Showing Forms From Another Thread?
Jun 20, 2009
my scenario is this: I have two forms and a module. Let's call one of the forms MainForm and the other SecondForm. My module is running on a seperate thread to MainForm. A sub routine is triggered in the module, and I want it to display SecondForm.
I understand that I cannot do this directly because SecondForm needs to be called from the UI thread, which is shared by MainForm. How would I go about doing this? I'm guessing that I would have to use a combination of invocation and calls to MainForm to activate SecondForm.
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May 7, 2010
Showing and Hiding Forms from a Console Application causes "Cross-thread operation not valid."
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Oct 18, 2011
I have a small problem that I am sure is due mostly to my inexperience with threading. I have used simple entirely self-contained threads before, but not to a great extent. I understand the basic laws that surround them, such as how a thread cannot access another thread's member directly, and must use delegates.
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Oct 31, 2010
My routine to check for updates is run as a separate process. Exiting the application is required to update, so a dialog asks the user, when an update is found, if they want to exit now. f they do, the code (from the update thread) calls Application.Exit().However, if the FormClosed event of any form that needs to be closed needs to access its controls, an invalid cross-thread operation is detected (which sounds pretty logical).
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Sep 4, 2009
How do run processes synchronously from a thread or backgroundworker thread? Is it even possible?We have program that allows the user to download several files from a remote server, compress them, and then email the files.It has several long running processes that must run in order. We want these to run on a separate thread so as not to make the form unresponsive. Does a way exist to do this? We attempted a rather clumsy way of approaching this problem by using background worker threads. When each thread is completed and returned back to RunWorkerCompleted, we start another background worker thread and repeat the the next process. It works somewhat but seems to take a lot of resources to run.
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Sep 21, 2010
I'm working on a website where we'll be getting a lot of videos to be uploaded. To keep things simple and secure, I'm just writing VB.net windows app to suck all the files in a directory in, allow you to set some options, and start the encode by spawning a new FFMpeg process.
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Jan 2, 2010
I have built an application where there is a MDI parent form and other forms which i have not declared as Child forms but have set these forms not to show in Taskbar. While the application is running, if i have any of these forms open and i switch over to any other application other than this and when i come back to it, all these forms hide. I cannot reopen it or see it anymore.. Why is this happening?? how can i sustain these forms as it is even when i leave the application.LuxCoder
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Feb 23, 2012
I have added a MDI parent to my application and assigned all new forms to it (i.e. Form1.MDIparent = myMDI). When i hide and then show a form, it loses all of the data previously typed in the textboxes.
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Dec 31, 2009
I have 5 Picture Boxes, each picture box has an image but all 5 of them has a visibility of false. I have a button, when clicked will show 5 of the images. But showing the 5 images with a delay. So it's going to be
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Aug 18, 2010
I have the following code in my project:
Private Sub Button1_Click_1(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim connectionString As String
[Code]....
I'm needing to do is to show in my messagebox.show the date from the sql query that I ran before this. I know that I havent declared a variable in that statement but I'm having a bit of a lapse today and was just wondering how to show that result in my messagebox.show.
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May 4, 2010
When my login screen loads, if the user has not created an account the form will close and a form to create an account will appear. However when I code this both forms stay visible, instead of just the one. Where am I going wrong?[code...]
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Mar 11, 2009
I've just upgraded from Visual Basic 6 to Visual Basic 2008 Express Edition.
1. Show anothor form (ie. Form2)
2. Close Form1.
At present when I use the me.form1 , but both Form1 and Form2 both closes.I would like to press a button or on a timer, to show Form2, while closing Form1.
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Jun 30, 2011
Well I accidently double clicked both of my forms in a project and then they weren't pinned anymore so I exited them out hoping they'd be pinned aghain, but now when I open the project, no forms show up. Just blank blue wall... How can I get the forms back?
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Oct 1, 2010
I am just learning vb.net using vs 2008. I have a small forms app which I have conected to a small, single table 2 column database. I enter some numbers into a text box, press a button and the data gets entered into the dbase. However the only data that gets displayed in the data table I have on my form is the existing data.No new data entered is shown until I close down and restart the app. I have tried many times using statements such as [code]...
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Jul 26, 2011
What is the difference between the following two statements (in terms of memory management):
Dim frm as New MyForm()
frm.Show()
VS
MyForm.Show()
I am originally a C# developer, how does the second one make sense or even compile for that matter in VB.NET? (Show() is not a Shared/Static method) What is happening in the second case?
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May 6, 2009
I've been trying to get my head round a problem for days now, I want to read 'File.ini' line by line checking if specific text exists in the file and then display on a windows form weather particular settings are turned on or off.
So far this code works if "TargetText" exists but if it doenst I get an error on the code line: "If line.Contains("TargetText") Then".
[Code]...
It works if "TargetText" existin in a line in the file but if it doesnt exist I get the 'Null Reference Exception. Object reference not set to an instance of an object.' Any suggestions greatfully recieved!
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Sep 28, 2010
I have the following
[Code]...
and as you can see, I am showing users the next available date open to them is determined with the value dteReturnValue.ToShortDateString .. but what I'd like to do is show the user both the start date and the end date, which will always be +7 days from the field in my database.
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Jun 4, 2011
When I create an inherited form, after creation for some reason I cant see the form to edit in designer, I mean I cant drag and drop buttons, labels or any control to it since I just CANT see it, I have included a pic of what I see below where Form1 is the Inherited Form. What Am I doing wrong or what is happening
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Oct 2, 2010
I'm trying to show a Windows Form from a DLL file - it's added to the application's refrences But I can't call the Windows Form from the DLL, I tried to make a function that shows the form but when I try to call that function in my application it says: Reference to a non-shared member requires an object reference How can I show the form? I'm tried to use this method: (it's in the DLL's form)
Public Sub Open()
Dim Instance As Windows.Forms.Control = Me
Instance.Show()
End Sub
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Apr 27, 2009
I make a program upon sending emails to my friends using smtp. The problem is that I have confusions why my another form will not show until it is not finished sending all of the messages. I want my next form to show how many percent were finished but the problem is that my form will show only until all the emails are sent on my listbox. I put my code on the load event of the for
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Feb 16, 2012
I am using a MDI parent to house each of the forms in my application. I have a main form and 2 sub forms. The sub forms are opened using the code below. Also, when I am finished entering info into these forms, i am hiding them so that I can reopen them with the same info still entered.
The problem is that when i show the form again, it is blank. Why would this be the case? I am never closing or disposing the form, so shouldn't it just unhide easily?Showing the sub-form(savingsfrm1) and and hiding the main form(riskfrm1)Public savingsfrm1 As Savings
Private Sub Button1_Click_1(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
[Code]...
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Mar 31, 2009
I have a form e.g. Form1 , which displays a datagridview.
1) On form load, the datagridview doesn't have any data
2) The user clicks on a button called filter, this opens a form where the user can specify parameters to filter the data by
3) This form calls a setData() in Form1, which fills the dataset with the data
This works fine. If I click on a button called controlPanel it launches another form and hides this. E.g.
dim cp as new ControlPanel()
this.hide()
cp.show()
On the controlpanel I have a button that links to form1. If I click on it. E.g.
dim frm as new Form1()
this.hide()
frm.show()
It redisplays Form1 but without any data in the datagridview.
I think the problem is that since I am creating a new instance for Form1 it comes up with the blank Form1. Is there a way to redisplay Form1 so that it retains the data that was displayed last, without having to retrieve the data from the database.
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Mar 15, 2010
Have anyone developed a textbox where it is possible to display 2 fields in the textbox. We want to be able to show ID + description in the same textbox. (When user enter the textbox description may go away and the user can enter an ID)
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May 6, 2009
I added a tooltip control in my form and set a tooltip for a checkbox. The tooltip shows fine until I check the checkbox... If I check the checkbox once and uncheck it, the tooltip never shows up when I hover the mouse over it... How to make the tooltip to show on mousehover no matter the checkbox is clicked or not?
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Apr 17, 2011
I've finally gotten multi-threading working on my application, but now I'm having trouble showing forms when I need to. I currently have three threads in my program: one for updating a textbox, one for transferring files, and one for displaying forms. Here's a snippet of code from my program:
[code]...
I'm getting the error: Control 'frmXCopy' accessed from a thread other than the thread it was created on. I know what this means, but I can't find a way to make the ShowForm Sub run off of the main application thread.
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Aug 13, 2010
In one application, I need use 4 simultaneous threads.When the threads finished, I need to update the text of a TextBox.So, I create 4 Textbox, and I wanna the threads change the text to FINISHED.Each thread change one distinct TB.I use this "example"
Dim Terminados As Integer = 0
Private Sub frmEnviarMensagem_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Timer1.Enabled = True
Timer1.Start()
[code]....
The problem is, I have an error in the red lines.The error is: INVALIDOPERATIONEXCEPTION "Cross-Thread operation not valid: Control tbPlaca1 Accessed from a thread other than the thread it was created on."I don't use cross threading. Each TB only was accessed for the correspondent thread, and for the "main program".
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Nov 3, 2011
This is the error message I am getting:
"Cross-thread operation not valid: Control 'Panel1' accessed from a thread other than the thread it was created on." The reason I am getting this error is because I am opening up a new form and then calling these three things:
Panel1.Show()
Label1.Show()
Label2.Show()
why I get this error message because it doesn't occur normally if I open Form2 after closing Form1, it only occurs when I open Form2 after closing Form4.
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Jul 21, 2009
I have done a program using vb2005 to display reading from my microcontroller bs2 board but have encountered some problems. My code are as follows.
Dim Stop_Rx As Boolean
Private Sub btnRead_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnRead.Click
SerialPort1.Open()
[code]....
I've encounter an error which is, (Cross-thread operation not valid: Control 'txt1' accessed from a thread other than the thread it was created on.)
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Jun 21, 2012
When my client try to connect to server I'm getting this error : Cross-thread operation not valid: Control 'l_users' accessed from a thread other than the thread it was created on.
Private Sub _socketManager_onConnectionAccept(ByVal SocketID As String) Handles _socketManager.onConnectionAccept
l_Users.Items.Add(SocketID)
End Sub
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Feb 17, 2012
Would anyone be able to help me here please. I'm fairly new to VB.net and threading so im just trying to figure out what is happening.When I debug this I am getting the error thread operation not valid: Control 'ProgressBar1' accessed from a thread other than the thread it was created on.
I'm a little lost as to why the error is occuring or how to fix it. I've had to put the progress bar in a separate thread otherwise the GUI crashes
[Code]...
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