C# Signature:
[DllImport("user32.dll")]
static extern bool BlockInput(bool fBlockIt);
VB.Net Signature:
Declare Fuhhhhhon BlockInput Lib "user32" (ByVal fBlockIt As Boolean) As Boolean
Or use:
''' <summary>The BlockInput function blocks keyboard and mouse input events from reaching applications
''' </summary>
''' <param name="fBlockIt">[in] Specifies the function's purpose. If this parameter is non-zero, keyboard
''' and mouse input events are blocked. If this parameter is zero, keyboard and mouse events are unblocked.
''' </param>
''' <returns>If the function succeeds, the return value is nonzero.
''' If input is already blocked, the return value is zero.
''' To get extended error information, call Marshal.GetLastWin32Error()</returns>
''' <remarks>Note that only the thread that blocked input can successfully unblock input</remarks>
<DllImport("user32.dll", EntryPoint:="BlockInput", SetLastError:=True, CharSet:=CharSet.Auto, CallingConvention:=CallingConvention.StdCall)>
Friend Shared Function BlockInput(fBlockIt As Boolean) As Integer
End Function
Note that this definition does not use Boolean input and return types
Notes:
This method requires administrator rights.
Blocks or unblocks mouse and keyboard input.
Can be disabled by pressing Ctrl+Alt+Del.
Tips & Tricks:
Useful to create a temporary block in input for sensitive GUI operations. For instance when manually activating a screen saver from within a GUI function, a short blocking delay will prevent the user mouse movements directly after selection from accidently escaping the screen saver.
Sample Code:
VB.Net:
Class BlockInput
<DllImport("user32.dll", EntryPoint:="BlockInput", SetLastError:=True, CharSet:=CharSet.Auto, CallingConvention:=CallingConvention.StdCall)>
Friend Shared Function BlockInput(fBlockIt As Boolean) As Boolean
End Function
Friend Shared Function DisableInput(makeDisabled As Boolean) as Boolean
Return BlockInput(makeDisabled)
End Function
End Class
Alternative Managed API:
The ManagedWindowsApi project (http://mwinapi.sourceforge.net) provides an InputBlocker class that can block input.
