VS 2008 Messagebox From Background Thread But Tied To UI
Jun 14, 2010
Currently I have a background worker doing a bunch of stuff and if a condition is met, it throws up a MessageBox for the user to pick from an the background thread pauses like I need it to, however most of the time the Messagebox shows up behind the main form (which is on the primary app thread, the UI thread) and I'd like the BW code to pause until it's acknowlegded and I also want the MessageBox to be owned by the main form (so it's always displayed in front and you can't get to the main form until you acknowledge the MessageBox. Later I'll be changing the MessageBox to be a modal form that matches the app's theme (I'll be opening this form using .ShowDialog()) should I go ahead and make that form now?
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Jun 9, 2009
Im trying to run a thread in the background. The sub would take a string as as input and the text to speech object would read the string.
1st problem is: How do I pass my value strIn to my sub SpeekEventWorker when im calling it like this
[code]...
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Aug 6, 2010
I'm working on a web application that uses the web browser control to get and set info from my website. The content on the site is pulled from different pages and the data the application stores becomes really huge so i used a background worker to do the work and keep the form responsive. On each loop i call to get the webbrowser's inner html so i can sort through it and grab what i need and it works; but only the first time!? After i call it the first time and try to call it again to update the variables the function hangs and then the console shows me a Thread Abort Exception, The try statement i used to contain it doesn't fire off an exception. When i debug the program and i get to that function, it hangs and then just stops working.
The function that loops:
vb.net
Dim ids As String = GrabIDs()
Dim IDCount As Long = ids.Split(CChar(",")).Length - 1
Do Until IDCount = 0
[Code]....
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Aug 27, 2011
I am trying to call a method that started on a background thread on the UI thread calling BeginInvoke and passing in a delegate as follows:
Dispatcher.BeginInvoke(Function() UpdateApplicationDataUI())
to call this method:
Private Sub UpdateApplicationDataUI()
...
End Sub
However, I get an error in the call to BeginInvoke (the UpdateApplicationDataUI portion of the delegate is stating "Expression does not produce a value").
Me.Dispatcher.BeginInvoke(Function() New Action(AddressOf UpdateApplicationDataUI))
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Dec 4, 2008
A non-UI thread in my prog needs to obtain data from a UI listview control. To prevent cross-thread errors I use the following, but it freezes the prog (probably because the "Else" part is never called).What am I doing wrong?
[Code]...
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Jan 26, 2010
I have a program that if user presses a key(while the program isn't focused),it presses some keys(some kind of macro to aid gamers).The program works,but I cannot stop the background thread.I use "t.abort()" (t is the name of background thread) but it keeps working(even when I close all forms) and at TaskManager "keypresser.exe" is still there.[code]
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Oct 4, 2010
I have an application that I need to load data in a background thread and make available to a combobox or list box on my main form or UI Thread. I am really new to threading in VB and how to best accomplish this. Here is some code from a test project:
[Code]...
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Jun 22, 2010
I have a a main thread and another background thread that does some work (see below).I want to do something within my worker thread and then wait until some other event happens in the main thread before continuing. How do I do this? I thought I could use ManualResetEvent but I can't get it to work properly. I'm a bit confused about the Set, Reset, WaitOne methods and where exactly I should call them from.When the worker thread is suspended it shouldn't affect the main thread.
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System. EventArgs) Handles MyBase.Load
End Sub
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
[code]....
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Jun 29, 2011
I am a novice in Threads, but I want to know how to order thread execution in my scenario, and is the following :
UI Thread : Windows Form Background
Thread : Kind of print daemon
implemented with recursive methods
IO Operation : a StreamWriter that do
the job of File.AppendText()
When I execute my main app.exe, sometimes it launches the Windows Forms and the execution process in the task manager (app.exe), in some opportunities its just launches the execution process in background. How can I determine the behavior of launching UI, I have to establish a priority or somewhat else? Code: I'm using framework 2.0 and any answers could be writted in C# or Vb.Net.
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Apr 7, 2011
I am in the planning stages for developing a VB.Net class (let's call it OpDAq) that is to obtain data via an API provided by a COM object (AxInterop.TWSLib) that makes requests to an Internet server. The API provides data via events. Class OpDAq should do its work on a separate thread; it takes several seconds (sometimes up to ~10) to collect the desired data. One should be able to create several instances of OpDAq in order to collect data in parallel. The class would be given a reference to the TWSLib object when its constructor is called, as well as several parameters. There needs to be a way for the class to provide results, preferably in the form of a generic list.
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Aug 28, 2011
I'm looking for a configurable way to run some code on a background thread and I'm not too sure what the "best practice" would be. Currently I have something along the lines of:
Dim sendEmails = Sub()
Dim emailToSend As New SendEmailRequest()
TransferCommonValuesTo(emailToSend, request, sendingUser)
usersToSendEmailTo.ForEach(Sub(u)
[Code] .....
Is this a good way of implementing my requirement? This will be called from an ASP.NET front-end (although others are possible) and I am using Framework 3.5.
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Aug 16, 2011
I've got an application with a ListView and I want to loop through each item in the ListView. But I want to do this in a separate thread.
This is a very simple version of the code - but its error is the same:
Private Sub StartToolStripMenuItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles StartToolStripMenuItem.Click
pingThread = New Thread(AddressOf loopingRoutine)
[Code].....
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Apr 6, 2012
I have a BackgroundWorkerThread which I want to use serially.So some of the code in the UI thread will look like this [code]But of course I can't do the second RunWorkerAsync until the UI thread has seen the RunWorkerCompleted event indicating that the "Sequences" work has been completed (or somehow knows that the "Sequences" work has been completed).So I need some sort of synchronization between the two RunWorkerAsync calls, but whatever I use cannot hang up the UI thread because it has to be able to handle ProgressChanged events.Maybe the RunWorkerCompleted event could make the second call but I really don't like that structure.So how do I delay the second call to RunWorkerAsync (for the "Templates" work) until the background thread has completed the "Sequences" work?
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Mar 2, 2010
I am running sum of my code in a background worker and I need to show sum tooltip text on a label, but nothing shows up.[code]...
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Feb 24, 2009
I can't seem to find a good tutorial on how to access uithread components from the background thread.. It seems like there is different means of accomplishing this. I'm not picky about which one I use.
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Apr 6, 2011
I have searched the forum and found several forums related to the backgroundworker thread but have been unsuccessful in finding my answer.My objective is to display an animated gif or progress bar while the program is executing a particular method which can take upwards of several minutes to complete. I cannot get the second thread to run the progress bar while the main progrem is executing the time consuming method. I have created a demo based on another thread and can't seem to get it to create two threads. I was attempting to get the backgroundworker to execute the progress bar while my main code runs on UI thread.
[Code]...
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Jul 8, 2011
I'm using the code below in a separate (background) thread, in order to read parts from a file, so they can be uploaded.
The problem is that when the user stops the upload, the thread is sometimes aborted while it's still reading from the file. This keeps the file locked and when the user starts the upload again, the following message appears.[code]...
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Jul 2, 2011
My application has a total of 1 form. I have several modules, one of which is a module that handles a background worker dynamically. But what I need to be able to do is update a textbox from the background worker thread. Again, this code is contained within a module, not directly on the main form, so I am totally clueless as to how to make a reference to it. It's easy in WinForms, but I can't for the life of me figure out how to do it in WPF...
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Apr 25, 2012
I have a application which processes 1000's datas.. for each processing it needs to update gui and db and many variables in my application. So what i have planned is to use 50~90 background worker with my own algorithm of thread pool, synchronization and thread close.So here is it efficient in terms of memory and performance. just confused what to use.. backgroundworker componenet or standard thread.
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Feb 24, 2009
I'm using the webbrowser control in VB.net. I want to click a button and have the webbrowser go to a certain website (done). Then I want it to wait a period of time and then do something on the page its on. The part I'm having a problem with is the waiting period. In the main form I have no problem manipulating controls or anything like that.
One solution would be to use thread.sleep() but that locks the ui and I don't like that. What I am trying to do is have a backgroundworker do the waiting then perform the necessary actions on the webpage, but the backgroundworker isn't able to access that thread, makes sense. I've explored delegates but that doesn't seem to do what I want as it doesn't allow me to put the background thread to sleep before it does its work.
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Aug 5, 2009
ReportViewer is a component I use frequently. Imagine my surprise in VS2010 when I find that a project MUST use the 4.0 framework choice or the toolbox will not display the component. I am trying to use a 2.0 project for compatability reasons. No matter how I try to reference the WinReportViewer it will not work unless I update the project for 4.0 framework.MS, I don't understand what this means for upgrade path for old projects being opened in VS2010. We are a VS2008 shop and it would be horrible to upgrade a bunch of projects to 2010 only to find that ReportViewer is no longer supported by 2.0 framework.
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May 30, 2011
I am testing a background workder. I am running the following code for the test.
Private Sub bgwTest_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles bgwTest.DoWork
Dim a As Integer = 0
Do While a < 10 'Infinite loop
ComboBox1.Items.Add(1)
[Code] .....
But this code generates the following error:
"Cross-thread operation not valid: Control 'ComboBox1' accessed from a thread other than the thread it was created on."
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May 19, 2010
Can someone tell me how to get the selected text in the combo as it encountered cross-thread in the following code:
[Code]...
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Sep 23, 2009
Is it possible to create a WebBrowser control in a background thread in BackgroundWorker?
Private Sub BackgroundWorker1_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
Using web1 As New WebBrowser[code].....
Does anyone know a way to create a background WebBrowser? I would like to do it to extract info from websites then spit out the various HTML DOM arrays
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Mar 15, 2010
I was looking for a solution to run a lengthy job (looking for files on the fixed drives) withouth freezing the UI, and saw that using a BackGroundWorker control is the recommended solution.
Problem is, I don't see its ProgressChange event being triggered:
Imports System.IO Imports System.Text.RegularExpressions
Public Class Form1 Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click Button1.Enabled = False
[Code]...
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Oct 4, 2010
What is the Invoke syntax to marshall data from a background thread receive callback method to a function on the UI Thread?(Form1).
Public Class Form1
MyDelegate = New DisplayData(AddressOf DisplayData)
Private Sub Form1_Load()
MyDelegate = New DisplayData(AddressOf DisplayData)
[code]....
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Mar 23, 2012
I created a background thread that get's data and returns it to the main thread; this works. Now I want to be able to stop the SQL request from the main thread (probably on a button click). This is my test code for creating the thread (working):
[Code]....
How can I access the background thread to stop the query on demand? Do I need to set a flag on the main thread telling the background thread to stop running then have the background thread poll the main thread at intervals? I was trying to look for an example but I wasn't able to find a good one.
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Nov 23, 2009
put method in main thread from background without declaring delegates
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Nov 17, 2008
I'm having some problems with updating a form from a background thread, started in the MyApplication_Startup sub.As far as I know updating forms or controls on forms have to be done threadsafely.
When the application starts up, some threads are being created which create an object in which a download for a zipfile will be started. The object has some delegates to let the GUI know what the status of the download is, for example 'started' or 'finished'. Also the mainform will be shown on which a datagrid has been placed to show the user which files will be downloaded and in which phase the download is.
All this works amazingly fine but when I want to update the datagrid's cells p�r thread the datagrid aint updated. I know the problem is that the thread in which the Form is created isn't the same as the thread which wants to update the grid?
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Nov 6, 2011
When I run the following code in the UI thread, it works without issue.
VB.NET private timer as new timer public sub test()timer.enabled = true timer.interval = 1000 timer.start()addhandler timer.tick, addressof timer_tickend sub private sub timer_tick(...) messagebox.show("fff")end sub
But if I run it within a background thread, nothing happens.
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