.net - KeyDown Event Firing When No Key Is Pressed?
Aug 20, 2011
I am running VS 2008 and building my app on a Windows 7 box. The main form/window has a KeyDown event handler as follows in it:
Private Sub Form1_KeyDown(ByVal sender As System.Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles MyBase.KeyDown
MsgBox("control = " + e.Control.ToString + ", shift = " + e.Shift.ToString + ", e.Keycode = " + e.KeyCode.ToString)
When I build it and run it within VS it seems to run fine. The messagebox appears with the state of the control and shift keys along with the key code of the key I pressed. However, if I take the executable and run it on an XP box (both using .Net Runtime 3.5) as soon as the main form opens, the messagebox appears. Basically the "KeyDown" event seems to be firing without any keys being pressed. The messagebox comes back with: "control = False, shift = False, e.Keycode = None".
How is this possible? How can the keyDown event be fired when no keys have been pressed (as is confirmed by the output contained in the messagebox?) how I can diagnose this on the XP box since it does not have Visual Studio on it?Update I tried creating a brand new project where there is only "form1" and the only code behind this is the keyDown event handler. It just opens a blank window and pops up the message box if a key is pressed. It worked as expected on the Win 7 box but when I moved the executable to the XP box, it immediately popped open the messagebox without pressing a key.
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Oct 22, 2009
I already have KeyPreview set to true in the form properties I'm working on a small program, and I'm having a problem where it seems that some of the controls on it inside groupboxes are not triggering the KeyDown event on my form when I press and release any arrow key, just the KeyUp event. Specifically, I've enabled KeyPreview on the form, and set breakpoints on e.SuppressKeyPress = True in both subroutines, and only the one for frmMain_KeyUp hits the breakpoint.
I added in the two GroupBox events hoping that might mitigate the issue, but no such luck. However, I have a custom control on the form that is specifically coded to ignore these keypresses, and the code works as expected on it.
Private Sub frmMain_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles Me.KeyDown, GroupBox1.KeyDown, GroupBox2.KeyDown
e.SuppressKeyPress = True
Select Case e.KeyCode
[code]....
The code in the user control that "ignores" keypresses is as such:
Private Sub TileDropDown_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles Me.KeyDown
If e.KeyValue = 40 OrElse e.KeyValue = 38 OrElse e.KeyValue = 39 OrElse e.KeyValue = 37 Then
e.SuppressKeyPress = True
End If
End Sub
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Apr 19, 2012
I have a textbox on a tabcontrol page, and when someone tabs out of the textbox, it is suppose to move to the next tab. This was working great before I switched the form from a UserControl to an actual Form. This change did not change actual code. So now, I have tried everything. I have the textbox to set to AcceptTab = True, and I have KeyPreview = False (because if the form grabs the event before the textbox does, it would mess things up I am assuming).Here is my code for the textbox:
Private Sub txtMsgDTG_KeyDown(ByVal sender As Object, ByVal e As KeyEventArgs) Handles txtMsgDTG.KeyDown
'check for tabbed out
If e.KeyCode = Keys.Tab Then[code]......
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Aug 8, 2010
I have a weird problem. Ive created a UserControl that can be used to pan and zoom an image but when ever I add the control to a form my arrow keys will not trigger the KeyDown event anymore. If I remove it no problem.
If I try and listen to the KeyDown event on the control itself nothing fires either!
Ive set the KeyPreview property on the for to True.
I'd be happy to supply the code if anyone think they could solve it..
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Feb 10, 2009
I am creating a keydown event that when the enter key is pressed it performs the button1_click event. I have this much:
if e.keycode = keys.enter then
//code here
endif
I just need to know how to make it perform the button1_click event.
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Oct 23, 2010
ABCDE keydown events, the ones I needed, are not firing. I even set my Form KeyPreview to true but no joy.
up and down arrow keydown events work though.[code]...
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Apr 22, 2009
Public Class Form1
Inherits System.Windows.Forms.Form
Dim ct, ctJmp, ctRgt, ctLft, wait, wait2, origTop As Integer
Dim jumping, up, down, lft, rght As Boolean
Private Sub Form1_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles MyBase.KeyDown
[Code] .....
Basically what I want to do is if the player is still holding the right arrow key after the up arrow is pressed and jumping finishes, I want him to continue to run.
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Dec 15, 2010
Is it possible to set focus on the keydown event so after the button control, sets the focus into the keydown? although says often control can have focus,.Putting a button and a keydown event on a form...
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Apr 9, 2010
Programming language is vb.net
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May 24, 2010
I have this code in the onKeyDown event of the datagridview.
Private Sub DataGridView1_KeyDown(ByVal sender As System.Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles DataGridView1.KeyDown
Select Case e.KeyCode[code]....
This works. When the Enter button is pressed, it acts as the TAB button.The problem I am having is this only works if the datagridviewer is selected.As soon as I enter data into a cell (A cell is selected) the code wont work as it is not set for the cell keyDown event. The event does not exist, so I have to somehow create it.
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Aug 9, 2011
I am trying to put an extra event in, UpdateID and it's not firing.
[Code]...
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Feb 15, 2011
I have alot of experience in working in VBA for excel, but not so much experience in creating my own structures so it's all still a bit foggy. I'm trying to capture the event for when the F1 key is pressed, not just when the form is active, but anytime the program is running. The code below expressing the handling is automatically generated for me in VB Express... But I'd like to change the situation to encompass anytime the program is open. I guess I have to reference events that happen in windows in general, but i don't know how to do it. I think i have to create the even in a class module?
[Code]...
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Aug 31, 2010
this code works
Private Sub TxtLname_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles TxtLname.KeyDown
If e.KeyCode = Keys.Enter Then
If IsNumeric(TxtLname.Text) Then[code]....
when I replace the keys.enter with "keys.tab" it won't work..
Private Sub TxtLname_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles TxtLname.KeyDown
If e.KeyCode = Keys.tab Then
If IsNumeric(TxtLname.Text) Then[code].....
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May 26, 2010
my child form is a game that allows user to move using keydown event (arrow key left and right). But when i import it to MDI, keydown event doesn't work anymore. Am i missing something here?
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Sep 17, 2008
how to use the keydown event soif you press 'A' a messagebox will popup saying you pressed A else it will say This function is not reconised i am hoping to use this knowlage to start a game so that if you press W the image will go up.
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Dec 7, 2010
why does the keydown event not responding when i put a button on the form?all are set but after i put one button keydown event is not working...
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Mar 31, 2011
in my Application i have created a status strip which has three lable to show capslock status, numlock status and current date.I have used the following code, it is working perfectly when Master(MDI Parent) Load but it dosen't change when key is pressed. every time i start my application it shows the current status of the keys but dosent change when key is pressed.[code]
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Jan 14, 2010
This simple code works at child form, but not at MDI form.
Is there anything should I add or change?[code]...
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May 11, 2011
I have checked my code countless times, tried other computers, and yet the keydown event will not work.
My code:Private Sub Form_KeyDown(KeyCode As Integer, Shift As Integer)
If KeyCode = vbKeyRight Then
imgPerson.Left = imgPerson.Left + 500
End If
End Sub
That's all there is because I was just testing it out. imgPerson does exist, so that's not a problem.
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Nov 9, 2010
if I press F1 on another program like, internet explorer, it will open music. When I press F1 on my Windows Form(My program), It work fine and it play my music but when i'm on internet explorer or anything else it doesn't work and I am wondering if I can.
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Nov 15, 2011
I need to make a simple yet cool program for my professor. The program is this: To get the program to work, the user first presses a button on the form. Then, when the user presses an up arrow on the keyboard, the cursor will change to a custom cursor (a cursor with an image of car {in .ico format} for example), when the user releases the up arrow key, the cursor turns back to default cursor -- which is arrow. When the user presses an up arrow and left arrow at the same time on the keyboard, then a different custom cursor will be shown instead of the default.
[Code]...
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Jun 18, 2011
In my program I've used a text box and KeyPreview is True.When press the Enter-key i hope go to next row but called the default key?
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Jun 1, 2011
How do you read a key down event when your application is not focus but other are?
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Dec 26, 2009
using a datagridview and it bind by 3 rows and 3 columns,my task is when the press the F5 key then need to execute some code, my problem is if the datagridview cell is focused then now i press F5 key then the next task is executed but if the cursor is in the cell and i press F5 Key then the Key events was fired
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Aug 3, 2010
How can I get VB.net to work out that i have pressed +-*/ in Keydown events?
At the moment i am using a Select Case:
Select Case e.Key
'Numpad Numbers Keydown Events'
Case Key.NumPad0
Display.Append("0")
txtAnswer.Text = Display.ToString
Case Key.NumPad1
Display.Append("1")
txtAnswer.Text = Display.ToString
However, I can't find a key. thing to work with the numpad function buttons.
I tried using:
Case AscW(Chr(107))
Display.Append("+")
txtAnswer.Text = Display.ToString
But it didn't work,
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Sep 1, 2009
I want to make it so that no matter which control has focus, it will do my event. So that I dont have to write a keydown event for all 137 of my objects. Is this possible?
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Nov 10, 2009
short question: What's better?
Form KeyDown event vb Private Sub MainForm_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles Me.KeyDown End Sub
Override OnKeyDown
vb Protected Overrides Sub OnKeyDown(ByVal e As System.Windows.Forms.KeyEventArgs) MyBase.OnKeyDown(e) End Sub
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Mar 10, 2011
I'm using VB.NET (2008) and .NET framework 3.5. In my application I've got an on screen button that, when pressed, sends "00" as the characters [via SendKeys.Send("00")]. I also have a keyboard that has a '00' key that sends "00", two zeros, when pressed. I'm picking up the keypress using the form's KeyDown event - it fires twice, once for each "0" and works whether the on-screen or keyboard '00' is pressed. There's also a singe '0' on-screen button and key on the keyboard that sends "0".
I want to be able to treat the "00" as a single event. I.E. in the KeyDown handler, if the character is a single zero "0", I would like to check the next character to see if it is also a zero "0". If it is then I can handle it appropriately, but also need to remove it (from the keyboard buffer?) so that it doesn't fire the second KeyDown event. If it's not a zero then it should be left to fire the next event in the normal fashion.
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Dec 18, 2011
How to make an event for keydown, but for second press?
Yes, i know how to make event, eg.:
If e.KeyCode = Windows.Forms.Keys.Escape Then
Me.Close()
End If
But i want code for second press. For example...:
First use button space: open form1 Second use button space: open form2
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Jun 8, 2012
I want to have a partial class to manage my focus bettwen radtextboxes when a user presses the enter key and I am looking for the telerik interpretation of this line of code " tbs(i).KeyDown += New KeyEventHandler(AddressOf textBoxes_KeyDown) "[code]...
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