SendKeys - Hold Down a Key

[HunterTTP]

Hey guys! It's been awhile. I've Googl(ed?) this for a few hours and can't seem to find a straight forward answer. I'm working on a program and I can't seem to figure out how to make SendKeys actually Hold Down a key.

If I do this-

SendKeys.Send(W)
Loop

Then it literally spams the key as fast as possible. I just need it to hold down the key. I found this bit of code but I don't really understand how to utilize it-

Private Sub LetKeyGo(ByVal key As Byte)

Const SPI_GETKEYBOARDDELAY = 22
    Const SPI_GETKEYBOARDSPEED = 10
    Private Declare Sub keybd_event Lib "user32.dll" (ByVal bVk As Byte, ByVal bScan As Byte, ByVal dwFlags As Integer, ByVal dwExtraInfo As Integer)
    Private Declare Function MapVirtualKey Lib "user32" Alias "MapVirtualKeyA" (ByVal wCode As Integer, ByVal wMapType As Integer) As Integer
    Private Declare Function SystemParametersInfo Lib "user32" Alias "SystemParametersInfoA" (ByVal uAction As Integer, ByVal uParam As Integer, ByRef lpvParam As Integer, ByVal fuWinIni As Integer) As Integer

        Dim kb_delay As Integer
        Dim kb_speed As Integer


        SystemParametersInfo(SPI_GETKEYBOARDDELAY, 0, kb_delay, 0)
        SystemParametersInfo(SPI_GETKEYBOARDSPEED, 0, kb_speed, 0)



        keybd_event(key, MapVirtualKey(key, 0), 2, 0)

    End Sub
    Private Sub HoldKeyDown(ByVal key As Byte)

        Dim kb_delay As Integer
        Dim kb_speed As Integer


        SystemParametersInfo(SPI_GETKEYBOARDDELAY, 0, kb_delay, 0)
        SystemParametersInfo(SPI_GETKEYBOARDSPEED, 0, kb_speed, 0)



        keybd_event(key, MapVirtualKey(key, 0), 0, 0)
    End Sub

Any help would be great! Thanks.

[jmcilhinney]

When you say that you need it to hold down the key, do you mean that you want to simulate the user depressing the key and then simulate the key being released after a pause? If so then, assuming that the code you posted there works, you would call HoldKeyDown (a better name would be DepressKey) and then Start a Timer with an appropriate Interval. When the TimerTicks, you Stop it and then call the LetKeyGo (a better name would be ReleaseKey). If you don't want a specific delay then don't use a Timer. Just call the methods on the Click of a Button or whatever.

Note also that you will need to provide a VB.NET compatible declaration for the keybd_event and SystemParmetersInfo functions, which should be easy enough to find online, probably wherever you found that code.

[HunterTTP]

When you say that you need it to hold down the key, do you mean that you want to simulate the user depressing the key and then simulate the key being released after a pause? If so then, assuming that the code you posted there works, you would call HoldKeyDown (a better name would be DepressKey) and then Start a Timer with an appropriate Interval. When the TimerTicks, you Stop it and then call the LetKeyGo (a better name would be ReleaseKey). If you don't want a specific delay then don't use a Timer. Just call the methods on the Click of a Button or whatever.

Note also that you will need to provide a VB.NET compatible declaration for the keybd_event and SystemParmetersInfo functions, which should be easy enough to find online, probably wherever you found that code.

Ahh, it seems like no matter what I do, I'm never specific enough. I'll learn one day

Anyway, to make this an easier learning experience, I have setup a listbox and two buttons.

The listbox has a bunch of keys listed so I can select the key that I want held down. Along with that I have 2 buttons, "On" and "Off".

I simply need it to "Hold Down" the key I've selected in the list box when I press "On" and keep holding it until I press "Off".

[DaDDy ICEPOC]

dont know if this will help, i am only 4 days in newbie coder but i managed to get this working to turn my caps on and off but simulating keypress. intheory all you would have to do is split this as it is set to press down and then release if that makes sense:

    Public Sub tmrCapsOff_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles tmrCapsOff.Tick

        If Label3.Text <> "seal5" And My.Computer.Keyboard.CapsLock = True Then
            Call keybd_event(System.Windows.Forms.Keys.CapsLock, &H14, 1, 0)
            Call keybd_event(System.Windows.Forms.Keys.CapsLock, &H14, 3, 0)
        End If

    End Sub

to make it work you do need this:

Private Declare Sub keybd_event Lib "user32" (ByVal bVk As Byte, ByVal bScan As Byte, ByVal dwFlags As Integer, ByVal dwExtraInfo As Integer)

so as u can see, to put the caps on it uses two lines so all u should need is to split them lines for when you want press down and release... i think..... hope it helps.

Paul

[Edgemeal]

Not sure this would actually work, but maybe try something like...

Public Class Form1

    Private Declare Sub keybd_event Lib "user32" (ByVal bVk As Byte, ByVal bScan As Byte, ByVal dwFlags As Integer, ByVal dwExtraInfo As Integer)
    Private Const KEYEVENTF_EXTENDEDKEY As Integer = &H1
    Private Const KEYEVENTF_KEYUP As Integer = &H2

    Private Sub iKeyDown(ByVal vKey As Keys)
        keybd_event(CByte(vKey), 0, KEYEVENTF_EXTENDEDKEY, 0)
    End Sub

    Private Sub iKeyUp(ByVal vKey As Keys)
        keybd_event(CByte(vKey), 0, KEYEVENTF_EXTENDEDKEY Or KEYEVENTF_KEYUP, 0)
    End Sub

    Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
        'set focus on window that receive the key
        TextBox1.Focus()
        ' press the "C" key down
        iKeyDown(Keys.C)
        ' start timer to release the "C" key in 1 sec.
        Timer1.Interval = 1000
        Timer1.Start()
    End Sub

    Private Sub Timer1_Tick(sender As System.Object, e As System.EventArgs) Handles Timer1.Tick
        ' stop the timer!
        Timer1.Stop()
        ' release the "C" key!
        iKeyUp(Keys.C)
        ' show msg.
        MessageBox.Show("'C' key released.")
    End Sub

End Class

[HunterTTP]

I've tried to do this as many ways as I can. I figured out how to use the code I posted originally. It doesn't show any errors but it simply doesn't work. Oh and I want this to simulate me holding down a key on my keyboard. So I want any application on my computer to be able to think that I'm constantly holding that key.

[DaDDy ICEPOC]

what will define the key release?

[dunfiddlin]

I've tried to do this as many ways as I can. I figured out how to use the code I posted originally. It doesn't show any errors but it simply doesn't work. Oh and I want this to simulate me holding down a key on my keyboard. So I want any application on my computer to be able to think that I'm constantly holding that key.

That doesn't actually make any sense. If you physically hold down a key, it repeats the relevant character continually until you stop, as in your Sendkey loop (the speed can obviously be regulated using a timer instead). If you hold down one of the modifiers (Ctrl, Alt etc.) it does nothing at all. There is nothing in between that simply says I'm holding this key but I don't want anything to happen as a result.

[HunterTTP]

That doesn't actually make any sense. If you physically hold down a key, it repeats the relevant character continually until you stop, as in your Sendkey loop (the speed can obviously be regulated using a timer instead). If you hold down one of the modifiers (Ctrl, Alt etc.) it does nothing at all. There is nothing in between that simply says I'm holding this key but I don't want anything to happen as a result.

You actually make a fantastic point. I didn't think about it really. So if I do the send key loop, how long should I set the time between sends?

[dunfiddlin]

100ms will give you 10 per second which seems reasonable. Fastest available in Windows is around 30 per second, slowest around 3. Anything much faster than 10 will put you in less reliable timer country however.

[HunterTTP]

100ms will give you 10 per second which seems reasonable. Fastest available in Windows is around 30 per second, slowest around 3. Anything much faster than 10 will put you in less reliable timer country however.

Alright well here is my code so far. The problem is that it freezes the program and sometimes even my computer. But it does everything else correctly. I was thinking about using a BackgroundWorker but how would I stop it once it started?

Imports System
Imports System.IO
Imports Microsoft.VisualBasic
Public Class Form1

    Private Sub CheckBox1_CheckedChanged(sender As Object, e As EventArgs) Handles CheckBox1.CheckedChanged

        Dim X As Integer
        X = 1

        If CheckBox1.Checked Then
            Do While X = 1
                SendKeys.Send("W")
                Threading.Thread.Sleep(25)
            Loop
        End If

    End Sub
End Class

[DaDDy ICEPOC]

the sendkeys thing for me when i was doing caps used to freeze mine. i would suggest using my code above to toggle the key press down and up

i think this should be it for you: (combination of yours and mine)

Imports System
Imports System.IO
Imports Microsoft.VisualBasic
Public Class Form1
    Private Declare Sub keybd_event Lib "user32" (ByVal bVk As Byte, ByVal bScan As Byte, ByVal dwFlags As Integer, ByVal dwExtraInfo As Integer)
    Private Sub CheckBox1_CheckedChanged(sender As Object, e As EventArgs) Handles CheckBox1.CheckedChanged

        Dim X As Integer
        X = 1

        If CheckBox1.Checked Then
            Do While X = 1
                Call keybd_event(System.Windows.Forms.Keys.W,  1, 0)
                Threading.Thread.Sleep(25)
            Loop
        End If

    End Sub
End Class

im not 100% about this but some more experience guys may be able to clean it up a little

good luck

[HunterTTP]

the sendkeys thing for me when i was doing caps used to freeze mine. i would suggest using my code above to toggle the key press down and up

i think this should be it for you: (combination of yours and mine)

Imports System
Imports System.IO
Imports Microsoft.VisualBasic
Public Class Form1
    Private Declare Sub keybd_event Lib "user32" (ByVal bVk As Byte, ByVal bScan As Byte, ByVal dwFlags As Integer, ByVal dwExtraInfo As Integer)
    Private Sub CheckBox1_CheckedChanged(sender As Object, e As EventArgs) Handles CheckBox1.CheckedChanged

        Dim X As Integer
        X = 1

        If CheckBox1.Checked Then
            Do While X = 1
                Call keybd_event(System.Windows.Forms.Keys.W,  1, 0)
                Threading.Thread.Sleep(25)
            Loop
        End If

    End Sub
End Class

im not 100% about this but some more experience guys may be able to clean it up a little

good luck

Thanks! But it gives me an error on Line 13. Looks like keybd_event not declared.