在WPF中使用不確定進度條和Backgroundworker

Question

我創建了一個用於將數據從一個數據庫導入和轉換爲另一個數據庫的小工具。由於這需要很長時間，我想用一個不確定的進度條爲用戶顯示某種進度。 只要導入正在運行，進度條也應該運行。 我用這個網站作爲參考：The ProgressBar control但是我很難理解DoWork-Method的作用，因爲一個不確定的進度條選項被設置一次。

我想出了一個半途而廢的解決方案，導入完成後我無法停止動畫。 有人可以幫我嗎？

XAML：

<ProgressBar Minimum="{Binding Path=Minimum}" Maximum="100" IsIndeterminate="{Binding Path=IsIndeterminate}" Height="20" Grid.Column="2" Grid.Row="5" Grid.ColumnSpan="2"/> 

視圖模型：

public void StartImportThread() 
    { 
     ButtonsEnabled = false; 
     var th = new Thread(new ThreadStart(StartImport)); 
     th.IsBackground = true; 
     th.Start(); 
    } 
public void StartImport() 
    { 
     _threadDispatcher = Dispatcher.CurrentDispatcher; 
     BackgroundWorker worker = new BackgroundWorker(); 
     worker.WorkerReportsProgress = true; 
     worker.WorkerSupportsCancellation = true; 
     worker.DoWork += worker_DoWork; 
     worker.RunWorkerCompleted += worker_Complete; 

     worker.RunWorkerAsync(); 

     // Doing Import Stuff 
     worker.CancelAsync(); // Import finished 
     ButtonsEnabled=true; 
    } 
    void worker_DoWork(object sender, DoWorkEventArgs e) 
    { 
     // while(true) 
    // { 
      Minimum = 0; 
      IsIndeterminate = true; 
    // } 


    } 


    private void worker_Complete(object sender, RunWorkerCompletedEventArgs e) 
    { 
     // if (e.Cancelled) 
     // { 
      IsIndeterminate = false; 
      Minimum = 100; 
     // } 

    } 

Answer 1

這裏是我的作品。 RelayCommand和ViewModelBase來自MvvmLight庫，DoWorkCommand被一個按鈕調用：

 <Button Name="BtnReload" Command="{Binding DoWorkCommand}" Width="75" Height="25"/> 
     <ProgressBar Minimum="{Binding Path=Minimum}" Maximum="100" IsIndeterminate="{Binding Path=IsIndeterminate}" Height="20"/> 



    public class MainViewModel : ViewModelBase { 

    private RelayCommand _doWorkCommand; 
    private bool _isIndeterminate; 
    private int _minimum; 
    private Dispatcher _threadDispatcher; 


    public int Minimum { 
     get { return _minimum; } 
     set { 
      _minimum = value; 
      RaisePropertyChanged(nameof(Minimum)); 
     } 
    } 

    public bool IsIndeterminate { 
     get { return _isIndeterminate; } 
     set { 
      _isIndeterminate = value; 
      RaisePropertyChanged(nameof(IsIndeterminate)); 
     } 
    } 

    public MainViewModel(IDataService dataService) { 

    } 

    public void StartImportThread() { 
     // ButtonsEnabled = false; 
     var th = new Thread(new ThreadStart(StartImport)); 
     th.IsBackground = true; 
     th.Start(); 
    } 

    public void StartImport() { 
     _threadDispatcher = Dispatcher.CurrentDispatcher; 
     BackgroundWorker worker = new BackgroundWorker(); 
     worker.WorkerReportsProgress = true; 
     worker.WorkerSupportsCancellation = true; 
     worker.DoWork += worker_DoWork; 
     worker.RunWorkerCompleted += worker_Complete; 

     worker.RunWorkerAsync(); 

     // Doing Import Stuff 
     worker.CancelAsync(); // Import finished 
     // ButtonsEnabled = true; 

    } 

    void worker_DoWork(object sender, DoWorkEventArgs e) { 
     Minimum = 0; 
     IsIndeterminate = true; 
     //for (int i = 0; i < 30; i++) { 
     // Thread.Sleep(100); 
     //}  
    } 

    void worker_Complete(object sender, RunWorkerCompletedEventArgs e) { 
     IsIndeterminate = false; 
     Minimum = 100; 
    } 

    public RelayCommand DoWorkCommand => _doWorkCommand ?? 
     (_doWorkCommand = new RelayCommand(() => StartImportThread())); 

}