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Updating progressbar through backgroundworker in method

My programm (in C# using Windows Forms) is reading and parsing large amounts of Data and I'm using a Backgroundworker which calls those global methods (reading and parsing). I'd like to keep the user updated on how long it's going to take, so the Backgroundworker is supposed to display what action its doing and has a progressbar that should fill for every individual action too.
Unfortunately, I can't get it to work, as the progressbar just doesn't update at all and just stays empty.
Here is what I have so far:
private void InitializeBackgroundWorker()
{
backgroundWorker1.DoWork += new DoWorkEventHandler(backgroundWorker1_DoWork);
backgroundWorker1.RunWorkerCompleted += new RunWorkerCompletedEventHandler(backgroundWorker1_RunWorkerCompleted);
backgroundWorker1.ProgressChanged += new ProgressChangedEventHandler(backgroundWorker1_ProgressChanged);
}
private void buttonParse_Click(object sender, EventArgs e)
{
DescriptionLabel.Visible = true;
progressBar1.Visible = true;
backgroundWorker1.RunWorkerAsync();
}
private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
progressBar1.Value = e.ProgressPercentage;
}
private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
BackgroundWorker worker = sender as BackgroundWorker;
Methods.ParsePerfusionData(backgroundWorker1); //Also tried using 'worker' here, but didnt work either
}
And in the method it looks like that:
public static void ParsePerfusionData(BackgroundWorker worker)
{
for (int i = 2; i < Globals.DataList.Count; i++)
{
worker.ReportProgress(i / amount * 100);
rest of the code etc.
}
}
Can I not use a backgroundworker in a global method like that? Thanks in advance!

When i < amount then i / amount * 100 = 0 * 100 = 0.
Simply use i * 100 / amount instead.
Also make sure backgroundWorker1.WorkerReportsProgress = true

You can only report progress between distinct operations. That means either:
using a very modern class that supports this level of reporting. Such a classs might not exist for your case.
reverse engineering parts of the code down to the loop you want to make reporting on. Usually the loop that itterates over files or the like.
GUI updates must be contained to RunWorkerCompelted and ProgressReport events. And depending on how often updates happen, ProgressReport may have to be kept to only updating a progress bar.
Here some old code I wrote with BackgroundWorker wich should get you started:
#region Primenumbers
private void btnPrimStart_Click(object sender, EventArgs e)
{
if (!bgwPrim.IsBusy)
{
//Prepare ProgressBar and Textbox
int temp = (int)nudPrim.Value;
pgbPrim.Maximum = temp;
tbPrim.Text = "";
//Start processing
bgwPrim.RunWorkerAsync(temp);
}
}
private void btnPrimCancel_Click(object sender, EventArgs e)
{
if (bgwPrim.IsBusy)
{
bgwPrim.CancelAsync();
}
}
private void bgwPrim_DoWork(object sender, DoWorkEventArgs e)
{
int highestToCheck = (int)e.Argument;
//Get a reference to the BackgroundWorker running this code
//for Progress Updates and Cancelation checking
BackgroundWorker thisWorker = (BackgroundWorker)sender;
//Create the list that stores the results and is returned by DoWork
List<int> Primes = new List<int>();
//Check all uneven numbers between 1 and whatever the user choose as upper limit
for(int PrimeCandidate=1; PrimeCandidate < highestToCheck; PrimeCandidate+=2)
{
//Report progress
thisWorker.ReportProgress(PrimeCandidate);
bool isNoPrime = false;
//Check if the Cancelation was requested during the last loop
if (thisWorker.CancellationPending)
{
//Tell the Backgroundworker you are canceling and exit the for-loop
e.Cancel = true;
break;
}
//Determin if this is a Prime Number
for (int j = 3; j < PrimeCandidate && !isNoPrime; j += 2)
{
if (PrimeCandidate % j == 0)
isNoPrime = true;
}
if (!isNoPrime)
Primes.Add(PrimeCandidate);
}
//Tell the progress bar you are finished
thisWorker.ReportProgress(highestToCheck);
//Save Return Value
e.Result = Primes.ToArray();
}
private void bgwPrim_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
pgbPrim.Value = e.ProgressPercentage;
}
private void bgwPrim_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
pgbPrim.Value = pgbPrim.Maximum;
this.Refresh();
if (!e.Cancelled && e.Error == null)
{
//Show the Result
int[] Primes = (int[])e.Result;
StringBuilder sbOutput = new StringBuilder();
foreach (int Prim in Primes)
{
sbOutput.Append(Prim.ToString() + Environment.NewLine);
}
tbPrim.Text = sbOutput.ToString();
}
else
{
tbPrim.Text = "Operation canceled by user or Exception";
}
}
#endregion

How can I make it work this "responsive Progressbar"?

Good morning, I'm trying to write an application that use in his interface a progressbar (in C#, WPF). I have read about the need of perform the UI task in a different thread, using Backgroundworker. I trying to make it work using a lot of information, but nothing happens (the program work fine, but the progressbar only shown at the end of the "hard-work tasks").
I'm civil engineer (not a software one), so I ask if anyone can help me with that.
namespace SAP2000___Quake_Definitions
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
private readonly BackgroundWorker bgWoker = new BackgroundWorker();
public MainWindow()
{
InitializeComponent();
this.bgWoker.WorkerReportsProgress = true;
this.bgWoker.WorkerSupportsCancellation = true;
this.bgWoker.DoWork += bgWorker_DoWork;
this.bgWoker.ProgressChanged += bgWorker_ProgressChanged;
this.bgWoker.RunWorkerCompleted += bgWorker_RunWorkerCompleted;
}
private void bgWorker_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
this.progBar.Value = e.ProgressPercentage;
}
private void bgWorker_DoWork(object sender, DoWorkEventArgs e)
{
BackgroundWorker bgWorker = (BackgroundWorker)sender;
Dispatcher.Invoke(new Action(() => DoTheHardWork()));
}
private void processButton_Click(object sender, RoutedEventArgs e)
{
this.bgWoker.RunWorkerAsync();
}
private void DoTheHardWork()
{
switch (this.chckBox2.IsChecked.GetValueOrDefault())
{
case true:
this.bgWoker.ReportProgress(0);
//more hardwork with inputs from WPF
case false:
this.bgWoker.ReportProgress(0);
//more hardwork with inputs from WPF
}
}
}
}

That is not how you should be using a BackgroundWorker. I wrote some example code a few years back. It should get you on the right track:
#region Primenumbers
private void btnPrimStart_Click(object sender, EventArgs e)
{
if (!bgwPrim.IsBusy)
{
//Prepare ProgressBar and Textbox
int temp = (int)nudPrim.Value;
pgbPrim.Maximum = temp;
tbPrim.Text = "";
//Start processing
bgwPrim.RunWorkerAsync(temp);
}
}
private void btnPrimCancel_Click(object sender, EventArgs e)
{
if (bgwPrim.IsBusy)
{
bgwPrim.CancelAsync();
}
}
private void bgwPrim_DoWork(object sender, DoWorkEventArgs e)
{
int highestToCheck = (int)e.Argument;
//Get a reference to the BackgroundWorker running this code
//for Progress Updates and Cancelation checking
BackgroundWorker thisWorker = (BackgroundWorker)sender;
//Create the list that stores the results and is returned by DoWork
List<int> Primes = new List<int>();
//Check all uneven numbers between 1 and whatever the user choose as upper limit
for(int PrimeCandidate=1; PrimeCandidate < highestToCheck; PrimeCandidate+=2)
{
//Report progress
thisWorker.ReportProgress(PrimeCandidate);
bool isNoPrime = false;
//Check if the Cancelation was requested during the last loop
if (thisWorker.CancellationPending)
{
//Tell the Backgroundworker you are canceling and exit the for-loop
e.Cancel = true;
break;
}
//Determin if this is a Prime Number
for (int j = 3; j < PrimeCandidate && !isNoPrime; j += 2)
{
if (PrimeCandidate % j == 0)
isNoPrime = true;
}
if (!isNoPrime)
Primes.Add(PrimeCandidate);
}
//Tell the progress bar you are finished
thisWorker.ReportProgress(highestToCheck);
//Save Return Value
e.Result = Primes.ToArray();
}
private void bgwPrim_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
pgbPrim.Value = e.ProgressPercentage;
}
private void bgwPrim_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
pgbPrim.Value = pgbPrim.Maximum;
this.Refresh();
if (!e.Cancelled && e.Error == null)
{
//Show the Result
int[] Primes = (int[])e.Result;
StringBuilder sbOutput = new StringBuilder();
foreach (int Prim in Primes)
{
sbOutput.Append(Prim.ToString() + Environment.NewLine);
}
tbPrim.Text = sbOutput.ToString();
}
else
{
tbPrim.Text = "Operation canceled by user or Exception";
}
}
#endregion
You have to limit all UI writing work to the Progress Report and Run wokrer compelte Events. Those will be raised in the thread that created the BGW (wich should be the UI thread) automagically.
Note that you can only report progress between distinct steps. I had the advantage that I had to write the loop anyway. But if you have existing code (like most download or disk code), you can usually only report between files.

my mistakes were three:
Trying to use "Dispatcher.Invoke(new Action(() => DoTheHardWork()));" to solve an exception related to my thread (exception caused by point #3).
Avoiding the instantiation: BackgroundWorker bgWorker = (BackgroundWorker)sender (thank you #Christopher).
Writing a code that manipulate a UI-Component inside the DoWork event handle of my Backgroundworker. MSDN says: You must be careful not to manipulate any user-interface objects in your DoWork event handler. Instead, communicate to the user interface through the ProgressChanged and RunWorkerCompleted events. Trying this, the exception occur.
Solving the point #2 and #3, the UI is perfectly responsive respect to the "hardwork" function (runned in background).

How to update a listbox dynamically?

I am making a search utility and using a BackgroundWorker to search. I want that as soon as the first result is found , a new window should open up with a ListBox with the first element displayed. Now, I want that as soon as subsequent results are found, the ListBox should be updated with those results.
The method thought by me was to report the progress as soon as results are found and pass "New" and "Update" as userState to the method.
Based on the userState, I can decide whether to create a new Form or update and existing one.
Here is the code :-
private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
if (e.UserState.ToString() == "New")
{
Form ResultForm = new Form();
ResultForm.Name = "ResultForm" + i.ToString();
LastFormName = ResultForm.Name;
ListBox ResultListBox = new ListBox();
ResultListBox.DataSource = SearchList;
ResultListBox.Name = "ResultListBox" + i.ToString();
LastListName = ResultListBox.Name ;
ResultForm.Container.Add(ResultListBox);
ResultListBox.Show();
ResultForm.Show();
i++;
}
else
{
;
}
}
I have stored the names of the Last open Form and it's ListBox in the variables LastFormName and 'LastListName'.
I am unable to understand what to put in the else condition, so as to update the ListBox.

What I would do is expose some properties on the popup form so that you can tell if it is open and have access to the list box.
public partial class Popup : Form
{
public bool isOpen;
public ListBox PopupListBox;
public Popup()
{
InitializeComponent();
}
void Popup_FormClosing(object sender, FormClosingEventArgs e)
{
isOpen = false;
}
private void Popup_Load(object sender, EventArgs e)
{
this.FormClosing += Popup_FormClosing;
PopupListBox = popupListBox;
}
}
Then on the calling form I would subscribe to the ProcessedChanged Event and update the listbox with the data you are passing through the ProcessedChangedEventArgs. Here is the code for the calling form
public partial class Form1 : Form
{
Popup popupForm = new Popup();
BackgroundWorker backgroundWorker = new BackgroundWorker();
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
backgroundWorker.WorkerSupportsCancellation = true;
backgroundWorker.WorkerReportsProgress = true;
backgroundWorker.DoWork += backgroundWorkerDoWork;
backgroundWorker.ProgressChanged += backgroundWorkerProgressChanged;
backgroundWorker.RunWorkerCompleted += backgroundWorkerRunWorkerCompleted;
}
void backgroundWorkerRunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
if ((e.Cancelled == true))
{
//What do you want to do if Cancelled?
}
else if (!(e.Error == null))
{
//What do you want to do if there is an error?
}
else
{
//What do you want to do when it is done?
}
}
void backgroundWorkerProgressChanged(object sender, ProgressChangedEventArgs e)
{
if (!popupForm.isOpen || popupForm == null)
{
popupForm = new Popup();
popupForm.Show();
popupForm.isOpen = true;
}
else
{
popupForm.Activate();
popupForm.WindowState = FormWindowState.Normal;
}
popupForm.PopupListBox.Items.Add(e.ProgressPercentage.ToString() + "%");
}
void backgroundWorkerDoWork(object sender, DoWorkEventArgs e)
{
BackgroundWorker worker = sender as BackgroundWorker;
for (int i = 1; (i <= 10); i++)
{
if ((worker.CancellationPending == true))
{
e.Cancel = true;
break;
}
else
{
// Perform a time consuming operation and report progress.
System.Threading.Thread.Sleep(500);
worker.ReportProgress((i * 10));
}
}
}
private void buttonStart_Click(object sender, EventArgs e)
{
if (backgroundWorker.IsBusy != true)
{
backgroundWorker.RunWorkerAsync();
}
}
private void buttonCancel_Click(object sender, EventArgs e)
{
if (backgroundWorker.WorkerSupportsCancellation == true)
{
backgroundWorker.CancelAsync();
}
}
}

You shouldn't be doing work in the ProgressChanged event handler
You won't have access to the results as it is only passed an int for progress and user state
This is on the UI thread. The entire point is to do your processing on a background thread
The name DoWork event handler is clear that this is where you should do your processing.
In answer to your question. Since you create the ListBox in your event handler it goes out of scope outside the if statement. You need to create this in a more global scope. Then to add to it ResultListBox.Items.Add("ResultListBox" + i.ToString());

Windows form progress bar not working?

I have a button .It will open a file and process a file .I want to show the progress bar while processing the file .
when i am doing .its working
public MainframeDataExchangeTool()
{
InitializeComponent();
_ProgressBar.Style = ProgressBarStyle.Marquee;
_ProgressBar.Visible = false;
_Random = new Random();
InitializeBackgroundWorker();
}
private void InitializeBackgroundWorker()
{
_BackgroundWorker = new BackgroundWorker();
_BackgroundWorker.WorkerReportsProgress = true;
_BackgroundWorker.DoWork += (sender, e) => ((MethodInvoker)e.Argument).Invoke();
_BackgroundWorker.ProgressChanged += (sender, e) =>
{
_ProgressBar.Style = ProgressBarStyle.Continuous;
_ProgressBar.Value = e.ProgressPercentage;
};
_BackgroundWorker.RunWorkerCompleted += (sender, e) =>
{
if (_ProgressBar.Style == ProgressBarStyle.Marquee)
{
_ProgressBar.Visible = false;
}
};
}
In my button click i am doing
private void btnOpenScriptFile_Click(object sender, EventArgs e)
{
try
{
loadScriptFlDlg.Filter = Constants.SCRIPT_FILE_FILTER;
loadScriptFlDlg.FilterIndex = 3;
loadScriptFlDlg.RestoreDirectory = true;
loadScriptFlDlg.FileName = string.Empty;
DialogResult objDialogResult = loadScriptFlDlg.ShowDialog();
if (objDialogResult.Equals(DialogResult.OK))
{
_BackgroundWorker.RunWorkerAsync(new MethodInvoker(() =>
{
_ProgressBar.BeginInvoke(new MethodInvoker(() => _ProgressBar.Visible = true));
for (int i = 0; i < 100; i++)
{
Thread.Sleep(10);
_BackgroundWorker.ReportProgress(i);
}
}));
EnableDisableControls("OpenScript");
string strScriptError = LoadScriptFromFile(loadScriptFlDlg.FileName);///loading will taking time but progress bar not showing
Basically progress bar is showing at the end of data load but not while loading the data

You cannot see the progress as UI thread cannot update UI because it is busy loading your file. You must call LoadScriptFromFile from the background worker and keep UI thread free to process events and update UI.

I used this in my project with 2 methode (exemple):
1* Invoke(new Action(() => _ProgressBar.Visible = true));
2* or use Application.DoEvents() after your _BackgroundWorker.ReportProgress(i);

Surprised the compiler didn't throw a hissy fit...because you need an extra }.
You open 4 levels of nesting, but only close 3.
I have modified your code as shown below:
private void btnOpenScriptFile_Click(object sender, EventArgs e)
{
try
{
if (objDialogResult.Equals(DialogResult.OK))
{
_ProgressBar.Style = ProgressBarStyle.Marquee;
_ProgressBar.BeginInvoke(new MethodInvoker(() => _ProgressBar.Visible = true));
for (int i = 0; i < 100; i++)
{
Thread.Sleep(10);
_ProgressBar.BeginInvoke(new Action(() => _ProgressBar.Value = i));
//Process my file here
}
}
}
Catch
{
}
}
I would always suggest reducing the number of empty lines, for readability.
I also find that the 'allman' style bracketing is easiest to debug.
But as always, each to his own.
EDIT:
After OP editted code:
Try adding:
application.doevents()
after your:
_BackgroundWorker.ReportProgress(i);
Why? The code will stay in the for loop until completes. By doing 'doevents' you are telling it to update externally, before the next loop.
Without the 'doevents' i guess you would see 0 and 100 only.

Simply do something like this with a BackgroundWorker (bgw).
private void MyMethod()
{
bgw.RunWorkerAsync(); //this calls the DoWork event
}
private void bgw_DoWork(object sender, DoWorkEventArgs e)
{
//Expensive task
//Calculate how far you through your task (ie has read X of Y bytes of file)
bgw.ReportProgress(myInteger);
}
private void bgw_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
myProgressBar.Value = e.ProgressPercentage;
}
Make sure you set the BackgroundWorker's "WorkerReportsProgress" property to True!

My issue is regarding handling multiple backgroud worker and multiple progressbar

my main problem is when i add dynamically a progressbar on flowLayoutPanel1 for each request then how can i increase right progressbar value frombackgroundWorker1_ProgressChanged event
when user click on start button then i will call RunWorkerAsync function of background worker....it is fine. here i am writing a sample code and try to show my problem.
my form has one textbox, one button and one flowLayoutPanel1 with FlowDirection topdown.
when user enter any url in textbox and click on start button then i will start file download with BackGroundWorker and add one progress bar dynamically on flowLayoutPanel1. 10 file can be downloaded at a time. so when user enter ten url one after after one and click on submit button then ten file will be downloading in background.
my problem is how to increment 10 progress bar progress properly from backgroundWorker1_ProgressChanged event another issue is when any file download will complete then the progress bar for which it has been created will be removed from panel
here is my full code. please have a look and tell me what i need to do to achieve my task. if anyone see there is problem in my code for which a dead lock may appear then also please guide me how to avoid dead lock. here is my code
public partial class Form1 : Form
{
static int pbCounter = 1;
public Form1()
{
InitializeComponent();
}
private void btnStart_Click(object sender, EventArgs e)
{
ProgressBar pb = new ProgressBar();
if (pbCounter <= 10)
{
pb.Width = txtUrl.Width;
flowLayoutPanel1.Controls.Add(pb);
pbCounter++;
System.ComponentModel.BackgroundWorker backgroundWorker1 = new System.ComponentModel.BackgroundWorker();
backgroundWorker1.DoWork += new DoWorkEventHandler(backgroundWorker1_DoWork);
backgroundWorker1.RunWorkerCompleted += new RunWorkerCompletedEventHandler(backgroundWorker1_RunWorkerCompleted);
backgroundWorker1.ProgressChanged += new ProgressChangedEventHandler(backgroundWorker1_ProgressChanged);
backgroundWorker1.RunWorkerAsync();
}
}
private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
// Get the BackgroundWorker that raised this event.
System.ComponentModel.BackgroundWorker worker = sender as System.ComponentModel.BackgroundWorker;
// Assign the result of the computation
// to the Result property of the DoWorkEventArgs
// object. This is will be available to the
// RunWorkerCompleted eventhandler.
//#e.Result = ComputeFibonacci((int)e.Argument, worker, e);
}
// This event handler deals with the results of the
// background operation.
private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
// First, handle the case where an exception was thrown.
if (e.Error != null)
{
MessageBox.Show(e.Error.Message);
}
else if (e.Cancelled)
{
//# "Canceled";
}
else
{
pbCounter--;
// Finally, handle the case where the operation
// succeeded.
//#resultLabel.Text = e.Result.ToString();
}
}
// This event handler updates the progress bar.
private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
this.progressBar1.Value = e.ProgressPercentage;
}
}
MY UPDATED PART
public partial class Form1 : Form
{
static int pbCounter = 1;
public Form1()
{
InitializeComponent();
}
private void btnStart_Click(object sender, EventArgs e)
{
ProgressBar pb = new ProgressBar();
if (pbCounter <= 10)
{
//pb.Step = 10;
pb.Minimum = 0;
//pb.Maximum = 100;
pb.Width = txtUrl.Width;
flowLayoutPanel1.Controls.Add(pb);
pbCounter++;
MyBackgroundWorker backgroundWorker1 = new MyBackgroundWorker();
backgroundWorker1.pbProgress = pb;
backgroundWorker1.WorkerReportsProgress = true;
backgroundWorker1.DoWork += new DoWorkEventHandler(backgroundWorker1_DoWork);
backgroundWorker1.RunWorkerCompleted += new RunWorkerCompletedEventHandler(backgroundWorker1_RunWorkerCompleted);
backgroundWorker1.ProgressChanged += new ProgressChangedEventHandler(backgroundWorker1_ProgressChanged);
backgroundWorker1.RunWorkerAsync(txtUrl.Text);
}
}
private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
int input = int.Parse(e.Argument.ToString());
for (int i = 1; i <= input; i++)
{
Thread.Sleep(2000);
(sender as MyBackgroundWorker).ReportProgress(i * 10);
if ((sender as MyBackgroundWorker).CancellationPending)
{
e.Cancel = true;
return;
}
}
}
// This event handler deals with the results of the
// background operation.
private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
// First, handle the case where an exception was thrown.
if (e.Error != null)
{
MessageBox.Show(e.Error.Message);
}
else if (e.Cancelled)
{
//# "Canceled";
}
else
{
ProgressBar pb = (sender as MyBackgroundWorker).pbProgress;
if (pb != null)
{
//pb.Value = 100;
//pb.Update();
while (pb.Value <= pb.Maximum)
{
//Thread.Sleep(1000);
flowLayoutPanel1.Controls.Remove(pb);
break;
}
}
// Finally, handle the case where the operation
// succeeded.
}
}
// This event handler updates the progress bar.
private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
ProgressBar pb = (sender as MyBackgroundWorker).pbProgress;
pb.Refresh();
//if (e.ProgressPercentage < pb.Maximum)
// pb.Value = e.ProgressPercentage + 10;
pb.Value = e.ProgressPercentage ;
Application.DoEvents();
}
}
public class MyBackgroundWorker : System.ComponentModel.BackgroundWorker
{
public ProgressBar pbProgress = null;
public MyBackgroundWorker()
{
}
public MyBackgroundWorker(string name)
{
Name = name;
}
public string Name { get; set; }
}

This is one way of doing it -
Create your own class inherited from BackgroundWorker, Add a public variable of type ProgressBar.
Each time you add a BackgroundWorker and Progressbar dynamically, pass the progressbar object to your class.
Your derived Class -
public class MyBackgroundWorker : BackgroundWorker
{
public ProgressBar pbProgress = null;
public void BackgroundWorker()
{
}
}
Button Event Code -
private void btnStart_Click(object sender, EventArgs e)
{
ProgressBar pb = new ProgressBar();
if (pbCounter <= 10)
{
pb.Width = txtUrl.Width;
flowLayoutPanel1.Controls.Add(pb);
pbCounter++;
MyBackgroundWorker backgroundWorker1 = new MyBackgroundWorker();
backgroundWorker1.pbProgress = pb;
backgroundWorker1.DoWork += new DoWorkEventHandler(backgroundWorker1_DoWork);
backgroundWorker1.RunWorkerCompleted += new RunWorkerCompletedEventHandler(backgroundWorker1_RunWorkerCompleted);
backgroundWorker1.ProgressChanged += new ProgressChangedEventHandler(backgroundWorker1_ProgressChanged);
backgroundWorker1.RunWorkerAsync();
}
}
Progress Changed Event -
private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
(sender as MyBackgroundWorker).pbProgress.Value = e.ProgressPercentage;
}

First declare a global dictionary and a GetInstance Method to access the form instance
public partial class Form1 : Form
{
Dictionary<String, ProgressBar> progressBars = new Dictionary<String, ProgressBar>();
static Form1 _form1 = null;
static int pbCounter = 1;
public Form1()
{
InitializeComponent();
_form1 = this;
}
public static Form1 GetInstance() {
return _form1;
}
Then with each url you get and you must be creating pb for each of them, just add them in this dictionary too
progressBars.Add("file1", pb1);
progressBars.Add("file2", pb2);
progressBars.Add("file3", pb3);
progressBars.Add("file4", pb4);
Create a function in form.cs in which you can pass the progressbar and then you can manually set the value of it.
public void ProgessReport(ProgressBar pb, int value)
{
if (pb.InvokeRequired)
{
pb.Invoke(new MethodInvoker(delegate { ProgessReport(pb, value); }));
} else
{
pb.Value = value;
}
}
now from where you are downloading the file you just have to call
Form1.GetInstance().ProgessReport(Form1.GetInstance().progressBars["file1"], 10);
Form1.GetInstance().ProgessReport(Form1.GetInstance().progressBars["file1"], 20);
Form1.GetInstance().ProgessReport(Form1.GetInstance().progressBars["file1"], 100);
and when your second file downloads then
Form1.GetInstance().ProgessReport(Form1.GetInstance().progressBars["file2"], 10);
Form1.GetInstance().ProgessReport(Form1.GetInstance().progressBars["file2"], 20);
Form1.GetInstance().ProgessReport(Form1.GetInstance().progressBars["file2"], 100);
like this ..