Global KeyHook in WPF application

Question

I need my WPF application to gain focus whenever the user press "window key + s".

My solution was to hook to the keyboard event with SetWindowsHookEx. however the handle I get in return is always 0. when I call to GetLastWin32Error the value is also 0 (i.e. so it actually reports that the previous operation succeeded)

_hookHandle = SetWindowsHookEx(WH_KEYBOARD_LL, _hookFunction, _hinstance, 0);
if (_hookHandle == IntPtr.Zero)
 throw new Win32Exception(Marshal.GetLastWin32Error()); 

(It goes without saying that _hinstance has a valid value and so does _hookFunction)

Any Ideas? other solutions?

Thanks.

Answer 1

Try using this to get the HINSTANCE:

Marshal.GetHINSTANCE(Assembly.GetExecutingAssembly().GetModules()[0]);

Answer 2

If you only need is to handle specific key combination then it is better to use hotkeys. This shows how setup hotkeys: Hotkeys

Answer 3

Here is a good artical on low level keyboard hook in C#. This might have a couple of things you are missing.

Answer 4

I used this hokey code for my app to not only bring focus to the app with a hotkey, but also to launch the app with a hotkey. So just like you press Win+E to launch Windows Explorer, you could press Win+S to launch your applicaiton. Very useful.

http://code.google.com/p/blinkln/source/browse/trunk/HotKey.cs?r=12