using?System;
using?System.Collections.Generic;
using?System.ComponentModel;
using?System.Data;
using?System.Diagnostics;
using?System.Drawing;
using?System.Text;
using?System.Threading;
using?System.Windows.Forms;

namespace?AsyncCalcPiWithBackgroundWorkerSample?{

??partial?class?AsyncCalcPiForm?:?Form?{
????public?AsyncCalcPiForm（）?{
??????InitializeComponent（）;
????}

????void?ShowProgress（string?pi?int?totalDigits?int?digitsSoFar）?{
??????//?Make?sure?we‘re?on?the?UI?thread
??????Debug.Assert（this.InvokeRequired?==?false）;

??????//?Display?progress?in?UI
??????this.resultsTextBox.Text?=?pi;
??????this.calcToolStripProgressBar.Maximum?=?totalDigits;
??????this.calcToolStripProgressBar.Value?=?digitsSoFar;
????}

????class?CalcPiUserState?{
??????public?readonly?string?Pi;
??????public?readonly?int?TotalDigits;
??????public?readonly?int?DigitsSoFar;

??????public?CalcPiUserState（string?pi?int?totalDigits?int?digitsSoFar）?{
????????this.Pi?=?pi;
????????this.TotalDigits?=?totalDigits;
????????this.DigitsSoFar?=?digitsSoFar;
??????}
????}

????void?CalcPi（int?digits）?{
??????StringBuilder?pi?=?new?StringBuilder（“3“?digits?+?2）;

??????//?Report?initial?progress
??????this.backgroundWorker.ReportProgress（0
????????new?CalcPiUserState（pi.ToString（）?digits?0））;

??????if（?digits?>?0?）?{
????????pi.Append（“.“）;

????????for（?int?i?=?0;?i???????????int?nineDigits?=?NineDigitsOfPi.StartingAt（i?+?1）;
??????????int?digitCount?=?Math.Min（digits?-?i?9）;
??????????string?ds?=?string.Format（“{0:D9}“?nineDigits）;
??????????pi.Append（ds.Substring（0?digitCount））;

??????????//?Report?continuing?progress
??????????this.backgroundWorker.ReportProgress（0
????????????new?CalcPiUserState（pi.ToString（）?digits?i?+?digitCount））;

??????????//?Check?for?cancelation
??????????if（?this.backgroundWorker.CancellationPending?）?{?return;?}
????????}
??????}
????}

????void?calcButton_Click（object?sender?EventArgs?e）?{
??????//?Don‘t?process?if?cancel?request?pending
??????//?（Should?not?be?called?since?we?disabled?the?button...）
??????if（?this.backgroundWorker.CancellationPending?）?{?return;?}

??????//?If?worker?thread?currently?executing?cancel?it
??????if（?this.backgroundWorker.IsBusy?）?{
????????this.calcButton.Enabled?=?false;
????????this.backgroundWorker.CancelAsync（）;
????????return;
??????}

??????//?Set?calculating?UI
??????this.calcButton.Text?=?“Cancel“;
??????this.calcToolStripProgressBar.Visible?=?true;
??????this.calcToolStripStatusLabel.Text?=?“Calculating...“;

??????//?Begin?calculating?pi?asynchronously
??????this.backgroundWorker.RunWorkerAsync（
????????（int）this.decimalPlacesNumericUpDown.Value）;
????}

????void?backgroundWorker_DoWork（object?sender?DoWorkEventArgs?e）?{
??????//throw?new?Exception（“Ooops!“）;

??????//?Track?start?time
??????DateTime?start?=?DateTime.Now;

??????CalcPi（（int）e.Argument）;

??????//?Indicate?

?屬性????????????大小?????日期????時間???名稱
-----------?---------??----------?-----??----
?????目錄???????????0??2013-11-07?17:53??AsyncCalcPiWithBackgroundWorkerWithCancelationSample\
?????文件????????4132??2005-12-16?16:32??AsyncCalcPiWithBackgroundWorkerWithCancelationSample\AsyncCalcPiForm.cs
?????文件????????8297??2005-12-16?16:32??AsyncCalcPiWithBackgroundWorkerWithCancelationSample\AsyncCalcPiForm.designer.cs
?????文件????????6399??2005-12-16?16:32??AsyncCalcPiWithBackgroundWorkerWithCancelationSample\AsyncCalcPiForm.resx
?????文件????????3070??2005-12-16?16:32??AsyncCalcPiWithBackgroundWorkerWithCancelationSample\AsyncCalcPiWithBackgroundWorkerSample.csproj
?????文件?????????962??2005-12-16?16:32??AsyncCalcPiWithBackgroundWorkerWithCancelationSample\AsyncCalcPiWithBackgroundWorkerSample.sln
?????文件???????14848??2013-11-07?16:50??AsyncCalcPiWithBackgroundWorkerWithCancelationSample\AsyncCalcPiWithBackgroundWorkerSample.suo
?????目錄???????????0??2013-11-07?17:53??AsyncCalcPiWithBackgroundWorkerWithCancelationSample\bin\
?????目錄???????????0??2013-11-07?17:53??AsyncCalcPiWithBackgroundWorkerWithCancelationSample\bin\Debug\
?????文件???????24576??2013-11-07?10:12??AsyncCalcPiWithBackgroundWorkerWithCancelationSample\bin\Debug\AsyncCalcPiWithBackgroundWorkerSample.exe
?????文件???????32256??2013-11-07?10:12??AsyncCalcPiWithBackgroundWorkerWithCancelationSample\bin\Debug\AsyncCalcPiWithBackgroundWorkerSample.pdb
?????文件????????5632??2013-11-07?10:12??AsyncCalcPiWithBackgroundWorkerWithCancelationSample\bin\Debug\AsyncCalcPiWithBackgroundWorkerSample.vshost.exe
?????文件????????3791??2005-12-16?16:32??AsyncCalcPiWithBackgroundWorkerWithCancelationSample\NineDigitsOfPiAt.cs
?????目錄???????????0??2013-11-07?17:53??AsyncCalcPiWithBackgroundWorkerWithCancelationSample\obj\
?????文件????????1312??2013-11-07?10:12??AsyncCalcPiWithBackgroundWorkerWithCancelationSample\obj\AsyncCalcPiWithBackgroundWorkerSample.csproj.FileListAbsolute.txt
?????目錄???????????0??2013-11-07?17:53??AsyncCalcPiWithBackgroundWorkerWithCancelationSample\obj\Debug\
?????文件?????????180??2013-11-07?10:12??AsyncCalcPiWithBackgroundWorkerWithCancelationSample\obj\Debug\AsyncCalcPiWithBackgroundWorkerSample.AsyncCalcPiForm.resources
?????文件?????????852??2013-11-07?10:12??AsyncCalcPiWithBackgroundWorkerWithCancelationSample\obj\Debug\AsyncCalcPiWithBackgroundWorkerSample.csproj.GenerateResource.Cache
?????文件???????24576??2013-11-07?10:12??AsyncCalcPiWithBackgroundWorkerWithCancelationSample\obj\Debug\AsyncCalcPiWithBackgroundWorkerSample.exe
?????文件???????32256??2013-11-07?10:12??AsyncCalcPiWithBackgroundWorkerWithCancelationSample\obj\Debug\AsyncCalcPiWithBackgroundWorkerSample.pdb
?????文件?????????180??2013-11-07?10:12??AsyncCalcPiWithBackgroundWorkerWithCancelationSample\obj\Debug\AsyncCalcPiWithBackgroundWorkerSample.Properties.Resources.resources
?????目錄???????????0??2013-11-07?09:55??AsyncCalcPiWithBackgroundWorkerWithCancelationSample\obj\Debug\Refactor\
?????目錄???????????0??2013-11-07?09:36??AsyncCalcPiWithBackgroundWorkerWithCancelationSample\obj\Debug\TempPE\
?????文件?????????456??2005-12-16?16:32??AsyncCalcPiWithBackgroundWorkerWithCancelationSample\Program.cs
?????目錄???????????0??2013-11-07?17:53??AsyncCalcPiWithBackgroundWorkerWithCancelationSample\Properties\
?????文件????????1333??2005-12-16?16:32??AsyncCalcPiWithBackgroundWorkerWithCancelationSample\Properties\AssemblyInfo.cs
?????文件????????3313??2005-12-16?16:32??AsyncCalcPiWithBackgroundWorkerWithCancelationSample\Properties\Resources.Designer.cs
?????文件????????5612??2005-12-16?16:32??AsyncCalcPiWithBackgroundWorkerWithCancelationSample\Properties\Resources.resx
?????文件????????1119??2005-12-16?16:32??AsyncCalcPiWithBackgroundWorkerWithCancelationSample\Properties\Settings.Designer.cs
?????文件?????????249??2005-12-16?16:32??AsyncCalcPiWithBackgroundWorkerWithCancelationSample\Properties\Settings.settings