long background process refreshing ui wpf

Question

I have long search operations which periodically updates UI (found occurence -> Update UI)

I've tried to realize it many ways:

1. async/await

   public void PushButton()
   {
       await AsyncSearchAll();
   }
   
   public async Task AsyncSearchAll(SearchPanelViewModel searchPanelViewModel, SearchSettings searchSettings, CancellationToken cancellationToken)
   {
       await Task.Factory.StartNew(() =>
                                         {
                                             //searching for occurence
                                             //write it into panel
                                         }, CancellationToken.None, TaskCreationOptions.None, TaskScheduler.FromCurrentSynchronizationContext());
   }
   

2. BackgroundWorker

   I want to use it but I don't want access UI using only .ReportProgress()

3. Simple background thread with calling Dispatcher.BeginInvoke(()=>{//updating UI})

   /// <summary>
   ///     Interaction logic for MainWindow.xaml
   /// </summary>
   public partial class MainWindow
   {
       public MainWindow()
       {
           InitializeComponent();
       }
   
       private void ButtonBase_OnClick(object sender, RoutedEventArgs e)
       {
           var backgroundThread = new Thread(CountToTen)
               {
                   IsBackground = true
               };
           backgroundThread.Start();
       }
   
       private void CountToTen()
       {
           for (int i = 1; i <= 10000; i++)
           {
               var j = i;
               Dispatcher.BeginInvoke(new Action(() => Seconds.Text = j.ToString(CultureInfo.InvariantCulture)));
           }
       }
   

All methods writing all data after completing thread. Is there any method to run background task which periodically updating UI without slowing program by blocking ui?

Answer 1

It's best if you can separate your "worker" logic from your "UI update" logic.

Something like this:

public async Task AsyncSearchAll(SearchPanelViewModel searchPanelViewModel, SearchSettings searchSettings, CancellationToken cancellationToken)
{
  while (..)
  {
    var results = await Task.Run(() => /* search more */);
    /* update panel with results */
  }
}

But if you want actual progress updates, there's ways to do that too:

public async void PushButton()
{
  Progress<MyUpdateType> progress = new Progress<MyUpdateType>(update =>
  {
    /* update panel */
  });
  await Task.Run(() => SearchAll(..., progress));
}

public void SearchAll(SearchPanelViewModel searchPanelViewModel,
    SearchSettings searchSettings, CancellationToken cancellationToken,
    IProgress<MyUpdateType> progress)
{
  while (..)
  {
    /* search more */
    if (progress != null)
      progress.Report(new MyUpdateType(...));
  }
}