SetKeyboardState Function

Declare Function SetKeyboardState Lib "user32.dll" (lpKeyState As Byte) As Long

Platforms

Windows 95: Supported.
Windows 98: Supported.
Windows NT: Requires Windows NT 3.1 or later.
Windows 2000: Supported.
Windows CE: Not Supported.

Description & Usage

SetKeyboardState sets the state of every key on the keyboard. Each element of the 256-element array identifies information about the virtual-key whose virtual-key code matches the index of the element. If the &H1 bit is set, that key is considered toggled. If the &H80 bit is set, the key is considered to be currently pressed down. The keyboard information set by this function is thread-specific; its settings do not necessarily change key states pertaining to the system as a whole.

Return Value

If an error occured, the function returns 0 (use GetLastError to get the error code). If successful, the function returns a non-zero value.

Visual Basic-Specific Issues

None.

Parameters

lpKeyState

A 256-element byte array which specifies the key status information for all virtual-keys. Each key is identified by the element corresponding with the key's virtual key code. Windows NT, 2000: In addition to the virtual keys, the array also sets information which distinguishes between the left and right Ctrl, Alt, and Shift keys, which are stored in the array at the following indices:

VK_LSHIFT: The left Shift key.
VK_RSHIFT: The right Shift key.
VK_LCONTROL: The left Ctrl key.
VK_RCONTROL: The right Ctrl key.
VK_LMENU: The left Alt key.
VK_RMENU: The right Alt key.

Constant Definitions

Const VK_LSHIFT = &HA0
Const VK_RSHIFT = &HA1
Const VK_LCONTROL = &HA2
Const VK_RCONTROL = &HA3
Const VK_LMENU = &HA4
Const VK_RMENU = &HA5

Example

' This code is licensed according to the terms and conditions listed here.

' Set the toggle status for every key on the keyboard to "not
' toggled."  This change only applies to the current thread.
Dim keystates(0 To 255) As Byte  ' holds states of entire keyboard
Dim c As Integer  ' counter variable
Dim retval As Long  ' return value

' First, get the current state of the keyboard.
retval = GetKeyboardState(keystates(0))

' Now, loop through each element and explicitly set the toggle bit to 0.
For c = 0 To 255
  ' Make sure the &H1 bit is not set.
  keystates(c) = keystates(c) And (Not &H1)
Next c

' Finally, set this to the current keyboard state.
retval = SetKeyboardState(keystates(0))