Low-level Keyboard Hooks/SendInput with Winkey+L possible? (workstation lockout is intercepted in Vista and higher)
I figured out a way to do this in C#. There are four states involved in a possible Win+L keypress sequence (None, Win, Win+L, L). Whenever the Win+L state is reached, set a flag ("winLSet" below). Whenever all of the keys have been released, we check for this flag and simulate the press if it's been set.
The final piece of the puzzle is to simulate the WinKey's KeyUp before the Ctrl-L (no KeyDown). I've tried similar approaches in AutoHotkey and it never worked, but it seems to work perfectly here.
The code is below. Please see explanatory notes at the bottom if you plan to use this code.
public partial class MainWindow : Window
{
LowLevelKeyboardHook hook;
bool winKeyDown;
bool lKeyDown;
bool winLSet;
public MainWindow()
{
InitializeComponent();
hook = new LowLevelKeyboardHook();
hook.KeyDown += OnKeyDown;
hook.KeyUp += OnKeyUp;
}
void OnKeyDown(object sender, LowLevelKeyEventArgs e)
{
e.EventHandled = true;
switch (e.Key)
{
case Key.L:
lKeyDown = true;
UpdateWinLState();
e.EventHandled = winKeyDown;
break;
case Key.LWin:
winKeyDown = true;
UpdateWinLState();
InputSimulator.SimulateKeyDown(VirtualKeyCode.LCONTROL);
break;
case Key.LeftCtrl:
InputSimulator.SimulateKeyDown(VirtualKeyCode.LWIN);
break;
default:
e.EventHandled = false;
break;
}
}
void OnKeyUp(object sender, LowLevelKeyEventArgs e)
{
e.EventHandled = true;
switch (e.Key)
{
case Key.L:
lKeyDown = false;
UpdateWinLState();
e.EventHandled = winKeyDown;
break;
case Key.LWin:
winKeyDown = false;
UpdateWinLState();
InputSimulator.SimulateKeyUp(VirtualKeyCode.LCONTROL);
break;
case Key.LeftCtrl:
InputSimulator.SimulateKeyUp(VirtualKeyCode.LWIN);
break;
default:
e.EventHandled = false;
break;
}
}
void UpdateWinLState()
{
if (winKeyDown && lKeyDown)
{
winLSet = true;
}
else if (!winKeyDown && !lKeyDown && winLSet)
{
winLSet = false;
InputSimulator.SimulateKeyUp(VirtualKeyCode.LWIN);
InputSimulator.SimulateModifiedKeyStroke(
VirtualKeyCode.LCONTROL,
(VirtualKeyCode)'L');
}
}
}
For posterity: please note that this code uses InputSimulator and LowLevelKeyboardHook, which are not from the .NET Framework. LowLevelKeyboardHook is a class I wrote a while back that exposes global KeyDown and KeyUp events as C# events. There are similar examples here, here, and a bunch can be found here.
Also notice that I'm using System.Windows.Input.Key, not System.Windows.Forms.Keys, which could confuse some people. System.Windows.Input.Key is the new enumeration of keys in .NET 3.0 and above, while System.Windows.Forms.Keys is the old enumeration from Windows Forms.