Detecting Key Presses In Thread?
Jun 13, 2009
I just finished building my robot and now I am trying to come up with the code that goes on the computer to control the dang thing. Right now I have a thread that constantly loops in a do until loop that will never be true. Inside that loop the program should check to see if the w,s,a, or d keys are pressed if they are then it finds out what key has been pressed and sends the appropriate value to the robot. If no key is pressed then it should send the stop value to the micro controller which halts the robot until a new key is pressed.This is the basic way that I thought the code should be constructed although this code DOES not work.
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code inside thread
Dim x as integer[code].....
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Sep 15, 2009
I am writing a program that expands the usage of the clipboard, but I need to tell when the user has either cut, copied, or pasted something so I can write code accordingly to that. I need to know how I can check to see when the user has entered a command like this.
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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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Sep 2, 2010
My understanding is that thread.join will suspend the execution of code on the calling thread until the spawned thread finishes or is aborted...
With that in mind, I tried this:
For i = 1 to 50
threads = New Thread(AddressOf test)
threads.IsBackground = True
threads.SetApartmentState(ApartmentState.STA)
[CODE]...
However, the rest of the code runs when the loop finishes, not waiting for all the spawned threads to finish. Since the rest of the code needs the threads to finish (otherwise the rest will error).
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Jun 6, 2010
I have written an application that loads a form - frmCad as well as AutoCad. It does this via a class which detects when AutoCad quits.
Friend Class CadApp Private WithEvents AppObject As AcadApplication... Private Sub AppObject_BeginQuit(ByRef Cancel As Boolean) Handles AppObject.BeginQuit RaiseEvent Quit() End SubEnd Class
My main class loads frmCad as well as CadApp.
Public Class Cad Private WithEvents frmCad As CadForm Private WithEvents app As CadApp... Public Sub ShowForm() If frmCad Is Nothing Then frmCad = New CadForm frmCad.Visible = True End Sub... Private Sub app_Quit() Handles app.Quit frmCad.Dispose() frmCad = Nothing .... End Sub
When I debug the program, it stops at frmCad.Dispose()The program continues to execute, but all the code after it fails to work.Looking more carefully I get an error message which contains:-Cross-thread operation not valid: Control 'Autocad' accessed from a thread other than the thread it was created on.
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Feb 9, 2011
My error:Cross-thread operation not valid: Control 'label2' accessed from a thread other than the thread it was created on. I want to be able to give my Public RunBot() sub access to edit Labels, buttons, etc without an error.
[Code]...
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Apr 1, 2010
I'm getting the 'System.InvalidOperationException' error on acccessing a thread from other than where it was created. My code is:
'Required by the Windows Form Designer
Public components As System.ComponentModel.IContainer ' changed from private
[code]....
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Jun 6, 2009
My problem is Cross-thread operation not valid: Control 'statusHO' accessed from a thread other than the thread it was created on.
System.InvalidOperationException was unhandled
Message="Cross-thread operation not valid: Control 'statusHO' accessed from a thread other than the thread it was created on."
Source="System.Windows.Forms"
StackTrace:
[Code]...
i used it and it works fine then. but as it is mentioned its not a good practice to use it. So what should i do? is it ok if i use this as i am not able to use correct practice. Mine application is not for enterprise purpose. its just my class project, and it works fine even if i put application working in background. System works ok. I dont know how to correct this error.As i dont have that much knowlege of threads.
So please guide me how to fix this in correct way otherwise i am force to go for bad programming practice
Please refer to Windows Mobile Developer Center > Smart Device Development Forums > Windows Mobile Development > Appendtext not working for all my code details
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Aug 4, 2009
Cross-thread operation not valid: Control 'lv1' accessed from a thread other than the thread it was created on.
Dim lvi As ListViewItem
For Each lvi In lv1.Items
[code]....
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Feb 7, 2011
Ok i have a Form with the following
Private Sub frmMain_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
txtNotepad.Text = LoadFile("notes.txt")
[code].....
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Jul 31, 2010
I am trying to create an application that will enable me to type in my local language. For that I need to modify the key presses. For example when I press key A it should change it to ”. Also I would like to know how to detect double and triple key presses e.g. shift + W and ctrl + shift + J and remap them to a different character. Also I would like to know how to detect a text string like and replacing them with other string like member. I have found a code that modifies key. But when I tried to change key A to key B it produces AB. I am including the code below. Hope I have made myself clear.
[Code]...
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Jun 16, 2009
I want to do a "code" that presses a button by ut self with help of a timer. [code\]...
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Feb 17, 2011
I'm trying to work out how to detect if the user has pressed an f key I have this so far:
Private Sub Form1_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles Me.KeyPress
Label1.Text = e.KeyChar
End Sub
This detects when the user presses a character key and outputs it via Label1.text, but it doesnt work on all keys?
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Jan 4, 2012
I want to get key presses on my application. The problem is when I use API.UnhookWindowsHookEx and after sometime to restart hooking as follows, application does NOT gets the key presses anymore. [code]
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Dec 14, 2010
I'm trying to capture two key presses in my VB.net application, for this example CTRL + B, the code below doesn't work but it does for single keys. I have tried setting keypreview as true but this has no effect. [Code]
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Oct 20, 2011
I am trying to make a program that has a multiple key press activation such as ctrl+alt+g and then it would for example open a message box.I am also trying to use a MDI form as a windows 7 desktop like area.What I mean here is that i want to create a MDI form or any other form that supports locking child forms inside it.
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Jul 22, 2009
I am looking for a way to send key presses to another program, Ive tried Sendkeys(), Keybd_event() , etc. is there a thrid party dll i could use? whatever i do it needs to be real low-level and totally undetectable.
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May 11, 2011
I would like my webbrowser1 to press tabs. I used this code to press tabs:
SendKeys.Send("{TAB}")But it clicks tabs, where ever there is a focus on an object. I want it to press tab inside the webbrowser1 without have to have the program focused.
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Nov 22, 2010
I am writing a function that should sound a beep every two seconds until the user either clicks the mouse or presses any key. The code I have written appears to work for the mouse click, but it ignores keystrokes:
[Code]...
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Jul 10, 2011
I file ComboBox_SelectionChangeCommitted event when a button pressed or form is loaded.
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Nov 13, 2011
I have an assignment from school where the program is supposed to close when the user presses Alt X.
I have done this using Java but that was a long time ago and I can't remember how I did it. How do you do it in VB?[code]...
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May 13, 2011
i know how to give the control + t command ( " SendKeys.Send("^t") ) and how to send the alt command ( "SendKeys.Send("%t") ) but how do i give a command that presses alt and ctrl and t in the same time?
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Feb 20, 2012
I have a system with 26 buttons but the buttons actaully run the same code; aside from the fact that the index number is used to distinguish between them (es, I know index values are out so I am using the object's name (btnKey1, btnKey2, etc).
Is there any event that occurs for all button presses or do I need to write the same line for all 26 events (actually 52 since I am using MouseDown and MouseUp - will get worse when I want to use the keypress side)?
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Apr 17, 2009
i want to make a message box appear when the user presses Alt k (then) Alt e (then) alt j . is this the correct code to use?:
Private Sub form1_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles txt3.KeyDown
Dim intcount As Integer = 0
If e.Alt And e.KeyCode.ToString = "k" Then
intcount = intcount + 1
[code]....
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Jun 17, 2011
I made a tic tac toe game. and i was wondering how would code it so that when a user presses a button or when a user wins it makes a beep or some kind of music
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May 30, 2012
How can I get the mouse and keyboard to simulate clicks and key presses from VB.net code?
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