Global Hotkeys With .NET

So, last year while working at Resolver Systems I worked with the author of Movable Python, which is a fairly neat application that lets you carry Python around on a USB stick. As an intellectual exercise I reimplemented the core functions in C# with a slightly less eccentric interface (no offence meant, Michael!), but was suprised to find I had to roll my own code to setup global hotkeys to run scripts, which was a nice feature of Movable I wanted to try and add.

The Win32 APIs for this are themselves are pretty grungy (all sorts of nastiness with bitflags and message loops), but I think I’ve been fairly successful in abstracting that away in this simple class, which you can get from here. With this, you can setup a hotkey like this:

Hotkey hk = new Hotkey();
hk.KeyCode = Keys.1;
hk.Windows = true;
hk.Pressed += delegate { Console.WriteLine(“Windows+1 pressed!”); };

if (!hk.GetCanRegister(myForm))
{ Console.WriteLine(“Whoops, looks like attempts to register will fail or throw an exception, show an error/visual user feedback”); }
else
{ hk.Register(myForm); }

// .. later, at some point
if (hk.Registered)
{ hk.Unregister(); }

Obviously this is a bit of a kitchen sink example to try and show every feature, but even then it’s a damn sight easier than what you would use to set up even a basic usage manually with P/Invoke. If you are wondering about the requirement for a form parameter to Register and GetCanRegister, this is simply a requirement of the underlying APIs, probably due to the fact that they signal hotkey presses in the application message loop rather than via a callback.

I hope someone finds this useful and to facilitate that process I hereby place all the code into the public domain to be messed around with to your hearts content. Enjoy!

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