class/System/System.ComponentModel/BackgroundWorker.cs

   1 //
   2 // BackgroundWorker.cs
   3 //
   4 // Authors:
   5 //      Atsushi Enomoto <atsushi@ximian.com>
   6 //
   7 // Copyright (C) 2006 Novell, Inc.
   8 //
   9
  10 //
  11 // Permission is hereby granted, free of charge, to any person obtaining
  12 // a copy of this software and associated documentation files (the
  13 // "Software"), to deal in the Software without restriction, including
  14 // without limitation the rights to use, copy, modify, merge, publish,
  15 // distribute, sublicense, and/or sell copies of the Software, and to
  16 // permit persons to whom the Software is furnished to do so, subject to
  17 // the following conditions:
  18 //
  19 // The above copyright notice and this permission notice shall be
  20 // included in all copies or substantial portions of the Software.
  21 //
  22 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  23 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  24 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  25 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  26 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  27 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  28 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  29 //
  30 #if NET_2_0
  31 using System.Collections.Generic;
  32 using System.Threading;
  33
  34 namespace System.ComponentModel
  35 {
  36 #if !NET_2_1
  37         [DefaultEvent ("DoWork")]
  38         public class BackgroundWorker : Component
  39 #else
  40         public class BackgroundWorker
  41 #endif
  42         {
  43                 public BackgroundWorker ()
  44                 {
  45                 }
  46
  47                 AsyncOperation async;
  48                 bool cancel_pending, report_progress = false, support_cancel = false, complete = false;
  49
  50                 public event DoWorkEventHandler DoWork;
  51                 public event ProgressChangedEventHandler ProgressChanged;
  52                 public event RunWorkerCompletedEventHandler RunWorkerCompleted;
  53
  54 #if !NET_2_1
  55                 [Browsable (false)]
  56 #endif
  57                 public bool CancellationPending {
  58                         get { return cancel_pending; }
  59                 }
  60
  61 #if !NET_2_1
  62                 [Browsable (false)]
  63 #endif
  64                 public bool IsBusy {
  65                         get { return async != null; }
  66                 }
  67
  68                 [DefaultValue (false)]
  69                 public bool WorkerReportsProgress {
  70                         get { return report_progress; }
  71                         set { report_progress = value; }
  72                 }
  73
  74                 [DefaultValue (false)]
  75                 public bool WorkerSupportsCancellation {
  76                         get { return support_cancel; }
  77                         set { support_cancel = value; }
  78                 }
  79
  80                 public void CancelAsync ()
  81                 {
  82                         if (!support_cancel)
  83                                 throw new InvalidOperationException ("This background worker does not support cancellation.");
  84
  85                         if (!IsBusy)
  86                                 return;
  87
  88                         cancel_pending = true;
  89                 }
  90
  91                 public void ReportProgress (int percentProgress)
  92                 {
  93                         ReportProgress (percentProgress, null);
  94                 }
  95
  96                 public void ReportProgress (int percentProgress, object userState)
  97                 {
  98                         if (!WorkerReportsProgress)
  99                                 throw new InvalidOperationException ("This background worker does not report progress.");
 100
 101                         if (complete)
 102                                 throw new InvalidOperationException ("The background worker has ended.");
 103
 104                         ProgressChangedEventArgs pcea = new ProgressChangedEventArgs (percentProgress, userState);
 105                         if (async == null) {
 106                                 // we can report progress before a call to RunWorkerAsync - but we do it sync
 107                                 OnProgressChanged (pcea);
 108                         } else {
 109                                 async.Post (delegate (object o) {
 110                                         ProgressChangedEventArgs e = o as ProgressChangedEventArgs;
 111                                         OnProgressChanged (e);
 112                                 }, pcea);
 113                         }
 114                 }
 115
 116                 public void RunWorkerAsync ()
 117                 {
 118                         RunWorkerAsync (null);
 119                 }
 120
 121                 delegate void ProcessWorkerEventHandler (object argument, AsyncOperation async, SendOrPostCallback callback);
 122
 123                 void ProcessWorker (object argument, AsyncOperation async, SendOrPostCallback callback)
 124                 {
 125                         // do worker
 126                         Exception error = null;
 127                         DoWorkEventArgs e = new DoWorkEventArgs (argument);
 128                         try {
 129                                 OnDoWork (e);
 130                         } catch (Exception ex) {
 131                                 error = ex;
 132                                 e.Cancel = false;
 133                         }
 134                         callback (new object [] {
 135                                 new RunWorkerCompletedEventArgs (
 136                                         e.Result, error, e.Cancel),
 137                                 async});
 138                 }
 139
 140                 void CompleteWorker (object state)
 141                 {
 142                         object [] args = (object []) state;
 143                         RunWorkerCompletedEventArgs e =
 144                                 args [0] as RunWorkerCompletedEventArgs;
 145                         AsyncOperation async = args [1] as AsyncOperation;
 146
 147                         SendOrPostCallback callback = delegate (object darg) {
 148                                 this.async = null;
 149                                 complete = true;
 150                                 OnRunWorkerCompleted (darg as RunWorkerCompletedEventArgs);
 151                         };
 152
 153                         async.PostOperationCompleted (callback, e);
 154
 155                         cancel_pending = false;
 156                 }
 157
 158                 public void RunWorkerAsync (object argument)
 159                 {
 160                         if (IsBusy)
 161                                 throw new InvalidOperationException ("The background worker is busy.");
 162
 163                         async = AsyncOperationManager.CreateOperation (this);
 164
 165                         complete = false;
 166                         ProcessWorkerEventHandler handler =
 167                                 new ProcessWorkerEventHandler (ProcessWorker);
 168                         handler.BeginInvoke (argument, async, CompleteWorker, null, null);
 169                 }
 170
 171                 protected virtual void OnDoWork (DoWorkEventArgs e)
 172                 {
 173                         if (DoWork != null)
 174                                 DoWork (this, e);
 175                 }
 176
 177                 protected virtual void OnProgressChanged (ProgressChangedEventArgs e)
 178                 {
 179                         if (ProgressChanged != null)
 180                                 ProgressChanged (this, e);
 181                 }
 182
 183                 protected virtual void OnRunWorkerCompleted (RunWorkerCompletedEventArgs e)
 184                 {
 185                         if (RunWorkerCompleted != null)
 186                                 RunWorkerCompleted (this, e);
 187                 }
 188         }
 189 }
 190 #endif