instead of using if control.invoke required in a procedure can I just call the procedure with begininvoke?I have, possibly, the following:
Private Sub UpDateTimer_Elapsed(sender As Object, e As System.Timers.ElapsedEventArgs) Handles UpDateTimer.Elapsed
UpdateTime()
If MicActive Then
PTTCancelTime += 1
[code]....
where is the best place to learn InvokeRequired and BeginInvoke.
View 4 RepliesI 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 RepliesThis code works fine in VB 2008 attempting to redo the program in vb2010:
in the GuiForm:
the following is declared in formgui:
Private Delegate Sub UpDateGSLDelegate(ByVal rpn As Integer)
Also the following sub is also in formgui:
Public Sub updateGSLDisplay(ByVal rpn As Integer)[code]....
"UpdateGSL", in turn, will be called from any subs running in another module in a separate thread.The purpose is to update one or more labels on formgui based on the "rpn" variable.now the program will just hang at " Invoke(New UpDateGSLDelegate(AddressOf UpDateTheGSL), rpn)" in the "updateGSLDisplay" sub. no error messages, just stops.also I'm now using the " Dim t1 As Task = Task.Factory.StartNew(Sub()" way to starting a new thread in case that is revelant.what has changed from 2008 to 2010 to cause this. Just started trying out vb 2010? How can I fix this in 2010?
I looked at this page: http:[url]...aspx but it doesn't say anything or maybe it does and I just didn't pickup on it.
I am using the under given code in a module and I am getting an error ['Me' is not valid within a Module]
[code]...
Get the current number of usage days, unique usage days, etc in an evaluation license using CryptoLicensing Generator.
View 1 RepliesI had a question about some logic of the InvokeRequired with a ListView. I have the following
vb.net
Public Sub ListviewSub If ListView.InvokeRequired = True Then Dim t As New MethodInvoker(AddressOf ListViewSub) picCurrent.Invoke(t) Else RunSub() End IfEnd Sub
[Code]...
Me.datagridview.InvokeRequired property means in vb.netadil
View 3 RepliesI read Accessing Controls from Worker Threads and implemented this
Private Sub myExplorer_Close() Handles myExplorer.Close
If Me.InvokeRequired Then
Me.Invoke(New MethodInvoker(AddressOf myExplorer_Close))
[code].....
I have the following test code. It does nothing useful, but it's there for me to understand VB:
Imports System
Imports System.IO
Imports System.Diagnostics
[code].....
I am working with tasks, so I've got the following code to update a label on my form:
Private Delegate Sub UpdateLabelDelegate(ByVal s As String)
Public Sub UpdateLabel(ByVal s As String)
If Me.InvokeRequired Then
Me.BeginInvoke(New UpdateLabelDelegate(AddressOf UpdateLabel), New Object() {s})
Return
This sub works fine:
Private Sub UpdateInfo(ByVal text As String, ByVal timeStamp As DateTime)
If Me.lstStatus.Dispatcher.Thread Is System.Threading.Thread.CurrentThread Then
' Do stuff with
[code].....
I am having a small 'head banging' experience working on one of our DLL products.The problem I am having is that this application is an outlook addin, and as such, does not own its own Message Pump. No problems there, I have a UI class, which starts a thread, and calls Application.Run(new fControlForm)
I use the Application.Run passing a form, rather than an ApplicationContext purely because I want this form to be in charge of displaying other forms: ie, I can use BeginInvoke to ensure that a second, and many more forms are created in the context of the thread that owns the Message Pump.
I however feel this to be quite hackish. I get a form displayed at startup (which I am sure I can hide if I needed to)My question: IS there any way to create some form of Invoke procedure in an applicationContext that uses the Message Pump thread? I have created a class which implements the ISynchronizeInvoke and can Invoke from a thread that it owns, however this is not the same as invoking from the Message Pump owner.
So from the comments section where this persons code was translated to VB.NET on [URL]it shows a little code to aid in calling cross thread UI stuff.
<System.Runtime.CompilerServices.Extension()> _
Public Function SafeInvoke(Of T As ISynchronizeInvoke, TResult)(ByRef isi As T, ByRef [call] As Func(Of T, TResult)) As TResult
[Code]....
Error 1 Data type(s) of the type parameter(s) in extension method 'Public Function SafeInvoke(Of TResult)(ByRef call As System.Func(Of frmLogin, TResult)) As TResult' defined in 'GvE.Globals' cannot be inferred from these arguments. Specifying the data type(s) explicitly might correct this error. C:GvEGvEfrmLogin.vb 37 9 GvE
I'm calling that code from inside a method defined in a form but that method is being called from another thread.
Just trying to avoid delegates and this is what the code above is supposed to do, but just can't get it to work.
I simply want to find documentation about invoke and begininvoke. A member of delegates. simply searching on it on bing and stuff don't show anything. It shows control.invoke, etc.In the delegate msdn entry there is no invoke member. At least not when I look for system.action or system.func.Where can I found begininvoke documentation? what will happen if I put nothing as callback function for example? Intuitively the program simply don't call any call back function but hei, I want to makes ure of it.
View 3 RepliesI 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 RepliesI 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 RepliesDisclaimer: I know that Thread.Abort is evil. I'm using it as a last resort since some I/O functions (e.g., File.Exists when used on a non-existing network share) block for a large amout of time and do not allow you to specify a timeout.
Question: Is it possible to Abort (as in Thread.Abort) a worker thread started using Delegate.BeginInvoke or do I have to do the Thread handling myself?
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 Repliesi am using wpf,vb,vs2008,.net framework3.5, in my application i am trying to show one progress dialog during the calculation done in backend.so i am running progress dialog and then in a new thread i am executing the calculation operation using dispatcher.begininvoke(priority normal). in this dispatcher operation i want to update the progress dialog .if i am trying to do somethimg then that update after the completion of dispatcher operation only .i want to show the message in mean time.
View 1 Repliesi am using wpf,vb,vs2008,.net framework3.5, in my application i am trying to show one progress dialog during the calculation done in backend.so i am running progress dialog and then in a new thread i am executing the calculation operation using dispatcher.begininvoke (priority normal). in this dispatcher operation i want to update the progress dialog .if i am trying to do somethimg then that update after the completion of dispatcher operation only .i want to show the message in mean time.
View 1 Repliesi 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]...
I've created a Delegate that I intend to call Async.
[Code]...
I am trying to call a method that started on a background thread on the UI thread calling BeginInvoke and passing in a delegate as follows:
Dispatcher.BeginInvoke(Function() UpdateApplicationDataUI())
to call this method:
Private Sub UpdateApplicationDataUI()
...
End Sub
However, I get an error in the call to BeginInvoke (the UpdateApplicationDataUI portion of the delegate is stating "Expression does not produce a value").
Me.Dispatcher.BeginInvoke(Function() New Action(AddressOf UpdateApplicationDataUI))
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 RepliesHow do I get the cpu usage percentage to display in the label on a form?
View 4 RepliesIn this discussion let us discuss every usage of interfaces in .NET. Any real time examples and difficulties in using interfaces can also be discussed here.
View 6 RepliesHow would i moniter how long a user uses my program and when it reaches a hour it will close the program, but then the user will have to wait 24 hours before they can gain accesss to the form again perhaps open a msgbox that shows how long is left till it can be used I like.. [code]...
View 2 Repliesim making a task manager and want to get cpu usage of a process this is how my code looks now
For Each proc As System.Diagnostics.Process In pList
Dim lstStuff As ListViewItem = New ListViewItem()
lstStuff.Text = proc.Id.ToString
[code]....
everything works but the cpu part it returns values over 100%?
im using visual basic 2010 express and im wanting to know how i can display the CPU usage (over all CPU usage like you would find on the task manager), the RAM usage, the temperature, and the frames per second all in separate list boxes.I have searched around on the internet for a long time looking for the code's to do this, none seem to be compatible with the 2010 express version.
View 12 Replies