How do I dynamically call a function with delegates by passing a string to a background thread in VB.NET?
Currently my code is this
Public Sub invertImageBK(ByVal image As Bitmap)
Dim snxl As System.ComponentModel.BackgroundWorker = createBW()
snxl.RunWorkerAsync(New ImageProperties(image.Clone, "invertImage", Nothing))
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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))
put method in main thread from background without declaring delegates
View 2 RepliesA non-UI thread in my prog needs to obtain data from a UI listview control. To prevent cross-thread errors I use the following, but it freezes the prog (probably because the "Else" part is never called).What am I doing wrong?
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I am trying to call the method with the following declaration[code]...
The structs should both be twodimensional arrays with indexes of 4,4 and 5,4 respectively. The second one is an out parameter.
I wrote vba function in excel and I want to call this function in vb.net with parameter passing.
View 2 RepliesI have in vb a selector
Dim ver =101
Select Case ver
Case 101
upd101()
Case 102
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How can I make this select better by calling function in more dynamically in this form: with the prefix "upd" followed by a ver integer.
What is the Invoke syntax to marshall data from a background thread receive callback method to a function on the UI Thread?(Form1).
Public Class Form1
MyDelegate = New DisplayData(AddressOf DisplayData)
Private Sub Form1_Load()
MyDelegate = New DisplayData(AddressOf DisplayData)
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I need to pass an uint8 array from C++ DLL to VB6 application but I receive always following error: "subscript out of range" if I try to work with the array 'pabyData' in my VB6 procedure. The C procedure is: typedef void (__stdcall *FUNCPTR2SendData) (const uint8_t* pabyData, uint16_t wDataLength); void SendData(const uint8_t* pabyData, uint16_twDataLength) { FUNCPTR2SendData vbFunc; vbFunc = (FUNCPTR2SendData) ptCBFPointers->p2NewDirectDataSMSEvnt; // ptCBFPointers are call back pointers, where is saved the call back address of VB6 functions vbFunc(pabyData, wDataLength); } The VB6 procedure is: Public Sub SendData(ByRef pabyData() As Byte, ByVal wDataLength As Integer
View 2 RepliesI've created a dialog which I'd like to popup from any function or sub in any class or form that I have in a project. It would nice to have it work exactly like a messagebox except it's got a progressbar and a cancel button on it. It's job is to display the progress of other functions so it should just stay open until I close it or the user selects cancel.Now I've found many of the basic examples on the net and have got the dialog working exactly as they have shown it. The trouble is that the examples are using a counter or thread.sleep which simply adds +1 in the DoWork sub. In other words, it validates that a worker thread can update a progressbar but it's a closed loop that only exists in the dialog's class.The examples don't show how to call an unkown function in another class dynamically, they're simply a hard coded 1+1 in DoWork. To me it's not a real world example because it doesn't show how to plug into the dialog or get a communication stream from other classes and functions that are running and wanting to increment the progressbar.[code]
View 3 RepliesI'm calling a class function in a thread function. I'm using invoke method to send a value to a progressbar in the main form and I don't know how to do that in an other class function called by the thread function.
My goal is to send a value to a progressbar to the main form from the thread function and even from the function called by the thread function.
My code:
' Invoke sub
Public Sub UpdPgEvent(ByVal value As Integer)
Me.pgFindEvent.Value = value
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I have a function in a module that returns a datatable.I need to call that function asynchronously and get the results in the Main thread (Main Form) in vb.net.
View 2 RepliesSome programs implement command parameters, Like my favourite computer game - Crysis - has them and windows media player has them.But how could i implement them in VB.NET..I want to have a component of my program built as a seperate exe - so it can be an Optional component.But of course the seperate exe, on load, needs data passing to it.So i need something like Process.start("Componentname.exe", "/StartDL <Suchandsuchastring>)/StartDL will need to call a function, and the string that it uses will be given to the function to initiate a download?
View 9 RepliesI 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 have a form with a DataGridView control. When i load the form, i fill the control with several records. Now sometimes it can be 1 to 30, but sometimes it could be 10000+ records.Now, what i'm trying to do is to grid.AutoResizeColumns
As you can imagine, when i have 30 records it goes like the Flash, but the more records, the longer it takes; obviously..So, for now i have a ugly label saying "WAIT PLEASE" and waitcursor=true; Yes, horrible, i know...
So i tried to do the following:I created a form called frmWAIT, and have a timer in it that shows 4 pictures at 250ms intervals, to make some kind of animation.In my Primary form, i added a BackgroundWorker, and in the DoWork Event, i tried to grid.AutoResizeColumns and it won't do it.
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I'm trying to establish a connection to my SqlDatabase while getting the connection string from a function. This will eventually lead to dealing with the appconfig file, but for now I'm just getting the basics established.
Imports System.Data.SqlClient
Public Class Form1
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
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I know strings are immutable, so the minute you change a string reference's value .NET makes a brand new string on the heap. But what if you don't change the value of a string reference; rather, you simply pass it into a function ByVal -- does this operation copy the string value on the heap as well? My inclination is "no," but I'd like to confirm.
For example:
Public Function IsStringHello(ByVal test As String) As Boolean
Return (String.Compare(test, "Hello") = 0)
End Function
Calling program:
Dim myWord as String = "Blah"
Dim matchesHello as Boolean = IsStringHello(myWord)
I know passing myWord by value makes a copy of the reference to "Blah", but since I have not tried to change the string itself, would it make another copy of the string on the heap?
I created a STRING SEARCH function in C/C++ - and I'm trying to use it in a multi-threaded situation in VB. I started this problem in a thread in the C/C++ section of the forum - here [URL] my last post shows me getting this error trying to call the function. Ran the code - got to that point - and in the immediate window I did
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What I have done is named a bunch of picture boxes "Q," "W," "E," etc. (the whole alphabet) and named picture that correspond to these picture boxes ("Q.png," "W.png," and so on) and added them to my resources.
For example, the following code would give the picture box named "Q" it's corresponding image "Q.png":
vb
Q.BackgroundImage = My.Resources.Q
Of course, it's kind of a pain in the backside to copy and paste this code and change all the Q's to W's and so on, so I was hoping to create a function to do the job for me:
vb
Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
'So that I can run the letter as a string through the function,
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Hopefully I've provided enough detail so that it is obvious what I'm trying to do.
Obviously, the code I tried above (the second block) doesn't work - it gives a syntax error. I need to change/write to make this function functional.
I was just wondering what is the meaning of placing the '$' character after a function call
E.g.: Dim time as string = Format$(Now, "Long Time")
And what is funny is that it is of no use (as far as I can see).
Can we pass parameters to a function using delegates
Private Sub UpdateLabel(byval text as string)
If Me.Label1.InvokeRequired Then
Me.Label1.Invoke(New MethodInvoker(AddressOf UpdateLabel))
Else
Label1.Text = text
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So I'm passing a masked telephone number in the form of (999)999-9999 to a Function that 'strips' the numbers out and puts them into a string that I then use in an Update SQL statement. So far I have the code below that of course doesn't do anything:
Function StripPhone(ByVal sPhone as String) as String
Dim i as Integer
Dim sStripped as String
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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;
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I want to create an ExpressionTree where a Func(of Vector, Vector, Vector, Vector, Double, Double, Vektor) should be called. So I use
Expression.Call(Forces(0).Function.Method, {Vec1, Vec2, Vec3, Vec4, Double1, Double2})(Vec1-4, Double1-2 are declared as ParameterExpression and Forces(0).Function as Func(of Vector, Vector, Vector, Vector, Double, Double, Vector). But I get an AgrumentException, because Forces(0).Function.Method has seven Arguments. (System.Runtime.CompilerServices.Closure as seventh argument at Index 0).
I've passed object sucessfully to threads in the past but I'm stumped on this one:-
HTML
Public Class TileDownload
Structure RequiredTileDetails
Public MapID As String
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VBasic / VS2008 / .NET 3.5 / Meas Studio 8.5 I've searched and seen a number of convoluted ways of doing this but.... What I am trying to do should be simple and in my mind (and from previous experience) it should work. It doesn't At least not after 10 hours of tweaking, editing, researching....
Straightforward project, 3 components - MainModule, MainForm, CNCNoForm. I declare public var NCPgmNo in the module. I open the CNCNoForm from the MainForm. This form has 2 controls - Numeric Up/Down Box & Close Button. I enter a number in the Num box (read only property is set to false), then assign the value to the var. NCPgmNo in the value-changed event sub. I close the form, returning to the MainForm. The variable does not pass even though it is public and declared in the module. I tried removing it from the Numupdown event and assigned the var before 'me.close'. Still N/G.
If I put a breakpoint right after the line that assigns the var, it is correct. It just does not pass to the MainForm. I started with a textbox, then changed to a Meas. Studio Numeric control, finally Numeric up/down. Same results with all 3. I though the CNCNoForm was broken so I removed it from the project and rebuilt it with a new name (yes name references in the MainForm and MainModule are correct). One other thing. If I call the CNCNoForm repeatedly, it reads the previous value. I am ready to give up computers and take up farming or hiking.
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I have a program that if user presses a key(while the program isn't focused),it presses some keys(some kind of macro to aid gamers).The program works,but I cannot stop the background thread.I use "t.abort()" (t is the name of background thread) but it keeps working(even when I close all forms) and at TaskManager "keypresser.exe" is still there.[code]
View 5 RepliesI have on timer thread that needs to pass every time a different data to another running thread to make the calculations.
View 5 Repliesi am adding the button on runtime. how can i assign its background image? (no hard code for path) vb.net 2003
View 6 RepliesIn a threadpooling situation is it possible for a modal form to be opened and data from that form to be passed back to the thread that opened it ?
View 1 Replies