DoWork's ReportProgress Not Raising ProgressChanged Until After Loop Is Done
Nov 9, 2010
I am trying to get a progress bar to update on my Form while waiting for a process to complete but could not get my progressbar control to update.
First of, I have tried to fix the problem for a day and a half now looking at various codes and examples in the forums but I'm afraid I probably do not have the necessary VB skills yet to troubleshoot my own code. I believe I will be able to eventually fix this after I am done with my VB book
I've attached the relevant part of my code below and the problem is that I can see my DoWork event firing off and changing the time and percentage that I want to pass on to ReportProgress() and the ProgressChanged handler. However, the ProgressChanged handler is not raised until after my Do Loop is done.
Imports System.ComponentModel
.
.
.
Public Class Form1
Private WithEvents TestWorker As System.ComponentModel.BackgroundWorker
[Code]....
Again, I can see the ProgressChange fire but only after my work (diagnostics) is complete so my progress bar is either 0% or 100%. In Dowork, I can verify that the progtimepercentage variable is indeed changing and ReportProgress is called but ProgressChanged is not being raised until after the job I wanted is done.
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Oct 13, 2009
[URL]
Occurs when ReportProgress is called.
but in my code ProgressChanged event doesn't fire after this line bgwBckp.ReportProgress(1)
[Code].....
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Jul 31, 2011
I need to write a long-running process with a While/End While loop.
To avoid freezing the UI, I added a BackgroundWorker object on the form.
Next, I needed to update the UI, but found that the thread cannot do this. Instead, the thread must call ReportProgress() to trigger the ProgressChanged() event.
However, I need to pass the text from the exception (ex.Message) to the event, but didn't find an example on how to do this. I need that text message to update the form's title bar.
Here's the code:
Private Sub BackgroundWorker1_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
While (True)
[Code]....
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Sep 27, 2011
I have a search function in my program that uses a background worker in order to get the results. The Progress changed event is used to update the listview with the new item.[code]
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Mar 18, 2012
My BackgroundWorker works perfectly in my main form frmMain. But when I run the ReportProgress method in another module, I get exception "This BackgroundWorker states that it doesn't report progress. Modify WorkerReportsProgress to state that it does report progress." This IS set to report progress; this works fine when run the same way in the main module.Basically, from a module called by my BackgroundWorker, I want to show progress on my main form.How can I fix this? The only idea I have is to move the code from the module into my main form, but this seems a backward step, which would involve extra work. Am hoping there are easier ways!
Calling code in class frmMain:
Friend WithEvents BackgroundWorker As New System.ComponentModel.BackgroundWorker
Private Sub btnTest_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnTest.Click
' Specify that we do NOT want the background operation to allow cancellation
[code]....
Code which generates the exception in separate module Invoices:
Public Function MyTest() As Boolean
frmMain.BackgroundWorker.ReportProgress(0)
End Function
Am using VB.NET in VS 2010, with .NET 3.5.
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Apr 27, 2011
Basically what I'm trying to do is Query AD for AD Computer objects, which are held in a compname variable. Then I go and check to see if I can attach to the WMI (to help filter out AD-joined linux boxes), if I can't, then I mark it as offline and vice versa. I've read and understand that background worker can't update UI stuff, so it needs to be done via the ProgressChanged sub..I want to update a list box on my main form but I can't get the ProgressChanged sub to see my compname variable from the BackgroundWorker_DoWork Function...I'm guessing I need to make the compname a global variable somehow?
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Aug 15, 2011
I have a progressbar on my form that is not getting updated.
When the Send Email button is clicked I do this:
Public Sub SendMail()
If CheckSettings() = False Then Exit Sub
BackUpEbillFile()
LockForm(True)
StatusBars(1, "Sending emails...")
[Code]...
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Apr 14, 2011
I have a long running process running in a backgroundworker, and want it to report progress to the user, and update a checked listbox as the items are discovered. The reportprogress is called, and the statements executed (placing a break in the reportprogress routine), I can see the control valuse change, but the change is not reflected in the dialog. Here is the reportprogress routine I'm using:
Private Sub BackgroundWorker2_ProgressChanged(ByVal sender As System.Object,
ByVal e As System.ComponentModel.ProgressChangedEventArgs) Handles BackgroundWorker2.ProgressChanged
Me.newlabel.ForeColor = Color.Cyan
[code]....
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Aug 4, 2009
I have a Worker.cs in a ZScreenLib DLL that does the following: 1. takes ZScreenGUI.cs (a Windows Form) as an argument 2. creates a Background Worker object and does everything 3. reports progress to the ZScreenGUI form via BackgroundWorker.ReportProgressThe user can create as many instances as possible of Worker.cs class and do the background worker tasks Now I need to create another Windows form called ZScreenCLI.cs and wish to make use of this Worker.cs class because ZScreenCLI and ZScreenGUI are pretty much the same but ZScreenCLI has much less features compared to ZScreenGUI. My question is, how do you manage to report progress to ZScreenCLI? The ReportProgress methods are tied with the controls in ZScreenGUI form. Obviously there is a problem with the concept I am using
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Sep 19, 2009
Public Function DownloadFile(ByVal URL As String) As Boolean If Not URL = "" Then Dim wc As New System.Net.WebClient() Dim Filename As String = Mid(URL, InStrRev(URL, "/") + 1, Len(URL)) wc.DownloadFile(URL, "C:TESTS" + Filename) Return True End If Return False End Function
I am using that function to download a file. It works. But there are two problems:1# While its downloading the file, the app is sort of frozen like its in a infinite loop.2# How do I get the download percentage?
edit: My resolution to freezing using BackgroundWorker (thread) and using ReportProgress to update the GUI is here: [URL]...
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Aug 30, 2009
As I teach myself VB, I'm working on using the backgroundworker. Mostly I'd like to use it to update a progress bar. But here the problem I'm running into...
When I use it like this:
Private Sub TestWorker_DoWork(ByVal sender As Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles TestWorker.DoWork
Dim ListText As String
For Value As Integer = 0 To 100
If TestWorker.CancellationPending Then
[Code] .....
Where GetPlayerNames() is the Sub that really contains a majority of my code, which uses a class library I wrote, and calls other functions, etc. But this just causes the backgroundworker to skip right to the RunWorkerCompleted and executes no code. It seems to me you should be able to call procedures from the DoWork and then pass updates back via the ProgressChanged event. I can't image you need to consolidate all your code into the DoWork.
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Jan 21, 2010
I am trying to do the following process in the method of BackgroundWorker.DoWork()
Private Sub BackgroundWorker1_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
For x = 0 To 100
[Code].....
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Sep 22, 2010
I have seen others with a similar issue but not quite what I was looking for. In the backgrounderworker class dowork event I create an instance of a new class and call one of it's function. Previously, I had this code in a windows.form.timer tick event and would pass a delegate in as one of the parameters which would allow the function and other functions it calls within the class to call a method on the form to update a datagrid on the GUI. Is there a way to do this within the dowork event? I need this because the function I call from dowork calls other functions and I want each of those functions to log information in the GUI datagrid.
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Jun 13, 2011
have a formthat hasa BackgroundWorker,on the do_work event i exe an SP:
Dim result As IAsyncResult = cmd.BeginExecuteNonQuery()
Dim rowCount As Integer = cmd.EndExecuteNonQuery(result)
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Feb 2, 2009
I have finally figured out how to download a file with background worker and downloader. Now the form does not freeze.. I have only one problem left now... How do I get the progress bar to increment in tandem with the data flow? I have listed my full code below. Towards the bottom where the DoWork() sub resides, I am just a few lines short of this year long goal.
Imports System.IO
Imports System.Net
Imports System.Text
Public Class Form1
[CODE]...
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Oct 26, 2009
I am trying to execute the following line of code within the DoWork event of a BackgroundWorker object: [code]
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Mar 27, 2012
I have a UserControl that has a ProgressBar on it. The purpose of the UserControl is to be able to show the progress % on the ProgressBar as text. To do this it uses the MyBase.Paint event. To make it work the ProgressBar is made invisible and the UserControl is 'painted' with an image of the ProgressBar and then the text is painted on top. The UserControl has a Value property that is passed through to the ProgressBar.Value property.
I use this UserControl in two places, on a Splash form (not a standard Splash Screen) and also on the main form of the application. It works on the Splash form but not on the main form - by work I mean that changes to the ProgressBar.Value property cause the ProgressBar to show its progress. The cause appears to be that in the Splash form case the MyBase.Paint event is called as a consequence of calling Me.Refresh in the Set procedure of the UserControl.Value property, in the main form case it isn't,
i.e. Me.Refresh isn't causing MyBase.Paint to run.
The main form has two BackgroundWorker components. The first gets called (RunWorkerAsync) from Form_Load after the Splash form has been shown. The BackgroundWorker.ProgressChanged event updates the Value property of the UserControl and it works exactly as intended. The second gets called as a result of a user starting an operation and again the BackgroundWorker.ProgressChanged event updates the Value property of the UserControl but MyBase.Paint doesn't run so the ProgressBar remains resolutely static.
Any ideas why it won't respond to Me.Refresh in one case but does in the other? Happy to make any of the code avaialble but didn't want to fllod the first post with reams of it. Here's what I think are the most relevant code sections. First the UserControl
[Code]...
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May 6, 2009
In my DoWork() function I register with our sip server. Then I have to wait for a response back. However, the response I get is received in another event. However, before I am able to check the flag in the DoWork() the DoWork() has all ready finished and the response comes after.
I am trying to find a way to wait in the DoWork() until I get a response in the Diagnotic event. I have a global flag that is set in that event that I have to check in the DoWork().I was thinking of maybe blocking in the DoWork() until the other event is finished. Maybe using a join.
' Do work in background worker
'Will return less than 8 if there are no error message from the library
If (Not Me.bgwProcessLogin.CancellationPending) Then
' Register and wait for response
[code]....
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Mar 26, 2010
How would you create and use a delegate to update the text of the main form from the DoWork event of a backgoundWorker?
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Oct 6, 2010
Let's say a custom exception is thrown in the DoWork event for a backgroundworker. How do I pass the custom exception to the backgroundworker so that it ends up being the e.Error in the RunWorkedCompletedEventArgs?
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Sep 20, 2010
Starting from my understanding about Background worker control, I understands that the background worker runs the code in its "DoWork" method in a seperate thread, while ProgressChanged and RunWorkerCompleted events are executed on the main thread.In my senerio, I report the progress and under an specail condition my application displays a message box to the user in "ProgressChanged" method using MessageBox.Show(). and in "Run Worker Completed" event the application finalize some work. There the sequence is important, suppose that the message is of Yes or No type and finalization depends on it. Now when i run my application, the background worker triggers "ProgressChanged", but as soon as backgroundWorker's cancelAsync() is called the program leaves the current "ProgressChanged" method and executes "RunWorkerCompleted" code first.How can i make sure that the "Run Worker Completed" code executes only after the completion of ProgressChanged method.
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Jul 22, 2009
I have a windows application which raises a particular event.I need to create a COM callable class whic will allow VB 6.0 to subscribe to this event.I have done a fair amount of research on this and am confused as hell.
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Mar 8, 2010
figured out a different way to code it that _should_ work around the problems people pointed out before.... but one problem is still the same, the examples I find to code pieces of this are all for old versions of visual basic, and don't workI'm a firefox extension developer. I wrote an extension to allow both private and normal browsing windows simultaneously by having two firefox processes. I figured out a way on the Mac to raise the private browsing process when appropriate... it looks like visual basic is the way to do it on Windows... so I'd like firefox to run a visual basic program that does the following:Look through the process table for all firefox.exe processesFind out the process id of the process that called the visual basic scriptThrow out the process ID of the parent process... now we should just be left with the "private browsing" firefox process
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Aug 15, 2011
can I call shared events contained in one class from another class?
for example:
logonclass.vb : handles login logic and authenticates against database
logonmanager.vb: hold current user reference and some logon and timeout events
Logon.vb: A form with a submit button.
I would like to do something like this but I can't get the compiler to agree with it
If VerifyEntries() Then
Try
privLvl = LoginClass.AttemptLogin(txtUserName.Text, txtPassword.Text)[code].....
If this isn't the proper way to wire things together let me know so I can learn to structure differently. In my planning it seemed like I was raising a lot of extra duplicate events from my logonclass to my loginmanager class. Then the loginmanager had to raise it again for the main form to see the change event. It got me thinking that if I publicly shared the events and could raise them from wherever then it would cut down on the amount of events I needed in code and the amount of them flying around at runtime.
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Jun 28, 2010
I am using the AxWindowsMediaPlayer1 control to play MP3 sound files in my application.
I would like to lower and raise the volume (master) via keypress from my gamepad.
I already have the logic for that established, I just do not see any way to raise and lower the volume within the Windows Media Player control.
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Dec 27, 2010
I am currently trying to make a calendar project it has 2 user controls one is the calendar and the other is the calender day control. When the month changes in the calender control I need to raise an event in daycontrol to update any holidays. In the calendar control I have the following code for the event:
Friend Event MonthChanged()
Public Sub New()
' This call is required by the Windows Form Designer.
[Code].....
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Jul 14, 2011
I want to have a collection of a class which inherits picturebox, with a couple of extra properties, so essentially the same. Only I get an error at runtime saying : 'An error occurred creating the form. See Exception.InnerException for details. The error is: Object reference not set to an instance of an object.' Here Is my code, I know that the error occurs here :
[Code]...
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Jul 26, 2010
I have a TAPI program that is very similar to [URL] I have a delegate ...
Delegate
Sub TapiEventCallback(ByVal
dwMessage As TapiEvent,
ByVal dwParam1
[code].....
From my program TAPI will call the number. My problem is that its not raising any events. I really need CallStateChange. I raised it from address and moved it up to my TAPI Manager. I put break points everywhere and I can not get anything to raise.
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Mar 16, 2012
I need to raise UAC shield. I found code over net
MyBase.OnLoad(e)
If Not IsAdmin() Then
AddShield(Me.elevateButton)
[code].....
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Mar 14, 2011
Makes the following statement about the code below:
**"The computer evaluates the loop condition in the Do...Loop statment to determine whether the loop instructions should be processed. In this case, the inputsales <> String.Empty condition compares the contenst of the input sales variable to the String.Empty value. As you know the String.Empty value represents a zero length, or empty, string if the inputsales variable is empty, the loop condition evaluates to True and the computer process the loop instructions. *If on the other hand the inputsales variable is not empty, the loop condition evaluates to false and the computer skips over the loop instructions.
Based on the code I think it is the opposite: ...that while the inputsales value is not empty it should evaluate to true and process the loop and if it is empty it should evaluate to false and skip the loop?
See below.
Option Explicit On
Option Strict On
Imports System.Globalization
[CODE]...
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