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 RepliesI 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 am fairly new to VB .Net and have ran into an issue when working with multiple threads using BackgroundWorker.In the new thread that is created I need to access TextBox1.Text to know what the user's input was.For example:When the 'OK' button is clicked BackgroundWorker1.RunWorkerAsync starts a new Thread.
Private Sub OkButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles OkButton.Click
'We cannot start more then one calculation at a single time
OkButton.Enabled = False[code]....
I know how to use Delegates and Invoke to change the value of a Textbox, but I cannot figure out how to simply access the text from a Textbox.
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.
anyone know how to invoke the KeyPress event ? This code shows what I would like to do, but it simply calls the eventhandler and does not insert the text into the text box, so is not what I want/need.
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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.
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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.
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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.
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 Replieslet me explain in more detail so you don't get the wrong idea of what I'm trying to accomplish.If I have a button object, say Button1, on my form and I select it with my mouse, it brings up another form or dialog. If in the text field property of Button1 I enter &Button1, the B will have an underscore under it and if I hold down the Alt key and press b, it too will invoke the other form or dialog. I would like to also have the capability to do that with a datepicker field or textbox field.
Right now, I can set up several buttons with Alt-keystroke combos that work by default, but it seems like I have to write some form of keystroke intercept routine and test for the conditions I'm looking for and force the focus to the datepicker or textbox. Am I missing something? Is there a better way to do this? Or is there actually a way of setting up a label on a textbox or datepicker object.
Kind of like when you're using MS Access and building a report, the fields have a leader that you can type a label in. That's what I'm looking to do. So if the label part of the datepicker field says Date: if I press and hold the Alt key and press d, it will invoke the datepicker field (aka open the calendar for selection).
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?
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]....
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]....
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 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
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What is Platform Invoke Service (P/Invoke)?
View 1 RepliesWe 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.
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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?
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].....
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].....
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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View 1 RepliesI've made my first little custom control. It is a textbox, then next to it a picture. I've written the code already for the picture box. It basically opens up a new form with a listview on it that displays details from the database. But now, I still want the text box to have the basic properties of a normal textbox like text alignment, enabled, backcolor, etc. But not sure how to do this.
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I have a text file that has different controls for text boxes. This text file controls the BackColor, BorderStyle, Font-Bold, Font-Size, Height, Width, ReadOnly, and TextMode a sample is below:
*****Detail Header
txtDetailHeaderBackColor = Black
txtDetailHeaderBorderStyle = None
txtDetailHeaderFont-Bold = False
[Code]....
I have checked out the webpage manipulation on VBForums but it did not help me in this case because this textbox is not part of a form.Okay so basically i need to be able to add text to the textbox where you type in your bid on eBay and then send the enter key to submit the form that i can't see (so just the enter key)
View 5 RepliesI am looking for a nice menu control to add some styling to my application. I search the forums and codeplex and codeproject. I found one that is nice..[URL] but I need to be able to embed a textbox for some input.
View 2 RepliesIt 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)'.
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))
I have created a User Control (UC) where user type the information it needed and save it ti MS SQL Database and also have created a User Control dedicated for it's button, since my main form has split container and has two panels, one for UC which contain the button only and the other one for my Main UC where user enter the information.I created a Module that contain the function on adding the data type in UC Main to the database.
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on My UCButton named "Save" I just call the function AddUserInformation. But the problem is the variable where it bind to the ucUserControlMain textbox remains Blank, When i query the my database table, only the UserInforID and the DateAdded has been updated and the other column remains blank where the variable get it in the UCMain Textbox...
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 .
View 3 RepliesI 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.
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