VS 2008 FilesystemWatcher - Treeview.invoke - Error "invoke Or Begininvoke Cannot Be Called On A Control Until The Window Handle Has Been Created"
Aug 27, 2010
I have a filesystewatcher object. On it`s event it runs a procedure which fills a treeview with a data. I had problems with treeview methods, but when I run them using invoke method everything is ok. But I still have one problem. When I load the form for the first time, everything works fine. But, when I then close the form (me.dispose, me.close), and load it once again, when Filesystemwathcer start the procedure i have an exception "invoke or begininvoke cannot be called on a control until the window handle has been created" trying to run a treeview.invoke method?
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Mar 5, 2009
i AM TRYING TO USE A THREAD TO UPDATE SOME CONTROL during runtime using invoke and i get this message.here is my scenario:im trying to build a performance monitor tooli have a mainform that is MDI parent and i create mdi child using
[Code]...
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Mar 26, 2012
I have a thread that loads a control from the database during a long running operation. If I close my window before that thread finishes, it throws a Invoke or BeginInvoke cannot be called on a control until the window handle has been created., when doing the Invoke.I've modified the code to look like the following:[code]However it still hits the Invoke line and throws the error. When debugging stops on the exception, IsDisposed is true, .Created is false, and .IsHandleCreated is false.how do i prevent it from running the invoke line in this situation?
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Nov 16, 2010
I have an annoying bug which is very difficult to replicate. When I start my application, from time to time, I get this error message "Invoke or BeginInvoke cannot be called on a control until the window handle has been created". This makes the user think the application is unstable... I have no idea what could cause this problem. The application uses a splash screen. It's built in Visual Basic using VS 2010 and .net framework 4.
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Jan 31, 2012
I show a waiting form (saying "Please wait...") on a different thread when there is long-running code in some forms (for example, during data loading). I show the form like this:
m_PopProcessingThread = New Thread(New ThreadStart(
Sub()
m_PopProcessingForm = New WaitingForm(m_Message)
Application.Run(m_PopProcessingForm)
End Sub))
[Code]...
The stack trace points to the part of code where I hide the form. How could the handle not have been created, when just before the Invoke call, I loop until said handle is created?
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Mar 16, 2010
I've got the following code:
[code]...
The problem is that, when I call the "SetStatusBarText" sub from another thread, InvokeRequired is True (as it should be), but then my threads stall on the Me.Invoke statement - pausing execution shows them all just sitting there, not actually invoking anything.
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May 13, 2009
i'am trying to open the autocomplete-window from a textbox without typing chars into the box.Normaly the autocompletewindow opens only if you type in a character, but this means, you have to know the first char.Is there any way to open the autocompletewindow without the first character? For example at the mouseover event of the textbox?
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Apr 10, 2009
What is Platform Invoke Service (P/Invoke)?
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Oct 13, 2010
We have a UI with a progressbar. I know how to invoke, safely, the control from which it was not created from a thread. there are threads being processed in a threadpool, all of which calls an "agent" (which is a notifier to raise an event back to the UI to then increase the progressbar). an "agent" is set as a property in a State object, which is then passed into a method which will be executed on the ThreadPool. so, I invoke on the UI the method to update the progressbar, but the bar does not seem to update at all (screen frozen) and it takes a very very long time for it to execute. without threading, no problem.
[Code]...
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Oct 7, 2010
I have been using a pretty slick generic invoke method for UI updating from background threads. I forget where I copied it from (converted it to VB.NET from C#), but here it is: Public Sub InvokeControl(Of T As Control)(ByVal Control As t, ByVal Action As Action(Of t))
[Code]....
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Aug 20, 2009
1. On the main form a scanner class is instantiated that (in the scanner's constructor) sets the scanner settings (baud rate, parity, etc) and opens the scanner for use
2. A barcode is scanned (via a scanner connected to the device in a seral port) while on the main form
3. In the scanner class, the DataRecieved event gets the needed info from the scanned code.
4. Then that info is passed back to the main form to a method RunCommandCode (which takes the scanned info as an argument)
5. On the main form the RunCommandCode calls another method CommandCodeHandler, passing the scanned info again
6. In the CommandCodeHandler sub a method is called in a Utils class (SetSelectedTab), which interacts with the form itself (determines how many tabs exist on a tab control), which is the reason for the invoke in the first place
So, before I figured out I needed to use the Invoke method (and, more specifically, that the scanner was working in a different thread), I was getting an error in step 6 on the line that got the TabControl.TabPages.Count.
[code]...
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Oct 1, 2009
I'm working with the DevExpress XtraGrid control.I have a routine that goes thru and adds all the controls on the current form dynamically, and launches on a seperate thread the routine for a given control to initialize it to the value that will be displayed to the end-user. Some of the controls are displaying calculated values, and take some time to return their values, so that's why we are doing it on a seperate thread.
[Code]...
I'm using a similar snippet of code for any control properties that have to be updated, and all work fine. On the above code when the actual Invoke is called, it APPEARS that the thread just ends and never calls the delegate, and doesn't return to finish either.
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Oct 6, 2010
how to invoke methods, but how does one change a simple property?
For demonstration-sake, here's a very simple set of code that should help. Let's say I need to set the visible property from a child form, and thus, it needs to be invoked:
Friend Sub activateItem(ByVal myItem As PictureBox)
If myItem.InvokeRequired = True Then
????
[Code]....
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Nov 9, 2009
I have a relatively simple question regarding the best way to call the DataGridView.Rows.Add function when it is inherited into the current control. Which is the best way to make the call to the inherited control? Call it directly in the invoke or call it using recursive-like function? They both seem to produce the same result, a row gets added and the quantity is returned, but which is the most efficient?The delegate: Private Delegate Function ReturnDelegate() As Object
The two ways are:
A)
Private Overloads Function AddRow() As Integer
If InvokeRequired Then
Return CInt(Invoke(New ReturnDelegate(AddressOf AddRow)))
[code]....
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Nov 10, 2005
I'm currently invoking a function that takes ByRef parameters using Control.Invoke (which I notice specifies the Object parameter array to be ByVal) but the array of parameters I give it isn't updated by the function. Is this possible with VB.Net 2003 or must there be some error in my code?
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Aug 19, 2010
This is the code i have so far (no i didn't write it all by my self took help from net) but i am unable to understand why i am getting this error
Imports CookComputing.XmlRpc
Public Structure blogInfo
Public title As String
[code]....
error i get is "Invoke on Non-Existent or Non-public proxy method"
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Apr 2, 2010
My application produces this error System.Data.SqlClient.SqlException: Login failed for user..This started after I added a stored proc in my dbml file. It works fine in my local enviroment, but throws that error when deploy to staging sever. the user it displays is foreign to me?
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Oct 6, 2009
I have a Tcp Client which I created on an application form but now I would like to create a class for it.
My prob is that when I check for any incoming data, I used to start a new thread. When this new thread finds any incoming data, I call a sub which invokes the form and everything works smooth.
This is what I am talking about,[code...]
How would I be able to do the same from a class? Or I dont have to create a separate thread when using classes?
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Feb 20, 2010
how to use BeginInvoke and EndInvoke on a ListView to add items so that it doesn't lock up the UI as the items are being added in a loop? Is it something like:
Public Delegate Sub DoLoadList()
Private Sub LoadList()
For i As Integer = 1 To 1000
[Code].....
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Jun 23, 2011
I'm using the following code to close a form (Inherits System.Windows.Forms.Form) but it sometimes hangs up at the Invoke() ...
Private Delegate Sub closeFormDelegate()
Private Sub closeForm()
If myForm.InvokeRequired Then
[code].....
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Feb 7, 2011
It was pretty simple in VB6 to invoke the 'click' event of a command button (i.e.; btnNext_Click). I am having difficulty trying to do the same think in VS2008.
I am getting errors at line btnNext_Click(): Error1Argument not specified for parameter 'e' of 'Private Sub btnNext_Click(sender As Object, e As System.EventArgs)'.
Error2Argument not specified for parameter 'sender' of 'Private Sub btnNext_Click(sender As Object, e As System.EventArgs)'.
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May 27, 2010
i got a background worker that has the following code in the do work.... one of the things i want to do is to add rows if theres none available ...but i got an error saying i need to do a safe call thread...i already read about it but im stuck i put control.invoke, but that gives me an error too saying Error1Reference to a non-shared member requires an object reference.what can i do to add rows safely?
vb.net
Private Sub BackgroundWorker2_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker2.DoWork
If DataGridView2.Rows.Item(num).Cells.Item(0).Value = "" Then
Control.Invoke(DataGridView2.Rows.Add(1))
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Mar 1, 2012
In My project, i have Multiple Forms in which same Function name with return values. i like to convert the String name to Form Object and try to call the user defined function in the corresponding form from the Module I am using vb.net 2008 .
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Mar 15, 2010
I am trying to invoke the onclick function in an html page that displays content. I am using the httpwebreqest control and not a browser control. I have traced the function and tried to find the link it calls but looking at the code below I tried inserting the link into the browser with the main url but it does not work.
[Code]...
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May 13, 2011
Example:
Two files - TestClass.vb, myForm.vb
TestClass.vb looks as follows:
Imports System.Threading
Public Class TestClass
Private myClassThread As New Thread(AddressOf StartMyClassThread)
[code]....
The result:Application runs, no errors or exceptions.Displayed is the listbox and the Start button.I press the start button and a msgbox says "Not Invoked" as expected and upon clicking OK to that msgbox "Start Button Pressed" is added to the Output listbox control.Immediately following that the msgbox pops up again and says "Not Invoked". I was expecting "Invoked" as a separate thread is trying to use the Output listbox control.Of course this results in the Output.Items.Add being attempted which results in no visible result as the thread is not allowed to directly update the UI control.
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Oct 25, 2009
I'm running into a strange error and I can't move forward Consider the following code
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Mar 20, 2010
I am trying to find the handle of the child window for the Yes button in the User Account Control window so i can click it. This window has a structure with a few child windows with the same name.
Dim hwnd As IntPtr = FindWindow(Nothing, "User Account Control")
Dim hwnd2 As IntPtr = FindWindowEx(hwnd, 0, "DirectUIHWND", vbNullString)
Dim hwnd3 As IntPtr = FindWindowEx(hwnd2, 0, "CtrlNotifySink", vbNullString)
Dim hwnd4 As IntPtr = FindWindowEx(hwnd3, 0, "Button", "&Yes")
There are multiple CtrNotifySink with its own Button child window or other child windows. How do i search thru the different CtrNotifySink window to find the one that contain the Yes button so i can send a click to it? I do need to find it before i can send a click, right? because i try just sending it to the main window with sendmessage and nothing happen.I even try sending it directly to the handle found by spy++ of the yes button with bm click but nothing happen?
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Oct 12, 2009
how do i create dll application in vb.net? how do i call a dll application from an exe application?
using VB.NET, is there sample code where an exe application invokes a dll appliction?
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Mar 5, 2009
Is it possible to execute some sort of code to determine whether or not it's a good idea to call Invoke? I dunno what you would do once you'd found out you can't but it could be useful for detecting some dead locks (like the one I have a the moment).
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Nov 11, 2009
Public Class StateObject
Public workSocket As Socket = Nothing
Public Const BufferSize As Integer = 1024
Public buffer(BufferSize) As Byte
[CODE]....
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