Background worker with progress bar timing issue

Blubbo

I've come across with this progress bar using worker.ReportProgress(). I was hoping to get a real-time progress Bar value from outside Write_Tag method. In this code below, it does seem to have some 1-2 seconds delay before showing the progress bar status. Any suggesion?

private void InitializeProgressBars()
{
for (int i = 0; i < DevicePath.Count; i++)
{
progressBar[i] = new ProgressBar();
progressBar[i].Location = new Point(3, 16);
progressBar[i].Size = new Size(605, 31);
progressBar[i].Maximum = 100;
}

gbProgressStatus0.Controls.Add(progressBar\[0\]);
gbProgressStatus1.Controls.Add(progressBar\[1\]);
gbProgressStatus2.Controls.Add(progressBar\[2\]);
gbProgressStatus3.Controls.Add(progressBar\[3\]);

}

private void InitializeBackgroundWorkers()
{
for (var f = 0; f < DevicePath.Count; f++)
{
bw[f] = new BackgroundWorker();
bw[f].WorkerReportsProgress = true;
bw[f].WorkerSupportsCancellation = true;

   switch (f)
   {
      case 0:
      {
          bw\[f\].DoWork += new DoWorkEventHandler(BackgroundWorkerFilesDoWork0);
          bw\[f\].RunWorkerCompleted += new RunWorkerCompletedEventHandler(BackgroundWorkerFilesRunWorkerCompleted0);
          break;
      }
      case 1:
      {
          bw\[f\].DoWork += new DoWorkEventHandler(BackgroundWorkerFilesDoWork1);
          bw\[f\].RunWorkerCompleted += new RunWorkerCompletedEventHandler(BackgroundWorkerFilesRunWorkerCompleted1);
          break;
      }
      case 2:
      {
          bw\[f\].DoWork += new DoWorkEventHandler(BackgroundWorkerFilesDoWork2);
          bw\[f\].RunWorkerCompleted += new RunWorkerCompletedEventHandler(BackgroundWorkerFilesRunWorkerCompleted2);
          break;
       }
       case 3:
       {
          bw\[f\].DoWork += new DoWorkEventHandler(BackgroundWorkerFilesDoWork3);
          bw\[f\].RunWorkerCompleted += new RunWorkerCompletedEventHandler(BackgroundWorkerFilesRunWorkerCompleted3);
          break;
       }
    }
 }

 bw\[0\].ProgressChanged += (sender, e) => { progressBar\[0\].Value = e.ProgressPercentage; };
 bw\[1\].ProgressChanged += (sender, e) => { progressBar\[1\].Value = e.ProgressPercentage; };
 bw\[2\].ProgressChanged += (sender, e) => { progressBar\[2\].Value = e.ProgressPercentage; };
 bw\[3\].ProgressChanged += (sender, e) => { progressBar\[3\].Value = e.ProgressPercent

Lost User

Blubbo wrote:

Any suggesion?

It seems to do an update only twice?

int status = tag_device0.Write_Tag(0, writeDat, en_statusDat, pb);

worker.ReportProgress(pb.Value);

if (ReadTag)
{
worker.ReportProgress(0);
byte[] tagData = new byte[1024];
tag5_device0.Read_Tag(0, 0, tagData .Length, ref tagData , pb);
worker.ReportProgress(pb.Value);
}

FWIW; the more often you report progress, the longer it'll take to complete the task.

Bastard Programmer from Hell :suss: If you can't read my code, try converting it here[^]

Matt T Heffron

(This looks like Windows Forms vs. WPF.) In the ...DoWork_n_() method you create a local ProgressBar that is passed to the Write_Tag and Read_Tag methods. There's not a tight linkage between that ProgressBar and the one that ReportProgress() is updating, so the one that is actually visible is not updated very often. If the Write_Tag and Read_Tag methods aren't careful to deal with possible cross-thread updating of the ProgressBar passed to them, then you're kind of out-of-luck. It doesn't appear that there's an event on the ProgressBar that could be used to redirect the updates to the .Value to use the worker.ReportProgress(..). If the Write_Tag and Read_Tag methods are dealing with the cross-thread updating correctly, then you can pass the visible ProgressBar into the BackgroundWorker with the argument to the RunWorkerAsync(progressBar[_n_]) and use the ReportProgress() when updating directly in the worker, and pass it into the Write_Tag and Read_Tag methods, counting on them to "do the right thing" when they update it. Something like:

private void InitializeProgressBars()
{
for (int i = 0; i < DevicePath.Count; i++)
{
progressBar[i] = new ProgressBar();
progressBar[i].Location = new Point(3, 16);
progressBar[i].Size = new Size(605, 31);
progressBar[i].Maximum = 100;
}

gbProgressStatus0.Controls.Add(progressBar[0]);
gbProgressStatus1.Controls.Add(progressBar[1]);
gbProgressStatus2.Controls.Add(progressBar[2]);
gbProgressStatus3.Controls.Add(progressBar[3]);
}

private void InitializeBackgroundWorkers()
{
for (var f = 0; f < DevicePath.Count; f++)
{
bw[f] = new BackgroundWorker();
bw[f].WorkerReportsProgress = true;
bw[f].WorkerSupportsCancellation = true;

switch (f)
{
  case 0:
  {
    bw\[f\].DoWork += new DoWorkEventHandler(BackgroundWorkerFilesDoWork0);
    bw\[f\].RunWorkerCompleted += new RunWorkerCompletedEventHandler(BackgroundWorkerFilesRunWorkerCompleted0);
    break;
  }
  case 1:
  {
    bw\[f\].DoWork += new DoWorkEventHandler(BackgroundWorkerFilesDoWork1);
    bw\[f\].RunWorkerCompleted += new RunWorkerCompletedEventHandler(BackgroundWorkerFilesRunWorkerCompleted1);

Blubbo

I have came up with a solution before I saw this reply with Action. I placed a new method in the class (same class with Read_Tag method in it). Works gracefully!

void UpdateProgressBar(ProgressBar pb, int value)
{
if (pb.InvokeRequired)
{
Action action = new Action(UpdateProgressBar);
object[] obj = new object[] { pb, value };
pb.BeginInvoke(action, obj);
}
else
pb.Value = value;
}

public int tag5_device0.Read_Tag(, ProgressBar pb)
{
//code snippet

for (int i = 0; i < 44; i++)
{
UpdateProgressBar(pb, i);
}

Matt T Heffron

I think you should just create the delegate once as it doesn't change. And the BeginInvoke's second argument is params so it will assemble the object array automatically, so this might be easier to read:

private static Action<ProgressBar, int> UpdateProgressBarAction = UpdateProgressBar;
private static void UpdateProgressBar(ProgressBar pb, int value)
{
  if (pb.InvokeRequired)
  {
    pb.BeginInvoke(UpdateProgressBarAction, pb, value);
  }
  else
    pb.Value = value;
}

You could even use a lambda to define this self-referentially to avoid the separate UpdateProgressBarAction:

private static Action<ProgressBar, int> UpdateProgressBar = (ProgressBar pb, int value) => {
  if (pb.InvokeRequired)
  {
    pb.BeginInvoke(UpdateProgressBar, pb, value);
  }
  else
    pb.Value = value;
};

Blubbo

Thanks for the suggestion. I'm still working on using the delegation of the code. I have never used it in my prior programs that I have created. Still learning new stuff. Thanks again!