I have a small form that notifies the user on the completion of events (such as SMO restore). I want this form to appear from various sources (such as the below SMO Restore complete event) so I guess I need to create a new thread before creating the form? As it could be called from outside the UI thread. (I also need to pass a string to this form)
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All the code i found for multi-threading is complex and not clear.What i want to do is creating a thread for reading and analyzing a big text file on Form_Load event, so that the form UI building continue without waiting for reading and analyzing the file finish.
View 2 RepliesBasically I want to Create a new thread which create a new timer.I can create a new timer in different button but when one of the timer has an idle time or sleeps the other timers also sleep. I do think because they are running in the same thread.
View 7 RepliesPreface: I know this is an unusual/improper way to do this. I can do this with a "real" ShowDialog(), background worker/thread, and so on. I am trying to do specifically what I describe here, even if it is ugly. If this is impossible for X reason, I have created a fancy progress dialog for some of our long running operations. I need to have this dialog shown on a new thread while having processing continue on the calling (UI in most cases) thread.
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I have a class that is in an assembly due to being required for other projects that I'm currently working on. One class lets call it Class Factory, creates a group of controls which require click event handlers to be attached, I have algorithms which determine polymorphic behavior based on certain features but that is relatively irrelevant.
Due to the event handler having to open up a specific form that isn't part of my assembly, and that form requiring this "Factory" class. Without creating circular reference is there any way I can essentially "delegate" the handler event for the form to define? As a simple work around I have had to maintain two separate classes, one in the project with the form and one in the assembly.
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Me.Width = 1500
Dim panel As New Panel
panel.Location = New Point(0, 0)
panel.Size = New Size(1000, 200)
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I tried to update the button text on a form from a backgroundworker.do_work event, and it failed, with the usual cross-thread exception message.However, by pure chance, I also tried to update text in a system.windows.form.toolstripstatuslabel also from this backgroundworker.do_work event, and it DOES work. Question: why is this? Is it perhaps because theres some kind of implicit shared behaviour with system.windows.form.toolstripstatuslabel?
View 4 Repliescould someone tell me how to fire an event in main thread from another thread as well as fire and forget without use a new thread?
View 9 RepliesI am currently working on a project that has a splashscreen This splash screen is designed to be shown when the main form begins to load its requirements, and then closes once it has loaded... Currently it works like so:
Private Sub frmMain_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
frmSplash.Show()
dolotsofloading()
frmSplash.Close()
End Sub
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how come this throws an error:
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I'm trying to create a structure wherin I have got 1 mother thread and 2 child threads. The child threads get variables to work with from their mother thread and after completion they report back to the mother with the resulting variables. I'd like to be as efficient as possible so creating a new thread every time a thread has finished it's work is kind of a no-go. How can I create this structure without creating a new thread for every iteration?
View 4 RepliesI've a little program that has got tabControl with 2 tabs - "results" and "log". My idea was that when an error occurs the tab will switch automatically on tbLog to show what the problem was. Most arguably the problem is in threading. This is the code that..I use:
Dim thread As New Thread(AddressOf ExecuteQuery)
thread.Start()
ExecuteQuery executes the query and I'm making an error deliberately to see if I'll be automatically switched to the log tab which is in Try-EndTry procedure:
tbGrid.SelectedTab = tbGrid.TabPages(1)
The program indeed switches to tabLog (which is number 1) but I don't see any controls on it (txtLog), then when I'm trying to switch tabs a couple of times I get "Error creating window handle in a thread". I read other forum threads about it where people as how many controls do they have in their programs but my program does not exceed 70 controls on a form.
i have a web browser control, that refreshes pages on a loop after calling a few subs, i need to create a delay in the loop so that the page has a chance to refresh and redisplay before it loops again. i tried the code below, but it seemed to freeze the entire form, elements including, so the web browser didnt refresh before the loop, so how could i create a non form-freezing delay for a loop?
For count = 1 To 20
WebBrowser1.Navigate("URL")
simcheckcheck()
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I'm trying to create a CBT hook to an application, in this case Notepad.
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EDIT: I have also tried it on a Windows XP system now, and it doesn't work there either.
I am trying to create a tcp server, and from I have read I should create a new thread for each connecting client. So This the code I have in my listener thread. I get a error and do not really know how to do it.
While _ListeningStatus = True
'Dim Client As TcpClient = TcpListener.AcceptTcpClient
'If Client.Connected Then
'Dim ClientThread As Thread
'ClientThread = New Thread(AddressOf New ThreadStart(AddressOf ClientThreadProcess(Client)))
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I tried raise an event from another thread, but various error about classes and so on. I try to avoid classes.
Error 1 Cannot refer to an instance member of a class from within a shared method or shared member initializer without an explicit instance of the class. C:Documents and SettingsLMMy DocumentsVisual Studio 2008Projectssarja4bWindowsApplication2formsForm1_saielyhyt.vb 179 32 sarja4b
I am using VB2008
I used threads because I wanted to test and play with them. Threads worked I think, but now I wonder what is wrong with events?
SerialPort1.DataReceived seems to suit better here, but why don't my events work?
Here is skeleton of my code
Imports System
Imports System.IO.Ports
Imports System.Threading
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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
I am using VB.NET for Windows applications. What is the difference between Load event,Activate event and Enter event in the Form and in which order the above event is executed.
View 2 RepliesI'd like to create a WebBrowser for the purpose of taking a screenshot of a website. Once its finished it will update a thumbnail image in a ListView. I'd like the whole operation to be done in the background so the UI remains responsive.I toyed with Creating the WebBrowser in a new thread and calling Navigate. I can use a loop to watch for the ReadyState of the webbrowser before I do the screencapture. However it will only continue with the thread if I use Application.DoEvents in that loop. I've never been a huge fan of doing this and would prefer to watch for an event instead. However if I add a handles clause to the WebBrowser it doesn't fire (I tried creating the WebBrowser in the thread, and also tried by declaring it as shared within the class scope).
View 3 RepliesAt the moment, I am writing a class that deals with starting an application in a thread, as well as being able to monitor the closure of the thread and process, and the creation of the thread and process through events. I have absoloutly no problems with monitering the creation of the thread and its internal process within the subs that create them. I placed notifications within the "myprocess_Exited",(for the process closure) and "myprocess_Disposed"(for the thread closure) events.
The problem comes when I terminate the outside application manually; these events do not appear to fire when the application is closed by the user, rather than by code.I thought, since the application closes with an error code when it is terminated in such a way, that it raises the "myprocess_ErrorDataRecieved" event. But this doesn't appear to happen either. Here is some of the code from that class:
'Some of the decleratoins
Event ProcessStarted(ByVal Process As Process)
Event ThreadStarted(ByVal Thread As System.Threading.Thread)
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What I'd like to do is raise an event inside a clsGateway instance running inside its own thread and have that be consumed by a clsLoader instance which is also running inside its own thread.
View 7 Repliesthe code below doesn't works...
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(I don't believe the reason for this is relevant, but just in case: I'll be raising events from code within a form's WndProc sub. If the code handling the event blocks with something on a form [such as a msgbox], then all sorts of trouble occurs with disconnected contexts and what not. I've confirmed that raising events on new threads fixing the problem.)[code]...
View 2 RepliesI am trying to use a separate thread to handle specific events in VB.Net. The idea being that I do not want the main application to be held up if a particular event handler takes awhile to finish. How do I get my main thread loop to suspend the thread while allowing it to handle events when they occur?When I create a Windows Forms application, there is a UI thread that handles the UI events. I do not imagine that this thread is continuously polling some variable to see if someone has pressed a button. I imagine the thread is suspended until the OS tells it there is something to do. I was trying to figure out how to ensure that my event handlers were not being executed by the UI thread. From what I have read, I can do this by raising the events from a different thread. But what does that thread do while it is waiting for other events, just exit?
I wanted to know how to create a thread that works like the UI thread, only it processes the events I want it to process. I am not sure how events work in .Net. I understand that event handlers are run on the thread that raises the event. I believe that .Net allocates threads from some thread pool to process events such as timer events. I am not clear on how it works, though, and what those threads are doing when they are not handling events.
Thread Completed Event Error
View 8 Replieshow can I raise an event after a thread has just ended?
View 2 RepliesIn 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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