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  #region ProgressSamples-03
  /// <summary>
  /// System.Progress<T>のサンプルです。
  /// </summary>
  /// <remarks>
  /// このクラスは、.NET Framework 4.5から追加された型です。
  /// </remarks>
  public class ProgressSamples03 : IExecutable
  {
    class SampleWindow : Window
    {
      TextBlock   _label;
      ProgressBar _bar;
      Button      _btn;
      
      public SampleWindow()
      {
        InitializeControl();
        InitializeEvent();
      }
      
      void InitializeControl()
      {
        Width  = 400;
        Height = 100;
        
        _label = new TextBlock
        {
          Text = string.Empty
        };
        
        _bar = new ProgressBar
        {
           Height = 20
          ,Minimum = 0
        };
        
        _btn = new Button
        {
           Content = "Cancel"
          ,Margin  = new Thickness(300, 0, 0, 0)
        };
        
        var panel = new StackPanel();
        
        panel.Children.Add(_label);
        panel.Children.Add(_bar);
        panel.Children.Add(_btn);
        
        Content = panel;
      }
      
      void InitializeEvent()
      {
        Loaded += async (s, e) =>
        {
          var tokenSource = new CancellationTokenSource();
          var progress    = new Progress<ProgressMessage>(SetProgress);
          
          _btn.Tag     = tokenSource;
          _bar.Maximum = Directory.EnumerateFiles(".").Count();
          
          await Compress(tokenSource.Token, progress);
          
          Title = "DONE";
          if (tokenSource.IsCancellationRequested)
          {
            Title = "CANCEL";
          }
        };
        
        _btn.Click += (s, e) =>
        {
          (_btn.Tag as CancellationTokenSource).Cancel();
        };
      }
      
      async Task Compress(CancellationToken token, IProgress<ProgressMessage> progress)
      {
        string ZipFilePath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Desktop), "ZipTest3.zip");
        string TmpFilePath = ZipFilePath + ".tmp";
        
        if (File.Exists(ZipFilePath))
        {
          File.Move(ZipFilePath, TmpFilePath);
        }
        
        using (var archive = ZipFile.Open(ZipFilePath, ZipArchiveMode.Create))
        {
          foreach (var filePath in Directory.EnumerateFiles("."))
          {
            if (token.IsCancellationRequested)
            {
              break;
            }
            
            progress.Report(new BeginMessage { Message = string.Format("{0}を圧縮しています...", filePath), Token = token });
            
            archive.CreateEntryFromFile(filePath, Path.GetFileName(filePath));
            await Task.Delay(1000);
            
            progress.Report(new AfterMessage { Message = string.Format("{0}を圧縮完了", filePath), Token = token });
          }
        }
        
        if (token.IsCancellationRequested)
        {
          File.Delete(ZipFilePath);
          if (File.Exists(TmpFilePath))
          {
            File.Move(TmpFilePath, ZipFilePath);
          }
        }
        else
        {
          if (File.Exists(TmpFilePath))
          {
            File.Delete(TmpFilePath);
          }
        }
      }
      
      void SetProgress(ProgressMessage message)
      {
        if (message.Token.IsCancellationRequested)
        {
          _label.Text = "処理はキャンセルされました。";
          return;
        }
        
        _label.Text = message.Message;
        if (message is AfterMessage)
        {
          _bar.Value++;
        }
      }
      
      class ProgressMessage
      {
        public string Message
        {
          get;
          set;
        }
        
        public CancellationToken Token
        {
          get;
          set;
        }
      }
      
      class BeginMessage : ProgressMessage {}
      class AfterMessage : ProgressMessage {}
    }
    
    public void Execute()
    {
      var app = new Application();
      app.Run(new SampleWindow());
    }
  }
  #endregion