Detecting whether CTRL key is down

Question

(I apologize if this is a duplicate posting.  I could not find my own post)

I would like to detect whether the CTRL key is down during a mouse click.  I do some processing using the Worksheet_Selection_Change sub.  If the CTRL key is down during the selection, I would like to alter the process.

Any suggestions?

Answer 1

Lon wrote:

Thanks for the comment about the key being released before the macro is called.  However, this program will be meant only for my own use, and I will know to keep the key down long enough.

Okay ;-).  See this article.  However, my experiments suggest that the article might not be accurate, at least for WinXP, my platform.

Try the following test event macro, pressing and releasing control in a number of contexts.  In addition to 0 ("not set") and &h80 ("set -128"), sometimes I get &h01 ("set 1") and &h81 ("set -127").

EDIT....  Well, if we limit ourselves to iResult And &h80 for VK_CONTROL, as this article states, it reliably tells us if the key is up or down.  It is my nature to question documentation to ferret out undocumented nuances, especially for kernel features.  So I'm curious what these other states might tell us, if anything.  But the other bits might simply be "garbage".  TBD.

Caveat:  try this with a new worksheet.  It destroys column A.

Private Declare Function GetKeyState Lib "user32" _

    (ByVal vKey As Long) As Integer

Private Const VK_SHIFT As Long = &H10

Private Const VK_CONTROL As Long = &H11

Private Const VK_MENU As Long = &H12

Private Const VK_CAPITAL = &H14

Private Const VK_NUMLOCK = &H90

Private Const VK_SCROLL = &H91

'initialize by resetting VBA; click Run > Reset

Private n As Long

Private Sub Worksheet_SelectionChange(ByVal Target As Range)

Dim iResult As Integer

If n = 0 Then Range("a:a").Clear: n = 1

iResult = GetKeyState(VK_CONTROL) And &H80  'EDITed

'note: iResult < 0 means bit 15 is set

If iResult <> 0 Then Cells(n, 1) = "set " & iResult _

Else Cells(n, 1) = "not set"

n = n + 1

End Sub

Answer 2

The article referred to led me to another article by Chip Pearson, which contained highly valuable information on testing the status of SHIFT, ALT, and CTRL keys.  Simplifying the coding presented solved my more focused issue of detecting whether the CTRL key is down.  Here is the code I ended up with:

Option Explicit

Option Compare Text

Private Declare Function GetKeyState Lib "user32" ( _

    ByVal nVirtKey As Long) As Integer

Private Const KEY_MASK As Integer = &HFF80 ' decimal -128

Public Const BothLeftAndRightKeys = 0   ' Note: Bit-wise AND of LeftKey and RightKey

Public Const LeftKey = 1

Public Const RightKey = 2

Public Const LeftKeyOrRightKey = 3      ' Note: Bit-wise OR of LeftKey and RightKey

Public Function IsControlKeyDown(Optional LeftOrRightKey As Long = LeftKeyOrRightKey) As Boolean

    Dim Res As Long

     Res = GetKeyState(vbKeyControl) And KEY_MASK

    IsControlKeyDown = CBool(Res)

End Function

Thanks for the help.

Answer 3

The following event macro is more fun.  It measures reaction time:  how quickly you can release Ctrl after releasing the left "mouse" button (left button on my touchpad).

I can do it before we enter the first GetKeyState call.  But when I try to delay the release the least, I have gotten it to be as little as about 20 milliseconds :-).  However, 115 to 190 milliseconds is more natural.

---

Private Const VK_SHIFT As Long = &H10

Private Const VK_CONTROL As Long = &H11

Private Const VK_MENU As Long = &H12

Private Const VK_CAPITAL = &H14

Private Const VK_NUMLOCK = &H90

Private Const VK_SCROLL = &H91

'initialize by reseting VBA; click Run > Reset

Private n As Long

Private Declare Function GetKeyState Lib "user32" _

    (ByVal vKey As Long) As Integer

Private Declare Function QueryPerformanceFrequency Lib "kernel32" _

   (ByRef freq As Currency) As Long

Private Declare Function QueryPerformanceCounter Lib "kernel32" _

   (ByRef cnt As Currency) As Long

Private Sub Worksheet_SelectionChange(ByVal Target As Range)

Dim iResult As Integer, iResult2 As Integer, x As Long

Dim sc As Currency, ec As Currency, dt As Double

'measure time for user to release CTRL, if set

sc = myTimer

iResult0 = GetKeyState(VK_CONTROL)

If (iResult0 And &H80) = 0 Then

   ec = myTimer

   dt = myElapsedTime(ec - sc)

   iResult2 = iResult0

Else

   Do

      x = DoEvents()

      iResult2 = GetKeyState(VK_CONTROL)

      ec = myTimer

      dt = myElapsedTime(ec - sc)

   Loop Until (iResult2 And &H80) = 0 Or dt >= 1

End If

'note: iResult < 0 means bit 15 is set

If n = 0 Then Range("a:c").Clear: n = 1

Cells(n, 1) = iResult0

Cells(n, 2) = iResult2

Cells(n, 3) = dt

n = n + 1

End Sub

Private Function myTimer() As Currency

QueryPerformanceCounter myTimer

End Function

Private Function myElapsedTime(dc As Currency) As Double

Static freq As Currency, df As Double

If freq = 0 Then QueryPerformanceFrequency freq: df = freq

myElapsedTime = dc / df

End Function

Answer 4

Thanks for the comment about the key being released before the macro is called.  However, this program will be meant only for my own use, and I will know to keep the key down long enough.

Answer 5

Lon wrote:

I would like to detect whether the CTRL key is down during a mouse click.  I do some processing using the Worksheet_Selection_Change sub.  If the CTRL key is down during the selection, I would like to alter the process.

The CTRL key will usually have been released by the time the Worksheet_SelectionChange event macro is called.  It depends on how lazy the user is ;-).