BackgroundWorker.cs :  » 2.6.4-mono-.net-core » System.ComponentModel » System » ComponentModel » C# / CSharp Open Source

//
// BackgroundWorker.cs
//
// Authors:
//  Atsushi Enomoto <atsushi@ximian.com>
//
// Copyright (C) 2006 Novell, Inc.
//

//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
// 
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
#if NET_2_0
using System.Collections.Generic;
using System.Threading;

namespace System.ComponentModel{
#if !NET_2_1
  [DefaultEvent ("DoWork")]
  public class BackgroundWorker : Component
#else
  public class BackgroundWorker
#endif
  {
    public BackgroundWorker ()
    {
    }

    AsyncOperation async;
    bool cancel_pending, report_progress = false, support_cancel = false, complete = false;

    public event DoWorkEventHandler DoWork;
    public event ProgressChangedEventHandler ProgressChanged;
    public event RunWorkerCompletedEventHandler RunWorkerCompleted;

#if !NET_2_1
    [Browsable (false)]
#endif
    public bool CancellationPending {
      get { return cancel_pending; }
    }

#if !NET_2_1
    [Browsable (false)]
#endif
    public bool IsBusy {
      get { return async != null; }
    }

    [DefaultValue (false)]
    public bool WorkerReportsProgress {
      get { return report_progress; }
      set { report_progress = value; }
    }

    [DefaultValue (false)]
    public bool WorkerSupportsCancellation {
      get { return support_cancel; }
      set { support_cancel = value; }
    }

    public void CancelAsync ()
    {
      if (!support_cancel)
        throw new InvalidOperationException ("This background worker does not support cancellation.");

      if (!IsBusy)
        return;

      cancel_pending = true;
    }

    public void ReportProgress (int percentProgress)
    {
      ReportProgress (percentProgress, null);
    }

    public void ReportProgress (int percentProgress, object userState)
    {
      if (!WorkerReportsProgress)
        throw new InvalidOperationException ("This background worker does not report progress.");

      if (complete)
        throw new InvalidOperationException ("The background worker has ended.");

      ProgressChangedEventArgs pcea = new ProgressChangedEventArgs (percentProgress, userState);
      if (async == null) {
        // we can report progress before a call to RunWorkerAsync - but we do it sync
        OnProgressChanged (pcea);
      } else {
        async.Post (delegate (object o) {
          ProgressChangedEventArgs e = o as ProgressChangedEventArgs;
          OnProgressChanged (e);
        }, pcea);
      }
    }

    public void RunWorkerAsync ()
    {
      RunWorkerAsync (null);
    }

    delegate void ProcessWorkerEventHandler (object argument, AsyncOperation async, SendOrPostCallback callback);

    void ProcessWorker (object argument, AsyncOperation async, SendOrPostCallback callback)
    {
      // do worker
      Exception error = null;
      DoWorkEventArgs e = new DoWorkEventArgs (argument);
      try {
        OnDoWork (e);
      } catch (Exception ex) {
        error = ex;
        e.Cancel = false;
      }
      callback (new object [] {
        new RunWorkerCompletedEventArgs (
          e.Result, error, e.Cancel),
        async});
    }

    void CompleteWorker (object state)
    {
      object [] args = (object []) state;
      RunWorkerCompletedEventArgs e =
        args [0] as RunWorkerCompletedEventArgs;
      AsyncOperation async = args [1] as AsyncOperation;

      SendOrPostCallback callback = delegate (object darg) {
        this.async = null;
        complete = true;
        OnRunWorkerCompleted (darg as RunWorkerCompletedEventArgs);
      };

      async.PostOperationCompleted (callback, e);

      cancel_pending = false;
    }

    public void RunWorkerAsync (object argument)
    {
      if (IsBusy)
        throw new InvalidOperationException ("The background worker is busy.");

      async = AsyncOperationManager.CreateOperation (this);

      complete = false;
      ProcessWorkerEventHandler handler =
        new ProcessWorkerEventHandler (ProcessWorker);
      handler.BeginInvoke (argument, async, CompleteWorker, null, null);
    }

    protected virtual void OnDoWork (DoWorkEventArgs e)
    {
      if (DoWork != null)
        DoWork (this, e);
    }

    protected virtual void OnProgressChanged (ProgressChangedEventArgs e)
    {
      if (ProgressChanged != null)
        ProgressChanged (this, e);
    }

    protected virtual void OnRunWorkerCompleted (RunWorkerCompletedEventArgs e)
    {
      if (RunWorkerCompleted != null)
        RunWorkerCompleted (this, e);
    }
  }
}
#endif