using System;
using System.Collections;
using System.ComponentModel;
using System.Threading;
using System.Windows.Forms;
 public class FibonacciForm : Form
{
private int numberToCompute = 0;
private int highestPercentageReached = 0;
private NumericUpDown numericUpDown1;
private Button startAsyncButton;
private Button cancelAsyncButton;
private ProgressBar progressBar1;
private Label resultLabel;
private BackgroundWorker backgroundWorker1; 
 public FibonacciForm()
{
    InitializeComponent();
    InitializeBackgroundWorker();
}
private void InitializeBackgroundWorker()
{
    backgroundWorker1.DoWork += new DoWorkEventHandler(backgroundWorker1_DoWork);
    backgroundWorker1.RunWorkerCompleted += new RunWorkerCompletedEventHandler(backgroundWorker1_RunWorkerCompleted);
    backgroundWorker1.ProgressChanged += new ProgressChangedEventHandler(backgroundWorker1_ProgressChanged);
}
private void startAsyncButton_Click(object sender, EventArgs e)
{
    resultLabel.Text = string.Empty;
    numericUpDown1.Enabled = false;
    startAsyncButton.Enabled = false;
    cancelAsyncButton.Enabled = true;
    numberToCompute = (int)numericUpDown1.Value;
    highestPercentageReached = 0;
    backgroundWorker1.RunWorkerAsync(numberToCompute);
}
private void cancelAsyncButton_Click(object sender, EventArgs e)
{
    backgroundWorker1.CancelAsync();
    cancelAsyncButton.Enabled = false;
}
private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
    BackgroundWorker worker = sender as BackgroundWorker;
    e.Result = ComputeFibonacci((int)e.Argument, worker, e);
}
private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
    if (e.Error != null)
    {
        MessageBox.Show(e.Error.Message);
    }
    else if (e.Cancelled)
    {
        resultLabel.Text = "Canceled";
    }
    else
    {
        resultLabel.Text = e.Result.ToString();
    }
    numericUpDown1.Enabled = true;
    startAsyncButton.Enabled = true;
    cancelAsyncButton.Enabled = false;
}
private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
    progressBar1.Value = e.ProgressPercentage;
}
long ComputeFibonacci(int n, BackgroundWorker worker, DoWorkEventArgs e)
{
    if ((n < 0) || (n > 91))
    {
        throw new ArgumentException("value must be >= 0 and <= 91", "n");
    }
    long result = 0;
    if (worker.CancellationPending)
    {
        e.Cancel = true;
    }
    else
    {
        if (n < 2)
        {
            result = 1;
        }
        else
        {
            result = ComputeFibonacci(n - 1, worker, e) + ComputeFibonacci(n - 2, worker, e);
        }
        int percentComplete = (int)((float)n / (float)numberToCompute * 100);
        if (percentComplete > highestPercentageReached)
        {
            highestPercentageReached = percentComplete;
            worker.ReportProgress(percentComplete);
        }
    }
    return result;
}
private void InitializeComponent()
{
    numericUpDown1 = new NumericUpDown();
    startAsyncButton = new Button();
    cancelAsyncButton = new Button();
    resultLabel = new Label();
    progressBar1 = new ProgressBar();
    backgroundWorker1 = new BackgroundWorker();
    numericUpDown1.Location = new Point(16, 16);
    numericUpDown1.Maximum = new Decimal(new int[] { 91, 0, 0, 0 });
    numericUpDown1.Minimum = new Decimal(new int[] { 1, 0, 0, 0 });
    numericUpDown1.Name = "numericUpDown1";
    numericUpDown1.Size = new Size(80, 20);
    numericUpDown1.TabIndex = 0;
    numericUpDown1.Value = new Decimal(new int[] { 1, 0, 0, 0 });
    startAsyncButton.Location = new Point(16, 72);
    startAsyncButton.Name = "startAsyncButton";
    startAsyncButton.Size = new Size(120, 23);
    startAsyncButton.TabIndex = 1;
    startAsyncButton.Text = "Start Async";
    startAsyncButton.Click += new EventHandler(startAsyncButton_Click);
    cancelAsyncButton.Enabled = false;
    cancelAsyncButton.Location = new Point(153, 72);
    cancelAsyncButton.Name = "cancelAsyncButton";
    cancelAsyncButton.Size = new Size(119, 23);
    cancelAsyncButton.TabIndex = 2;
    cancelAsyncButton.Text = "Cancel Async";
    cancelAsyncButton.Click += new EventHandler(cancelAsyncButton_Click);
    resultLabel.BorderStyle = System.Windows.Forms.BorderStyle.Fixed3D;
    resultLabel.Location = new Point(112, 16);
    resultLabel.Name = "resultLabel";
    resultLabel.Size = new Size(160, 23);
    resultLabel.TabIndex = 3;
    resultLabel.Text = "(no result)";
    resultLabel.TextAlign = ContentAlignment.MiddleCenter;
    progressBar1.Location = new Point(18, 48);
    progressBar1.Name = "progressBar1";
    progressBar1.Size = new Size(256, 8);
    progressBar1.Step = 2;
    progressBar1.TabIndex = 4;
    backgroundWorker1.WorkerReportsProgress = true;
    backgroundWorker1.WorkerSupportsCancellation = true;
    this.ClientSize = new Size(292, 118);
    this.Controls.Add(progressBar1);
    this.Controls.Add(resultLabel);
    this.Controls.Add(cancelAsyncButton);
    this.Controls.Add(startAsyncButton);
    this.Controls.Add(numericUpDown1);
    this.Name = "FibonacciForm";
    this.Text = "Fibonacci Calculator";
}
 
 }