24 Apr 2015•tags c# delegate dispatcher progress Revit

Update WPF ProgessBar in Revit loop

In WPF, the ProgressBar control is a great control for showing the progress of an operation. If you have already used it in a non Revit context, you probably know that in order to update the UI during a lengthy task you need to have this logic on a different thread than the main one.

But the Revit API cannot be used in multithreading.

If you try to set up a BackgroundWorker or a second thread to accomplish you long lasting operation, you will most likely end up having Revit to crash without notice.

A simple solution to allow the ProgressBar to update is the use of a Dispatcher:

//set up a delegate    
private delegate void ProgressBarDelegate();

//long busy loop
private void CreateAThousandBuildings()
{
  progressBar.IsIndeterminate = false;
  progressBar.Maximum = 1000;
  progressBar.Minimum = 0;

  for (var i = 0; i < 1000; i++)
  {
    progressBar.Dispatcher.Invoke(new ProgressBarDelegate(UpdateProgress), DispatcherPriority.Background);
    //Create a Building...
    //...
  }
}

//update the progress bar
private void UpdateProgress()
{
  progressBar.Value += 1;
}