Backgroundworker and progress

[brco900033]

Hello everyone. I want a BackgroundWorker reports its progress and send that to a ProgressBar. I did alot of research on the internet but I can't get it working.
Thanks

[Snake_eyes]

There are 2 ways of doing that through delegates or through reporting its progress i'll demonstrate both ways

First and the easiest is through reporting its progress:

[code2=vbnet]Private Sub Button9_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button9.Click
BackgroundWorker1.RunWorkerAsync()

End Sub

Private Sub BackgroundWorker1_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
Dim i As Integer = 0
For i = 0 To 100 Step 1
Threading.Thread.Sleep(50)
BackgroundWorker1.ReportProgress(i)
Next
End Sub

Private Sub BackgroundWorker1_ProgressChanged(ByVal sender As Object, ByVal e As System.ComponentModel.ProgressChangedEventArgs) Handles BackgroundWorker1.ProgressChanged
ProgressBar1.Value = e.ProgressPercentage
End Sub

Private Sub BackgroundWorker1_RunWorkerCompleted(ByVal sender As Object, ByVal e As System.ComponentModel.RunWorkerCompletedEventArgs) Handles BackgroundWorker1.RunWorkerCompleted
ProgressBar1.Value = 0
End Sub[/code2]

The second method is through delegates it is more complicated but i prefer this one when i need to modify UI on the form

[code2=vbnet]Public Delegate Sub IncrementPregressbarCallBack(ByVal value As Integer)
Private Sub IncrementProgressbar(ByVal value As Integer)
If Me.ProgressBar1.InvokeRequired Then
Dim s As New IncrementPregressbarCallBack(AddressOf IncrementProgressbar)
Me.Invoke(s, New Object() {value})
Else
ProgressBar1.Value = value
End If
End Sub
Private Sub Button9_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button9.Click
BackgroundWorker1.RunWorkerAsync()

End Sub

Private Sub BackgroundWorker1_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
Dim i As Integer = 0
For i = 0 To 100 Step 1
Threading.Thread.Sleep(50)
IncrementProgressbar(i)
Next
End Sub[/code2]

[brandonio21]

Thanks a lot for your reply, Snake_eyes. Your method would definitely work. However, don't you have to also call Refresh on the progress bar? As in,
[code2=vbnet]'progress bar value change
ProgressBar1.Refresh()[/code2]

[Snake_eyes]

No you don't the progress bar will work fine.

[brandonio21]

No you don't the progress bar will work fine.

Awesome! I always thought you had to call refresh. Guess I was wrong!

[brco900033]

Thanks for the code, I've tested it and it worked but isn't it like a 'pre-defined' progress? I want to download a file and report the progress but it only wants to download the file after the progress reached 100.
Maybe I put the download code in the wrong place?

[Snake_eyes]

The exaple i gave you is a general one on how to simply increment the progress bar, you have to modify the snippet for your specific use.

Maybe I put the download code in the wrong place?

If it starts the download after the progress bar is at 100% you did put the code in the wrong place but until you don't post your download code i cannot help you.

[brco900033]

Sorry for the late reply but I was a little busy the last few weeks. My download code is:

Code:

Dim downloader As New System.Net.WebClient()
downloader.DownloadFile("url", "save_path")

Does the progress reporting of a BackgroundWorker work with all codes or are there restrictions?

[Snake_eyes]

Well in that case you dont need a background worker to display the download progress because WebClient object has it's own set of event handlers just declare the web client under the main class of your project

Example:
[code2=vbnet]Public Class Form1
Dim WithEvents WC As New WebClient[/code2]

Then start the download :

[code2=vbnet]Private Sub Button1_Click(ByVal sender As Object, ByVal e As EventArgs) Handles Button1.Click
WC.DownloadFileAsync("Address", "FileName")
End Sub[/code2]

Increment the progressbar acording to the download percentage:

[code2=vbnet]Private Sub WC_DownloadProgressChanged(ByVal sender As Object, ByVal e As DownloadProgressChangedEventArgs) Handles WC.DownloadProgressChanged
ProgressBar1.Value = e.ProgressPercentage
End Sub[/code2]

This is the most simple way of downloadng a file and showing progress in a progressbar. You can also use a background worker but that will only complicate things

NOTE : Leave the progressbar at it's default value of 100 because e.ProgressPercentage should be a integer no larger than 100

[brco900033]

Thanks, needed this alot! A downloader without a progressbar isn't good at all. I didn't know it is possible to report the progress without a backgroundworker.