Event From An Other Thread?
Sep 10, 2009
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
[Code]....
View 3 Replies
ADVERTISEMENT
Sep 24, 2009
could 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 Replies
May 6, 2012
I'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 Replies
Aug 24, 2010
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)
[Code]...
View 1 Replies
Jul 12, 2009
At 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)
[code]....
View 3 Replies
Aug 8, 2009
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 Replies
Aug 18, 2009
the code below doesn't works...
[Code]...
View 1 Replies
Feb 13, 2012
(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 Replies
Jul 1, 2011
I 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.
View 2 Replies
Jul 10, 2011
Thread Completed Event Error
View 8 Replies
Apr 20, 2009
how can I raise an event after a thread has just ended?
View 2 Replies
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".
View 3 Replies
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.
View 4 Replies
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.)
View 7 Replies
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
View 3 Replies
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]...
View 2 Replies
Sep 2, 2010
My understanding is that thread.join will suspend the execution of code on the calling thread until the spawned thread finishes or is aborted...
With that in mind, I tried this:
For i = 1 to 50
threads = New Thread(AddressOf test)
threads.IsBackground = True
threads.SetApartmentState(ApartmentState.STA)
[CODE]...
However, the rest of the code runs when the loop finishes, not waiting for all the spawned threads to finish. Since the rest of the code needs the threads to finish (otherwise the rest will error).
View 4 Replies
Jan 18, 2012
I have a processing in a do loop. In variois points within the loop I check if the variable "bCancel" is true. If so then I exit the loop and terminate the treatment. When I click the "Cancel" button, I set the variable "bCancel" to true. Basic stuff, but I would like to know how the click event is ran while my current thread is busy looping? I've found a reference to a "Gui thread" on the net but Its not very clear is this thread in inside windows or the .NET frameworks?
View 7 Replies
Apr 1, 2011
I actually have gotten the events firing like I expect except for trying to close the dialog window.
Background: I have a wrapper around my "Jabber Client" that sets the delegates for the client wrapper and basically generates a messageProcess event. This event is wired in the main program Class[code]...
View 4 Replies
Aug 22, 2011
I'm developing some code to detect new files in a directory and signal it in a new thread through the Created event of FileSystemWatcher. While testing this I noticed that after I removed the eventhandler from the event the thread that was being used was not closed. Why is that? Am I doing something wrong when I'm removing the eventhandler? [code]So first I start off clicking Button 2 to start the event handler. I copy a xml file to the Temp folder and the event will trigger and set the name of the thread. After that I will click Button 1 to remove the event handler. If I then pause the execution the Thread "UpdateSomething" will still be there.
View 1 Replies
Jul 3, 2011
I want to raise an event from a non-UI thread where the event will be handled by the UI. Currently, I have to use .Invoke in my methods (which updates UI) called from the event.
How can I raise the event, similar to Background Worker's progress update event, where I don't have to specifically do an .Invoke for UI updates?
Do I wrap the event with a delegate or something? Sample code will be fine though, if the explanation was tedious.
View 9 Replies
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.
View 4 Replies
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]...
View 8 Replies
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]....
View 3 Replies
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
View 1 Replies
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]....
View 1 Replies
Nov 10, 2011
I have a control thread that starts up a secondary thread and when the secondary thread finishes, the control thread restarts the secondary thread. On this secondary thread, I use a stopwatch to record a thread.sleep event. Is there any reason, under any circumstance, why the stopwatch elapsed millisecond value (499) would be 1ms less than the sleep time (500 ms)This doesn't happen all the time or even a lot, I'm just curious if there is any physical reason for this to happen.
View 1 Replies
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.
View 15 Replies
Mar 29, 2012
I'm trying to follow the technique discribed by jmcilhinney in this HTML [URL]..I have all the drawing code in the .Paint event. Reading the above mentioned thread I would need .Invalidate(all or parts of the picturebox) AND .Update() in order to repaint (all or parts of) my PictureBox, however in my case it works without .Update. Am I doing something wrong?
View 5 Replies
Jun 17, 2012
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 Replies
