更新另一个线程中的进度条

Question

I've read so many articles and other questions about this topic but because i am very new to C# and working with threads in general the answers were sadly mostly to complicated for me and or not applicable for my problem.

I have this progressbar which will be filled with very small steps mostly 0.03%. When including this normally it went from 0-100 in an instand at the very end of the operation altough i runs through every time and updates it in 0.03% steps every time. I believe updating the progress bar in another thread will do the trick, but i sadly have no understanding of this topic as of now altough reading into it.

This is the code section where my progress bar will be updated:

public void CopyAll(DirectoryInfo source, DirectoryInfo target)
{
    string source4count = source.ToString();
    if (checkSubdirCase == 0)
    {
        allfiles = System.IO.Directory.GetFiles(source4count, "*.*", System.IO.SearchOption.AllDirectories);
        allFilesNum = allfiles.Length;
        progressbarinterval = 0;                    
        progressbarinterval = 100 / allFilesNum;
        Progressbarvalue = 0;
    }

    if (Directory.Exists(target.FullName) == false)
    {
        Directory.CreateDirectory(target.FullName);
    }

    foreach (FileInfo fi in source.GetFiles())
    {
        //HERE IS THE UPDATING OF THE PROGRESSBAR
        fi.CopyTo(System.IO.Path.Combine(target.ToString(), fi.Name), true);
        Progressbarvalue = Progressbarvalue + progressbarinterval;                      
        ProgressBarCopy.Value = Progressbarvalue;
    }
    foreach (DirectoryInfo diSourceSubDir in source.GetDirectories())
    {
        DirectoryInfo nextTargetSubDir = target.CreateSubdirectory(diSourceSubDir.Name);
        checkSubdirCase = 1;
        CopyAll(diSourceSubDir, nextTargetSubDir);
    }
}

I hope someeone can help me and explain in a simple way how to tackle this and how background workers actually work. Regards

Answer 1

You will probably want to create a background worker (this happens on the UI thread) like this:

var worker = new BackgroundWorker();
worker.WorkerReportsProgress = true;
worker.DoWork += new DoWorkEventHandler(WorkerDoWork);
worker.ProgressChanged += new ProgressChangedEventHandler(WorkerProgressChanged);

In your DoWork-method, you will do everything that you currently do in the CopyAll-method, only the progress handling will change. You need to call worker.ReportProgress(...), this will then marshal back to the UI thread and invoke your WorkerProgressChanged-method. In the WorkerProgressChanged-method, you can update your progress bar.

However, you should be aware of the fact that switching between the UI thread and your BackgroundWorker thread is rather expensive, so you should only report progress when it has really changed by an amount that has an effect on the UI.

Answer 2

A other solution is the use of an task with a invoke on the progressbar

Change the code on your Button

//CopyAll(); //Old
Task.Run(() => CopyAll());

Your method with a invoke

public void CopyAll(DirectoryInfo source, DirectoryInfo target)
{
    string source4count = source.ToString();
    if (checkSubdirCase == 0)
    {
        allfiles = System.IO.Directory.GetFiles(source4count, "*.*", System.IO.SearchOption.AllDirectories);
        allFilesNum = allfiles.Length;
        progressbarinterval = 0;                    
        progressbarinterval = 100 / allFilesNum;
        Progressbarvalue = 0;
    }

    if (Directory.Exists(target.FullName) == false)
    {
        Directory.CreateDirectory(target.FullName);
    }

    foreach (FileInfo fi in source.GetFiles())
    {
        //HERE IS THE UPDATING OF THE PROGRESSBAR
        fi.CopyTo(System.IO.Path.Combine(target.ToString(), fi.Name), true);
        Progressbarvalue = Progressbarvalue + progressbarinterval;                      
        ProgressBarCopy.Invoke(new MethodInvoker(delegate { ProgressBarCopy.Value = Progressbarvalue; }));
    }
    foreach (DirectoryInfo diSourceSubDir in source.GetDirectories())
    {
        DirectoryInfo nextTargetSubDir = target.CreateSubdirectory(diSourceSubDir.Name);
        checkSubdirCase = 1;
        CopyAll(diSourceSubDir, nextTargetSubDir);
    }
}

Answer 3

Using the Background Worker is a good option.

var worker = new BackgroundWorker();
worker.DoWork += new DoWorkEventHandler(Worker_DoWork);
worker.ProgressChanged += new 
ProgressChangedEventHandler(Worker_ProgressChanged);
worker.RunWorkerCompleted += new 
RunWorkerCompletedEventHandler(Worker_RunWorkerCompleted);


private void Worker_DoWork(object sender, DoWorkEventArgs e)
{

 ...
  foreach (FileInfo fi in source.GetFiles())
   {
    //Copying the files..

  // Calling the ReportProgress method would fire the worker_ProgressChanged event
    worker.ReportProgress(0, progressState)
} 


  }

  private void worker_ProgressChanged(object sender, 
                                      ProgressChangedEventArgs e)
   { 
        // This is where you would have the UI related changes. 
       //In your case updating the progressbar. 
      // While the files are being copied this would update the UI.
  }

 private void Worker_RunWorkerCompleted(object sender, 
 RunWorkerCompletedEventArgs e)
 {
 worker.CancelAsync();

 }