Cancel flag to true. This means
// that RunWorkerCompletedEventArgs.Cancelled will
// not be set to true in your RunWorkerCompleted
// event handler. This is a race condition.
for (int i = 1; i <= n; i++)
{
if (worker.CancellationPending)
{
e.Cancel = true;
break;
}
else
{
result += i;
Thread.Sleep(100);
// Report progress as a percentage of the total task.
int percentComplete = (int)((float)i / (float)n * 100);
worker.ReportProgress(percentComplete);
}
}
return result;
}
void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
// Get the BackgroundWorker that raised this event.
BackgroundWorker worker = sender as BackgroundWorker;
// Assign the result of the computation
// to the Result property of the DoWorkEventArgs
// object. This is will be available to the
// RunWorkerCompleted eventhandler.
e.Result = ComputeAdd((int)e.Argument, worker, e);
// If the operation was canceled by the user,
// set the DoWorkEventArgs.Cancel property to true.
if (worker.CancellationPending)
{
e.Cancel = true;
}
}
void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
this.progressBar1.Value = e.ProgressPercentage;
}
void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
// First, handle the case where an exception was thrown.
if (e.Error != null)
{
MessageBox.Show(e.Error.Message);
}
else if (e.Cancelled)
{
// Next, handle the case where the user canceled
// the operation.
// Note that due to a race condition in
// the DoWork event handler, the Cancelled
// flag may not have been set, even though
// CancelAsync was called.
resultLabel.Text = "Canceled";
}
else
{
// Finally, handle the case where the operation
// succeeded.
resultLabel.Text = e.Result.ToString();
}
// Enable the UpDown control.
this.numericUpDown1.Enabled = true;
// Enable the Start button.
startAsyncButton.Enabled = true;
// Disable the Cancel button.
cancelAsyncButton.Enabled = false;
}
private void startAsyncButton_Click(object sender, EventArgs e)
{
// Reset the text in the result label.
resultLabel.Text = String.Empty;
// Disable the UpDown control until
// the asynchronous operation is done.
this.numericUpDown1.Enabled = false;
// Disable the Start button until
// the asynchronous operation is done.
this.startAsyncButton.Enabled = false;
// Enable the Cancel button while
// the asynchronous operation runs.
this.cancelAsyncButton.Enabled = true;
// Get the value from the UpDown control.
int numberToCompute = (int)numericUpDown1.Value;
// Reset the variable for percentage tracking.
//highestPercentageReached = 0;
// Start the asynchronous operation.
backgroundWorker1.RunWorkerAsync(numberToCompute);
}
private void cancelAsyncButton_Click(object sender, EventArgs e)
{
// Cancel the asynchronous operation.
this.backgroundWorker1.CancelAsync();
// Disable the Cancel button.
cancelAsyncButton.Enabled = false;
}
}
}
