Update A WPF Control From A Background Thread From A Module?

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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WebBrowser Control - Background And UI Thread Components

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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Creating A Webbrowser Control In A Background Thread In Backgroundworker?

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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Cannot Update Control From Class Function That Works In A Thread

Feb 27, 2012

Updating the TextBox from a Thread that calls a function within a Class does not work. I'm trying to get this to work in a DLL (but I tried without as well). The DLL is accepting an Object as an argument[code]....

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Call A Method That Started On A Background Thread On The UI Thread Calling BeginInvoke And Passing In A Delegate?

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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VS 2010 Error - Cross-Thread Operation Not Valid: Control TbPlaca1 Accessed From A Thread Other Than The Thread It Was Created On

Aug 13, 2010

In one application, I need use 4 simultaneous threads.When the threads finished, I need to update the text of a TextBox.So, I create 4 Textbox, and I wanna the threads change the text to FINISHED.Each thread change one distinct TB.I use this "example"

Dim Terminados As Integer = 0
Private Sub frmEnviarMensagem_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Timer1.Enabled = True
Timer1.Start()

[code]....

The problem is, I have an error in the red lines.The error is: INVALIDOPERATIONEXCEPTION "Cross-Thread operation not valid: Control tbPlaca1 Accessed from a thread other than the thread it was created on."I don't use cross threading. Each TB only was accessed for the correspondent thread, and for the "main program".

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Cross-thread Operation Not Valid: Control 'Panel1' Accessed From A Thread Other Than The Thread It Was Created On." ?

Nov 3, 2011

This is the error message I am getting:

"Cross-thread operation not valid: Control 'Panel1' accessed from a thread other than the thread it was created on." The reason I am getting this error is because I am opening up a new form and then calling these three things:

Panel1.Show()
Label1.Show()
Label2.Show()

why I get this error message because it doesn't occur normally if I open Form2 after closing Form1, it only occurs when I open Form2 after closing Form4.

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Error - Cross-thread Operation Not Valid: Control 'txt1' Accessed From A Thread Other Than The Thread It Was Created On

Jul 21, 2009

I have done a program using vb2005 to display reading from my microcontroller bs2 board but have encountered some problems. My code are as follows.

Dim Stop_Rx As Boolean
Private Sub btnRead_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnRead.Click
SerialPort1.Open()

[code]....

I've encounter an error which is, (Cross-thread operation not valid: Control 'txt1' accessed from a thread other than the thread it was created on.)

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Error : Cross-thread Operation Not Valid: Control 'l_users' Accessed From A Thread Other Than The Thread It Was Created On

Jun 21, 2012

When my client try to connect to server I'm getting this error : Cross-thread operation not valid: Control 'l_users' accessed from a thread other than the thread it was created on.

Private Sub _socketManager_onConnectionAccept(ByVal SocketID As String) Handles _socketManager.onConnectionAccept
l_Users.Items.Add(SocketID)
End Sub

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Threading Progress Bar In .net - Thread Operation Not Valid Control 'ProgressBar1' Accessed From A Thread Other Than The Thread It Was Created On

Feb 17, 2012

Would anyone be able to help me here please. I'm fairly new to VB.net and threading so im just trying to figure out what is happening.When I debug this I am getting the error thread operation not valid: Control 'ProgressBar1' accessed from a thread other than the thread it was created on.

I'm a little lost as to why the error is occuring or how to fix it. I've had to put the progress bar in a separate thread otherwise the GUI crashes

[Code]...

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Cross-thread Operation Not Valid: Control 'Autocad' Accessed From A Thread Other Than The Thread It Was Created On

Jun 6, 2010

I have written an application that loads a form - frmCad as well as AutoCad. It does this via a class which detects when AutoCad quits.

Friend Class CadApp Private WithEvents AppObject As AcadApplication... Private Sub AppObject_BeginQuit(ByRef Cancel As Boolean) Handles AppObject.BeginQuit RaiseEvent Quit() End SubEnd Class

My main class loads frmCad as well as CadApp.

Public Class Cad Private WithEvents frmCad As CadForm Private WithEvents app As CadApp... Public Sub ShowForm() If frmCad Is Nothing Then frmCad = New CadForm frmCad.Visible = True End Sub... Private Sub app_Quit() Handles app.Quit frmCad.Dispose() frmCad = Nothing .... End Sub

When I debug the program, it stops at frmCad.Dispose()The program continues to execute, but all the code after it fails to work.Looking more carefully I get an error message which contains:-Cross-thread operation not valid: Control 'Autocad' accessed from a thread other than the thread it was created on.

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Cross-thread Operation Not Valid: Control 'label2' Accessed From A Thread Other Than The Thread It Was Created On?

Feb 9, 2011

My error:Cross-thread operation not valid: Control 'label2' accessed from a thread other than the thread it was created on. I want to be able to give my Public RunBot() sub access to edit Labels, buttons, etc without an error.

[Code]...

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Cross-thread Operation Not Valid: Control 'lblStatus' Accessed From A Thread Other Than The Thread It Was Created On

Apr 1, 2010

I'm getting the 'System.InvalidOperationException' error on acccessing a thread from other than where it was created. My code is:

'Required by the Windows Form Designer
Public components As System.ComponentModel.IContainer ' changed from private

[code]....

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Cross-thread Operation Not Valid: Control 'statusHO' Accessed From A Thread Other Than The Thread It Was Created On

Jun 6, 2009

My problem is Cross-thread operation not valid: Control 'statusHO' accessed from a thread other than the thread it was created on.

System.InvalidOperationException was unhandled
Message="Cross-thread operation not valid: Control 'statusHO' accessed from a thread other than the thread it was created on."
Source="System.Windows.Forms"
StackTrace:

[Code]...

i used it and it works fine then. but as it is mentioned its not a good practice to use it. So what should i do? is it ok if i use this as i am not able to use correct practice. Mine application is not for enterprise purpose. its just my class project, and it works fine even if i put application working in background. System works ok. I dont know how to correct this error.As i dont have that much knowlege of threads.

So please guide me how to fix this in correct way otherwise i am force to go for bad programming practice
Please refer to Windows Mobile Developer Center > Smart Device Development Forums > Windows Mobile Development > Appendtext not working for all my code details

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Function Returns UI Thread Value To Background Thread?

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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Cross-thread Operation Not Valid: Control 'lv1' Accessed From A Thread Other Than The Thread It Was Created On?

Aug 4, 2009

Cross-thread operation not valid: Control 'lv1' accessed from a thread other than the thread it was created on.

Dim lvi As ListViewItem
For Each lvi In lv1.Items

[code]....

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Error Saying "Cross-thread Operation Not Valid: Control 'lblOnline' Accessed From A Thread Other Than The Thread It Was Created On."?

Feb 7, 2011

Ok i have a Form with the following

Private Sub frmMain_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
txtNotepad.Text = LoadFile("notes.txt")

[code].....

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Update ProgressBar From Another Thread (Thread Is Not A BackgroundWorkerThread)

Nov 18, 2009

I have a program that runs for some time and I would like to update the user on its progress. The rest of the GUI is updated using Delegates and Invokes and such (Java is Soooo much cleaner in this regard - everything is thread safe!!), but there is no invoke method for the progress bar. How can I use a delegate to update the progress bar when there is no invoke to invoke!!

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Form Callback - Create A Module That Will Start A Thread

Mar 2, 2012

i am trying to create a module that will start a thread to go do something. once the "something" is done i want to notify the calling form that the event is complete. i left out the thread stuff since its not relevant to the question. the following code would work fine in VB6, but .net sees it as an error because FRM does not have a FRM.done, "DoSomething" would could called by multiple forms [Code]

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Module With Functions (thread 1) That Starts A BeginRead For A TCPClient?

Jul 2, 2010

Even though there are many examples of Invoke operations, I can't find something that works for me. (I'm using VS 2008, and working in VB)Here is what i have:

A main module with functions (thread 1) that starts a BeginRead for a TCPClient. When the callback function executes (on thread 3), I want to call a function from the main module, in the main thread. All I get even with Invokes is calling functions that always run in thread 3, not the parent thread.

I call:MsgBox("Function name: " & Thread.CurrentThread.ManagedThreadId)

in each of my functions do determine on what thread it is executed. At some point, from the infinite read callback function I will have to get a function to show a form, but that function gets caught in the callback thread and freezes, instead of running in the main thread.PS: the callback that I pass to the BeginRead of the TCPClient is a function, not a class, so I can't use raise events.All I need is to call a function to run in the main thread (main module) from another thread.

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Call A Function In Module And Get Result In The Main Thread Asynchronously

Mar 2, 2011

I have a function in a module that returns a datatable.I need to call that function asynchronously and get the results in the Main thread (Main Form) in vb.net.

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Forms :: Access Main Form From Second Thread Running In A Module?

Jun 22, 2010

I was a vb6 user, done a few projects only with forums Now i am moving to vb.net(vb2010) and i have some trouble.Lets say we have a form(form1), a module(mod1) and a textbox on the form1.

i want to start a Sub (DoWork) in the module but in a new thread.

Dim Thread1 As System.Threading.Thread
Thread1 = New Threading.Thread(AddressOf mod1.DoWork)
Thread1.Start()

The DoWork sub does some stuff and when it's finished i want to change the text of a textbox1 in the main form and start another sub (DoWork2) on the main form under the main thread not the one DoWork is running under.

Plese do not refer me to another post that mighe give me a part answer, try to explain to me what i have to do and why.

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Threading Class FrmMain To A Module And Modifying UI Thread Values?

Jan 15, 2010

In frmMain:

Private Sub DBReadAccountInfo(ByVal strAccountID As String)
Dim tmpaccountInfo As New PublicFunctions.clsAccountInfo
tmpAccountInfo.strAccountID = strAccountID
Dim ReadAccountInfo_Thread As New Thread(AddressOf tmpAccountInfo.DBLookupAccount)
ReadAccountInfo_Thread.IsBackground = True

[code]....

In "sub UpdateAccount", frmMain.InvokeRequired is always false. There's a MenuStrip control I'd like to update the .Text on.

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"Cross-thread Operation Not Valid: Control 'TextBox1' Accessed From A Thread?

Sep 18, 2009

When i run the program i am getting the following error in this line TextBox1.Text &= "File Created: " & FullPath & vbCrLf"Cross-thread operation not valid: Control 'TextBox1' accessed from a thread other than the thread it was created on."

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Cross-thread Operation Not Valid Control 'FormSplash' Accessed From A Thread Other?

Sep 5, 2009

I need your help on the following. In debugging mode only the program is stopping to the following line "My.Forms.FormMain.HelpProviderMain.HelpNamespace = "Reports.chm"" with the following error ""An error occurred creating the form. See Exception.InnerException for details. The error is: Cross-thread operation not valid: Control 'FormSplash' accessed from a thread other than the thread it was created on.""

I noticed that when I am putting NONE in SPLASH screen option in the properties of the project, there is no problem.I am no familiar with treating that's why can you give me detail instruction how to overcome this annoying problem?

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Cross-thread Operation Not Valid: Control 'FormSplash' Accessed From A Thread Other

Sep 5, 2009

In debugging mode only the program is stopping to the following line "My.Forms.FormMain.HelpProviderMain.HelpNamespace = "Reports.chm""
with the following error ""An error occurred creating the form. See Exception.InnerException for details. The error is: Cross-thread operation not valid: Control 'FormSplash' accessed from a thread other than the thread it was created on.""I noticed that when I am putting NONE in SPLASH screen option in the properties of the project, there is no problem.

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Cross-thread Operation Not Valid: Control 'hiddenrtb2' Accessed From A Thread

Mar 10, 2010

im getting this error and i cant figure it out.

Public Sub mlogin()
Invoke(chkb, New Object() {"disable"})
Invoke(d, New Object() {achidrtb, "", "="})
Invoke(d, New Object() {hiddenrtb2, "", "="})

[code]....

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Multi-thread Accessing The UI Thread Control, No Exception Thow?

Oct 11, 2011

As we know, one STA UI thread creats the controls only canbe accessed in the UI thread in Winform application. And we need to call control.invoke or begininvoke to run the code in the background thread.

Yes, below code in VB.Net , VS 2010 Winform project can throw the exception "Cross-thread operation not valid: Control 'Form1' accessed from a thread other than the thread it was created on."

[Code]...

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Controls Created On One Thread Cannot Be Parented To A Control On A Different Thread?

Feb 15, 2010

My program crashes with the following error:Controls created on one thread cannot be parented to a control on a different thread.Purpose of the program is to add a control from a thread outside the main thread.Below is the code Private Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click

[Code]...

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Background Thread Not Terminating

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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