I am trying to add a picture box to my form that contains an animated progress gif, in a separate thread, but I can't seem to get the picture box to appear on the form. Here is my form
vb.net
Private Delegate Sub AddProgress()
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I've got a TCP Listener running on a separate thread. I want to have it log the incoming and outgoing messages in a list on the form instead of in message boxes. I've been reading about multiple threads, and I know there's something extra I need to do because form controls are not thread safe.
Unfortunately I've tried several tutorials on delegates and invoking but it still doesn't seem to insert the log items to the list. I even spent $60 on this Mastering Visual Basic 2010 book to "Build Rich Client and Web Applications with Visual Basic", but there isn't a single chapter on how to handle multiple threads.
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()
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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".
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.
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()
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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.)
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
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
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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.
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.
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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
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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
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]....
I'm trying to dynamically add a control to a form from an event that is raised from an asynchronious socket's thread.
In other words, when I get an OnDataArrival event is raised from the socket thread, I raise DataArrival event in my form. The form's DataArrival sub then tries to create and parent a control.
Whenever I try this, I get the following error: Controls created in one thread cannot be parented to a control in a different thread.I know a bit about delegates and invoking, and I think that's how to solve this problem, but I don't know where to declare the delegates and how to use them.
Ideally, I want a delegate/invoker to handle the DataArrival sub in the socket class so that everything that happens after that will be thread safe. Can this be done?
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].....
I have a program where I don't want the UI going white and unusable while processing some SQL queries. So what I did was set the two long queries into a Thread and put a ProgressBar in Marquee mode just to indicate something is happening.
My issue is that I need certain Buttons enabled and disabled at certain times, so the only way to do this is to, after the SQL statements are run, do the proper testing to see which Buttons need to be Enabled. However, I obviously can't put these after the Thread execution or it happens immediately after the .Start() command. So, they need to go in the thread. But, I'm not understanding exactly how to go about changing the state of the Buttons from a different thread. Here is my
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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."
View 13 RepliesI 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?
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.
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]....
just wondering if it is possible to have a form and then load up a control on that form but so it runs in a different thread to its parent... i tried:
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But it still seemed to be running on the form's thread And just so you know ctlMTTest is just a control that has a button on it, that, when you click the button, a loop runs.
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."
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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
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I'm adding multi-threading facilities for the first time. I have a function that is wrapped to be run in a separated thread. This function retrieves data (text) from a combobox and it works for sure without multi-threading.
When I call it as multi-threaded, I get the following error when I try to retrieve the data from the cmobobox: Cross-thread operation not valid: Control 'cmb1stBL' accessed from a thread other than the thread it was created on.
It looks like a restriction of thread-safety... I assume that the child thread cannot read from his parent, to make sure that he doesn't change his parent data. So how can I read the data from the combobox? Should I read the comoboxbox data before calling the child thread?
I have a VB.NET form created in VS 2008. This form contains an ActiveXControl (MapPoint 2006 Europe ocx) located and reference here:[code]The project compiles just fine. However, when I run this starting form I receive this error:An error occurred creating the form. See Exception.InnerException for details. The error is: Cross-thread operation not valid: Control 'AxMappointControl1' accessed from a thread other than the thread it was created on.[code]I mention that the very same project was upgraded from VS 2005 on which worked just fine.
View 12 RepliesI am programmatically creating a Tabcontrol and adding Tabpages to it. To each Tabpage, I am adding 2 Pictureboxes (Testpicture1 and Testpicture2). The amount of Tabpages depend on the amount of frames in my .tif file. So, each picturebox holds an image (frame) from my .tif file sequentially from˜0 to totalpages. All good so far. I can click each tab and correct images are displayed in correct order. The problem is that when I drag a control (picturebox) and try to add it to Testpictue1 or Testpicture2 it does not work correctly. At first I thought the it didn't work at all, but when I checked each Tabpage I have found that all pictureboxes got added (draped) to my last Tabpage, in this case Tabpage4. So this is puzzling. Even though each Tabpage holds 2 Pictureboxes and they display the correct images yet the picturebox is added to the Testpictue1 or Testpicture2 of the last created Tabpage? [code]
View 3 RepliesI need some help to understand my options to get this working. I try to update a textbox control by a property-changed event from a class variable. I've digged around for a day and have a vague understanding that this can be solved in three ways:
1. Using some "if InvokeRequired", "Invoke" code in the handler method
2. By programming a special delegate class for this variable
3. By using a databinding directly linking the control (textbox) to the class event
Now.. Are these options correct? And would it be possible to get some help to show these three solutions in actual code (relevant to mine)? I can't seem to manage to sort all the information to a working code. Also, what are the pros and cons of the different solutions?
As my code stands now, it's obviously none of the above, as it gives a cross-thread error, as indicated.
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I need to add an X button on my tab headers so that the user can close the tabs easily and intuitively. I want it to work like firefox tabs, where you can press the X on any tab to close it at any time. Is there any way to do this?
View 2 RepliesIm learning .net from vb6 and been stuck with this a while
Option Explicit Private Sub Command1_Click() Dim i As Long
For i = 1 To 3 Me.Controls("Text" & CStr(i)).Text = "This is textbox number: " & CStr(i) Next End Sub
Wasn't really sure what to name this thread or how to explain it. I have a form with a dateTimePicker control on, textbox for days, button and label, when the button is pressed I'd like the amount of days put into the textbox to be added to the value in the datetimpicker then the result being put into the label.
E.g. Select 26th November in the DTP, then put 6 into the textbox, press the button then have 2nd December come out in the label. I've tried a few things but all fails and just gives me back the original value in the DTP.
I have added a freshly compiled ObjectListView.DLL to my VB.NET project and I've added a ObjectListView control to my form. But, thus far I have been unable to do anything with it except make it throw exception errors of various kinds. I know I'm not supposed to use it using the same syntax that ListView uses, but the documentation for this control is as well developed as MSDN's for ListView--which is to say vague to nonexistent. I can't use ListView because it gives me no control over row height and cell padding. Both need to be minimal, but with the defaults used by ListView, you could move in and and make a living between the entries. Too much space. I need things compact because the application I'm developing needs all the real estate it can get for other purposes.
View 3 Replies