Question

                    foreach (string line in textBox3.Lines)
                    {
                        int pos = line.IndexOf("?v=");
                        string videoid = line.Substring(pos + 3, 11);
                        GetFile(videoid);
                    }

        GetFile() {
        ...code

        WebClient webClient = new WebClient();
        webClient.DownloadFileCompleted += new AsyncCompletedEventHandler(Completed);
        webClient.DownloadProgressChanged += new DownloadProgressChangedEventHandler(ProgressChanged);
        webClient.DownloadFileAsync(new Uri(fileRequest), @textBox2.Text + @"\" + title + ".mp3");
    }

    private void ProgressChanged(object sender, DownloadProgressChangedEventArgs e)
    {
        progressBar1.Value = e.ProgressPercentage;
    }

Question is how to hadle one progressbar and many webclients? This scenario doesn’t work, because every client is updating bar on it’s own and it’s going crazy, so what’s the proper way? PS. I cannot use just one WebClient, I’m making requests before for every file.

Answer 1

I’d imagine you could do something like this:

public class WebClientProgressManager : INotifyPropertyChanged
        {
            private readonly Dictionary<WebClient,int> _clients = new Dictionary<WebClient, int>();
            private const string TotalProgressPropertyName = "TotalProgress";
            public void Add(WebClient client)
            {
                if (client == null)
                    throw new ArgumentNullException("client");
                if (_clients.ContainsKey(client)) return;

                client.DownloadProgressChanged += (s, e) =>
                                                      {
                                                          if (e.ProgressPercentage == 100)
                                                          {
                                                              _clients.Remove((WebClient)s);
                                                          }
                                                          RaisePropertyChanged(TotalProgressPropertyName);
                                                      };
                _clients.Add(client,0);

            }

            private void RaisePropertyChanged(string propertyName)
            {
                if (PropertyChanged != null)
                {
                    PropertyChanged.Invoke(this,new PropertyChangedEventArgs(propertyName));
                }
            }

            public int TotalProgress
            {

                get
                {
                    if (_clients.Count == 0) return 100; //need something here to prevent divide-by-zero 
                    int progress = _clients.Sum(client => client.Value);
                    return progress/_clients.Count;
                }
            }

            #region Implementation of INotifyPropertyChanged

            public event PropertyChangedEventHandler PropertyChanged;

            #endregion
        }