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.
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]....
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.
where is the best place to learn InvokeRequired and BeginInvoke.
View 4 RepliesI 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 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 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 RepliesI want to make an numerical integration method with takes in an analytic function and integrate it over a specific interval. For the numerical integration procedure I want to use some procedures in nr.com. The problem is that these are programmed in C++ and they uses functors to pass a function to the integration method. How can I do this in VB 2010?
I want to initialize the function (i.e. set a=1,b=0 for function y(x)=a*x+b) and then pass the function to the integration method. Then when the integration method call the function it only calls the function with one parameter (i.e. x since a,b is already set)
What is the best way to do this in VB2010?I want to make a general integration method where I can pass any single valued function and integration limits.
I have just started using VB, and from what I have found so far it seems like the tools you have is
- to us a delegate for the function
- to use a lambda expression for the function
- send a pointer/adressOf
- to create a function class/structure and submit this to the function
As for now I am most inclined to create a function-class. But I am not really sure how.F.ex. I make different classes for each "uniqe function" I want to integrate, but how can I pass them to the integration function when I need to specify the argument type in the integration-function-call?This seems like a basic problem which applies to many Math operations, so I think it would be very useful to clarify this.
I'm trying to undersatnd the syntax of calling a funciton and it seem confusing when I'm using a web service in ASP.net. Maybe this question should be in an ASP forum, but it is a VB question. This simple web service allows you to type in your name and it response with an alert box with you name.
My question is, How can you call a function with 2 arguments when the function is only defined for one. I understand that the second argument is actually a method that handling the respons, but how can you interchange function arguments for methods and how do you know that there are methods for
Here's my call:
<script type="text/javascript">
function HelloWorld()
{
var yourName = $get('txtYourName').value;
[CODE]...
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]....
I am trying to convert a DLL function call which has the Callback function routine called within the DLL function call.The DLL function call signature is like this:
typedef void *HANDLE;
typedef HANDLE HACQDESC;
DECLARE_HANDLE (HWND);
[code]....
how to convert this DLL call to VB.NET and also how to create the callback function and send it as parameter to this function
call.
i wanted to ask how to make picturebox1 ,to which functions are already assigned, perform the same function as picturebox2 ,to which no functions are assigned.For example:I have already made picturebox1 and have assigned it alot of function like when play button is pressed then picturebox1.visible = true and when we press pause button picturebox1.visible = false. So now i decided to make a theme and have to remove the picturebox1 and want to allow the picturebox2 to havefunction of picturebox1.But when i disable the theme the function of picturebox1 should go back to picturebox1.
View 6 RepliesI need to execute a stored function in oracle or sql through vb.net. I created a command object. Depending on the database type(oracle or SQL) i am preparing the Command text as Select functionName(?,?,?,?,?,?,?,?) from dual; (For Oracle) Adding the parameter values of the function. Now performing the ExecuteScalar which is not working saying invalid parameter. This works with ODBC connection string. But ODBC doesn't with 64bit. My Requirement: Code should execute a user defined stored procedure by taking the values at runtime.
View 1 RepliesI'm currently working with a client's VB.Net code, which was developed for them by a small development shop a few years ago and which they purchased and have been maintaining and uprgrading since. This client's primary developer is out on indefinite (likely permanent) medical leave and I'm now filling in until they bring in a full timer (as I'm a contractor here). My current task is to add some functionality to a the VB.Net code they purchased. I'm finding practices and techniques in the code that absolutely baffle me and can't make the code do what I want. I'm starting to wonder if it's me and was hoping to get some thoughts on the code I've encountered.
For example: Setting a variable to accept the result of a function by calling the function with many parameters, clearing the parameters in the function, setting them to some value, calling another function with those new values, then never using the values returned by the functions. I'll add a code snippet in the first comment since this is already getting long.
Hi. what is the difference of sleep function and pause function (using timer) between a loop.
View 12 RepliesWhat does this error mean in VB6? Function or interface marked as restricted, or the function uses an Automation type not supported in Visual Basic.
I keep getting it when i call a particular method of a dll that comes with windows xp and beyond (in system32 called upnp.dll)
How can I call a function from inside another function and suspend the calling function until the called function is finished? I hope I can get some replies because I don't know how to ask the question and make sense:).
Anyway what I am trying to do in steps:
1. The user clicks button1 which triggers the click event.
2. From the click event I call a function
3. I then pop-up a form, that has instructions for the user to read.
4. After the user has read the form he will click the "Done" button and return to the calling function.
The problem is the the calling function continues to execute. I want to stop execution of the calling function until the users clicks the "Done" button on the instruction pop=up. I know I can use a msgbox but the instructions can be lengthly and does not look good in a msgbox.
I have tried the Call method with return in the "Done" button click but I can make that work. I also tried a goto statement but I can get that to work either. In the call statement I said call frmInstruction.show() and it got there but as I said the calling function continued to execute.
ive two custom controls, which are used to draw and edit etc...(like paint but customized....) i want to save their images with a single click....So im using the Getimageofcontrol function to do it....its code is below:::
Public Function GetImageOfControl(ByVal c As Control) As Image
Dim rc As New Rectangle(c.PointToScreen(c.Location), c.Size)
Dim i As Image = New Bitmap(rc.Width, rc.Height)[code].....
and the code to call this function for saving the images is simply.. ...
GetImageOfControl(pboxd).Save("c:78.jpg")
GetImageOfControl2(pboxf).Save("c:lp.jpg")
but the problem is that both the images have the same content....
I have a function where I am performing a lot number of database operations inside a Sub. The operation when called directly like:ExecProcess()
takes about 11 seconds to run.However, if I create a Delegate, and call the sub using BeginInvoke(), the very same process takes over 40 seconds to execute.Here's the threaded code:
Protected del As ProcessDelegate
Protected Delegate Sub ProcessDelegate()
del = New ProcessDelegate(AddressOf SELocal.ExecJob)
Dim cb As New AsyncCallback(AddressOf Me.ExecJobComplete)
del.BeginInvoke(cb, del)
Anyone know what may cause a function to take longer inside a new thread, rather than calling directly?
I have 1 string : abc @#ABC.xyz123ZYX
Now I need to encode the string:
The encoding alphabetic characters,
CODE:
With this string, after encoding, the result is: zyx @#ZYX.cba123ABC
About Function Encrypt and Function Decrypt?