Invoke Or BeginInvoke Cannot Be Called On A Control
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.
View 1 Replies
ADVERTISEMENT
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?
View 9 Replies
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]...
View 4 Replies
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?
View 1 Replies
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]....
View 1 Replies
Jun 27, 2011
I have a (legacy) form where I had to add the InvokeRequired/BeginInvoke(Delegate) to avoid the "Control control name accessed from a thread other than the thread it was created on." exception.This seems to work fine but there are some scenarios where the BeginInvoke is not calling the Delegate (which I can tell from the output log). [code]
View 1 Replies
Jun 9, 2011
I am referring to this document on MSDN. I understand what ".BeginInvoke" does, however looking at the example code on the document.[code]The delegate myDelegate (and the DelegateMethod) accepts a control and a string, but, at the .BeginInvoke, a Label control is passed and an array.[code]Shouldn't a string be passed instead of the array? Am I missing something?
View 2 Replies
Apr 11, 2012
Can you look at my coding and let me know what I'm missing or doing wrong?I have a SSRS report that is called from a ReportViewer control and the ProcessingMode for this control is Remote. The report also has 1 parameter in it's DataSet.In the code I placed a MsgBox to make sure the code is finding the parameter and returning the parameter name. I am trying to stick the value of 10 into the parameter for playerID 10. Data for this player does exist.
I believe I need to add some more code to make this work but I'm not sure what else to add.
When the code executes the report is displayed but no data is shown in the report.
[Code]...
View 1 Replies
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.
View 1 Replies
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]...
View 2 Replies
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.
View 2 Replies
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?
View 1 Replies
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]....
View 1 Replies
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?
View 3 Replies
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]....
View 1 Replies
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?
View 5 Replies
Mar 3, 2010
I have three buttons on my main form, say Form1. Clicking any of the buttons brings up Form2 modally for input, it's a number pad. Now, depending on which button was clicked to get there, after the user enters his numbers, I need to change a specific label on Form1. In other words, btn1 clicked puts user input into lbl1 and so on... I could probably do this with a variable but wondering if there is a more elegant way.
View 3 Replies
Apr 10, 2009
What is Platform Invoke Service (P/Invoke)?
View 1 Replies
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]...
View 8 Replies
Apr 14, 2009
I have three buttons that all share the same context menu. How can I determine which control called the context menu to appear?
View 4 Replies
Feb 15, 2010
I've created my own textbox control which has a property called 'StatusBerText'. The idea is when the control has focus an event is raised and the text is shown in the status bar.
Below is my code which works, it starts with me.controls and looks for my textbox to add the handler. If it comes across a container it then starts again looping through all the controls in the container.
Private Sub NewCompany_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
SetControls(Me.Controls)
End Sub
Private Sub SetControls(ByVal obj As Object)
[Code]...
As I said this all works, however, I would ideally like to put the 'SetControls' in a class so I just call it in each form rather than having to paste the entire code in all the time. To do this I will need to pass the address of the StatusBarChanged function through, is this possible?
View 4 Replies
Jul 20, 2009
If I set a .ascx control's visible attribute to true, what event is called? What method can I create in that control's codebehind to act on this event?
View 1 Replies
Jun 25, 2009
In C# Windows Forms, a user control's InitializeComponent is called from the form's/control's constructor. When I create same scenario in VB.NET I don't get a constructor, and I can't locate a place where InitializeComponent is called.I need to call my code between InitializeComponent and when the control's Load event is raised, preferably still in the control's constructor. How do I do this in VB.NET?
View 2 Replies
Feb 9, 2011
i was wondering if it possible to have a condition where lets say you have a column in the datatable called amount and a textbox acting as the filter called say maxamount to set it so the rowfilter when filtering the table will sum the number in the amount column until the number in maxamount is met, then stop and only return the rows where the total sum of the amount column is equal or less than the maxamount value, so i guess if the next row takes us over the maxamount it discards this row and returns the rows previous to it. is this possible using datagridview rowfilter or should i be loooking elsewhere to achieve this?
View 4 Replies
Jun 5, 2011
I have an sql table called Stock with two fields called StockID and StockCode. I want the user to select the stockcode from a combo which in turn populates the stockid for that item into a lable on my form. I have already populated the stockcode into the combo but dont know how to compelte the rest.
Imports System.Data.SqlClient
Public Class cbo2
Private Sub cbo2_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
[CODE]...
View 4 Replies
Aug 11, 2009
I have a form called FrmPracDetails which is built up with a List view called LvwColProc. Therefore when you click a field on the LvwColProc it takes you to another form called FrmColProcessing, here you can make changes to certain fields which are also present on FrmPracDetails. What I want to do is when you make changes on FrmColProcesing and Click the Save Button (which calls the Save function)the changes appear instantly on FrmPracDetails. Please note, FrmColProcessing will always be open next to FrmPracDetails. I have tried to put this code in the Save function present in FrmCol Processing as shown below, but it doesnt Refresh FrmPracDetails form. [code]
View 1 Replies
May 26, 2010
I found that if you press F5 or refress from browser window, the last event fires again
example, I have clicked on a button, the button event is carried out normally, but if I refresh the page by pressing F5 key the same event is fired again.
View 1 Replies
Apr 2, 2012
I have the following line of code in my program:
JCL_History.Enqueue(JCL_History(I))
This JCL_History object is basically a Generic.List encapsulated in a wrapper and has the following method:
Public Sub Enqueue(ByRef value As String)
If Members.Contains(value) Then
Me.RemoveAt(Members.IndexOf(value))
[Code].....
In my testing I have 2 items in this JCL_History list. When I call that first line of code I posted (the one that invokes Enqueue) with I = 1 I expect the first item to be shuffled to the bottom and the second item to be shuffled to the top.
After the thread returns from Enqueue I notice that this is exactly what happens to my list, HOWEVER if I hit the "step_in" button after the execution of Enqueue I go into the Default Property's set method where Index = 1 and value = and it screws everything up, because the item that got shuffled to the end (index 1) gets overwritten by the item value shuffled to the top.
So basically the set method on the default property is getting called at what I think to be a completely ridiculous time. What gives? By the way I'm running VS2005 on XP.
View 1 Replies
Jan 7, 2010
In a ASP.NET app from a procedure IN a VB code file a dynamic control is called. The first problem may solve the second. In the following line of code I am getting an "end of statement expected" error at the following line.
[Code]....
View 2 Replies
Jul 24, 2011
I am sorry to keep bothering you about this damn DataGridView control ... As you might have noticed I am having a hard time with the DataGridView control ... My latest problem has to do with updating the data base file (Access) through a DataGridView control .
Up to now I have managed to successfully edit an entry in the DataGridView control and moreover to successfully update the data base file itself .
The above form and its code work fine . The problem starts when I am trying to run the code of the Update button from another form .
You see , I have another form , through which I change the contents of some of the cells in the DataGridView control (back in Form1) . What I want next is to simply update the data base file itself , just like I was doing with the button in the first form , after I manually changed the cell in the DataGridView control .Thus , on the second form I have a button with this code :
Form1.Button1_Click(Nothing, Nothing) (of course the Click event is declared public)I have also tried :
Form1.Button1.PerformClick()
but still nothing ...Although Form2 successfully changes the cells back in Form1 , the data base file itself does not get updated ...If I manually press the Update button in Form1 I once again successfully update the data base file , but I want to do the whole thing by calling the Update button from Form2 .
View 5 Replies
